introduction mehta engg

7/28/2019 Introduction Mehta Engg

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Introduction

Mehta Engineers Limited is family managed, professionally run

company, which started its operations in 1979 with vision of

becoming a supplier of quality auto parts for the Original Equipment

Manufacturers.

Mehta Engineers Limited is public limited company. Most of its shares

are closely held with 95% of the shareholding with the family.

In 1984, with the coming of major Japanese motorcycle companies in

India, there was a strong need of good quality parts suppliers. The

company became an automatic choice for these companies due to its

commitment to quality and on time delivery. Since then the company

is supplying to these two wheeler majors.

Our Commitment towards quality, timely delivery and competitive

pricing makes us the first choice of our customers.

Our Strength lies in highly skilled and motivated manpower, which is

the backbone of the company. Our manpower is a combination of

experienced managers, young and dedicated engineers and skilled

blue collared employees, who work as team to pursue company's

vision and goals. We have a record of excellent coordinal industrial

relation in our company since inception.

The company started exports in 2002 after passing stringent quality

standards of it's esteemed customers. Today, we export to leading

automotive companies in Europe

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Mission and Vision

>> Focus on stated and implied customer needs.

>> Become partners and not suppliers.

>> Keep abreast with new technology.

>> Continual human skill up gradation through regular trainings.

>> Improvement in quality and productivity through Kaizen.

>> Enhance company value through profitable growth.

Product Category

Machined Forgings

Sheet Metal Fabricated Components

Sheet Metal Stampings

Categories

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Machined Forgings

Quality System

We are an ISO/TS 16949 certified company. We have been regularly

getting orders from our customer on the strength of it's quality

products. Consistent quality and continual improvements help us in

customer satisfaction. We believe that only way to grow and succeed

is to make and supply consistently good quality products.

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During Component Development

Quality of component is ensured right from the development stage.

We follow all the guidelines of PPAP, FMEA, MSA and customer

specified requirements during the development of components and

their tools.

Regular record of quality are maintained which form basis for further

improvement and trainings to be given by Quality Assurance Team

Operators and inspectors are regularly trained on the importance of

quality and on

How to ensure consistent quality at all times. All the production

tooling and checking fixtures are fully checked before actual use. The

tools and gauges are regularly calibrated to ensure consistency.

During Process

The company has been following TQM

techniques to ensure 100% defect free

material at customer end.

Quality Control is done at three stages:

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>> Receiving Quality Control

>> In-Process Quality Control

>> Pre-delivery Quality Control

The finished products then pass through Pre-Delivery inspection

department, which ensure that no non-conforming components is

passed on the customer. We have latest equipment to check the

quality of the products and for calibration of measuring and test

equipment. The facilities include a Profile Projectors, Vickers

Hardness Testers, Rockwell Hardness Testers, Cupping test

machine, Coating thickness checking machine, salt spray chambers

and other regular calibration lab equipment.

The company has also access to facilities like metallurgical tests,

crack tests etc

Quality Policy

Mehta Engineers Limited is an ISO 9001 certified company certified

by TUV, Suddeutschland of Germany.

We at Mehta Engineers Limited are commited to manufacture

and supply automative components to achieve customer satisfaction.

We strive to continually improve the quality of our products,

processes and quality management system.

This can be achieved through

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>> Introducing new technology / equipment

>> Improving / enhancing knowledge of our employees

>> Reducing customer complaints

>> Reducing internal rejections & rework

>> Improving operational performance

Today the company is actively working towards achieving ISO/TS

16949:2002 certification.

Quality objective have been established at different levels and

functions and these are monitored regularly to ensure continual

improvements.

Research and Development

In today's world, every customer demands faster product

development. It means that the transition time from drawing to actual

sample has to be reduced.

New product development is a very strong area of the company. The

company has got highly skilled manpower in new component

development department. This coupled with the state of art machines

in development area reduces the lead time for development of new

components

Design Department

The company has complete facilities of CAD CAM. The design

facilities include 2D and 3D modeling with facilities of solid modeling,

reverse engineering and machining programming. The machines in

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development area are CNC Machining Centers, CNC Wire Cut,

Milling, Plano Miller, Shapers, Lathes, and grinders among other tool

room machines.

We can make drawings from the models given by the customers and

can develop accurate tooling for production at very fast pace.

In todays every customer demands faster product development.

It means that the transition time from drawing to actual sample has to

be reduced. We at Mehta Engineers follow a policy of

"Do it right the first time, every time". This is achieved by

continuous research and development activities to reduce the product

development time and ensuring that the product is developed

correctly in the very first attempt.

Our strength in tool designing help us in making correct sample and

tools in the very fast time and thus reducing the time for redesigning

and development. All the tools, jig, fixtures, checking gauges are

designed and made in-house which ensure timely development and

best quality.

VA & VE Activities

Our Development team works along with teams of our

customers helping in Value Addition and Value Engineering activities.

We also focus on cost cutting exercise through continuous research

and development activities on existing and new components.

Infrastructure

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The three unit of Mehta Engineers Limited are built in an area of

22,500 sq. meters. One of the biggest advantages that the company

enjoys is the wide variety of products from company. Apart from

production, the company has latest infrastructure for development,

inspection and testing, surface coating and other related

infrastructure.

Metal fabrication

Metal fabrication is a value added process that involves theconstruction of machines and structures from various raw materials.

A fab shop will bid on a job, usually based on the engineeringdrawings, and if awarded the contract will build the product.

Fabrication shops are employed by contractors, OEMs and VARs.Typical projects include; loose parts, structural frames for buildingsand heavy equipment, and hand railings and stairs for buildings.

Metal fabrication is the fabrication of metal by cutting, bending, andassembling processes:

Cutting is done by sawing, shearing, or chiseling (all with manual andpowered variants); torching with handheld torches (such as oxy-fuel torches or plasma torches); and via CNC cutters (using alaser, torch, or water jet).

Cutting process.

Cutting is a collection of processes wherein material is brought to aspecified geometry by removing excess material using various kindsof tooling to leave a finished part that meets specifications. The net

result of cutting is two products, the waste or excess material, and thefinished part. If this were a discussion of woodworking, the wastewould be sawdust and excess wood. In cutting metals the waste ischips or swarf and excess metal. These processes can be dividedinto chip producing cutting, generally known as machining. Burning orcutting with an oxyfuel torch is a welding process not machining.

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There are also miscellaneous specialty processes such as chemicalmilling.

Cutting is nearly fully represented by:

Chip producing processes most commonly known as machining Burning, a set of processes which cut by oxidizing a kerf to

separate pieces of metal Specialty processes

Drilling a hole in a metal part is the most common example of a chipproducing process. Using an oxy-fuel cutting torch to separate a plateof steel into smaller pieces is an example of burning. Chemical millingis an example of a specialty process that removes excess material by

the use of etching chemicals and masking chemicals.

There are many technologies available to cut metal, including:

Manual technologies: saw, chisel, shear or snips Machine technologies: turning, milling, drilling, grinding, sawing Welding/burning technologies: burning by laser, oxy-fuel

burning, and plasma Erosion technologies: by water jet or electric discharge.

Cutting fluid or coolant is used where there is significant friction andheat at the cutting interface between a cutter such as a drill or an endmill and the work piece. Coolant is generally introduced by a sprayacross the face of the tool and work piece to decrease friction andtemperature at the cutting tool/work piece interface to preventexcessive tool wear. In practice there are many methods of deliveringcoolant.

Grinding uses an abrasive process to remove material from theworkpiece. A grinding machine is a machine tool used for producing

very fine finishes, making very light cuts, or high precision formsusing an abrasive wheel as the cutting device. This wheel can bemade up of various sizes and types of stones, diamonds or inorganicmaterials.

The simplest grinder is a bench grinder or a hand-held angle grinder,for deburring parts or cutting metal with a zip-disc.

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Grinders have increased in size and complexity with advances in timeand technology. From the old days of a manual tool room grindersharpening end mills for a production shop, to today's 30000 RPMCNC auto-loading manufacturing cell producing jet turbines, grindingprocesses vary greatly.

Grinders need to be very rigid machines to produce the requiredfinish. Some grinders are even used to produce glass scales forpositioning CNC machine axis. The common rule is the machinesused to produce scales be 10 times more accurate than the machinesthe parts are produced for.

In the past grinders were used for finishing operations only becauseof limitations of tooling. Modern grinding wheel materials and the use

of industrial diamonds or other man-made coatings (cubic boronnitride) on wheel forms have allowed grinders to achieve excellentresults in production environments instead of being relegated to theback of the shop.

Modern technology has advanced grinding operations to include CNCcontrols, high material removal rates with high precision, lending itselfwell to aerospace applications and high volume production runs ofprecision components.

A file is an abrasive surface like this one that allows machinists toremove small, imprecise amounts of metal.Filing

Filing is combination of grinding and saw tooth cutting using a file.Prior to the development of modern machining equipment it provideda relatively accurate means for the production of small parts,especially those with flat surfaces. The skilled use of a file allowed amachinist to work to fine tolerances and was the hallmark of the craft.Today filing is rarely used as a production technique in industry,though it remains as a common method of deburring.

Broaching is a machining operation used to cut keyways into shafts.Electron beam machining (EBM) is a machining process where high-velocity electrons are directed toward a work piece, creating heat andvaporizing the material. Ultrasonic machining uses ultrasonicvibrations to machine very hard or brittle materials.

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Bending is done hammering (manual or powered) or via pressbrakes and similar tools.

Assembling (joining of the pieces) is done by welding, bindingwith adhesives, riveting, threaded fasteners, or even yet morebending in the form of a crimped seam. Structural steel andsheet metal are the usual starting materials for fabrication,along with the welding wire, flux, and fasteners that will join thecut pieces. As with other manufacturing processes, both humanlabor and automation are commonly used. The productresulting from fabrication may be called a fabrication. Shopsthat specialize in this type of metal work are called fab shops.The end products of other common types of metalworking, suchas machining, metal stamping, forging, and casting, may besimilar in shape and function, but those processes are not

classified as fabrication.

Fabrication comprises or overlaps with various metalworkingspecialties:

Fabrication shops and machine shops have overlappingcapabilities, but fabrication shops generally concentrate onmetal preparation and assembly as described above. Bycomparison, machine shops also cut metal, but they are moreconcerned with the machining of parts on machine tools. Firms

that encompass both fab work and machining are alsocommon.

Blacksmithing has always involved fabrication, although it wasnot always called by that name.

The products produced by welders, which are often referred toas weldments, are an example of fabrication.

Boilermakers originally specialized in boilers, leading to theirtrade's name, but the term as used today has a broadermeaning.

Similarly, millwrights originally specialized in setting up grainmills and saw mills, but today they may be called upon for abroad range of fabrication work.

Ironworkers, also known as steel erectors, also engage infabrication. Often the fabrications for structural work begin asprefabricated segments in a fab shop, then are moved to thesite by truck, rail, or barge, and finally are installed by erectors.

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Raw Materials

A raw material or feedstock is the basic material from which a productis manufactured or made, frequently used with an extended meaning.

Cutting and burning

The raw material has to be cut to size. This is done with a variety oftools.

The most common way to cut material is by Shearing (metalworking);

Special band saws designed for cutting metal have hardened bladesand a feed mechanism for even cutting. Abrasive cut-off saws, alsoknown as chop saws, are similar to miter saws but with a steel cuttingabrasive disk. Cutting torches can cut very large sections of steel withlittle effort.

Burn tables are CNC cutting torches, usually natural gas powered.Plasma and laser cutting tables, and Water jet cutters, are alsocommon. Plate steel is loaded on a table and the parts are cut out asprogrammed. The support table is made of a grid of bars that can bereplaced. Some very expensive burn tables also include CNC punchcapability, with a carousel of different punches and taps. Fabrication

of structural steel by plasma and laser cutting introduces robots tomove the cutting head in three dimensions around the material to becut.

Forming

Hydraulic brake presses with v-dies are the most common method offorming metal. The cut plate is placed in the press and a v-shaped dieis pressed a predetermined distance to bend the plate to the desiredangle. Wing brakes and hand powered brakes are sometimes used.

Tube bending machines have specially shaped dies and mandrels tobend tubular sections without kinking them.

Rolling machines are used to form plate steel into a round section.

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English Wheel or Wheeling Machines are used to form complexdouble curvature shapes using sheet metal.

Machining

Fab shops will generally have a limited machining capabilityincluding; metal lathes, mills, magnetic based drills along with otherportable metal working tools.

Welding

Welding is the main focus of steel fabrication. The formed andmachined parts will be assembled and tack welded into place then re-checked for accuracy. A fixture may be used to locate parts forwelding if multiple weldments have been ordered.

The welder then completes welding per the engineering drawings, ifwelding is detailed, or per his own judgment if no welding details areprovided.

Special precautions may be needed to prevent warping of theweldment due to heat. These may include re-designing the weldmentto use less weld, welding in a staggered fashion, using a stout fixture,covering the weldment in sand during cooling, and straightening

operations after welding.

Straightening of warped steel weldments is done with an Oxy-acetylene torch and is somewhat of an art. Heat is selectively appliedto the steel in a slow, linear sweep. The steel will have a netcontraction, upon cooling, in the direction of the sweep. A highlyskilled welder can remove significant warp age using this technique.

Steel weldments are occasionally annealed in a low temperatureoven to relieve residual stresses.

Final assembly

After the weldment has cooled it is generally sand blasted, primedand painted. Any additional manufacturing specified by the customeris then completed. The finished product is then inspected andshipped.

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Press Shop

Press Shops having a variety of

Hydraulic, Pneumatic and Mechanical

presses with a capacity ranging from 20

Tons to 400 Tons. The operations in the

press shop include shearing, blanking, stamping, piercing, bending,

forming, drawing, deep drawing, coining, flaring, embossing and

many other related operations.Types of Press

Hydraulic press

A hydraulic press is a machine using a hydraulic cylinderto

generate a compressive force. It uses the hydraulic equivalent of a

mechanical lever, and was also known as a Bramah press after the

inventor, Joseph Bramah, of England. He invented and was issued apatent on this press in 1795. As Bramah he studied the existing

literature on the motion of fluids and put this knowledge into the

development of the press.

Principle

The hydraulic press depends on Pascal's principle:

the pressure throughout a closed system is constant. One part of the

system is a piston acting as a pump, with a modest mechanical force

acting on a small cross-sectional area; the other part is a piston with

a larger area which generates a correspondingly large mechanical

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force. Only small-diametertubing (which more easily resists

pressure) is needed if the pump is separated from the press cylinder.

Pascal's law: Pressure on a confined fluid is transmitted undiminished

and acts with equal force on equal areas and at 90 degrees to the

container wall.

A fluid, such as oil, is displaced when either piston is pushed inward.

The small piston, for a given distance of movement, displaces a

smaller amount ofvolume than the large piston, which is proportional

to the ratio of areas of the heads of the pistons. Therefore, the small

piston must be moved a large distance to get the large piston to move

significantly. The distance the large piston will move is the distance

that the small piston is moved divided by the ratio of the areas of the

heads of the pistons. This is how energy, in the form ofwork in this

case, is conserved and the Law of Conservation of Energy is

satisfied. Work is force times distance, and since the force is

increased on the larger piston, the distance the force is applied over

must be decreased.

The pressurized fluid used, if not generated locally by a hand or

mechanically-powered pump, can be obtained by opening a valve

which is connected to a hydraulic accumulatoror a continuously-

running pump whose pressure is regulated by a relief valve. When it

is desired to generate more force than the available pressure would

allow, or use smaller, higher-pressure cylinders to save size and

weight, a hydraulic intensifiercan be used to increase the pressure

acting on the press cylinder.

When the pressure on the press cylinder is released (the fluid

returning to a reservoir), the force created in the press is reduced to a

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low value (which depends on the friction of the cylinder's seals. The

main piston does not retract to its original position unless an

additional mechanism is employed.

Servomechanism Press

A servomechanism press, also known as a servo press or a 'electro

press, is a press driven by anAC servo motor. The torque produced

is converted to a linearforce via a ball screw. Pressure and position

are controlled though a load cell and an encoder. The main

advantage of a servo press is its low energy consumption; its only 10-

20% of other press machines. Another advantage is a quiet and clean

work environment.

Mechanical Presses:

Mechanical presses has a mechanical flywheel to store the energy,

transfer it to the punch and to the work piece. They range in size from

20 tons up to 6000 tons. Strokes range from 5 to 500 mm (0.2 to 20

in) and speeds from 20 to 1500 strokes per minute. Mechanical

presses are well suited for high-speed blanking, shallow drawing and

for making precision parts.

Processes in Press Shop

Blanking and piercing

Blanking and piercing are shearing processes

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in which a punch and die are used to modify webs. The tooling and

processes are the same between the two,

only the terminology is different: in blanking the punched out piece is

used and called a blank; in piercing the punched out piece is scrap.

Blanking

Blanking is cutting up a large sheet of stock into smaller pieces

suitable for the next operation in stamping, such as drawing and

forming. Often this is

combined with piercing.

Blanking can be as simple as a cookie cutter type die to produce

prototype parts, or high speed dies that run at 1000+ strokes per

minute, running coil stock which has been slit to a specified width.

For production parts, the final configuration of the drawn or formed

shape needs to be established before the blank die can be built-since

the blank size and the slit width size needs to be established

precisely.

Piercing

Piercing is the operation of cutting internal features (holes or slots) in

stock. Piercing can also be combined with other operations such as

lance and form (to make a small feature such as tab), pierce and

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extrude (to make an extruded hole). All these operations can be

combined with blanking.

Piercing of all the holes is best done together to ensure good hole-to-

hole tolerance and part repeatability. However if the material distorts,

the method described below can be done.

When there are large numbers of holes, in a tight pitch, there could

be distortions, due to the high amount of tension on the upper surface

due to stretching and compression on the bottom surface. This

causes the material not to lay flat. This can be avoided/lessened by

staggering the piercing of the holes. Holes are punched in a

staggered pattern; then the other holes are punched in the alternate

staggered pattern.

Stamping

Stamping, is a forming process

that utilizes a series of stamping

stations to perform simultaneous

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operations on sheet metal. The final metal work piece is developed

as the strip of metal is processed through the stamping die.

The progressive die stamping process characteristics include:

The utilization of multiple cutting and/or forming operations

simultaneously,

Excellent suitability to produce small work pieces at a rapid

rate,

The necessity to invest in expensive die sets,

The ability to save time and money by combining forming

operations,

The capability to maintain close tolerances, depending on the

tools.

The illustration that follows provides a two-dimensional look at a

typical progressive die metal drawing process in two steps one

open die and one closed die.

As the metal strip is moved through the drawing process, it is

exposed to a series of progressive die stations, each one changing

the metal configuration left on the metal by the previous station.

Therefore, the metal workpiece is created in a series of stamping

stages.

Notching

Notching is a piercing operation that removes material from the edgeof the workpiece. Nibbling

The nibbling process cuts a contour by producing a series ofoverlapping slits or notches. This allows for complex shapes to beformed in sheet metal up to 6 mm (0.25 in) thick using simple tools.The nibbler is essentially a small punch and die that reciprocates

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quickly; around 300900 times per minute. Punches are available invarious shape and sizes; oblong and rectangular punches arecommon because they minimize waste and allow for greaterdistances between strokes, as compared to a round punch. Nibblingcan occur on the exterior or interior of the material, however interiorcuts require a hole to insert the tool.

The process is often used on parts that do not have quantities thatcan justify a dedicated blanking die. The edge smoothness isdetermined by the shape of the cutting die and the amount the cutsoverlap; naturally the more the cuts overlap the cleaner the edge. Foradded accuracy and smoothness most shapes created by nibblingundergo filing or grinding processes after completion.

Shaving

The shaving process is a finishing operation where a small amount ofmetal is sheared away from an already blanked part. Its mainpurpose is to obtain better dimensional accuracy, but secondarypurposes include squaring the edge and smoothing the edge.Blanked parts can be shaved to an accuracy of up to 0.025 mm(0.001 in).

Trimming

The trimming operation is the last operation performed because itcuts away excess or unwanted irregular features from the workpiece.

Cutoff

The cutoff process is used to separate a stamping or other productfrom a strip or stock. This operation is very common with progressivedie sequences. The cutoff operation often produces the peripherycounter to the workpiece

Bending

Bending is a process by which metal can be deformed by plastically

deforming the material and changing its shape. The material is

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stressed beyond the yield strength but below the ultimate tensile

strength. The surface area of the material does not change much.

Bending usually refers to deformation about one axis.

Bending is a flexible process by which many different shapes can be

produced. Standard die sets are used to produce a wide variety of

shapes. The material is placed on the die, and positioned in place

with stops and/or gages. It is held in place with hold-downs. The

upper part of the press, the ram with the appropriately shaped punch

descends and forms the v-shaped bend.

Bending is done using Press Brakes. Press Brakes normally have a

capacity of 20 to 200 tons to accommodate stock from 1m to 4.5m (3

feet to 15 feet). Larger and smaller presses are used for specialized

applications. Programmable back gages, and multiple die sets

available currently can make for a very economical process.

Types

There are three basic types of bending on a press brake, each isdefined by the relationship of the end tool position to the thickness ofthe material. These three are Air Bending,Bottoming and Coining. The configuration of the tools for these threetypes of bending is nearly identical. A die with a long rail form toolwitha radiused tip that locates the inside profile of the bend is called apunch. Punches are usually attached to the ram ofthe machine by clamps and move to produce the bending force. A

die with a long rail form tool that has concave or V shaped lengthwisechannel that locate the outside profile of the form is called a die. Dies

are usually stationary and located under the material on the bed ofthe machine. Note that some locations do not differentiate betweenthe two different kinds of dies (punches and dies.) The other types ofbending listed use specially designed tools or machines to performthe work.

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Air bending

This bending method forms material by pressing a punch (also calledthe upper or top die) into the material, forcing it into a bottom V-die,which is mounted on the press. The punch forms the bend so that thedistance between the punch and the side wall of the V is greater thanthe material thickness (T).

Either a V-shaped or square opening may be used in the bottom die(dies are frequently referred to as tools or tooling). A set of top andbottom dies are made for each product or part produced on the press.Because it requires less bend force, air bending tends to use smallertools than other methods.

Some of the newer bottom tools are adjustable, so, by using a singleset of top and bottom tools and varying press-stroke depth, differentprofiles and products can be produced. Different materials andthicknesses can be bent in varying bend angles, adding theadvantage of flexibility to air bending. There are also fewer toolchanges, thus, higher productivity.

A disadvantage of air bending is that, because the sheet does notstay in full contact with the dies, it is not as precise as some othermethods, and stroke depth must be kept very accurate. Variations in

the thickness of the material and wear on the tools can result indefects in parts produced.

Depending on material properties, the sheet may be overbended tocompensate for springback.

Air bending does not require the bottom tool to have the same radiusas the punch. Bend radius is determined by material elasticity ratherthan tool shape.

The flexibility and relatively low tonnage required by air bending arehelping to make it a popular choice. Quality problems associated withthis method are countered by angle-measuring systems, clamps andcrowning systems adjustable along the x and y axes, and wear-resistant tools.

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The K-Factor approximations given below are more likely to beaccurate for air bending than the other types of bending due to thelower forces involved in the forming process.

Bottoming

In bottoming, the sheet is forced against the V opening in the bottomtool. U-shaped openings cannot be used. Space is left between thesheet and the bottom of the V opening. The optimum width of the Vopening is 6 T (T stands for material thickness) for sheets about3 mm thick, up to about 12 T for 12 mm thick sheets. The bendingradius must be at least 0.8 T to 2 T for sheet steel. Larger bendradius require about the same force as larger radii in air bending,however, smaller radii require greater forceup to five times as much

than air bending. Advantages of bottoming include greateraccuracy and less springback. A disadvantage is that a different toolset is needed for each bend angle, sheet thickness, and material. Ingeneral, air bending is the preferred technique

Coining

In coining, the top tool forces the material into the bottom die with fiveto 30 times the force of air bending, causing permanent deformationthrough the sheet. There is little, if any, spring back. Coining can

produce an inside radius is as low as 0.4 T, with a 5 T width of the Vopening. While coining can attain high precision, higher costs meanthat it is not often used.

Three-point bending

Three-point bending is a newer process that uses a die with anadjustable-height bottom tool, moved by a servo motor. The heightcan be set within 0.01 mm. Adjustments between the ram and theupper tool are made using a hydraulic cushion, which accommodates

deviations in sheet thickness. Three-point bending can achieve bendangles with 0.25 deg. precision. While three-point bending permitshigh flexibility and precision, it also entails high costs and there arefewer tools readily available. It is being used mostly in high-valueniche markets.

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Bottoming or Coining is the bending process where the punch and

the work piece bottom on the die. This makes for a controlled angle

with very little spring back. The tonnage required on this type of press

is more than in air bending. The inner radius of the work piece should

be a minimum of 1 material thickness in the case of bottoming; and

upto 0.75 material thickness, in the case of coining.

Draw

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Drawing is a metalworking processwhich uses tensile forces to stretch metal. It is broken up into two

types: sheet metal drawing and wire, bar, and tube drawing.The specific definition for sheet metal drawing is that it involvesplastic deformation over a curved axis. For wire, bar, and tubedrawing the starting stock is drawn through a die to reduce itsdiameter and increase its length. Drawing is usually done atroom temperature, thus classified a cold working process,however it may be performed at elevated temperatures to hotwork large wires, rods or hollow sections in order to reduceforces.Sheet metal

The success of forming is in relation to two things, the flow andstretch of material. As a die forms a shape from a flat sheet of metal,

there is a need for the material to move into the shape of the die. Theflow of material is controlled through pressure applied to the blankand lubrication applied to the die or the blank. If the form moves tooeasily, wrinkles will occur in the part. To correct this, more pressureor less lubrication is applied to the blank to limit the flow of materialand cause the material to stretch or thin. If too much pressure isapplied, the part will become too thin and break. Drawing metal is thescience of finding the correct balance between wrinkles and breakingto achieve a successful part.

Deep draw

Sheet metal drawing becomes deep drawing when the workpiece isdrawing longer than its diameter. It is common that the workpiece isalso processed using other forming processes, such as piercing,ironing, necking, rolling, and beading.

Bar, tube & wire

Bar, tube, and wire drawing all work upon the same principle: thestarting stock drawn through a die to reduce the diameter andincrease the length. Usually the die is mounted on a draw bench. Theend of the work piece is reduced or pointed to get the end through thedie. The end is then placed in grips and the rest of the workpiece ispulled through the die. Steels, copper alloys, and aluminum alloys arecommon materials that are drawn.

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Drawing can also be used to produce a cold formed shaped cross-section. Cold drawn cross-sections are more precise and have abetter surface finish than hot extruded parts. Inexpensive materialscan be used instead of expensive alloys for strength requirements,due to work hardening.

Bar drawing

Bars or rods that are drawn cannot be coiled therefore straight-pulldraw benches are used. Chain drives are used to draw work piecesup to 30 m (98 ft). Hydraulic cylinders are used for shorter lengthwork pieces.

The reduction in area is usually restricted to 20 to 50%, because

greater reductions would exceed the tensile strength of the material,depending on its ductility. To achieve a certain size or shape multiplepasses through progressively smaller dies or intermediate annealsmay be required.

Tube drawing

Tube drawing is very similar to bar drawing, except the beginningstock is a tube. It is used to decrease the diameter, improve surfacefinish and improve dimensional accuracy. A mandrel may or may not

be used depending on the specific process used.

Wire drawing

This technique has long been used to produce flexible metal wire bydrawing the material through a series of dies of decreasing size.These dies are manufactured from a number of materials, the mostcommon being tungsten carbide and diamond

Notching

Notching is a metal-cutting process used on sheet metal or thin barstock, sometimes on angle sections or tube. A shearing or punchingprocess is used in a press, so as to cut vertically down andperpendicular to the surface, working from the edge of a workpiece.Sometimes the goal is merely the notch itself, but usually this is aprecursor to some other process: such as bending a corner in sheet

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or joining two tubes at a tee joint, notching one to fit closely to theother.

Notching is a low-cost process, particularly for its low tooling costswith a small range of standard punches. The capital cost of the punchpress can be expensive though, so small fabrication shops often out-source their notching work to a press shop or notching specialist.Notching of large or heavy sections, particularly for large tubefabrication or HVAC, is increasingly carried out by plasma cuttingrather than punch tools.

The accuracy of punch notching is good, depending on the care withwhich it's carried out. For manual folding work, prior notching canoften improve resultant accuracy of the folding itself.

The speed of notching is usually limited by manual handling whenloading the work pieces into the press. Pieces some feet long may bemanually loaded into a single-stroke press. Smaller pieces are stillgenerally hand-fed, limiting speeds to perhaps 100 strokes / minute.

Almost any workable metal can be notched. It's particularly suitablewhere the metal is otherwise awkward to drill, such as stainlesssteels, titanium or previously heat-treated aluminum alloys.

Tube notchingTube notching is commonly performedbefore joining light-gauge tubes to makea tee or similar joint, as by welding.Either one or both tubes may be notchedbefore assembly. A familiar example oftube notching is in the manufacture ofbicycle frames.

End notching works the end of the tube, such as a semicircularconcavity to make the base of a tee, or a convex vee to fit into amitre.

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Side notching (also called offsetnotching) works the side of a tube with avee notch for bending, semicircular orvee notches for tee joint.

Tube being hollow, it's not practical touse a simple punch operation to notch it, as it would be squashed.

Although punching is possible, it requires support mandrels andawkward handling. Where tube is worked with a punch press otherthan for side notching, this is generally described as slotting.

Tube notching for fabrication of circular tube is thus most commonlydone with a rotary hole saw in which a hole saw of the diameter of thetube being attached to is fed into the stock to be notched at a semi-

perpendicular angle. This produces a semi-circular notch. Ratherthan using large presses, such saw notching may simple jig, alsomaking it suitable for on-site working.

A much more accurate way of notching the end of tube stock is to usea specially made milling cutter called an end mill. The stock to benotched is clamped into a vise and can then be fed slowly andaccurately into a rotating, hardened metal, end mill. The equipmentrequired for this method is considerably more expensive than the holesaw method and does not lend well to the same portability of the hole

saw method as the machine is usually bolted to the floor for stabilityand safety reasons. This method of end notching is much faster andthus greatly minimizes the chance of damaging the stock either bywarping due to heat build up or by squashing as can still happen witha hole saw.

Notching in thin-wall tube may also be carried out by abrasive tools,reducing some of the risk of damage from a hole saw snatching. Thisalso allows more complex shapes to be performed, such as veenotches. In some cases, a helical end mill cutter may be used.

Computer numerical control (CNC) notching is enabling designers towork with more complex geometries

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Notch and bend

Vee notches in tube, particularly square tube, may be cut so deep asto cut almost through the tube: three sides of a square tube. This thenallows the tube to be bent into a mitred corner, usually finished bywelding.

On a smaller scale for jewellery making, this operation is performedby hand-filing precious-metal strip before bending and soldering tomake box frames or stone mounts.

EmbossingSheet metal embossing is a process for producing raised or sunkendesigns or relief in sheet metal. This process can be made by means

of matched male and female roller dies, or by passing sheet or a stripof metal between rolls of the desired pattern.

The metal sheet embossing operation is commonly accomplishedwith a combination of heat and pressure on the sheet metaldepending on what type of embossing is required. Theoretically, withany of these procedures, the metal thickness has changed in itscomposition.

Metal sheet is drawn through the male and female roller dies

producing a pattern or design on the metal sheet. Depending on theroller dies used, different patterns can be produced on the metalsheet. This pressure and a combination of heat actually "irons" whileraising the level of the image higher than the substrate to make itsmooth. The term "impressing" enables one to distinguish an imagelowered into the surface of a material, in distinction to an imageraised out of the surface of a material

In most of the pressure embossing operation machines, the upper rollblocks are stationary, while the bottom roll blocks are movable. The

pressure with which the bottom roll is raised is referred to as thetonnage capacity.

Embossing machines are generally sized to give 2" of strip clearanceon each side of an engraved embossing roll. Many embossingmachines are custom-manufactured, so there are no industry-standard widths. It is not uncommon to find embossing machines in

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operation producing patterns less than 6" wide all the way up tomachines producing patterns 70"+ wide.

Characteristics

The ability to form ductile metals Use in medium to high production runs The ability to maintain the same metal thickness before and

after embossing The ability to produce unlimited patterns, depending on the roll

dies The ability to reproduce product with no variation

Welding Shop

Welding Shop infrastructure

includes MIG Welding, Spot Welding,

Projection Welding and brazing

machines. Apart from highly skilled

manpower, the company has got a

Special Purpose Machine and Welding

ROBOT leading to automation in

Welding. Welding has now become a specialization at the company

with high quality Welding and Welded components. Welding shop

infrastructure includes MIG Welding, Spot Welding, Projection

Welding and brazing machines. Apart from highly skilled manpower,

the company has got a host of Special Purpose Machines and

Welding Robot leading to automation in Welding. Welding has now

become a specialization at the company with high quality Welding

and Welded components.

Welding is the process of permanently joining two or more metal

parts, by melting both materials. The molten materials quickly cool,

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and the two metals are permanently bonded. Spot welding and seam

welding are two very popular methods used for sheet metal parts.

Spot welding is primarily used for joining parts that normally upto 3

mm (0.125 in) thickness.

Spot-weld diameters range from 3 mm to 12.5 mm (0.125 to 0.5 in) in

diameter

Types of Welding

Welding permanently joins materials together without using fittings.

There are three basic types of welding methods: TIG welding, MIG

welding and stick welding. Most methods of welding employ shielding

gases to improve weld quality and smoothness of the weld. They also

prevent weld point contamination as well as stabilize the arc of

electricity between the welding electrode and the workload. Each

method offers advantages and disadvantages.

Arc Welding

Stick welding, also known as

shielded metal arc welding, was

one of the earliest methods of

welding. Stick welding is

frequently used outdoors

because rain and wind will not

affect weld quality. Stick

welding is used on piping and

bridges as well as to fix tractors and create art. A workload does not

even need to be clean for using this method of welding. However, many

stick welding electrodes don't penetrate the material very deeply. Also,

only a few inches of welds can be made before an electrode needs

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replacing. Stick welding requires a very high level of skill to produce

quality welds.

MIG Welding

MIG welding (gas metal arc welding) is most often used with steel. MIG

welders do not have to start and stop

too often while welding, which allows

for long, uninterrupted welds. This

method of welding is relatively clean,

creating only a little spatter while

welds are made. Drawbacks linked

with MIG welding include the

possibility of excessive melt-through

and incomplete joint penetration or fusion. Sometimes, it can be difficult

to create a starting arc in MIG welding. MIG welds are known to leave

deposits that are heavily oxidized.

TIG Welding

TIG welding (gas tungsten arc

welding) is often employed to make

welds on nickel alloys, magnesium,

aluminum, titanium and copper

alloys. TIG welds can be made with

or without metal fillers, unlike MIG

welding, which exclusively employs

filler metals to create welds. TIG

welding pinpoints heat better than MIG welding, allowing for smaller,

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more precise welding. However, TIG welds can take longer to complete

than MIG welds. In addition, TIG welding is a very clean process,

creating no spatter whatsoever while a weld is being made.

Despite the many benefits of TIG welding, there are a number of

drawbacks similar to the drawbacks linked with MIG welding. They

include excessive melt-through, incomplete fusion or joint

penetration, and difficulty in producing a starting arc.

Gas welding

Definition

Metal joining process in which the ends

of pieces to be joined are heated at

theirinterface by producing coalescenc

e with one or more gas flames (such as

oxygen and acetylene), with or without

the use of a filler metal.

In gas welding, the heat to produce

fusion of the parent metal and filler rod is provided by burning a

suitable gas in oxygen or air. A number of gases can be used but

acetylene is the most popular, since it burns in oxygen and gives a

high flame temperature of 3100o - 3200o. C. . Oxygen and acetylene

stored in cylinders under pressure are passed through flexible tubes

to the torch, which is either hand-operated or mechanically

manipulated. By adjusting the proportions of oxygen or acetylene

the flame can be neutral, or have either reducing or oxidizing

properties. For most materials a neutral flame is used but, for

welding high carbon steel, or aluminum and its alloys an oxidizing

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flame is used as, by these means, the volatilization of the zinc is

suppressed.

The capital cost of oxyacetylene equipment is low compare with that

for arc welding. The equipment is also easily portable and the

process is very versatile. However, its comparative slowness

means that it is more expensive than arc welding if there is a

considerable amount of welding to be done.

Oxyacetylene welding requires the following equipment.

1) A cylinder of oxygen (full pressure about 15MPa)

2) a cylinder of acetylene (full pressure about 1,7

3) Pressure regulator valves for each cylinder

4) Hoses to transfer gas flow to torch.

5) Welding torch with various sizes of torch tips

The gas pressures at the torch are each regulated to be about 7 to 70

kPa.

Spot welding

Spot welding is a process in which

contacting metal surfaces are joined by

the heat obtained from resistance to

electric current flow. Work-pieces are

held together under pressure exerted

by electrodes. Typically the sheets are

in the 0.5 to 3 mm (0.020 to 0.12 in)

thickness range. The process uses two

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shaped copperalloyelectrodes to concentrate welding current into a

small "spot" and to simultaneously clamp the sheets together. Forcing

a large current through the spot will melt the metal and form the weld.

The attractive feature of spot welding is a lot of energy can be

delivered to the spot in a very short time (approximately ten

milliseconds). That permits the welding to occur without excessive

heating to the rest of the sheet.

The amount of heat (energy) delivered to the spot is determined by

the resistance between the electrodes and the amperage and

duration of the current. The amount of energy is chosen to match the

sheet's material properties, its thickness, and type of electrodes.

Applying too little energy won't melt the metal or will make a poor

weld. Applying too much energy will melt too much metal, eject

molten material, and make a hole rather than a weld. [4] Another

attractive feature of spot welding is the energy delivered to the spot

can be controlled to produce reliable welds.

Projection welding

Projection welding is a modification of spot welding. In this process

the weld is localized by means of raised sections, or projections, on

one or both of the work pieces to be joined. Heat is concentrated at

the projections, which permits the welding of heavier sections or the

closer spacing of welds. The projections can also serve as a means

of positioning the work pieces. Projection welding is often used to

weld studs, nuts, and other screw machine parts to metal plate. It's

also frequently used to join crossed wires and bars. This is another

high-production process, and multiple projection welds can be

arranged by suitable designing and jigging

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Machine Shop

The Machining Shops at the company have a host of precision

machines required for the high quality components produced. The

machines include CNC, automatic, semi automatic and manual

machine.

The machining facilities include Gear Hobbing, Milling, Broaching,

Rolling, Tapping, Turning, Centreless Grinding, Cylindrical Grinding

and other regular machines

Gear Hobbing

Hobbing is a machining process

for making gears, splines,

and sprockets on a hobbing

machine, which is a special type

ofmilling machine. The teeth or

splines are progressively cut into

the workpiece by a series of cuts made by a cutting tool called a hob.

Compared to other gear forming processes it is relatively inexpensive

but still quite accurate, thus it is used for a broad range of parts and

quantities. It is the most widely used gear cutting process for creating

spur and helical gears and more gears are cut by hobbing than any

other process since it is relatively quick and inexpensive

Milling

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Milling is the most common form of machining,

a material removal process, which can create

a variety of features on a part by cutting away

the unwanted material. The milling process

requires a milling machine, work piece, fixture,

and cutter. The work piece is a piece of pre-

shaped material that is secured to the fixture, which itself is attached

to a platform inside the milling machine. The cutter is a cutting tool

with sharp teeth that is also secured in the milling machine and

rotates at high speeds. By feeding the work piece into the rotating

cutter, material is cut away from this work piece in the form of small

chips to create the desired shape.

Milling is typically used to produce parts that are not axially symmetric

and have many features, such as holes, slots, pockets, and even

three dimensional surface contours. Parts that are fabricated

completely through milling often include components that are used in

limited quantities, perhaps for prototypes, such as custom designed

fasteners or brackets. Another application of milling is the fabrication

of tooling for other processes. For example, three-dimensional molds

are typically milled. Milling is also commonly used as a secondary

process to add or refine features on parts that were manufactured

using a different process. Due to the high tolerances and surface

finishes that milling can offer, it is ideal for adding precision features

to a part whose basic shape has already been formed.

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Broaching

Broaching is a machining process that

uses a toothed tool, called a broach, to

remove material. There are two main

types of broaching: linear and rotary. In

linear broaching, which is the more

common process, the broach is run linearly against a surface of the

work piece to effect the cut. Linear broaches are used in a broaching

machine, which is also sometimes shortened to broach. In rotary

broaching, the broach is rotated and pressed into the work piece tocut an axis symmetric shape. A rotary broach is used in

a lathe orscrew machine. In both processes the cut is performed in

one pass of the broach, which makes it very efficient.

Broaching is used when precision machining is required, especially

for odd shapes. Commonly machined surfaces include circular and

non-circular holes, splines, keyways, and flat surfaces. Typical work

pieces include small to medium sized castings, forgings, screw

machine parts, and stampings. Even though broaches can be

expensive, broaching is usually favored over other processes when

used for high-quantity production runs.[1]

Broaches are shaped similar to a saw, except the teeth height

increases over the length of the tool. Moreover, the broach contains

three distinct sections: one for roughing, another for semi-finishing,

and the final one for finishing. Broaching is an unusual machining

process because it has the feed built into the tool. The profile of the

machined surface is always the inverse of the profile of the broach.

The rise per tooth (RPT), also known as the step or feed per tooth,

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determines the amount of material removed and the size of the chip.

The broach can be moved relative to the workpiece or vice-versa.

Because all of the features are built into the broach no complex

motion or skilled labor is required to use it.[2] A broach is effectively a

collection ofsingle-point cutting tools arrayed in sequence, cutting

one after the other; its cut is analogous to multiple passes of

a shaper.

Rolling

In metalworking, rolling is a metal forming process in which metal

stock is passed through a pair of rolls. Rolling is classified accordingto the temperature of the metal rolled. If the temperature of the metal

is above its recrystallization temperature, then the process is termed

as hot rolling. If the temperature of the metal is below its

recrystallization temperature, the process is termed as cold rolling.

In terms of usage, hot rolling processes more tonnage than any other

manufacturing process and cold rolling processes the most tonnage

out of all cold working processes.[1][2]

There are many types of, ring rolling, roll bending, roll forming, profile

rolling, and controlled rolling.

Tapping & Threading

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Taps

A tap cuts a thread on the inside surface of a hole, creating a female

surface which functions like a nut. There are three basic types of tap

commonly used in the shop:

Bottoming Tap: has a continuous cutting edge with no taper.

This feature enables a bottoming tap to cut threads to the bottom

of a blind hole. A bottoming tap is never used to cut threads in

an unthreaded hole, as the cutting edges lack the taper required

to successfully start into such a hole.

Plug Tap: Also known as an intermediate tap, it has tapered

cutting edges, which assist in aligning and starting the tap into

an untapped hole. Plug taps are the most commonly used type

of tap in the shop and can be found out on the shop floor in

various sizes at all times.

Taper Tap: very similar to a plug tap but has a more

pronounced taper to the cutting edges. This feature gives the

taper tap a very gradual cutting action that is less aggressive

than that of the plug tap. A taper tap is most often used when the

material to be tapped is difficult to work (e.g., alloy steel) or the

tap is of a very small diameter and thus prone to breakage.

The taps used in the shop are all hand taps, since they are, by

design, intended to be manually operated. During operation, it is

necessary with a hand tap to periodically reverse rotation to break the

chip formed during the cutting process, thus preventing an effect

called "crowding" that may cause tap breakage.

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Threads can be either cut with a tap and/or die (see above) or chased

manually. In order to cut your own threads, internal or external, it's

important to know both the major and minor diameter of the threads

you want to cut.

Turning

Turning is a form of machining, a

material removal process, which is

used to create rotational parts by

cutting away unwanted material. The

turning process requires a turning

machine or lathe, workpiece, fixture,

and cutting tool. The workpiece is a

piece of pre-shaped material that is secured to the fixture, which itself

is attached to the turning machine, and allowed to rotate at high

speeds. The cutter is typically a single-point cutting tool that is also

secured in the machine, although some operations make use of multi-

point tools. The cutting tool feeds into the rotating workpiece and cuts

away material in the form of small chips to create the desired shape.

Turning is used to produce rotational, typically axi-symmetric, parts

that have many features, such as holes, grooves, threads, tapers,

various diameter steps, and even contoured surfaces. Parts that are

fabricated completely through turning often include components that

are used in limited quantities, perhaps for prototypes, such as custom

designed shafts and fasteners. Turning is also commonly used as a

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secondary process to add or refine features on parts that were

manufactured using a different process. Due to the high tolerances

and surface finishes that turning can offer, it is ideal for adding

precision rotational features to a part whose basic shape has already

been formed.

Grinding process

For material removal, the method used in grinding is called abrasion.

In other words, in grinding, an abrasive material rubs against the

metal part and clears or removes tiny pieces of material. The process

implies that instead of cutting like a lathe bit, the material is slowly

and steadily worn away. This is because compared to the material

being ground, the abrasive is harder. The grinding wheel actually acts

like many hundreds of very small lathe bit, each cutting off some

metal. The abrasive must be strong enough to bear any kind of forces

acting upon it while grinding. Usually some sort of impact shock

occurs when the abrasive comes in contact with the material.

Grinding abrades material in a way similar to sanding. The grinding

operation is performed on a several machines like the lathe and the

mill, with the appropriate add-on accessories, the most important of

which is the spindle.

Why grinding is necessary?

Grinding is necessary for the following reasons:

The material is too hard to be machined economically.

If the surface is adequately supported, grinding can produce

flatness tolerances of less than 0.0001 in. (0.0025 mm) on a

5 x 5 in. (127 x 127 mm) steel surface.

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Machining removes excessive material.

Grinding should be used when size tolerance specifications are

Beyond the capability of turning.

It is also applied if the requirements of surface finish are too

Tight for hard turning.

Types of grinding

Grinding can be of various types, like as follows:

Surface grinding

Centered grinding

Centerless grinding

Contour grinding

Surface grinding

This is perhaps the most fundamental of operations. Surface grinding

is the process of providing precision ground surfaces either to a

critical size or for the surface finish. In other words, it accurately

processes or grounds a surface. Parts require surface grinding for

various reasons like:

Produce a flat surface.

For specifying accurate tolerance thickness.

A very smooth surface roughness is required.

For sharpening of cutting tool.

Centered grinding

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In this type of grinding, the grinding is performed at the center. There

are two types of centered grinding-OD grinding and ID grinding. In

Outside Diameter (OD) grinding , the work piece has center drilled

ends, accommodating center points and surface is removed by

rotating the grinder's face plate. With OD grinding the work piece and

the grinding wheel moves or rotates in clockwise directions. Inside

Diameter (ID) grinding is performed on tubular parts that are

generally held in a chuck or collet. The grinding wheel turns at very

high speed to maintain the proper surface speed but it moves

anticlockwise.

Centerless grinding

Centerless grinding is a method of material removal through grinding,

similar to centered grinding except for the absence of the spindle. It

has high throughput, i.e., a large number of parts can be

manufactured in a short time.

The work piece is set up between the regulating wheel (or back up

wheel) and the grinding wheel, and is supported by the work blade or

work rest. The work rest is located between the wheels. The work is

placed on the work rest, and the latter together with the regulating

wheel is fed forward forcing the work against the grinding wheel. Axial

movement of the work past the grinding wheel is accomplished by

tilting the regulating wheel at a slight angle from horizontal. An

angular adjustment of 0 to 8 or 10 degrees is provided in the machine

for this purpose.

Centerless grinding is classified into two types:

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Through feed grinding - the work piece is fed into the machine

along the work blade

Plunge grinding - the work piece is placed between the wheels

on a work blade and the grinding wheel is plunged into the work

piece.

Some of the benefits of

centerless grinding include the

ability to grind parts with

geometries that do not allow

them to be OD ground, the

ability to remove three, five and

other odd numbered lobbing on

the shaft of a part, and to

maintain size beyond what is

typically capable of an OD grinder due to the low overall pressures

spaced out along the work piece.

Standard Room

Coordinate Measuring MachineA coordinate measuring machine is a 3D device for measuring the

physical geometrical characteristics of an object. This machine maybe manually controlled by an operator or it may be computercontrolled. Measurements are defined by a probe attached to the

third moving axis of this machine. Probes may be mechanical, optical,laser, or white light, amongst others. or a machine which takesreading in six degree of freedom and give reading in mathamaticalform is known as cmm.

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Description

The typical 3 "bridge" CMM is composed of three axes, an X, Y andZ. These axes are orthogonal to each other in a typical threedimensional coordinate system. Each axis has a scale system thatindicates the location of that axis. The machine will read the inputfrom the touch probe, as directed by the operator or programmer. Themachine then uses the X,Y,Z coordinates of each of these points todetermine size and position with micrometre precision typically.

A coordinate measuring machine (CMM) is also a device used inmanufacturing and assembly processes to test a part or assemblyagainst the design intent. By precisely recording the X, Y, and Zcoordinates of the target, points are generated which can then be

analyzed via regression algorithms for the construction of features.These points are collected by using a probe that is positionedmanually by an operator or automatically via Direct Computer Control(DCC). DCC CMMs can be programmed to repeatedly measureidentical parts, thus a CMM is a specialized form of industrial robot.

Parts

Coordinate-measuring machines include three main components:

The main structure which include three axes of motion Probing system Data collection and reduction system - typically includes a

machine controller, desktop computer and application software.

Uses

They are often used for:

Dimensional measurement

Pr DMIS standard

The machines are available in a wide range of sizes and designs witha variety of different probe technologies. They can be operatedmanually or automatically through Direct Computer Control (DCC).They are offered in various configurations such as benchtop, free-standing, handheld and portable.

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Specific parts

Machine body

The first CMM was developed by the Ferranti Company of Scotland in

the 1950s as the result of a direct need to measure precisioncomponents in their military products, although this machine only had2 axes. The first 3-axis models began appearing in the 1960s (DEA ofItaly) and computer control debuted in the early 1970s (Sheffield ofthe USA). Leitz Germany subsequently produced a fixed machinestructure with moving table.

In modern machines, the gantry type superstructure has two legs andis often called a bridge. This moves freely along the granite table withone leg (often referred to as the inside leg) following a guide railattached to one side of the granite table. The opposite leg (oftenoutside leg) simply rests on the granite table following the verticalsurface contour. Air bearings are the chosen method for ensuringfriction free travel. In these, compressed air is forced through a seriesof very small holes in a flat bearing surface to provide a smooth butcontrolled air cushion on which the CMM can move in a frictionlessmanner. The movement of the bridge or gantry along the granite tableforms one axis of the XY plane. The bridge of the gantry contains acarriage which traverses between the inside and outside legs and

forms the other X or Y horizontal axis. The third axis of movement (Zaxis) is provided by the addition of a vertical quill or spindle whichmoves up and down through the center of the carriage. The touchprobe forms the sensing device on the end of the quill. Themovement of the X, Y and Z axes fully describes the measuringenvelope. Optional rotary tables can be used to enhance theapproachability of the measuring probe to complicated workpieces.The rotary table as a fourth drive axis does not enhance themeasuring dimensions, which remain 3D, but it does provide adegree of flexibility. Some touch probes are themselves poweredrotary devices with the probe tip able to swivel vertically through 90degrees and through a full 360 degree rotation.

As well as the traditional three axis machines (as pictured above),CMMs are now also available in a variety of other forms. Theseinclude CMM arms that use angular measurements taken at the joints

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of the arm to calculate the position of the stylus tip. Such arm CMMsare often used where their portability is an advantage over traditionalfixed bed CMMs. Because CMM arms imitate the flexibility of ahuman arm they are also often able to reach the insides of complexparts that could not be probed using a standard three axis machine.

Mechanical probe

In the early days of coordinate measurement mechanical probeswere fitted into a special holder on the end of the quill. A verycommon probe was made by soldering a hard ball to the end of ashaft. This was ideal for measuring a whole range of flat, cylindrical orspherical surfaces. Other probes were ground to specific shapes, forexample a quadrant, to enable measurement of special features.

These probes were physically held against the workpiece with theposition in space being read from a 3-Axis digitalreadout (DRO) or, in more advanced systems,being logged into a computer by means of afootswitch or similar device. Measurements takenby this contact method were often unreliable asmachines were moved by hand and eachmachine operator applied different amounts ofpressure on the probe or adopted differingtechniques for the measurement

A further development was the addition of motorsfor driving each axis. Operators no longer had tophysically touch the machine but could driveeach axis using a handbox with joysticks in muchthe same way as with modern remote controlledcars. Measurement accuracy and precision improved dramaticallywith the invention of the electronic touch trigger probe. The pioneer ofthis new probe device was David McMurtry who subsequently formed

what is now Renishaw plc. Although still a contact device, the probehad a spring-loaded steel ball (later ruby ball) stylus. As the probetouched the surface of the component the stylus deflected andsimultaneously sent the X.Y,Z coordinate information to thecomputer. Measurement errors caused by individual operatorsbecame fewer and the stage was set for the introduction of CNCoperations and the coming of age of CMMs.

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Motorised automated probe head with electronic touch trigger probe

Optical probes are lens-CCD-systems, which are moved like themechanical ones, and are aimed at the point of interest, instead oftouching the material. The captured image of the surface will beenclosed in the borders of a measuring window, until the residue isadequate to contrast between black and white zones. The dividingcurve can be calculated to a point, which is the wanted measuringpoint in space. The horizontal information on the CCD is 2D (XY) andthe vertical position is the position of the complete probing system onthe stand Z-drive (or other device component). This allows entire 3D-probing.

New Probing Systems

There are newer models that have probes that drag along the surfaceof the part taking points at specified intervals, known as scanningprobes. This method of CMM inspection is often more accurate thanthe conventional touch-probe method and most times faster as well.

The next generation of scanning, known as non-contact scanningincludes high speed laser single point triangulation, laser linescanning, and white light scanning, is advancing very quickly. Thismethod uses either laser beams or white light that are projected

against the surface of the part. Many thousands of points can then betaken and used to not only check size and position, but to create a 3Dimage of the part as well. This "point-cloud data" can then betransferred to CAD software to create a working 3D model of the part.These optical scanners often used on soft or delicate parts or tofacilitate reverse engineering.

Micro metrology Probes:

Probing systems for micro scale metrology applications are another

emerging area There are several commercially available coordinatemeasuring machines (CMM) that have a microprobe integrated intothe system, several specialty systems at government laboratories,and any number of university built metrology platforms for microscalemetrology. Although these machines are good and in many casesexcellent metrology platforms with nanometric scales their primarylimitation is a reliable, robust, capable micro/nano probe. Challenges

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for microscale probing technologies include the need for a highaspect ratio probe giving the ability to access deep, narrow featureswith low contact forces so as to not damage the surface and highprecision (nanometer level).Additionally microscale probes aresusceptible to environmental conditions such as humidity and surfaceinteractions such as stiction (caused by adhesion, meniscus, and/orVan der Waals forces among others).

Technologies to achieve microscale probing include scaled downversion of classical CMM probes, optical probes, and a standingwave probe among others. However, current optical technologiescannot be scaled small enough to measure deep, narrow feature, andoptical resolution is limited by the wavelength of light. X-ray imagingprovides a picture of the feature but no traceable metrology

information.

Physical Principles:

Optical probes and/or laser probes can be used (if possible incombination), which change CMMs to measuring microscopes ormulti-sensor measuring machines. Fringe projection systems,theodolite triangulation systems or laser distant and triangulationsystems are not called measuring machines, but the measuring resultis the same: a space point. Laser probes are used to detect the

distance between the surface and the reference point on the end ofthe kinematic chain (i.e.: end of the Z-drive component). This can usean interferometrical function, focus variation, light deflection or a halfbeam shadowing principle.

Portable Coordinate Measuring Machines

Portable CMMs are different from "traditional CMMs" in that theymost commonly take the form of an articulated arm. These arms havesix or seven rotary axes with rotary encoders, instead of linear axes.Portable arms are lightweight (typically less than 20 pounds) and canbe carried and used nearly anywhere. The inherent trade-offs of aportable CMM are manual operation (always requires a human to useit), and overall accuracy is somewhat to much less accurate than abridge type CMM. Certain non-repetitive applications such as reverse

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engineering, rapid prototyping, and large-scale inspection of low-volume parts are ideally suited for portable CMMs.

Multi-Sensor Measuring Machines

Traditional CMM technology using touch probes is today oftencombined with other measurement technology. This includes laser,video or white light sensors to provide what is known as multi-sensormeasurement.

Radius Gauge

A radius gauge, also known as a fillet gauge, is a tool used tomeasure the radius of an object.

Radius gauges require a bright light behind the object to bemeasured. The gauge is placed against the edge to be checked andany light leakage between the blade and edge indicates a mismatchthat requires correction.

A good set of gauges will offer both convex and concave sections,and allow for their application in awkward locations.

Calliper

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A caliper (British spelling also calliper, in technical and formal use apair of callipers) is a device used to measure the distance betweentwo opposing sides of an object. A caliper can be as simple as acompass with inward or outward-facing points. The tips of the caliperare adjusted to fit across the points to be measured, the caliper isthen removed and the distance read by measuring between the tipswith a measuring tool, such as a ruler.

It is used in many fields such as mechanical engineering,metalworking, woodworking, science and medicine.

Types

Inside caliper

The inside calipers are used to measurethe internal size of an object.

The upper caliper in the image (atthe right) requires manualadjustment prior to fitting, finesetting of this caliper type is performed by tapping the caliperlegs lightly on a handy surface until they will almost pass over

the object. A light push against the resistance of the centralpivot screw then spreads the legs to the correct dimension andprovides the required, consistent feel that ensures a repeatablemeasurement.

The lower caliper in the image has an adjusting screw thatpermits it to be carefully adjusted without removal of the toolfrom the workpiece.

Outside caliper

Outside calipers are used to measure theexternal size of an object.

The same observations and techniqueapply to this type of caliper, as for theabove inside caliper. With someunderstanding of their limitations and usage these instruments can

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provide a high degree of accuracy and repeatability. They areespecially useful when measuring over very large distances, considerif the calipers are used to measure a large diameter pipe. A verniercaliper does not have the depth capacity to straddle this largediameter while at the same time reach the outermost points of thepipe's diameter.

Divider caliper

In the metalworking field divider calipersare used in the process of marking outsuitable workpieces. The points aresharpened so that they act as scribers,one leg can then be placed in the dimple created by a center or prick

punch and the other leg pivoted so that it scribes a line on theworkpiece's surface, thus forming an arc or circle.

A divider caliper is also used to measure a distance between twopoints on a map. The two caliper's ends are brought to the two pointswhose distance is being measured. The caliper's opening is theneither measured on a separate ruler and then converted to the actualdistance, or it is measured directly on a scale drawn on the map. Ona nautical chart the distance is often measured on the latitude scaleappearing on the sides of the map: one minute of arc of latitude is

approximately one nautical mile or 1852 me

introduction mehta engg

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