6. manufacturing.pdf

7/29/2019 6. MANUFACTURING.pdf

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6.1 MANUFACTURING METHODS OF

CONNECTING ROD

1. Casting

2. Forging

3. Direct machining

4. Powder metallurgy

Casting:It is defined as the process of making casts or molds. Something cast in a mold.

The act of throwing a fishing line.

Forging:It is defined as the shaping of metal using localized compressive forces.

Direct machining: It is defined as the process of removing metal to form or finish a

part.

Powder metallurgy: It is defined as the technology of powder metals, especially the

production utilization of metallic objects. With high quality of material purity.


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6.2 POWDER METALLURGY

Powder metallurgy is a forming and fabrication technique consisting of three major

processing stages. First, the primary material is physically powdered, divided into many

small individual particles. Next, the powder is injected into a mold or passed through a die

to produce a weakly cohesive structure (via cold welding) very near the dimensions of the

object ultimately to be manufactured. Pressures of 10-50 tons per square inch are

commonly used. Also, to attain the same compression ratio across more complex pieces, it

is often necessary to use lower punches as well as an upper punch. Finally, the end part is

formed by applying pressure, high temperature, long setting times (during which self-

welding occurs), or any combination thereof.

Two main techniques used to form and consolidate the powder are sintering and metal

injection molding. Recent developments have made it possible to use rapid manufacturing

techniques which use the metal powder for the products. Because with this technique the

powder is melted and not sintered, better mechanical strength can be accomplished.

6.3 Design Considerations:

The powder metallurgy manufacturer is often confronted by a drawing for a component

designed with an alternative manufacturing process in mind. It is not sensible or desirable

for the powder metallurgy component manufacturer to attempt to quote or produce to these

drawings or designs as it is likely that certain features cannot be produced. It is desirable to

redesign the component so that it can fulfill its design function, as well as take full

advantage of the powder metallurgy process, in particular cost effective manufacture to

near neat shape with close dimensional tolerances.

There are a few simple factors to consider:


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The need to avoid feather-edged tooling. Stresses on the edge would cause it todeform under pressing loads and bind against the mating parts of the tooling. (This

problem can be overcome by the use of a small flat section.)

The inability of the powder metallurgy process to introduce re-entrant angle andcross holes. Such features would have to be machined using a post processing step.

Sharp corners should be avoided, being replaced by small radiuses. The need to be able to eject the part from the tools after pressing

Other design rules relate to the practicalities of producing certain tooling configurations

and have to be considered on a component-by-component basis.

6.4 MATERIALS USED FOR CONNECTING ROD:

Steel Light alloy metals

Aluminum Titanium


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6.5 Practicalities of Production:

There are constraints on the height and wall thickness of parts. The initial height of powder

in the die is about 2.5 times that of the pressed compact. Consequently components with

final dimensions of height to wall thickness of greater than about 16:1 are not possible.

Filling also becomes a problem with this height to wall ratio when the wall thickness itself

is small. Usually wall thicknesses of less than 2 mm at this ratio are not possible.

Normally a powder metallurgy component is a single, pressed and sintered part. It is

possible to produce a complex component, impossible to press in one operation, by

pressing two simpler sub-components and co-sintering, or sinter-brazing them together

during the sintering process.

Co-sintering relies upon the interdiffusion of the two parts during sintering with no

additional joining aid, whereas sinter brazing uses an intermediate layer of a braze material

between the two parts, which joins them together whilst they are at the sintering

temperature. A third option is to resistance weld the two parts together after sintering.

It is highly desirable to seek the advice of a powder metallurgy component manufacturer to

ascertain the most cost effective design for the component by discussing the function of

the component and all of the critical features.


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6.6 Generation of powder:

Powders are manufactured by various methods. The size of the powder largely effects

the properties of the part produced. Some of the methods to generate the powders are

1) Mechanical processesa. Machining

b. Crushing

c. milling

d. shooting

e. Graining

f. Atomization


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2) Physical processesa. Condensation

b. Thermal decomposition

3) Chemical processes

a. Reduction

b. Intergrannular corrosion

c. Generation of powders from aqueous solutions by precipitation

d. Electro chemical process.

A right type of powder should be employed for producing a part with required properties.

6.7 Blending or mixing:

Powders are to be blended or mixed properly for obtaining the required

properties after sintering. In this process the powder and blender are mixed together very

finely. A lubricant is also employed some times to reduce the friction and hence obtaining

a finer mixing. The lubricant should be removed of the die before submitting it for

sintering as the presence of lubricant may change the properties of the final object. Many

types of blenders are being used for the manufacturing of various parts by powder

metallurgy technique.


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6.8 Compacting:

Compacting is done for shaping of the powder in to the required shape. In this the mixed

mixture is subjected to pressure and due to the application of pressure the gap between the

molecules gets reduced and the powder becomes compact and gains sufficient strength to

with stand ejection and handling. Pressures applied on the powder should be strictly

regulated as if low pressures are applied on then the part generated will be very fragile in

nature. If the pressure applied is more then there may be a deformation of tool. In general a

pressure of 1to 150N.m2. Compacting is done by various processes like

Isostatic pressing

b. Explosive forming

c. Powder rolling or roll compacting

d. Powder extrusion

e. Vibratory compacting

In addition to the forming of poper shape compacting also have other important effects

1) Density of the material is increased by removing the voids in the material

2) Adhesion and cold welding provides sufficient green strength to the part

3) Powders are plastically deformed by this due to this re crystallization occurs easily

during sintering

4) Due to plastic deformation of the powder particles the contact area between the particles

increases and hence helping in developing the green strength of the particle and also

facilitating subsequent sintering

Other than compaction shaping of powders can also be done by various other processes

like

1) Hot compaction

2) Hot extrusion


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3) Hot rolling

4) Hot isostatic compaction

5) Hot coning

6) Powder (or) sinter forging

6.9 Sintering:

This process is carried out for increasing the strength and also the hardness of the part. In

this the part is subjected to heating without any pressure for certain period of time under

highly controlled conditions.

Sintering is concerned with

a. Diffusion

b. Densification

c. Re crystallization and grain growth


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6.9.1 Recrystallization and grain growthThis occurs between the contact surface which leads to a structure similar to the original

component to be produced.

Depending on the temperature of sintering these are classified in to two types

1) Solid phase sintering

2) Liquid phase sintering

In solid phase sintering the part to be sintered is heated to a temperature above the

Recrystallization temperature.

In liquid phase sintering the part to be sintered is heated to a temperature above the

melting point of one of its components or the melting point of the alloy formed.

It is very necessary to maintain a proper atmosphere while sintering. Vaccum is preferred

than maintaining a proper atmosphere. The atmosphere maintained during sintering may

be either reducing or oxidizing or neutral.

Of all reducing atmosphere is most commonly used.


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6.10 sizing or impregnation

From the above we understood that during the process of densification in

sintering there may be a variation in size. So after sintering the produced part is checked

by using a master die and pressure is applied over the part. This process is called sizing.

Because of this process the interconnected porosity of the part gets closed and it will be

not possible to fill the pores with oil or any other metal. So sizing is not frequently

adopted. A pre machining operation is adopted before impregnation.

6.11 Testing and inspection

A component is to be checked clearly about its properties and other things before

it is employed for the work. Some of the most commonly performed tests are

1) Compressive strength

2) Tensile strength

3) Porosity

4) Density

5) Hardness

6) Composition

7) Microstructure etc.

Inspection is done on the size shape tolerances and the total number of defects. After all

this if the parts is qualified then it is used for the real time applications the properties of the

products obtained by sintering process depends on the following 6.12


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6.12 Parameters

1) Size of particles

2) Shape of particles

3) Distribution of particles

4) Porosity of particles

5) Density of particles

6) Chemical composition of particles

7) Surface characteristics of particles

8) Compacting pressure

9) Type of lubricant used during mixing (or) blending

10) Sintering temperature

11) Sintering time

12) Sintering type employed

13) Type of atmosphere maintained


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6.13 PRO/ENGINEER MANUFACTURING (MOLD

EXTRACTION)

What You Can Do with Pro/MOLDESIGN and Pro/CASTING

Pro/Moldesign is an optional module for Pro/ENGINEER that provides the tools to

simulate the mold design process within Pro/ENGINEER. This module lets you create,

modify, and analyze the mold components and assemblies, and quickly update them to the

changes in the design model.

Pro/CASTING provides tools to design die assemblies and components and prepare

castings for manufacturing.

Pro/MOLDESIGN and Pro/CASTING, together with Pro/ENGINEER Foundation,

provide tools to do the following:

Design Part Creation and Modification

Create models in Pro/ENGINEER including features requiring Pro/SURFACE

Import and repair geometry if necessary

The import functionality can be used with the following: See Data Doctor Option and

Interface for Pro/ENGINEER

Analyze if a design part is moldable, using Draft Check and Thickness Check capabilities

Automatically create parting lines and detect undercuts using Silhouette Curve

functionality

Fix problem areas by creating draft, rounds, and other features as needed Cavity Creation


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Assemble and orient design model dynamically while checking draft and projected area

Apply a shrinkage that corresponds to design part material, geometry, and molding

conditions

Automatically create the workpiece stock from which core, cavity, and inserts will be split

Create parting geometry, including sliders, inserts, automatic parting lines, and automatic

parting surfaces

Automatically split the workpiece to create cores, cavity, and inserts as solid models

For casting, create and assemble sand cores

Mold Layout Creation

About Mold Layout

The Mold Layout application provides a dynamic environment for designing and

assembling single or multi-cavity tooling in an assembly. Mold Layout also provides

efficient tools for fast and robust design of single or multi-cavity molds. You can easily

populate your assembly with cavity subassemblies, a mold base assembly, standard

components, and an injection molding machine. You can also create some mold-specific

features.

The Mold Layout application is mold functionality that is accessible from Assembly mode.

You create or open a regular assembly (.asm) file to use this application.

You can switch from working on a multi-cavity mold assembly to working on an

individual cavity. To do this, use a regular assembly structure where the multi-cavity mold

assembly model is a top level assembly and each cavity model is a subassembly. These

cavity subassemblies are represented by Mold or Cast assemblies


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You can make changes in one cavity assembly model appear in all cavity assembly models

in the multi-cavity mold assembly.

The cavity population tool allows flexible patterning of the cavities according to

rectangular, circular, and user defined pattern rules. You can add, remove, move, or

reorient each cavity pattern member individually, or even replace any cavity model with a

family table instance.

Other functions specific to Mold Layout are as follows:

Selecting and placing mold bases with the Mold Base Selection dialog box

Selecting and placing Injection Molding Machine models

Creating runners at the assembly level

Creating waterlines at the assembly level

Creating ejector pin holes at the assembly level

Using the standard component Catalog to add, redefine, delete, trim, and cut components

Opening the mold by defining steps, deleting, modifying, reordering, and exploding

The Mold Layout application contains the same basic Mold Opening information as the

Mold or Die Opening process. Click Mold or Die Opening Process in the Help Table of

Contents for more information.

Create top level mold assembly

Placement and patterning of mold cavities to allow multi-cavity molding

Online selection and automatic assembly of standard mold bases


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Modification of mold base plates to allow for assembly of mold cavity

Online selection and automatic assembly of ejector pins and other Mold Catalog items

Automated creation of runners

Automated creation of waterlines, including 3-D waterline interference checks

Define and simulate mold opening and check for interference between mold components

Drawing Creation

Create complete production drawings, including dimensions, tolerances, automatic bill of

materials (BOMs) with or without balloon notes

Use of drawing templates

About Splitting to Volumes

Instead of creating a volume, you can split the work piece into one volume or two volumes

using one of the following Split commands:

MOLD > Feature > Work piece > Solid Split

MOLD > Mold Volume > Split

Features resulting from the splitting are created as assembly features.

Splitting does not alter work piece or die block geometry. Whenever a work piece or die

block is split, the system copies the work pieces or die blocks into one or two volumes that

you can then use in creating mold components or die blocks.

You can split the work piece or die block or a mold or cast volume using a surface, a

parting surface, or a volume. You can specify that you want to ignore one of the volumes

and create a volume to one side of the parting surface only.


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About Extracting Mold Components or Die Blocks

Mold components or die blocks are produced by filling previously defined mold volumes

with solid material. This process, performed automatically, is called extracting.

Extract features looks for mold or die volumes at the assembly level for extraction into

parts. When a split results in more than two volumes, the system prompts you to classify

the extracted part as belonging to one volume or another.

Once extracted, the mold components or die blocks are fully functional Pro/ENGINEER

parts; they can be retrieved in Part mode, used in drawings, machined with Pro/NC. New

features can be added, such as chamfers, rounds, cooling passages, draft, gating, and

runners.

About Applying Shrinkage :

You must consider the shrinkage of the material and proportionally increase dimensions of

the reference model before you start molding the reference model. You can apply

shrinkage to the reference model in Mold (Cast) mode and depending on the method of

applying shrinkage, it may propagate to the design model. You can also apply shrinkage to

the design model or reference model in Part mode.

The two methods of applying shrinkage are:

By Dimensionallows you to set up one shrink coefficient for all model dimensions,

and specify shrink coefficients for individual dimensions. You can choose to apply

shrinkage to the design model.

By Scaling allows you to shrink the part geometry by scaling it with respect to a

coordinate system. You can specify different shrinkage ratio for the X-, Y-, and Z-


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coordinates. If you apply shrinkage in Mold (Cast) mode, it applies only to the reference

model and does not affect the design model.

Pro/ENGINEER uses two formulae to calculate shrinkage. The formula 1/(1S) allows

you to specify a shrinkage factor that is based upon the final geometry of the reference part

once shrinkage is applied. The formula 1+S uses a pre-calculated shrinkage factor that is

based upon the original geometry of the part.

To Specify a Shrinkage Formula

Click MOLD (CAST) > Shrinkage. The SHRINKAGE menu appears.

Note: If you are in the part mode, click Edit > Setup. The PART SETUP menu appears.

Click Shrinkage. The SHRINKAGE menu appears.

Click By Dimension or By Scaling. Alternatively, you can click or on the toolbar. The

Shrinkage by Dimension or Shrinkage by Scale dialog boxes open, respectively.

Under Formula, select 1+S or 1/ (1-S) to calculate the shrinkage ratio.

1+Sspecifies a pre calculated shrinkage ratio based on the original geometry of the part.

This is the default.

1/ (1S)Specifies a shrinkage ratio based on the resulting geometry of the part, after

shrinkage is applied.

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