cnc milling report

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1.0TITLE : CNC Milling (Non Traditional Machining) 2.0OBJECTIVE 1. To develop more understanding about development and principle of CNC machine 2. To understand the fundamentals of NC programming which need to be taken for completing a successful CNC program 3. To learn how to produce a product through the process 1

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report about the cnc milling

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Page 1: cnc milling report

1.0 TITLE : CNC Milling (Non Traditional Machining)

2.0 OBJECTIVE

1. To develop more understanding about development and principle of CNC machine

2. To understand the fundamentals of NC programming which need to be taken for

completing a successful CNC program

3. To learn how to produce a product through the process

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3.0 INTRODUCTION

Non-traditional manufacturing processes is defined as a group of processes that remove

excess material by various techniques involving mechanical, thermal, electrical or chemical

energy or combination of these energies but do not use a sharp cutting tools as it needs to be used

for traditional manufacturing processes.

Extremely hard and brittle materials are difficult to machine by traditional machining

processes such as turning, drilling, shaping and milling. Non -traditional machining processes,

also called advances manufacturing processes, are employed where traditional machining

processes are not feasible, satisfactory or economical due to special reasons

Numerical control (NC) refers to the automation of tools that are operated by abstractly

programmed commands encoded on a storage medium, as opposed to manually controlled or

mechanically automated via cams alone. The first NC machines were built in the1940s and '50s,

based on existing tools that were modified with motors that moved the controls to follow points

fed into the system on paper tape. These early servomechanisms were rapidly augmented with

analog and digital computers, creating the modern computer numerical controlled (CNC)

machine tools that have revolutionized the design process.

In modern CNC systems, end-to-end component design is highly automated using

CAD/CAM  programs. The programs produce a computer file that is interpreted to extract the

commands needed to operate a particular machine, and then loaded into the CNC machines for

production. Since any particular component might require the use of a number of different tools,

modern machines often combine multiple tools into a single “cell”.

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Figure 1: CNC Milling Machine

Modern CNC milling differs little in concept from original model built at MIT in 1952.

Mills typically consist of a table that moves in the Y-axis, and a tool chuck that moves in X and

Z (depth). The position of the tool is driven by motors through a series of step-down gears in

order to provide highly accurate movements, or in modern design, direct-drive stepper motors.

As the controller hardware evolved, the mills themselves also evolved. One change has been to

enclose the entire mechanism in a large box as a safety measure, often with additional safety

interlock to ensure the operator is far enough from the working piece for safe operation.

Mechanical manual controls disappeared long ago. CNC like system are now used for any

process that can be described as a series of movement and operations. This include laser cutting,

welding, friction stir welding ultrasonic welding, flame and plasma cutting, bending, spinning,

pinning, gluing, fabric cutting, sewing, tape and fiber placement, routing, picking and placing

(PnP), and sawing.

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4.0 APPARATUS

Figure 3: Rough Stock

Figure 2: CNC Milling Machine

Figure 4: Machine Controller Figure 5 : NC Program

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Figure 6: Cutting tool

Figure 7: Work Holding Device

4.1 INDUSTRIAL APPARATUS

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Figure 8: CNC Milling Machine

Limitations:

- Relatively high initial cost of the equipment.

- The need and cost for programming and computer time.

- Special maintenance with trained personnel.

- High preventive maintenance since breakdowns are costly.

5.0 EXPERIMENTAL PROCEDURE

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We were only shown simplified procedure by the lecturer, machine setting and

specification is done by lecturer on side. The below procedure is the simplified

procedure:

1 . At first, we have to check the programs to ensure that the machinery will

function properly and that the output will meet specifications. We downloaded the NC

program to the controller by key in the data, cabling RS232 or APT after the

programming work is completed.

2. Tool layout. Before the machining was started, the tool layout must be check so that

we got the desired shape of work piece.

3. Work piece setting. In this step, operator loaded the proper cutting tools into the tool

holder and positions the work piece that is piece of metal or plastic that is being shaped

on the CNC machine tool.

4. In machining process, after operator load work pieces and cutting tools into a machine,

after that the start button was pressed. Operator monitored the machine for problems, and

measure the parts produced to check that they match specifications.

6.0 RESULT AND DATA ANALYSIS

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Figure 9: Product design in CATIA

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Figure 10: product design in CNC Milling screen

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Figure 11: Final Product

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6.1 SAMPLE CALCULATION

NC programme code (G-Code)

Start Fifo

N1 T1 M6 ----- Tool 1

N2 S1000 M3 M8

N3 G0 X18.5 Y18.5 210

N4 G1 Z-15 F100

N5 G0 Z10

N6 G0 X-18.5 Y18.5

N7 G1 Z-15 F100

N8 G0 Z10

N9 G0

N10

N11

N12

N13 T2 M6 ----- Tool 2

N14 G0 X-26 Y18.5 Z10

N15 G01 Z-15

N16 G2 X-12.394 Y22.856 R7.5 F75

N17 G2 X12.394 Y22.856 R36 F75

\

N18 G2 X26 Y18.5 R7.5 F75

N19 G1 Y-18.5 F100

N20 G2 X12.394 Y-22.856 R7.5 F75

N21 G2

N22 G2

N23 G3 G1 X-26 Y18.5

N24 G0 Z10

N25 M5 G40

N26 M9

N27 M30

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7.0 DISCUSSION OF RESULT

For our experiment, our aims are to learn and understand the use and capabilities of

computer numerical control (CNC) milling machine. For the set up of the CNC operation, the

computer numerical control is attached to the milling machine. Firstly, Computer Aided Design

(CAD) is used to make a design of a product. In CAD, it involves a special symbolic

programming languages or codes that determine the coordinate points of corner, edges and

surfaces of the work piece. Once the design is completed, we transfer the coding that we made

using ISO NC programmed to the CNC milling machine. All the data about the process from the

beginning to the end is included in those codes. Wrong coding will damage the work piece. In

order to prevent damage, we need to view the simulation on the CNC screen and do some final

editing so that the milling machine is operating in a good condition as we will obtain perfect

work piece. Any errors or mistakes will affect the work piece as well as the machine. The

machine’s cutting tool might break. We have to set up the h of cutting tool, cutting fed, cutting

speed , spindle speed that is suitable with the specimen to avoid error occur during the process.

From the experiment, we can say that our product is perfect and thus our experiment is 100%

success. The product follows the original design and the surfaces are completely smooth. From

the product obtained, the coordinate system plays an important role to make sure the product is

not defected.

While CNC machines are expensive and complicated, they have a lot of advantages.

These are some advantages of CNC machine:

1. It improves automation, removing the need of an operator for all but a few parts of the

work. CNC machines can be left unattended for hours or even days if necessary, allowing

operators to focus on other tasks.

2. CNC machines can be used continuously 24 hours a day, 365 days a year and only need

to be switched off for occasional maintenance.

3. CNC machines can be updated by improving the software used to drive the machines.

4. Training in the use of CNCs is available through the use of ‘virtual software’. This is

software that allows the operator to practice using the CNC machine on the screen of a

computer. The software is similar to a computer game

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8.0 CONCLUSION

From the experiment, we learned the principle of CNC machine. We gained better

understanding in the modes of operation of CNC machine. There is various type of modern CNC

machines use in industrial. Different preparatory (G codes) and miscellaneous function (M

codes) is used in CNC part programming for completing a successful CNC program.

Specifically, CNC milling machine works with a computer numerical control that writes and read

G-code instructions to drive machine tool to fabricate components with a proper material

removal rate. G-codes are commands for CNC machines to follow so that they can operate on

their own without human control. Zero set up is very important step to obtain an accurate

geometry of the work piece. We also gain information about the advantages and disadvantages of

CNC machines and its application.

CNC machine can be used to cut complex shapes of metal and other solid materials. The

advantages of CNC machine over Traditional Machine (TM) besides the availability of low cost

programmable controllers played a major role in the successful implementation of CNC on

manufacturing plants.

From the experiment, we can conclude that the objective students with Numerical

Control (NC) Programming and Computer Numerical Control (CNC) milling machine has been

successfully achieved.

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9.0 RECOMMENDATION

Getting the appropriate feeds and speeds for the work piece material, tooling, and cutting

conditions is the most important first step. Consistent speeds and feeds will make a huge

difference on the surface finish. Getting the right speeds and feeds is just as important to obtain a

good surface finish.

Good chip clearing is essential to both surface finish and tool life. It's impossible to get

good surface finish if chips are being re-cut over and over again. If chip clearance is minimal,

clumped up chips can jam the cutter to the point where it breaks.

Flood coolant or an air blast should be used to clear the chips at all times. Aside from

cooling the tool, the coolant cools the work piece. Sometimes this is helpful to accuracy, as a

work piece that heats up is a work piece that is moving due to thermal expansion. Another

advantage of coolant is that it lubricates the tool/work piece interface.

The primary impact of work holding on surface finish is vibration. In the worst case

vibration will turn into chatter, which is a harmonic effect that will be very visible in your

surface finish. Clearly, the more solid we can make our work holding, the less likelihood of

vibration there will be. Make sure the work piece is supported and clamped over as much area as

possible surrounding the cut while still leaving room for the cutter to get in there and do its job.

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10.0 REFERENCES

1) Kalpakjian, S., and R.S. Schmid, “Automation of Manufacturing Process”,

Manufacturing Engineering and Technology, 4th. Edition, Prentice Hall, 2000.

2) Youssefi, K, “Computer Numerical Control (CNC)”, Product Design and Manufacturing

Minicurriculum, 6 Oct. 2004.

3) Mikell P. Groover , Principles of Modern Manufacturing, 4th Edition, Wiley 2011.

4) http://www.technologystudent.com/despro2/cncsys1.htm

5) http://en.wikipedia.org/wiki/Milling_machine

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