GOVERNMENT POLYTECHNIC

MUZAFFARPUR

LAB MANUAL of advanced manufacturing

processes LAB

SUBJECT CODE – 1625507

Government Polytechnic Muzaffarpur

Name of the Lab: ADVANCED MANUFACTURING PROCESSES LAB

Subject Code: 1625507

List of Experiments

Exp.

No.

Experiments Name Page No.

1 One assignment on part programming on machining center. 1-4

2 One assignment on USM, CHM, EBM, AJM, WJM, PAM. 5-9

3 Industrial visit to observe automats and report on the tools, fixtures

and cams used on automats.

10

4 Industrial visit to observe at least one non-traditional machining

process and report on visit.

11

5 Report on mounting and dismounting procedure of Milling machine

arbor

12

1

EXPERIMENT NO - O1 AIM:

One assignment on part programming on machining center.

THEORY:

The part program is a sequence of instructions, which describe the work, which has to be done on

a part, in the form required by a computer under the control of a numerical control computer

program. It is the task of preparing a program sheet from a drawing sheet. All data is fed into the

numerical control system using a standardized format. Programming is where all the machining

data are compiled and where the data are translated into a language which can be understood by

the control system of the machine tool. The machining data is as follows :

(a) Machining sequence classification of process, tool start up point, cutting depth, tool

path, etc.

(b) Cutting conditions, spindle speed, feed rate, coolant, etc.

(c) Selection of cutting tools.

While preparing a part program, need to perform the following steps :

(a) Determine the startup procedure, which includes the extraction of dimensional data from

part drawings and data regarding surface quality requirements on the machined component.

(b) Select the tool and determine the tool offset.

(c) Set up the zero position for the workpiece.

(d) Select the speed and rotation of the spindle.

(e) Set up the tool motions according to the profile required.

(f) Return the cutting tool to the reference point after completion of work.

(g) End the program by stopping the spindle and coolant.

The part programming contains the list of coordinate values along the X, Y and Z directions of the

entire tool path to finish the component. The program should also contain information, such as

feed and speed. Each of the necessary instructions for a particular operation given in the part

program is known as an NC word. A group of such NC words constitutes a complete NC

instruction, known as block. The commonly used words are N, G, F, S, T, and M. The same is

explained later on through examples.

Standard G and M Codes

The most common codes used when programming NC machines tools are G-codes (preparatory

functions), and M codes (miscellaneous functions). Other codes such as F, S, D, and T are used

for machine functions such as feed, speed, cutter diameter offset, tool number, etc. G-codes are

sometimes called cycle codes because they refer to some action occurring on the X, Y, and/or Z-

axis of a machine tool. The G-codes are grouped into categories such as Group 01, containing

codes G00, G01, G02, G03, which cause some movement of the machine table or head. Group 03

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includes either absolute or incremental programming. A G00 code rapidly positions the cutting

tool while it is above the workpiece from one point to another point on a job. During the rapid

traverse movement, either the X or Y-axis can be moved individually or both axes can be moved

at the same time. The rate of rapid travel varies from machine to machine.

The total numbers of these codes are 100, out of which some of important codes are given as under

with their functions :

G-Codes (Preparatory Functions)

M-Codes (Miscellaneous Functions)

M or miscellaneous codes are used to either turn ON or OFF different functions, which control

certain machine tool operations. M-codes are not grouped into categories, although several codes

3

may control the same type of operations such as M03, M04, and M05, which control the machine

tool spindle. Some of important codes are given as under with their functions:

CNC Machining Center Programming:

4

O0010

N10 G00 X-15 Y-15

N20 G41 G01 X0 Y0 F100

N30 Y40

N40 X30 Y80

N50 X60

N60 G02 X100 Y40 R40

N70 G01 Y30

N80 G03 X70 Y0 R30

N90 G01 X0

N100 X-15 Y-15

5

EXPERIMENT NO -2

ULTRASONIC MACHINE:

Ultrasonic machining, or strictly speaking the "Ultrasonic vibration machining", is a

subtraction manufacturing process that removes material from the surface of a part through high

frequency, low amplitude vibrations of a tool against the material surface in the presence of fine

abrasive particles. The tool travels vertically or orthogonal to the surface of the part at amplitudes

of 0.05 to 0.125 mm (0.002 to 0.005 in.). The fine abrasive grains are mixed with water to form

a slurry that is distributed across the part and the tip of the tool. Typical grain sizes of the abrasive

material range from 100 to 1000, where smaller grains (higher grain number) produce smoother

surface finishes.

Ultrasonic vibration machining is typically used on brittle materials as well as materials with a

high hardness due to the microcracking mechanics.

Fig. Ultrasonic Machining

CHEMICAL MACHINING:

In chemical machining, some chemicals are used to remove material from the required portions of

the workpiece. This process is also called chemical milling. Chemical milling is done in the

following steps.

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Cleaning

The workpiece surface is carefully cleaned.

Masking

The portions of the workpiece which do not require machiningis covered with masking sheets. The

sheet is cut and taken from the area where machining is required. Templates are used for this

purpose. If the entire area of the workpiece is to be machined, masking is not necessary. Usually

vinyl, neoprene and rubber based materials are used as mask sheets.

Etching

After masking, the workpiece is submerged in a hot chemical solution. This solution is called the

etchant. For Aluminium Caustic soda is used as etchant. Acids are used for steel, magnesium and

titanium alloys. The etchant removes the metal from workpiece by chemical action. The rate of

metal removal is about 0.025mm per minute. The rate of metal removal depends upon the

concentration and the temperature of the etchant. For higher concentration and higher temperature,

the rate of metal removal is more. The amount of metal removal also depends upon the time

duration for which the workpiece is immersed in the etchant.

Demasking

After etching, the workpiece is taken out from the etchant. The workpiece is cleaned with the help

of water. Then the masking is removed.

ELECTRON BEAM MACHINING:

Electron-beam machining (EBM) is a process where high-velocity electrons concentrated into a

narrow beam are directed toward the work piece, creating heat and vaporizing the material. EBM

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can be used for very accurate cutting or boring of a wide variety of metals. Surface finish is better

and kerf width is narrower than those for other thermal cutting processes.

The EBM beam is operated in pulse mode. This is achieved by appropriately biasing the biased

grid located just after the cathode. Switching pulses are given to the bias grid so as to achieve pulse

duration of as low as 50 μs to as long as 15 ms. Beam current is directly related to the number of

electrons emitted by the cathode or available in the beam. Beam current once again can be as low

as 200 μamp to 1 amp. Increasing the beam current directly increases the energy per pulse.

Similarly, increase in pulse duration also enhances energy per pulse. High-energy pulses (in excess

of 100 J/pulse) can machine larger holes on thicker plates. The energy density and power density

is governed by energy per pulse duration and spot size. Spot size, on the other hand is controlled

by the degree of focusing achieved by the electromagnetic lenses. If a higher energy density is

combined with a smaller spot size, the material removal would be faster though the size of the hole

would be smaller. The plane of focusing would be on or just beneath the surface of the work piece.

The electron beam is generated by the potential difference between the negatively-charged cathode

and the positively-charged anode.

Fig: Electron Beam Machining

ABRASIVE JET MACHINING:

Abrasive jet machining (AJM), also known as abrasive micro-blasting, pencil blasting and micro-

abrasive blasting,[1] is an abrasive blasting machining process that uses abrasives propelled by a

high velocity gas to erode material from the workpiece. Common uses include cutting heat-

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sensitive, brittle, thin, or hard materials. Specifically it is used to cut intricate shapes or form

specific edge shapes.

Material is removed by fine abrasive particles, usually about 0.001 in (0.025 mm) in diameter,

driven by a high velocity fluid stream; common gases are air or inert gases. Pressures for the gas

range from 25 to 130 psig (170–900 kPag or 4 bars) and speeds can be as high as 300 m/s (1,000

km/h).

WATER JET MACHINING:

Water Jet Machining (WJM) is a mechanical energy based non-traditional machining process used

to cut and machine soft and non-metallic materials. It involves the use of high velocity water jet

to smoothly cut a soft workpiece. It is similar to Abrasive Jet Machining (AJM).

In water jet machining, high velocity water jet is allowed to strike a given workpiece. During this

process, its kinetic energy is converted to pressure energy. This induces a stress on the workpiece.

When this induced stress is high enough, unwanted particles of the workpiece are automatically

removed.

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PLASMA ARC WELDING:

Plasma arc machining is a nontraditional thermal process. Plasma is defined as a gas that has been

heated to a sufficiently high temperature to become partially ionized and therefore electrically

conductive. The term plasma, as employed in physics, means ionized particles. The temperature

of plasma may reach as high as 28000 ° C. Various devices utilizing an electric arc to heat gas to

the Plasma State have been in existence since the early 1900’s. However, the development of such

apparatus into commercial plasma arcs equipment for metal cutting applications dates back to only

about 1955.

The plasma arc produced by modern equipment is generated by a plasma torch that is constructed

in such a manner as to provide an electric arc between an electrode and workpiece. A typical

plasma torch consists of an electrode holder, an electrode, a device to swirl the gas, and a water-

cooled nozzle. The geometry of the torch nozzle is such that the hot gases are constricted in a

narrow column.

Primary gasses, such as nitrogen, argon-hydrogen, or air, are forced through the nozzle and arc

and become heated and ionized. Secondary gases or water flow are often used to help clean the

kerf of molten metal during cutting.

The stream of ionized particles from the nozzle can be used to perform a variety of industrial jobs.

The plasma arc, as an industrial tool, is a most heavy employed in sheet and plate cutting operations

as an alternative to more conventional oxy-fuel torches or other cutting tools. Plasma arc is

routinely used as an integral component of some modern punching machines. Plasma arc methods

are also employed in special applications to replace conventional machining operations such as

lathe turning, milling and planing, heat treatment and metal deposition operations, and plasma arc

welding.

Fig. Plasma Arc Machining

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EXPERIMENT NO – 03

AIM:

Industrial visit to observe automats and report on the tools, fixtures and cams used on automats.

THEORY:

In this particular visit students are expected to visit an Industry where they can learn thorough

things about tools, fixtures and cams. They are also intended to write a Technical Report on the

visit.

11

EXPERIMENT NO – 04

AIM:

Industrial visit to observe at least one non-traditional machining process and report on visit.

THEORY:

In this particular visit students are expected to visit an Industry to observe at least where they can

learn thorough things about at least one non-traditional machining. They are also intended to write

a Technical Report on the visit.

12

EXPERIMENT NO – 05

AIM:

Report on mounting and dismounting procedure of Milling machine arbor

Mounting and Removing Arbor:

When mounting or removing an arbor, follow the proper procedure to preserve the accuracy of the

machine. An improperly mounted arbor may damage the taper surfaces of the arbor or machine

spindle, cause the arbor to bend, or make the cutter run out of trueness.

To Mount an Arbor:-

(a) Clean the tapered hole in the spindle and the taper on the arbor using a clean cloth.

(b) Check to make sure that there are no cuttings or burrs in the taper that would prevent the

arbor from running true.

(c) Check the bearing bushing and remove any burrs using a honing stone.

Removing an Arbor or Adopter:

Changing an adopter or arbor on milling machine needs lot of patience. Operator must follow the

procedure carefully.

(a) Give a light blow on the bolt head with a hide face hammer.

(b) Take hold of the arbor with your left hand and unscrew the draw in bolt with your right

hand. Remove the arbor.