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Proses Pemesinan Moden(Modern Machining Process)

BDD 4073

Lecturer:

Mohd Amri Lajis, PhD

Dept. of Manufacturing and Industrial EngineeringFaculty of Mechanical and Manufacturing Engineering

Universiti Tun Hussein Onn Malaysia

Room no.: A4 building, Level 2, PPSK officeContact no.: 019-7796970

Email: [email protected]

Review of Machining

• Machining is a generic term, applied to material removal processes.• Traditional machining: turning, milling, drilling, grinding, etc.• Metal cutting/machining refers to processes in which excess metal is

removed by a harder tool (mechanical contact), through a process ofextensive plastic deformation or controlled fracture.

• Advanced/Modern or Non-Traditional machining: non-mechanical contactprocess, i.e. chemical machining, ECM, EDM, EBM, LBM, machining of non-metallic materials.

Chapter 1: Introduction

© ASSOC. PROF. DR. MOHD AMRI LAJIS, Faculty of Mech. and Manuf. Engineering, UTHM (2012)


There are basically six (6) processes used in modern machining

process/non-traditional machining to cut/machine material:

1) Electricity (i.e. spark erosion) – Wire EDM and EDM Die Sinking

2) Water – Water Jet pressure

3) Abrasives – Abrasive Water Jet and Ultrasonic Machining

4) Chemicals – Electrochemical Machining and Photochemical

Machining

5) Ionized Gas or Plasma – Plasma Arc Cutting (PAC)

6) Light or Electron – Laser Cutting, Electron Beam Machining

*High Speed Machining (HSM) is an

alternative process which is also

categorised as Modern/Advanced

Machining Process included in this

subject


EDM-Die Sinker EDM-Wirecut

1) Electricity – Wire EDM and EDM Die Sinking

Wire EDM and EDM die sinking uses electricity to cut electrically

conductive material by means of spark erosion



(2) Water – Water Jet Machining (WJM)

WJM uses high pressure water (up to 3 times the speed of sound) to cut material. Since

water is used, any material can be cut if it is soft enough for high pressure water to

penetrate.



AWJM USM

(3) Abrasives – Abrasive Water Jet (AWJM) and Ultrasonic Machining (USM)

AWJM uses garnet, silicate abrasive material, to a high pressure water jet. This allows

any material to be cut. USM uses fine, water-based abrasive slurry to machine parts, the

vibrating machine causes abrasives to remove material.


Leads to

energize

transducer

winding

Magnetostri

ction

transducer

Cooling

water

Flow

Flow

Concentrator

Abrasive

slurryWorkpiece

Tool


ECM PCM

(4) Chemicals – Electrochemical Machining (ECM) and Photochemical

Machining (PCM)

PCM relies on chemicals to remove exposed material to etch or cut parts. ECM combines

chemicals and electricity to remove material through a deplating process. As a salt solution

electrolyte surrounds an electrode, an electrical current passes from the electrode to the

workpiece removing the material.



(5) Ionized Gas or Plasma – Plasma Arc Cutting (PAC)

PAC utilizes ionized gas (Nitrogen, argon, carbon dioksida) to cut electrically conductive

materials



(6) Light or Electron Beam – Laser Beam Machining (LBM), Electron Beam Machining

(EBM)

Lasers rely on highly magnified light to cut materials. Since light is used, both electrical and

non-electrical material can be processed. Beside cutting, lasers are used for welding,

cladding, alloying, heat treating, marking, and drilling.



Modern machining process/Advanced machining process/

Non-traditional machining

Chemical Milling

Photochemical Blanking

Electrochemical Machining

Pulsed Electrochemical Machining

Electrochemical Grinding

Electrical-Discharge Machining

Electrical-Discharge Grinding

Electrical-Discharge Wire Cutting

Laser-Beam Machining

Electron Beam Machining

Plasma Arc Cutting

Water Jet Machining

Abrasive Water Jet Machining

Abrasive Jet Machining


*Recent technology:- Hybrid machining: a

combination of EDM, Milling,Turning, etc.


Examples of parts made by advanced Machining

Processes

These parts are made by advanced machining processes and would bedifficult or uneconomical to manufacture by conventional processes.

(a) Cutting sheet metal with a Laser beam.

(b) Microscopic gear with a diameter on the order of 100 µm (0.1 mm), made by a special etching process (photochemical machining).



Chemical attacks

metals and etch

them by removing

small amounts of

material from the

surface using

reagents or

etchants

(a) Missile skin-panel section contoured by chemical milling to improve the stiffness-toweight ratio of the part. (b) Weight reduction of space launch vehicles by chemical millingaluminum-alloy plates. These panels are chemically milled after the plates have first beenformed into shape by processes such as roll forming or stretch forming. The design of the

chemically machined rib patterns can be modified readily at minimal cost.

Chapter 1: IntroductionExamples of parts made by advanced Machining

Processes – Chemical machining


a) Turbine blade made of a nickel alloy, 360 HB; note the shapeof the electrode on the right. (b) Thin slots on a 4340-steelroller-bearing cage. (c) Integral airfoils on a compressor disk.


Processes – Electrochemical machining (ECM)



(a) Schematic illustration of the electrical-discharge machining process.

(b) Examples of cavities produced by the electrical-discharge machiningprocess, using shaped electrodes. Two round parts (rear) are the set of dies forextruding the aluminum the aluminum piece shown in front.

(c) A spiral cavity produced by EDM using a slowly rotating electrode, similarto a screw thread.

(a) (b) (c)


Processes – Electrical Discharge Machining (EDM)



Stepped cavities produced with a squareelectrode by the EDM process. Theworkpiece moves in the two principalhorizontal directions (x-y), and its motionis synchronized with the downwardmovement of the electrode to producethese cavities. Also shown is a roundelectrode capable of producing round orelliptical cavities.

Schematic illustration of producing an inner cavity by EDM, using aspecially designed electrode with a hinged tip, which is slowly openedand rotated to produce the large cavity.


Processes – Electrical Discharge Machining (EDM)



(a) Schematic illustration of water-jetmachining.

(b) A computer-controlled, water-jetcutting machine cutting a granite plate.(c) Example of various nonmetallic partsproduced by the water-jet cuttingprocess.


Processes – Water Jet Machining (WJM)



Abrasive Waterjet and Waterjet

Machining - Part Examples


Water Jet and Abrasive Water Jet Cutting

High pressure water (20,000-

60,000 psi).

Can cut extremely thick parts

(5-10 inches possible).

Thickness achievable is a

function of speed.



Laser Beam Machining (LBM)

FIGURE (a) Schematic illustration of the laser-beam-machining process. (b) and (c)

Examples of holes produced in nonmetallic parts by LBM.



Ultrasonic Machining of CeramicsChapter 1: Introduction


Examples of parts made by advanced Machining Processes – High Speed Machining (HSM)


HSM allows a forging supplier to produce

dies like this one in a single setup on a

machining center, where once a

combination of milling and EDM was

required. HSM produces the die faster.

HSM is also more accurate, because

fewer steps result in reduced error

stacking.

The finest of the machined

surface is determined by

applying high speed

cutting which is drastically

reduced polishing time.


Why modern machining processess are important?


1) The strength and hardness of the material are very high (above 400 HB/43 HRC).

2) Work-piece is too brittle to be machined without damage to WP

3) Workpiece are difficult to clamp in fixtures and work-holding devices

4) The shape of the part (workpiece) is complex

5) Special surface finish and dimensional tolerance requirements cannot be obtained by other manufacturing processes.

6) Undesirable temperature rise, residual stress developed inside workpiece

7) The size of the part to be machined is too small


Why modern machining processess are important?


(8) Speed and Accuracy

The speed and accuracy of various methods modern machining

process are very substantially.

An understanding of the characteristics of the various systems can

greatly affect the profitability of manufacturers. For example, sheet

metal parts can be cut very fast with lasers, but lasers cut parts one

at a time. With wire EDM, thin sheet metal parts can be stacked, and

the parts will be cut burr free, more economically, and with greater

accuracy.

Certain jobs require extremely close tolerances but excessively close

tolerances are often unnecessary and add substantial costs to the

machining process. So, understanding tolerances is an important

asset in reducing machining costs.


The FutureChapter 1: Introduction

Companies can only remain successful if they actively struggle to

keep their operations competitive and to produce the best products at

the lowest prices.

Therefore, to remain successful, companies need to keep informed of

the newest technologies in order to remain competitive. In addition,

they need to train their employees to work efficiently and accurately.

Engineering universities should be concerned that their graduating

engineers are properly equipped to enter the workforce knowing the

latest technologies. But generally, non-traditional machines are

expensive, and universities are unable to justify having these

machines.


The FutureChapter 1: Introduction

Finally, the future belongs to those keeping abreast and

applying the latest technologies to stay competitive.

Those becoming satisfied and refusing to look at the new

ways of machining, will fail to compete in global market.


Thank you


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