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ME 330

Manufacturing Processes


CUTTING PROCESSES

What is manufacturing?


Application of physical and chemical
processes to alter the geometry,
properties, and/or appearance of a
given starting material to make parts
or products.


Also includes assembly of parts into
products.


Goal:
to achieve a product


Transformation of materials into
items of
greater value (added
value)

by processing and/or
assembly operations


Goal:
to make money through a
product


A Technical Process:

An Economic Process:

©2010 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

4/e


Overview of processes

Cutting processes

Cutting processes to manufacture
parts from
sheets & plates

Purpose to manufacture parts by cutting from
sheets and plates
:


Fast to manufacture


Parts are low in cost


Helps drive costs assembled products down


From low to high quantities


Simple to complex parts


Parts can later be formed (bent) to make more
complex shapes



Major cutting processes


Mechanical processes:


Machining and grinding (will cover in later classes)


Shearing, blanking, and punching (sheet metalworking operations)


Ultrasonic machining (USM)


Water jet cutting (WJC or
hydrojet
)


Abrasive water jet cutting (AWJC or abrasive
hydrojet
)


Electrochemical process:


Electrochemical
Machining (ECM)


Thermal Energy Processes


Ram electric
discharge machining
(Ram EDM)


Wire electric
discharge
machining (Wire EDM)


Electron beam
machining (EBM)


Laser beam
machining (LBM)


Plasma arc cutting
(
PAC) or plasma arc machining (PAM)


Air carbon arc
c
utting


Oxyfuel

Cutting (OFC)
or flame cutting


Chemical Processes:


Chemical Machining (CHM)


Red

indicates non
-
traditional processes

©2007 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

3/e

Importance of Nontraditional
Processes


Need to machine newly developed metals and
non
-
metals with special properties that make
them difficult or impossible to machine by
conventional methods


Need for unusual and/or complex part
geometries that cannot readily be
accomplished by conventional machining


Need to avoid surface damage that often
accompanies conventional machining

©2010 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

4/e


Shearing, Blanking, and Punching


Three principal operations in pressworking
that cut sheet metal:


Shearing


Blanking


Punching

©2010 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

4/e


Shearing Operation


(a) Side view of the operation; (b) front view
of power shears equipped with inclined upper
cutting
blade

©2010 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

4/e


Dies for Sheet Metal Processes

Most
pressworking

operations are performed
with conventional punch
-
and
-
die tooling


Usually custom
-
designed
for the particular
part

Note:


Tooling cost is higher than cutting machines
that require no tooling


Tooling wears out so needs continual
replacement


Components of a punch
and die for a blanking
operation

Punch and Die Components


Components of a punch
and die for a punch
operation

Die

Punch

©2010 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

4/e


Blanking and Punching


Blanking (a)
-

sheet metal cutting to separate
piece (called a
blank
) from surrounding stock


Punching (b)
-

similar to blanking except cut
piece is scrap, called a
slug


©2010 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

4/e


Press


For punching/blanking
and bending operations


Have to feed material
manually into correct
position



(photo courtesy of
Greenerd

Press &
Machine Company, Inc.)

©2010 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

4/e


CNC Turret Press


Advantage:


Automatic positioning
of punch and dies


Can be used for
punching/blanking
and bending
operations


Disadvantage:


Tooling cost is high


©2007 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

3/e


Uses high pressure, high velocity stream of
water directed at work surface for cutting

Figure 26.3 Water jet cutting.

Water Jet Cutting (WJC
) or
Hydrojet

Cutting

©2007 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

3/e

WJC
& Applications


Usually automated by CNC or industrial
robots to manipulate nozzle along desired
trajectory


Water also acts as a cooling agent


Can cut complex shaped parts


Used
to cut
narrow slits
in flat stock such as
plastic, textiles, composites, floor tile,
carpet, leather, and cardboard


Not suitable for brittle materials (e.g., glass)

©2007 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

3/e

Abrasive Water Jet Cutting (AWJC)


Most common for cutting metal


Abrasive particles
are added to jet stream for
quicker cutting


Slower than laser cutting, but produces a
cleaner finish


Note that the water jet cut is
tapered


©2007 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

3/e

Material removal by anodic dissolution,
using
electrode
(tool) in close proximity to work but
separated by a rapidly flowing electrolyte

Figure 26.5

Electrochemical
machining
(ECM).

Electrochemical Machining (ECM)

©2007 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

3/e

Electrochemical Machining Processes


Electrical energy used in combination with
chemical reactions to remove material


Reverse of electroplating


Work material must be a conductor


Processes:


Electrochemical machining (ECM)


Electrochemical
deburring

(ECD)


Electrochemical grinding (ECG)

©2007 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

3/e

ECM Operation

Material is deplated from anode workpiece
(positive pole) and transported to a cathode tool
(negative pole) in an electrolyte bath


Electrolyte flows rapidly between two poles to
carry off deplated material, so it does not plate
onto tool


Electrode materials: Cu, brass, or stainless steel


Tool has inverse shape of part


Tool size and shape must allow for the gap

©2007 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

3/e

Figure 26.8 Electric discharge machining (EDM): (a) overall setup, and (b)
close
-
up view of gap, showing discharge and metal removal.

Electric Discharge Machining (EDM)

©2007 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

3/e

EDM Operation


One of the most widely used nontraditional processes


Shape of finished work surface produced by a shape of
electrode
tool


Can be used only on electrically conducting work
materials


Requires dielectric fluid, which creates a path for each
discharge as fluid becomes ionized in the gap.


Metal is melted/vaporized by the series of electrical
discharges


Can be very precise and produces a very good surface
finish

©2007 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

3/e

Work Materials in EDM


Work materials must be
electrically conducting


Hardness and strength
of work
material are not factors in EDM


Material removal rate depends on
melting point of work material

©2007 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

3/e


Special form of EDM uses small diameter wire
as electrode to cut a narrow kerf in work

Figure 26.10 Electric discharge wire cutting (EDWC).

Wire EDM

©2007 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

3/e

Operation of Wire EDM


Work is fed slowly past wire along desired
cutting path, like a
bandsaw

operation


CNC used for motion control


While cutting, wire is continuously advanced
between supply spool and take
-
up spool to
maintain a constant diameter


Dielectric fluid is required


Applied using
nozzles directed at tool
-
work
interface or submerging
workpart

©2007 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

3/e

Wire EDM Applications


Ideal for stamping die components


Since kerf is so narrow, it is often possible to fabricate
punch and die in a single cut


Other tools and parts with intricate outline
shapes, such as lathe form tools, extrusion
dies, and flat templates

©2007 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

3/e

Dental part cut
from
nitinol

material

by
wire EDM



©2007 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

3/e


Uses the light energy from a laser to remove
material by vaporization and ablation

Figure 26.14 Laser
beam machining (LBM).

Laser Beam Machining (LBM)

©2007 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

3/e

LBM Applications


Drilling, slitting, slotting, scribing, and marking
operations


Drilling small diameter holes
-

down to 0.025
mm (0.001 in)


Generally used on thin stock


Work materials: metals with high hardness
and strength, soft metals, ceramics, glass and
glass epoxy, plastics, rubber, cloth, and wood

©2007 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

3/e

Laser beam cutting
operation performed
on sheet metal




(
photo courtesy of PRC
Corp.).

©2007 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

3/e


Uses plasma stream operating at very high
temperatures to cut metal by melting

Figure 26.15 Plasma
arc cutting (PAC).

Plasma Arc Cutting (PAC)

©2007 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

3/e

Operation of PAC


Plasma = a superheated, electrically
ionized gas


PAC temperatures: 10,000

C to
14,000

C (18,000

F to 25,000

F)


Plasma arc generated between
electrode in torch and anode
workpiece


The plasma flows through
water
-
cooled nozzle that constricts and
directs stream to desired location

©2007 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

3/e

Applications of PAC


Most applications of PAC involve cutting of flat
metal sheets and plates


Hole piercing and cutting along a defined path


Comparable to laser cutting, but cuts are
usually is more course


Can cut any electrically conductive metal


Most frequently cut metals: carbon steel,
stainless steel, aluminum

©2007 John Wiley & Sons, Inc.
M P Groover,
Fundamentals of
Modern Manufacturing

3/e

Important: Water Jet, Laser, Plasma


Need to start the cut away from the wanted
cut to prevent a rough surface irregularity
where the cut starts

Starting cut

Wanted cut

Summary of Cutting
Processes for Sheets
and
Plates in terms of Quality & Cost

Quality

(In terms of
tolerances &
surface finish

Cost

Punching/
Blanking

Plasma

Water Jet

Wire EDM

Machining

Laser