PRODUCTION PROCESSES AND EQUIPMENT

1
PRODUCTION PROCESSESAND EQUIPMENT

• Kristo Karjust

MET0180_Basic of Production Engineering
2
Cutting processes will divide

• Mechanical cutting processes
• Electrical and chemical cutting processes
• Thermal cutting processes.

3
Mechanical cutting processes
Chip-removal operations
Turning
The turning process is characterized by solid
work material, two-dimensional forming and a
shear state of stress. The workpiece (W) is
supported clamped in a chuck (C) and supported
by a center and rotated (the primary motion R).
Through the primary motion (R) and the translator
feed (Ta axial feed for turning and Tr radial
feed for facing) of the tool (V) the workpiece is
shaped.
4
Possible workable shapes and typical turning
tools
Turning is used primarily in the production of
various cylindrical components with nearly
unlimited number of external and internal axial
cross-sectional shapes (including tapers, threads
etc.). Facing is used for both regular and
irregular shapes. Turning is the most extensively
used industrial process, because it is quite
cheap and easy.
In the turning process is important workpiece
quality, for instance if we want to get surface
quality IT6, then blank quality should be IT7.
The material should not be too hard (HBlt300) and
should possess a minimum of ductility to confine
deformation mainly to the shear zone. Generally
turning provides close tolerances, often less
than 0.01 mm. Tighter tolerances may be
obtained. The surface roughness after turning is
in the range 0.02 Ra 3.2 µm and quality at
least IT6.
5
Cutting-Tool Geometry
Tool geometryexternal turning 18.
6
Lathe cutting equipment
A wide variety of lathes are on the market for
instance, the engine lathe, the turret lathe,
single- and multispindle screw machines,
automatic lathes and NC lathes. In figure 1.1.1.3
is shown some lathes. Lathes are most frequently
used machine in industry, because they are
available in a wide range of sizes.
Horizontal lathe and vertical lathe
If heavy and large workpieces are to be machined,
the horizontal lathe is impractical. Therefore,
the vertical boring mill, which can be considered
as a vertical lathe, has been developed 2.
7
Drilling
The drilling process is characterized by solid
work material, two-dimensional forming and a
shear state of stress. The workpiece (W) is
clamped on a table (B) and the tool (V) is given
a rotation (the primary motion R) and translator
feed (T). In drilling lathes, the workpiece is
rotated and the feed is applied to the tool.
8
Thrust forces and torque in drilling operation
18.
9
The drilling process is primarily used to produce
interior circular, cylindrical holes. Through
various tools (twist drills, combination drills,
spade drills, etc.) different hole shape can be
produced as cylindrical holes, drilled and
counterbored, drilled and countersunk, multiple
diameter holes, etc. drilling is an important
industrial process. Plants and equipment. Twist
drills are manufactured in a wide variety of
types and sizes. Various surface treatments such
as cyaniding and nitriding are applied to
high-speed-steel drills in order to increase the
hardness of the outer layer of material. Special
polishing and black oxiding are beneficial to
minimize friction between the drill and the
workpiece or the chips in the flutes.
10
Drilling
Spiraalpuur
Spiraalpuur puidule
Reguleeritav puur
Tapipuur
Tüüblipuur
11
Betoonipuur
Betooni haamerpuur
Freespuur
Freespuur
12
Juhtmepuur
Keermepuur
NC-tsentripuur
Oksapuur
Astmeline puur
13
Kooniline plekipuur
Kooniline plekipuur
Puur kahhelkivile
Tsentripuur
14
Topelttsentripuur
Tsentripuur
15
Milling
The milling process is characterized by solid
work material, two-dimensional forming (one
dimensional forming may be used in a few cases)
and a shear state of stress. The workpiece (W) is
clamped on the table (B), which is given a
translatory feed (T), that together with the
primary motion (R) of the cutter (V) provides the
many geometrical possibilities.
16
(No Transcript)
17
The milling process, through the various types of
cutters and the wide variety of machines, is a
versatile high-production process. Typical
milling cutters like arbor-mounted cutters (a)
and shank mounted (b) cutters. Milling cutters
are usually made of hard alloys, sometimes also
diamonds and metal ceramics. Hard alloy cutters
permit roughness in steel Rz 1...2 ?m and cast
Rz 4...7 ?m. Generally diamonds and metal
ceramics cutters is used quit little, because
they are slight 5.
18
Kalasabafrees
Otsfrees
2-he teraline sõrmfrees
Sõrmfrees 2-he teraline soonfrees
19
Mitmeteraline sõrmfrees laastujagajaga
3-me teraline sõrmfrees
Mitmeteraline sõrmfrees
Otsraadiusega sõrmfrees
Ümardusfrees- sõrmfrees
T-soonefrees
20
Kõvasulamplaadiga nurgafrees
Kõvasulamplaadiga otsfrees
Kõvasulamplaadiga sõrmfrees
21
There are a - key-seating milling with disk
cutters b - slot milling with disk cutter c -
difficult contour cutting with different cutters
(1,2,3,4,5) d angle milling with angle cutter
e - T- slot milling with T-slot cutter f- step
milling with end mill g slot milling with
T-slot cutter h two sided angle milling with
angle cutter i incline surface milling with
tool bit angle cutter. Generally the milling
process comes close to turning in extensive
industrial use, since the geometrical
possibilities are enormous and the removal rate
high 3.
Typical milling operations
22
Surface quality and accuracy. The hardness of the
material should not be too high ( HB lt 250 300)
and a minimum of ductility is advisable. The
obtained tolerances are 0.05 mm, surface
roughness is 3.2 Ra 6.3 µm and the quality
IT7. Manufacturing depends on material structure
and strength 5
Cutting action in up-and-down milling 18.
23
Many different milling machines are on the
market for instance universal column-and-knee-typ
e milling machines (plain column-and-knee-type
milling machines supplied with a swivel on the
saddle, enabling helices to be cut when swiveling
the work table), ram-type milling machines and
planer-type milling machines. Milling machines
can also be used for drilling and boring. Milling
machines are among the most important machine
tools, as they can produce wide variety of
machined surfaces 2.
Horizontal milling machine and plain
column-and-knee-type milling machine
24
Reaming
Reaming is a sizing or scraping operation in
which the tool cuts slightly larger than its own
diameter, usually direct proportion to the amount
of stock to be removed. For efficient operation,
reamers must be cutting at all times, which is
possible only when they are being used in
properly drilled holes. Removal of too much stock
by reaming often causes oversize and rough holes.
Surface quality and accuracy. We can ream
cylindrical and conical holes, different
materials like steel, cast iron, colored metals
and alloys. Accuracy is generally 5..6 IT and the
surface roughness will normally be in the range
0,08 lt Ra lt 0,63 µm
25
Product design factors related to reaming
26
Plants and equipment. A reamer is a rotary
cutting tool, generally of cylindrical or conical
shape, intended for enlarging and finishing holes
to accurate dimensions. It is usually equipped
with two or more peripheral grooves or flutes,
either parallel to its axis or in a right-or
left-hand helix as required. Those with helical
flutes provide smooth shear cutting and produce a
better finish. The flutes form cutting teeth and
provide grooves for removing the chips.
Commercial types of reamers
27
Broaching
Broaching is a high-production metal removal
process that sometimes is required to make
one-of-a-kind parts. Broaching is at its best in
machining simple surfaces or complex contours.
Properly used modern broaching processes can
greatly increase productivity, hold tight
tolerances, produce precision finishes and
eliminate the need for highly skilled machine
operators. The length of a broaching tool is
determined by the practice by the amount of stock
to be removed and limited by the machine stroke,
bending moments, stiffness, accuracy and other
factors. The length of an internal push broach
should not exceed 25 times the diameter of the
finishing teeth, a pull broach usually is limited
to 75 times the finishing diameter.
28
Standard broach part and nomenclature 18.
29
The broaching tool may be pulled or pushed across
a workpiece surface or the surface may move
across the tool. Internal broaching requires a
starting hole or opening in the workpiece for
insertion of the broaching tool. The final shape
may be a smoother, flatter surface, a larger hole
or a complex splined, flanged, toothed, notched,
curved, spiral or irregularly shaped section.
Possible workable shapes
30
Examples of types of broaching tools
31
A simple classification scheme for broaching
machines
Surface quality and accuracy. Generally any
material that can be machined can be broached.
Good tolerances can be obtained ( 0.1 mm 0.02
mm) and accuracy generally IT 7. The surface
roughness will normally be in the range 0,8 lt Ra
lt 2,0 µm 5.
32
Planing
The planning process is characterized by solid
work material, two-dimensional forming (sometimes
one-dimensional forming) and a shear state of
stress. The workpiece (W) is clamped on the table
(B), which is given a translatory primary motion
(Tb) and the tool (V) is given a translator feed
(Tv), providing the geometrical possibilities2.
The hardness of the material should generally not
exceed HB 300 and a minimum of ductility is
advisable. Planing depends on material structure
and strength. Surface quality depends on cutting
velocity and depths. The obtained tolerances are
normally 0.05 to 0.10 mm and accuracy
generally IT 3..4. The surface roughness is in
the range 0.63 Ra 2.5 µm 5.
33
There are used straight and clinced planing
cutters in planing machines. a straight
cutters b loop cutters c expansive loop
cutters d edge cutters e slash cutters.
There are many different types of planing
machines like pit-type planer, double housing
planer, open-side planer, edge or plate planers.
34
The planing process is in general used to produce
large horizontal, vertical, inclined flat
surfaces, also T slot and angle-shape grooves.
Some planing examples are shown in figure, where
a horizontal, vertical and incline surface
planing b groove planing c T slot planing
d angle planing e dificult surface planing.
35
Grinding
The grinding process is characterized by solid
work material, two-dimensional forming
(one-dimensional may occur) and a shear state of
stress. The workpiece (W) is supported between
centers (P) or clamped on a table (B) and given a
rotary (R) and translatory (T) feed. The tool V
(the grinding wheel) is given a rotary primary
motion (Rv) and depending on the particular
process, sometimes a feeding motion also.
Tolerances are around 0.001 mm and surface
roughness is 0,04 µm lt Ra lt 0,32 µm. the surface
accuracy should be at least IT 7 and in plain
grinding IT 6. The grinding processes have a low
material removal rate 5.
36
where a straight profile plain wheel, which is
used for cylindrical, internal, center less and
surface grinding b, c conical profile plain
wheels, which are used for thread, gear etc.
grinding d opened hole plain wheels, which are
used for cylindrical and surface grinding e
sheet wheels (thickness 0.5 5 mm), which are
used for cutting f, g, h band and pan wheels,
which are used for flat grinding.
37
The grain size of the abrasive is an important
factor in selecting the correct grinding wheel.
Grain sizes are classified in accordance with an
international mesh size in mesh/inch, ranging
from 8 (coarse) to 1200 (super-fine). In the
case of diamond and boron nitride grinding
wheels, European grinding wheel manufacturers
indicate grain size by the diameter of the
abrasive grains in microns
38
The most frequently used grinding tool is the
grinding wheel used for cylindrical or plain
grinding. Grinding offers close dimensional
control and fine surface finishes and has become
extremely important in recent years, because of
the increasing demands of high accuracy and
surface quality. Formerly grinding was used
only for finishing operations, but rapid
development is taking place with regard to
roughing (high-speed) grinding, which may
substitute for turning and milling 2.
39
The grinding processes are used primarily in
finishing cylindrical or flat surfaces which have
been produced by various other processes.
Different grinding operations.
40
Today roughing grinding including profile
grinding at high cutting speeds, can sometimes
substitute for turning, milling or planing.
Different grinding operations.
41
Typical grinding machines (A) grinding wheel
(B) workpiece
42
Honing
Honing is a low-velocity abrading process using
bonded-abrasive stick for removing stock from
metallic and nonmetallic surfaces. As one of the
last operations performed on the surface of a
part, honing generates functional characteristics
specified for a surface and involves the
correction of errors resulting from previous
operations. Functional characteristics generated
by honing include geometric accuracy, dimensional
accuracy and surface character (roughness, lay
pattern and integrity)
In honing the tolerances are around 0.001 mm
and surface roughness is 0,08 µm lt Ra lt 0,32 µm.
The surface accuracy should be at least IT 6 and
in flat honing IT 4. 5, lk2900
43
Common types of fixtured honing tools
44
The most common application of honing is on the
internal cylindrical surfaces. However, honing is
also used to generate functional characteristics
on external cylindrical surfaces, flat surfaces,
truncate spherical surfaces and toroidal surfaces
(both internal and external).
Honing operations (A) internal cylindrical
surface honing (B) external cylindrical surface
honing (C) flat surface honing (1) tool (2)
workpiece
45
Electrical and chemical finishing processes

• Electrical, chemical and electrochemical
  machining are relatively new methods of removing
  metal directly by electrical, chemical and/or
  thermal energy and without mechanical forces.
• Such processes have been called nonconventional
  or nontraditional, several them (especially
  electrical-discharge machining, electrochemical
  machining and electrochemical grinding) are now
  being widely used and should be considered with
  the standard manufacturing methods.

46
Electrical discharge machining (EDM)
Electrical-discharge machining (EDM) is a method
of removing metal by a series of rapidly
recurring electrical discharges between an
electrode (the cutting tool) and the workpiece in
the presence of a liquid (usually hydrocarbon
dielectric). Minute particles of metal or chips
(generally in the form of hollow spheres) are
removed by melting and vaporization and are
flushed from the gap between tool and work.
Basic components of an electrical discharge
machine
47
Types of power-supply circuits used for EDM
48
The EDM tool electrode is the means by which
electric current is transported to the work
piece. Shape of the electrode establishes a
pattern whereby sparks will occur between the
tool and work piece and the desired shape will be
machined. Shapes machined are the opposite of the
electrode shapes. A requirement for any
material used for an EDM electrode is that it be
a conductor of electricity. Insulating materials
are not usable. A wide variety of materials are
used in the manufacture of electrodes. Most used
materials are graphite, copper, brass, copper
tungsten, silver tungsten, carbide and zinc
alloys.
49
The several methods of introducing dielectric
fluid to the arc gap fall into four broad
classifications normal flow reverse flow jet
flushing immersion flushing.
Several methods of introducing dielectric fluid
Generally the surface roughness is Ra 1,6...3,2
µm, but it could be also 0,05...0,1 µm. Generally
EDM provides close tolerances, often 50 µm and IT
7.. As a result, the smoothness of surfaces
produced by EDM is generally limited more by
economics than by the technological potential of
the process.
50
Electrochemical machining
Electrochemical machining (ECM) is important
method of removing metal without the use of
mechanical or thermal energy. Electric energy
is combined with a chemical to form a reaction of
reverse plating. Direct current at relatively
high amperage and low voltage is continuously
passed between that anodic work piece and
cathodic tool (electrode) through a conductive
electrolyte. At the anode surface, electrons
are removed by the current flow and the metallic
bonds of the molecular structure of this surface
broken. These surface atoms proceed to go into
solution as metal ions. Simultaneously positive
hydrogen ions are attracted to the negatively
charged surface and emitted at the cathode
surface to form hydrogen atoms, which combine to
form hydrogen molecules. Dissolved material is
removed from the gap between work and tool by the
flow of electrolyte, which also aids in carrying
away the heat and hydrogen formed.
51
Schematic of arrangement for electrochemical
machining
52
Schematics of electrochemical machining (ECM)
operations. (a) die sinking (b) shaping of
blades (c) drilling (d) milling (e) turning
(f) wire ECM (g) drilling of curvilinear holes
(h) deburring and radiusing.
53
A typical ECM machine consists of a table for
mounting the work piece and a platen mounted on a
ram or quill for mounting the cathode tool,
inside an enclosure. The work piece is mounted
on the table and connected in a manner ensuring
good electrical contact to the positive side of
the power supply. The tool is mounted on the
platen, with electrical connection to the
negative side of the power supply. Electrolyte
is pumped under pressure between the work and
tool. As the tool feeds into the work with
current flowing, the electrolyte carries away
machining products.
54
Electrochemical machining equipment schematic.
(1) tool electrode (2) finishing workpiece (3)
tank of electrolyte (4) clamping system (5)
electrolyte supply system (6) power supply. 6
55
Materials used for ECM tools must have good
electrical and thermal conductivity, be corrosion
resistant and machinable, and be stiff enough to
withstand the electrolyte pressures without
vibrating or distorting. Copper, brass, bronze,
copper-tungsten, stainless steel and titanium are
most frequently used. Graphite can also be used,
but it must be coated to prevent rapid erosion.
The tools must be smoothly finished to assure
uniform electrolyte flow and produce good surface
finishes on the work.
Cathode accuracy directly affects product
accuracy in ECM, because the product cannot be
more accurate than the cathode tool whish
produced it. Part accuracy is also affected by
irregularities in electrolyte flow or current
flow. Average surface finishes obtained range
from 0,1 to 1,0 ?m and accuracy IT 7 5.
Applications. Major advantages of the ECM process
include stress and burr-free machining, no
burning or thermal damage to workpiece surface
and elimination of tool wear. Small thin disks
are being consistently machined to tolerances
within 0,007 mm on such machines. Die sinking is
a major application with over cut throughout the
surface being consistently maintained within 0,05
mm. Aircraft and aerospace components are
frequently produced with this method because the
high-strength, temperature resistant materials
used are difficult to machine in other ways.
56
Electrochemical discharge grinding
Electrochemical discharge grinding (ECDG),
sometimes called ECDM grinding, is a combination
of electrochemical grinding (ECG) and electrical
discharge grinding (EDG), with some
modifications. Most of the stock is removed by
ECG, with the oxides that from on the positively
charged workpiece surfaces being removed by the
intermittent spark discharges of EDG. A bounded
graphite wheel without any abrasive grains is
used and the conductive electrolyte is generally
a water solution of inorganic salts. Alternating
current or a pulsing type d-c circuit at
relatively high amperage and low voltage, is used
to obtain random spark discharges. No arc or
spark suppressor circuit is required, since the
work is held in direct contact with the wheel
under low pressure. For profile grinding, the
workpiece is traversed along the periphery of a
performed wheel.
57
Electrical discharge grinding.
58
Wheel rotation is necessary in ECDG to introduce
clean electrolyte through the gap and reduce the
possibility of gap-spark information. Rotation
also increases electrolyte pressure at the gap
and helps to avoid electrolyte boiling.
Accuracy can be held to ? 0,01 mm under carefully
controlled conditions and about ? 0,02 mm in
normal operations (IT 5-6). A surface finish of
0,2 ?m can be obtained in grinding tungsten
carbide with the ECDG process. Applications.
An advantage is the use of a low cost wheel.
Application of this process, howerver, has been
limited 5.
59
Photochemical machining

• Photochemical machining or chemical blanking is
  the process of producing metallic and non
  metallic parts by chemical action.
• The process consists of placing a
  chemical-resistant image of the part on a sheet
  of metal and exposing the sheet to chemical
  action which dissolves all the metal except the
  desired part.
• The photographic-resist process of photochemical
  machining is by far the most common one in use
  today.

60
Metal can be chemically cleaned in numerous ways,
including degreasing, pumice scrubbing, electro
cleaning or chemical cleaning. The cleaned metal
is coated with photographic material which, when
exposed to light of the proper wavelength, will
polymerize and remain on the panel as it goes
through a developing stage. This polymerized
layer then acts as the barrier to the etching
solution applied to the metal. After coating with
resist, it is necessary to bake the panel prior
to exposing it. This is used to drive off
solvents in a simple drying operation. The
metallic coated panel is placed between sets of
negatives (either film or glass) and is clamped
by either vacuum or pressure. Certain resist
require an additional baking operation following
development. The next step is etching to remove
the unwanted metal unprotected by the photo
resist.
61
Process steps involved in the photographic-resist
process of photochemical machining
62
Applications. The use of photochemical machining
is generally limited to relatively thin
materials, from 0,002 to 1,2 mm thick. The limit
on material thickness is generally a function of
the tolerance desired on finished parts.
Photochemical machining has a number of
applications wherein it provides unique
advantages, for instance

• work on extremely thin materials where handling
  difficulties and die accuracies preclude the use
  of normal mechanical methods
• working on hardened or brittle materials where
  mechanical action would cause breakage or
  stress-concentration points
• production of parts which must be absolutely
  burr-free
• production of extremely complex parts where die
  cost would be prohibitive 5.

63
Thermal finishing processes
Ion beam machining

• Ion beam machining (IBM) is sometimes considered
  a thermoelectric process, but it does not rely
  primarily on heating the workpiece locally to the
  evaporation temperature.
• Instead it depends on sputtering and therefore
  differs fundamentally from electron- or
  laser-beam machining.
• In this sputter etching process, bombarding ions
  disclose surface atoms by the transfer of kinetic
  energy from the incident ions.

64

• The use of IBM to provide selective removal of
  material has found only limited commercial
  application, mostly in micromachining.
• Ion beam equipment can be designed having greater
  resolution than equivalent energy electron beam
  equipment.
• Limitations include the relatively high cost of
  the capital equipment and the extremely slow
  stock removal rate.
• IBM equipment using a d-c power source is simpler
  in less expensive, but it can be used only for
  etching conductive materials. For dielectrics
  more costly radio frequency equipment must be
  used.
• Little heat is generated in the process, but the
  workpiece can be cooled to increase removal rate.
  One application is etching surfaces of specimens
  prior to studying their microstructure.
• A promising application is etching circuit
  patterns on integrated- circuit substrates.
• Advantage over chemical etching is better
  resolution, since undercutting is eliminated and
  there is no need to rely on powerful enchants
  that can propagate along cracks and possible
  degrade the photoresist mask.
• Also IBM can be used to etch multilayered
  structures regardless of the materials.

65
Ion beam machining equipment
Ion-beam machining is a precise process. Because
of the small beam diameter, tolerances of ?
0,001nmm can be held (IT 2-3). Surface roughness
is normally in the range Ra 1 ?m 1.
66
Electron beam machining

• Electron beam machining (EBM) uses electrical
  energy to generate thermal energy for removing
  material.
• A pulsating stream of high-speed electrons
  produced by a generator is focused by
  electrostatic and electromagnetic fields to
  concentrate energy on a very small area of work.
• High-power beams are used with electron
  velocities exceeding one-half the speed of light.
  As the electrons impinge on the work, their
  kinetic energy is transformed into thermal energy
  and vaporizes the material locally.

67
Electron-beam machining
The electron beam is formed inside an electron
gun which is basically a triode and consists of
cathode which is a hot tungsten filament emitting
high-negative-potential electrons, a grid cup
negatively biased with respect to the filament
and an anode at ground potential through which
the accelerated electrons pass.
68
EBM is generally limited to drilling extremely
small holes and cutting narrow slots or contours
in thin materials to close tolerances. There is
no tool wear or pressure on the work. Stock
removal rate is generally about 1,5 mm3/s. Using
this process, it is possible to drill a
cross-shaped hole, for example, through a piece
of stainless steel 1 mm thick. Extremely high
energy density makes it possible to drill the
hole while, a few thousandths of an mm away from
the wall of the hole, the work piece remains at
room temperature. We can make hole which diameter
is 1,5 mm and length 10 mm. Any known material,
metal or nonmetal that will exist in high vacuum
can be cut. Electron-beam machining is a
precise process. Because of the small beam
diameter, tolerances of ? 0,001 to 0,005 mm can
be held (IT 2-3). Surface roughness is normally
in the range Ra 5-20 ?m 1.
69
Laser beam machining (LBM)

• Laser beam machining (LBM) is based on the
  conversion of electrical energy to light energy
  and then into thermal energy.
• In a typical system, electrical energy stored in
  capacitors is discharged through a gas-filled
  flash lamp to produce an intense flash of white
  light. Radiation from the lamp is directed into
  the laser, where the light is amplified and
  emitted as a coherent, highly collimated beam of
  single wavelength.
• This narrow beam is focused by an optical lens to
  produce a small intense spot of light on the work
  surface. Optical energy is converted into heat
  energy upon impact and temperatures generated can
  be made sufficient to melt and vaporize every
  known material.
• Low efficiency with respect to power consumption
  and slow stock removal make this process costly.

70
Typical setup for laser beam machining
71
Laser-beam machining.
72
Many types of lasers exist which produce highly
directive beams of optical or infrared radiation.
They can be classified as solid-state, gas or
liquid. Solid-state units have laser rods made of
any one of a number of a number of solid
materials including ruby, neodymium-doped glass
and neodymium-doped yttrium-aluminum-garnet
(called YAG). Gas units have glass tubes filled
with CO2, helium-neon, cadmium gas or argon
(figure 3.10.3). Only a few of the many types of
lasers are practical for metalworking. Ruby
lasers produce the highest energy and peak power
outputs, but they cost more. They generally used
where a large amount of material must be removed
with a single pulse. CO2 lasers are most
efficient with respect to converting electrical
energy to laser light energy. They are
generally used in a repetitively pulsed mode for
metalworking and are sometimes assisted by air,
inert gas or oxygen to facilitate coupling energy
from the beam to the work piece.
73
Solid-state laser
CO2-, N2-, He- laser
74
To meet the basic requirements for industrial
applications, the laser systems must meet the
following specifications

• sufficient power output
• controlled pulse length
• suitable focusing system
• adequate repetition rate
• reliability of operation
• suitable safety characteristics.

75
Machining of small holes in thin parts is a
typical application. The process is being used
to pierce diamond wire-drawing dies and to remove
metal from work pieces without stopping their
rotation during dynamic balancing. Other
applications include hole drilling, resistor
trimming and scribing of silicon wafers. It
should be emphasized that laser is unlikely to
replace any of the common drilling processes, but
rather will continue to supplement them and
enhance productivity. One of the present
drawbacks in laser applications is cost.
76
Other limitations include low efficiency, slow
repetition rate, limited durability and
reliability, and the necessity for careful
control and effective safety procedures.
Because of the lasers ability to melt or
vaporize any known metal and operate in any
desired atmospheric environment, it is sometimes
preferred over EBM. Other advantage include the
ability to machine areas not readily accessible
and extremely small holes, the fact that there is
no direct contact areas between the tool (laser)
and the work piece, small heat affected zones,
and easy control of beam configuration and size
of exposed areas. 5 To the sheet metal we can
machine 60 240 holes/minute. Surface roughness
is Ra 0,4...0,10 µ m, which depends workable
material and machining process. Structural
changes could be in depth 1...100 µm 1.
77
Ultrasonic machining

• Ultrasonic machining uses high frequency
  vibrations in a cleaning system.
• In the process a cleaning solution is subjected
  to the rapid oscillation of longitudinal waves,
  identical to audible waves but of higher
  frequency.

78
Before ultrasonic can be used effectively, it is
important to realize the following

• Parts to be cleaned must be immersed in a liquid
• The entire volume of liquid must be supplied with
  ultrasonic energy
• The use of ultrasonic does not eliminate the need
  for cleaning chemicals.

79
Workpieces to be cleaned are placed in the
solution and the rapid oscillation of the
solution resulting from the high-frequency sound
waves creates minute vapor voids in the solution
that implode against the workpiece and
effectively clean its surfaces. Mechanically
held contamination is released from the surfaces,
soluble materials are rapidly dissolved and oil
and similar contaminants are easily emulsified.
Industrial ultrasonic cleaning systems are
composed of three basic components generator,
transducer and tank containing the cleaning
solution. The generator transforms standard line
current of 50 or 60 Hz into desired higher
frequency. This high-frequency current is
converted into sound waves (mechanical energy) of
a corresponding frequency via a transducer, which
radiates the waves into a cleaning solution in
the tank.
80
Ultrasonic machining scheme
81
There are two major types of ultrasonic cleaning
units integrated and modular. Integrated units
have all components, including the tank for the
cleaning solution in a single enclosure. Modular
systems consist of a separate generator linked to
either tanks equipped with transducers or
immersible transducers. The number of
transducer elements per tank is determined by the
tank volume and its designated power rating. It
is important that the selected tank and generator
have matched ratings for power and frequency,
otherwise serious damage will result, usually the
generator. Tank heating is the common option
for tanks with transducers and is specified by a
majority of users to keep the cleaning solution
at its best temperature for cavitations and
cleaning effectiveness.9
82
Plasma-Beam Machining

• Plasma-beam machining (PBM) removes material by
  using a superheated stream of electrically
  ionized gas.
• The 20,00050,000F (11,00028,000C) plasma is
  created inside a water-cooled nozzle by
  electrically ionizing a suitable gas, such as
  nitrogen, hydrogen, or argon, or mixtures of
  these gases.
• The process does not rely on the heat of
  combustion between the gas and the workpiece
  material, it can be used on almost any conductive
  metal.
• Generally, the arc is transferred to the
  workpiece, which is made electrically positive.

83

• The plasmaa mixture of free electrons,
  positively charged ions, and neutral atomsis
  initiated in a confined, gas-filled chamber by a
  high-frequency spark.
• The high-voltage dc power sustains the arc, which
  exits from the nozzle at near-sonic velocity. The
  high-velocity gases blow away the molten metal
  chips.
• Dual-flow torches use a secondary gas or water
  shield to assist in blowing the molten metal out
  of the kerf, giving a cleaner cut.
• PBM is sometimes called plasma-arc cutting (PAC).
  
• PBM can cut plates up to 6.0 in. (152 mm) thick.
• Kerf width can be as small as 0.06 in. (1.52 mm)
  in cutting thin plates.

84
Plasma-beam machining 18.
85
Plasma-beam machining
86
Water-Jet Machining

• is low-pressure hydrodynamic machining. The
  pressure range for WJM is an order of magnitude
  below that used in HDM.
• There are two versions of WJM one for mining,
  tunneling, and large-pipe cleaning that operates
  in the region from 250 to 1000 psi (1.7 to 6.9
  MPa) and one for smaller parts and production
  shop situations that uses pressures below 250 psi
  (1.7 MPa).

87
Water-jet machining.
88

• The first version, or high-pressure range, is
  characterized by use of a pumped water supply
  with hoses and nozzles that generally are
  hand-directed.
• In the second version, more production-oriented
  and controlled equipment is involved.
• In some instances, abrasives are added to the
  fluid flow to promote rapid cutting.
• Single or multiple-nozzle approaches to the
  workpiece depend on the size and number of parts
  per load.
• The principle is that WJM is high-volume, not
  high-pressure.

89
Water-jet machining
90
Rapid Prototyping and Rapid Tooling

• In the past, when making a prototype, a
  full-scale model of a product, the designed part
  would have then machined or sculptured from wood,
  plastic, metal, or other solid materials.
• Now there is rapid prototyping, also called
  desktop manufacturing, a process by which a solid
  physical model of a product is made directly from
  a three-dimensional CAD drawing.

91
Rapid Prototyping using laser to photopolymerize
the liquid photopolymer.
92
Rapid Prototyping using Sintering Process
(powder).
93

• Rapid prototyping entails several different
  consolidation techniques and steps resin curing,
  deposition, solidification, and finishing.
• The conceptual design is viewed in its entirety
  and at different angles on the monitor through a
  three-dimensional CAD system.
• The partis then sliced into horizontal planes
  from 0.004 to 0.008 in. (0.10 to 0.20 mm).
• Then a heliumcadmium (HeCd) laser beam passes
  over the liquid photopolymer resin.
• The ultraviolet (UV) photons harden the
  photosensitive resin. The part is lowered only
  one layer thickness.

94

• The recoater blade sweeps over the previously
  hardened surface, applying a thin, even coat of
  resin.
• Upon completion, a high-intensity broadband or
  continuum ultraviolet radiation is used to cure
  the mold.
• Large parts can be produced in sections, and then
  the sections are welded together.
• Other techniques, such as selective laser
  sintering (SLS) (Fig. 60), use a thin layer of
  heat-fusable powder that has been evenly
  deposited by a roller. A CO2 laser, controlled by
  a CAD program, heats the powder to just below the
  melting point and fuses it only along the
  programmed path.

95
1. Vällo, A. Eritöötlusviisid. TTÜ. Tallinn,
1994, 69 p. 2. Alting, L. Manufacturing
engineering processes. New York. 1994, 492 p. 3.
Ostapenko, N. Krapivnitski, N. Metallide
tehnoloogia. Tallinn, 1975, 297 p. 4. Poluhhin,
P.I. Grinberg, B.G. Metallide tehnoloogia.
Tallinn, 1969, 424 p. 5. Daniel B.Dallas. Tool
and manufacturing engineers handbook. SME, 1976,
2932 p. 6. Cotell, C. Sprague, J. ASM Handbook.
Volume 5. Surface Engineering. ASM International.
1994, 1039 p. 7. Handbuch feubearbeitung.
Prof. Werner Degner, Hans-Christian Böttger. VEB
VERLAG HECHNIK. Berlin, 1979, 474 p. 8.
Delstar Metal Finishing Inc. Electropolishing.
Houston, Texas, 1998, 25 p. 9. Veilleux, F.R.
Tool and manufacturing engineers handbook. Volume
3. Materials, Finishing and Coating. SME, 1985,
2530 p. 10. AFP/SME. Finishing processes Tech
Trends 2001, 28 p. 11. MTA/SME. Machining Tech
Trends 2002, 39 p. 12. SlipNaxos AB. Precision
grinding product guide. Sweden. 2000, 4 p. 13.
Uddeholm. Grinding of tool steel. Germany. 1998,
15 p. 14. Lepikson. H. Masinaehitaja käsiraamat
I.Tallinn. 1968, 688 p. 15. Lepikson. H.
Masinaehitaja käsiraamat II.Tallinn. 1971, 868
p. 16. ?????????. ?. ?. ??????????
?????????-???????????????. ??? 1, 1986, 655
c. 17. ?????????. ?. ?. ??????????
?????????-???????????????. ??? 2, 1986, 495
c. 18. Kutz, M. Mechanical Engineers' Handbook.
Third Edition, 2006, 785 p