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Machinist Period 4 2019 Cash > Specialized Manufacturing 150402d > Flashcards

Specialized Manufacturing 150402d Flashcards

1
Q

In EDM, is the electrode negatively or positively charged?

A

Negatively

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2
Q

Dielectric means that the……

A

Fluid is non-conductive.

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3
Q

What are the three most common materials used to make the dies in die sink EDM?

A

Graphite, copper, carbide.

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4
Q

Which die material is cheapest to use?

A

Graphite.

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5
Q

Does the electrode wear faster or slower when the power level is reduced?

A

Faster.

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6
Q

Can wire EDM cut Plastics?

A

Only if the plastic is electrically conductive.

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7
Q

How does the laser beam get to The Cutting head of a laser cutting machine?

A

The laser beam is created in the back of the machine and directed by a series of mirrors to the optic lens in The Cutting head.

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8
Q

What method of operation is used to start a hole in the middle of a workpiece with a laser beam?

A

It’s common to operate the laser in a series of short pulses or bursts of light when starting a cut in the middle of the work.

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9
Q

What is the purpose of assist gasses in a laser cutting operation and what are four common assist gases used?

A

The melted metal called kerf gets blown out of the way by assist gasses before it can set. Oxygen, nitrogen, Argon, and air are all used as assist gasses.

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10
Q

What is the danger in using oxygen as an assist gas in laser cutting?

A

Oxygen sometimes reacts to form a hard layer of oxide.

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11
Q

What is the main disadvantage of using short focal length lenses for laser cutting.

A

Limited to cutting thinner work pieces because beams diverge too quick beyond focal point.

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12
Q

How does a moving beam system on a laser cutting machine work?

A

The laser cutting head moves instead of the table.

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13
Q

Why is it more difficult for a laser to cut copper than mild Steel?

A

Liquid copper is very reflective and very conductive.

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14
Q

What principle does electro-chemical Machining use to remove metal? Is it the same as for EDM?

A

ECM uses a reverse electroplating process to dissolve the metal into solution in a pressurized system of electrolyte. Unlike EDM, no sparks are involved.

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15
Q

What is the difference between the dielectric fluid in the EDM process and the electrolyte in the ECM process?

A

The dielectric fluid in EDM acts as an insulator, creating a spark gap between the electrode and the workpiece. The electrode gets close enough to the work to cause a spark to jump the Gap. The electrolyte in ECM is a conductive solution.

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16
Q

What properties should an electrode have to be effective?

A

Must be made of material that is conductive, rigid, machinable and corrosion resistant.

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17
Q

What are the advantages of ECM over EDM?

A

ECM produces no tool wear, much faster, doesn’t cause hardening or distortion, can machine very thin cross-sections of work without bending or distorting.

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18
Q

Are the abrasive particles on an ECM grinding wheel conductive, and what is their purpose?

A

They are not conductive. Provide grinding assist to the dissolving process.

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19
Q

How do you control porosity obtained in a component made by the powder Metallurgy process?

A

Control the amount of compacting pressure to allow porosity.

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20
Q

What process must green Parts go through before sintering, and why?

A

Place the green Parts in a controlled hot room or oven to sweat out an evaporate any moisture. Otherwise part explodes.

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21
Q

What type of atmosphere are powdered metal components sintered in?

A

Parts are heated in a protective oxygen-free atmosphere containing perhaps nitrogen, anhydrous ammonia, endothermic or exothermic gas.

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22
Q

Three basic thermal spraying processes to build up a workpiece?

A

Wire, powder, plasma spraying.

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23
Q

How do you protect the unsprayed part of a shaft against thermal spray?

A

Coat the metal to be left on sprayed with anti splatter compound or metal flashing.

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24
Q

Why should overspray not be allowed to fall onto the workpiece?

A

Creates a layer of weakly bonded metal. It’s highly undesirable.

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25
Q

Name of thermal spraying which the high temperature of inert gas raises the temp of coating material to between 6500 C and 11000 C?

A

Plasma spraying.

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26
Q

In gundrilling, drilling head has a single______ and two ______ that run against the inside diameter of the hole at 180° and 90° angles to The Cutting Edge.

A

Cutting Edge, bearing points.

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27
Q

A laser Cuts mild steel up to 8 in thick. True or false?

A

False.

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28
Q

The carbon cutting tool in electrical discharge Machining is called the…

A

Electrode

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29
Q

A limiting factor with wire EDM would be that…

A

The workpiece material must be electrically conductive.

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30
Q

The process whereby 90% of the metal is removed by electrolytic chemical action and 10% is removed by a conventional cutting action is called :

A

Electrochemical grinding ECG

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31
Q

Which advanced process uses the cutter as the negative pole/ charge of the process?

A

Electro-chemical Machining ECM

32
Q

The complete powder Metallurgy process involves blending,

A

Mixing, compacting, drying, sintering

33
Q

What are the types of lasers used in industry?

A

Solid, gas, liquid, semiconductor.

34
Q

Waterjet cutting is done with,

A

50000 PSI through a ruby or Sapphire nozzle.

35
Q

The main advantage of electro-chemical Machining is,

A

There is no tool wear caused by spark erosion.

36
Q

Which laser type is commonly used to cut material which is organic in nature?

A

CO2 (gas)

37
Q

The dielectric fluid used for wire EDM cutting is,

A

Deionized distilled water.

38
Q

There are two types of EDM machines, they are?

A

Die sink and wire.

39
Q

Hole making EDM machines use a tubular electric Rod that rotates up to 100 RPM during the drilling process true or false?

A

True

40
Q

In the Wire EDM process, the guides for the wire are manufactured from which material?

A

Diamond

41
Q

What feature in gun drilling allows long drills to hold alignment while Machining?

A

Bearing pads

42
Q

A portable keyseat milling machine is centered on the shaft by which of the following?

A

V base

43
Q

Chips on a gun drill are expelled from the hole by which of the following?

A

Chips are expelled through the inside of the drill.

44
Q

Which specialized Machining process uses both welding and Milling?

A

Hybrid machining-laser deposition welding

45
Q

What size of gap must be maintained for flow in front of electrode?

A

.002”-.003”

46
Q

What materials is the electrode made from?

A

Brass, copper, graphite, stainless steel.

47
Q

The work piece is given a high voltage positive charge, T or F?

A

False. Low voltage negative charge.

48
Q

ECM is how many times faster than EDM?

A

5x

49
Q

In ECG, what percent of metal is removed by chemical and what percent is removed by grinding wheel?

A

90%, 10%

50
Q

In ECG, what materials are grinding wheels made from?

A

Copper, Brass and Nickel.

51
Q

Which laser can be used for engraving?

A

C02 gas laser.

52
Q

Explain wire spraying process.

A

Wire is melted and then sprayed onto work piece.

53
Q

Explain powder spraying process.

A

Work piece is heated and then sprayed onto surface.

54
Q

Explain plasma spraying process.

A

Very high temps are used to spray tough coatings.

55
Q

What is the purpose of coatings?

B.C.P.D.

A

Build up worn or undersized parts
Correct castings
Protect components from corrosion
Deposit hard wear resistant surface onto exposed surface

56
Q

What does HVOF stand for?

A

High Velocity Oxygen Fuel Spraying(Powder Spray).

57
Q

How do you fuse HVOF coating to surface?

A

Heat and pressure.

58
Q

What spraying process used Zirconia, tungsten, alumina, ceramics?

A

Plasma spraying.

59
Q

What process utilizes high depth to diameter ratios?

A

Gun drilling. Up to 300x.

60
Q

What is trey panning?

A

Used to cut large holes in thin mat, using either single point or multi point cutting tool.

61
Q

What is rapid prototyping?

A

An additive process that layers material to build a part.

62
Q

Which process combines both laser deposition welding and machining?

A

Hybrid machining.

63
Q

What process uses a metal powder welded to a base material in thin layers?

A

Laser deposition welding.

64
Q

In die sink EDM electrode is fed into work at a set feed. T or F?

A

True.

65
Q

In wire EDM what is the size of thin brass wire?

A

.010”

66
Q

In wire EDM the wire must constantly be what?

A

Constantly feeding.

67
Q

What is wire EDM’s accuracy?

A

.0005”

68
Q

What EDM machine can tilt spools?

A

Five axis wire EDM.

69
Q

List 8 types of portable machines.

A 
Line boring
Flange facing
CNC mill
Circular mill
Linear mill
Lathe(OD)
ID welder
Keyseat machine
70
Q

Explain annodizing.

A

Converts the surface of aluminum part into very hard, corrosion resistant aluminum oxide finish.
Oxide is porous and colored using dies.

71
Q

What is the maximum mild steel a laser can cut?

A

1 inch

72
Q

In ECG what happens if the abrasive particles don’t maintain the space between the work in the bond?

A

The system short circuits

73
Q

What size range are the electrodes in small hole EDM?

A

.004 in to .250 in

74
Q

To check an air gauge

A

Master ring at upper and lower limit and master ring gauge fron manufacturer

75
Q

To ensure cmm measures properly

A

Calibrate against master ball

76
Q

To face on a boring mill

A

Use face plate and spindle but not at same time

Machinist Period 4 2019 Cash (24 decks)

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