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Machinist 3 > Abrasives/grinding > Flashcards

Abrasives/grinding Flashcards

1
Q

Abrasives offer high metal removal rates, great precision and the ability to machine intricately shaped parts. Allows for tight tolerances and provides good surface finish. T or f

A

Truw

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2
Q

5 types of abrasives

A

-emery
-silicon carbide
-almunim oxide
-diamond
-CBN carbon boron nitride

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3
Q

___ also caller conundrum, is the best know if the natural abrasives and has been used for many centuries in the form of loose grain, coated abrasives and eventually grinding wheels

A

Emery

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4
Q

___ produces a very hard and sharp abrasive grain. Has black silicon for low strength material ie. Cast iron, aluminum and non metallic materials. And green silicon carbide for sharpening cemented carbide.

Made of silica sand and petroleum coke

A

Silicon carbide

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5
Q

___ is the most common abrasive. Used for cutting steel and other ferrous alloys. Found on most bench or pedestal grinders for sharpening twist drills, hss lathe tools. White or light gray in appearance

A

Aluminum oxide

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6
Q

The hardest abrasive. Used for finishing carbide and ceramic cutting tools. Used for cutting granite, concrete, glass and other similar substances. Typically used for non ferrous and non metallic materials

A

Diamond

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7
Q

___ is a synthetic abrasive second in hardness only to diamond. It is most useful for grinding hard and tough allot steels or tool steels having a hardness of 50 RC or more

A

CBN cubic boron nitride

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8
Q

4 types of abrasives and their hardness

A

Diamond- 7000
Cbn - 4700
Silicon carbide - 2480
Aluminum oxide- 2100

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9
Q

The American national standards institute (ANSI) has developed such a system and Canadians have adopted it. There is 1 numbering system for aluminum oxide and silicon carbide and another system for diamond wheels. T or f?

A

True

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10
Q

Aluminum oxide and silicon carbide wheels consist of these 5 standard elements

A

Abrasive 1st
Grains size 2nd
Grade 3rd
Structure 4th
Bond type 5th

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11
Q

Letter designation for aluminum oxide and silicon carbide

A

A for aluminum oxide
C for silicon carbide

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12
Q

Grit sizes are subdivided into 4 groups

A

Very fine
Fine
Medium
Coarse

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13
Q

The ___ of the grinding wheel is a measure of strength of the bond between the grains. A wheel with a strong bond is said to be hard, a weak bond releases the grain easily such a wheel is said to be soft

A

Grade or hardness

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14
Q

The grade of a wheel is specified by the third element in designation, which consist of letters A(softest) to Z (hardest) t or f?

A

True

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15
Q

Structure of a wheel refers to the size of the open spaces (or voids) between the grains. If these voids are large, the wheel is said to be open. If the voids are small the wheel is said to be closed or dense. T or f

A

True

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16
Q

The structure of a grinding wheel is specified by the fourth element in the designation, which consist of a number from 1-16 (1 having the highest density) t or f?

A

True

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17
Q

Bond type is identified by a letter standing as the fifth element in the designation, t or f?

A

True

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18
Q

Types of bonds and letters

A

Vitrified- V *most common
Resinoid -B
Resinoid reinforced- BF
Rubber- R
Rubber reinforced - RF
Shellac- E
Silicate- S
Metal-M

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19
Q

The designation for diamond wheels is similar to the designation used for aluminum oxide and silicon carbide wheels with these 4 differences

A

-7 elements instead of 5
-abrasives are identified by different set of letters
-fourth element identifies the concentration of abrasives
-seventh element identifies the depth of abrasive layer

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20
Q

5 shapes of grinding wheels

A

-straight
-tapered
-cylindrical
-straight cuo
-flaring cup

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21
Q

___ grinding wheels are used for surface and cylindrical, tool grinding, offhand grinding and snagging

A

Straight grinding wheel

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22
Q

___ grinding wheels have a taper on both sides and are used for snagging type operations

A

Taper grinding wheel

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23
Q

___grinding wheels are used on horizontal and vertical spindle surface grinders. Cutting takes place mainly on the face

A

Cylindrical grinding wheel

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24
Q

___ are used for both surface grinding, tool and cutter grinding. The edge may be plain or bevelled

A

Straight cup grinding wheel

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25
Q

___ are used almost exclusively on tool and cutter grinders. If the bond is resinoid, the wheel may be used for snagging

A

Flaring cup grinding wheel

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26
Q

___ is a process whereby a revolving grinding wheel is used as a cutting tool to produce either a flat surface or an irregular contour on a workpiece. The workpiece is passed under the grinding wheel at a controlled rate

A

Surface grinding

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27
Q

Surface grinders are classified according to the orientation of the spindle and the type of table motion. 4 types of surface grinders are

A

-horizontal spindle with reciprocating table
-horizontal spindle with rotary table
-vertical spindle with reciprocating table
-vertical spindle with rotary table

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28
Q

This is the most common type of surface grinder and is often referred to as a tool room grinder or simply a horizontal surface grinder

A

Horizontal spindle with reciprocating table

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29
Q

This surface grinder leaves the wheel in constant contact with the workpiece and leaves a circular pattern finish, which is desirable for metal to metal sealing of mating round parts

A

Horizontal spindle with rotary table

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30
Q

This grinder uses a cylindrical or straight cup grinding wheel mounted on a vertical spindle. The wheel cuts on its face and rim and the wheel can be tilted a few degrees to increase pressure on the rim where the wheel makes contact with the workpiece

A

Vertical spindle with reciprocating table

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31
Q

This surface grinder is used for grinding large plates flat and parallel and is considered to be the most efficient because the wheel is in constant contact with the work.

A

Vertical spindle with rotary table

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32
Q

A surface grinding table is traversed manually with the ___ and crossfed manually with a ___

A

Table traverse hand wheel

Crossfeed hand wheel

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33
Q

2 types of magnetic chucks are

A

Electromagnetic

Permanent

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34
Q

An ___ uses electricity to produce the magnetic field necessary to hold the workpiece. The major drawback of electromagnetic chuck is that if the power fails, the grinding wheel throws the wp off the table

A

Electromagnetic chuck

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35
Q

On a ___ the holding power is provided by a series of permanent magnets fastened in a silicon iron grid separated by grid conductor bars

A

Permanent magnetic chuck

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36
Q

5 magnetic chuck accessories

A

Adapter plate
Magnetic chuck blocks
Magnetic blocks
Magnetic sine chuck
Magnetic vise clamps

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37
Q

3 types of grinding fluids

A

Soluble oil and water- used for light to moderate stock removal

Chemical grinding fluids- for moderate to heavy stock removal where surface finish us required

Straight grinding oil- lacks cooling ability of other fluids but offers superior accuracy, finish and permits grinding of very hard material

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38
Q

3 methods od delivering coolant on a surface grinding machine

A

-Flood cooling system
-through wheel cooling system
-mist cooling system

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39
Q

___ grinding is used for any surface that is not flat, such as angles, radii or irregular profiles. It involves dressing the wheel to the mirror image of the desired contour

A

Form grinding

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40
Q

__ grinding is capable of much higher metal removal rates than other types of grinding. A very large depth of cut sometimes in excess of 1inch is combined with a very low feed rate

A

Creep feed grinding

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41
Q

The purpose of a cylindrical grinder is to finish a shaft to a precise size and shape and to impart an excellent surface finish. 2 main types of cylindrical grinders are

A

Center and centerless

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42
Q

Center type of grinders are for custom, one off work and are the type most commonly used in a general purpose machine shop. Centerless grinders are for production work, t or f?

A

True

43
Q

There are 2 types of center grinders

A

-plain center grinder - used primarily for manufacturing

-universal center grinder- more versatile since both wheel and headstock can be swiveled to allow the grinding of tapers

44
Q

__ grinding uses the face of the wheel to grind a steep taper or irregular profile I to the workpiece. The wheel head is fed straight in

A

Plunge grinding

45
Q

___ grinding is performed on cylindrical and centerless grinders with specially dressed wheels matching the shapes if the threads. Threads produced by grinding are the most accurate of any manufacturing process and have very fine surface finish

A

Thread grinding

46
Q

Common problem when internal grinding when the stone first enters the work

A

Bell mouth shaped hole

47
Q

The purpose of ___ is to restore the cutting qualities of the wheel by removing worn or loaded grains

A

Dressing

48
Q

The purpose of ___ is to ensure the grinding wheel is round and concentric with the machines spindle axis and to shape the face of the wheel

A

Truing

49
Q

3 tools used for dressing and truing wheels

A

-star wheel dresser
-abrasive stick and wheels
-diamond dresser

50
Q

A ___ is a quick means of dressing and truing a wheel, although it is not an accurate means. Used on off-hand rough/grinding machines and not on precision grinding machines

A

Star wheel dresser

51
Q

An __ is guided across the face of the wheel by hand and is typically used to shape wheels on tool and cutter grinders. Made of silicon carbide with a hard bond

A

Abrasive stick and wheels

52
Q

A ___ is used for surface, cylindrical and internal grinders and consists of either a single diamond point or a cluster of small diamonds. Most precision grinders have a built in dresser with a feeding mechanism

A

Diamond dresser

53
Q

Do NOT use a diamond dresser on a diamond wheel or CBN wheel, t or f

A

True

54
Q

5 steps to installing a grinding wheel

A

-inspecting
-mounting
-balancing
-truing/dressing
-secondary balancing and truing

55
Q

Many cracks are too fine to be seen during a visual inspection. Perform a ___ to check for these cracks.

A

Ring test

56
Q

There should be approximately 0.005in clearance between the bore of the grinding wheel and the spindle adapter. If it’s too tight, scrape the bore, too loose, install a sleeve. T or f

A

True

57
Q

The flanges on a grinding wheel should be the same size as each other and not less that 1/3 diameter of the wheel, t or f

A

True

58
Q

A ___ is a piece of paper fitted between the grinding wheel and flanges

A

Blotter

59
Q

___ is a machining operation that uses a long, straight, multi toothed cutting tool. It is guided past or through a workpiece, leaving a precise, smooth and often intricately shaped surface. Has teeth like a file but wirh each tooth a little higher than the one before it

A

Broaching

60
Q

Most broaching is ___ , meaning that it takes place inside a pre drilled hole

A

Internal broaching

61
Q

4 advantages of broaching

A

-High production rate
- very precise. Up to .0005 tolerance
-produce surface finish as fine as 32
-certain tasks can’t be done any other way ie small internal gears

62
Q

2 limitations of broaching

A

-cannot be used on a blind hole or cut up to a shoulder

-cannot be used for one off xustom work. The cost of the broach can be justified only for high volume work or for often repeated tasks

63
Q

Besides the common shop application of cutting internal keyway with a broach and arbor press, machine broaching is used for mass production. Common in automotive/aircraft industry. T or f

A

True

64
Q

There should always be atleast 2 teeth in contact with the workpiece when broaching. T or f

A

True

65
Q

The overall length of a broach is the length of the cutting area plus the shank at each end of the broach, t or f?

A

True

66
Q

Most vertical broaching machines pull the broach because a pulled broach is less likely to break, distort or be misaligned. The most common type of vertical broaching machine pulls the broach up and is called a ___ type machine

A

Pull up

67
Q

___ broaching machines have a much longer stroke than vertical broaching machines and theu generally pull rather than push. Better suited for operations requiring a very long broach

A

Horizontal

68
Q

A rotary broaching tool is also called a __ broaching tool, for cnc lathes, mills and screw machines is a precision method for producing internal and external polygon forms at an extremely fast rate

A

Wobble

69
Q

Rotary broaching produces a very accurate form. Although the broaching tool is held at a 1deg angle, the incline is so slight that the resulting dimensional accuracy matches the cutting tool. Can hit .0005 tolerance. T or f

A

True

70
Q

__ are grooves running along a shaft. These grooves matecup with similar grooves in a hub or bore ro provide a positive drive. Is much stronger than a keyed assembly

A

Splines

71
Q

2 main types of splines

A

Involute splines

Straight sided splines

72
Q

An ___ spline is so called because the teeth have an involute shape, just like teeth on a spur gear. The most widely used standard is the American national __ series

A

Involute

73
Q

3 advantages of involute spline over straight sided splines

A

-can transmit more torque
-can be cut in a similar manner as standard involute gear teeth
-self centering

74
Q

Involute splines are usually formed by hobbing, rolling, broaching or on a gear shaper. T or f

A

True

75
Q

An __ spline is so called because the teeth have an involute shape, just like teeth on a spur gear. Most used standard for it is the American Involute series

A

Involute spline

76
Q

3 advantages of an involute spline

A

-transmit more power
-require specialized cutters but can be cut in similar manner as standard involite gear teeth
-are self centering

77
Q

Straight sided splines have the advantage of being easier to make and design than involute splines. Straight sided splines are not as standardized as involute splines, t or f?

A

True

78
Q

Most common straight side spline is the SAE type, which is available in 4 series..what are the 4

A

-4 spline
-6 spline (3/4-3in dia)
-10 spline
-16 spline (3/4 - 6in dia)

79
Q

On a ___ spline, the sides of the teeth contact each other. Clearance exists between the top and bottom of the mating teeth

A

Side fit

80
Q

On a ___ fit spline, no clearance exists between the major dia of the external spline and the major dia of the internal spline, the sides of the teeth act as drivers. Only used with 30deg pressure angle

A

Major diameter fit

81
Q

3 standard pressure angles on splines

A

30 - most common
37.5
45

82
Q

The ___ denotes the radial distance from the pitch circle to the major diameter of the external spline or distance from the pitch circle to the minor diameter of an internal spline

A

Stub pitch

83
Q

A spline is identified by the # of teeth. For example, a spline having 6 teeth is called a six spline, t or f

A

True

84
Q

Some precautions should be taken when manufacturing long splines. Do not attempt to machine splines to finish size one at a time. Always take roughing and finishing cuts and mill on opposite sides, t or f?

A

True

85
Q

The purpose of a ___ is to make production work faster and more accurate, it quickly positions a workpiece in relation to the cutting tool, thereby eliminating the need for a layout

A

Fixture

86
Q

Fixtures does not guide the cutting tool, although some fixtures have a ___ for aligning the tool with the workpiece. Fixtures are typically used in milling machines, lathes and grinders

A

Setting block

87
Q

3 advantages of using a fixture

A

-Semi skilled operates can mass produce parts using fixtures
-parts in a fixture are interchangeable
-skilled machinist can use a fixture to hold a wp that may be difficult or impossible to hold any other way

88
Q

A __ locates and holds the workpiece and guides the cutting tool. Typically used on drill presses

A

Jig

89
Q

The purpose ofna fixture is to prevent the workpiece from moving or rotating in space. There are 6 ways an object can move called the ___

A

Degrees of freedom

90
Q

The ability to move in a straight line along an axis is called a ___. There are 3 axis to move along (x,y,z) so there are 3 __

A

Freedom of translation

91
Q

The ability to rotate around an axis is called ___. There are 3 axes to rotate around so there are 3 ___

A

Freedom of rotation

92
Q

Sometimes a workpiece can be put into a fixture more than one way. If so, use a ___ or other similar feature to make it impossible to load the wp incorrectly

A

Fouling pin

93
Q

3 parts of a fixture

A

-base aka frame
-locators
-clamps

94
Q

The ___ also known as a frame, is the underlying structure of the fixture. Can be custom made from cast iron or a general purpose one can be purchased from a catalogue

A

Base

95
Q

___ ensure the workpiece is held in it’s correct orientation. They can take many forms, depending on the nature of the wp

A

Locators

96
Q

___ hold the workpiece in place against the locators. Like bases and locators, it can be custom made or bought from a catalogie

A

Clamps

97
Q

The most efficient way to locate a workpiece is to use a __ in a cylindrical feature on the wp such as a reamed hole

A

Cylindrical locator

98
Q

A __ is used for locating against outside diameter of a cylindrical feature on the workpiece

A

Vee locator

99
Q

Irregular workpieces like castings and forgings can be positioned by visually lining them up with a ___

A

Sighting plane

100
Q

A __ or 2 point clamp is designed to clamp 2 wp at the same time

A

C- clamp

101
Q

Single or plain fixtures hold only 1 wp at a time and multiples fixtures hike several identical wp at the same time
T or f?

A

True

102
Q

A ___ fixture holds several workpieces in a line so they can all be machined in 1 pass of the cutter.

A

String milling fixture

103
Q

Most turning and boring fixtures are mounted on the faceplate of a lathe, but few are mounted directly to the spindle, t or f?

A

True

104
Q

___ fixtures are used on cylindrical grinders, surface grinders, tool and cutter grinders

A

Grinding

Machinist 3 (6 decks)

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