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Millwright Level 1 > Grinders > Flashcards

Grinders Flashcards

1
Q

What test do you preform before installing a new wheel? How is it done?

A

Ring test

Support the wheel by its bore and tap around it with a non metallic object. If you hear a dull noise the wheel is cracked and must be thrown out.

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2
Q

What rpm do you use?

A

The one suggested by the manufacture. Never use the a wheel with the wrong rpm.

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3
Q

What is the gap your tool rest should be at?

A

1/16

Never more then an 1/8

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4
Q

When grinding thin metal what must you do?

A

Always use the tool rest. Thin metal can jam on wheel and kick back.

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5
Q

What causes excessive vibration?

A

Unbalanced wheel
Bent or worn shaft
Bad bearings

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6
Q

What are the main types of hand grinders?

A

Bench - sharpening cutting tools
Pedastool - larger more powerful then bench

Side wheel grinder - grinding wheel is flat vs convex like a bench grinder
Angle of work rest does not change as wheel gets smaller.

Belt grinders - grinding and polishing. Useful for quickly deburring

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7
Q

What are grinders typically used for?

A

Sharpening cutting tools
Deburring
Chamfering (when precision is not crucial)

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8
Q

What angle do wheel guards extend past the vertical?

A

30-45 degrees

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9
Q

Where is the best location for the tool rest to be mounted?

A

1/16 away from wheel and just above centre.

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10
Q

What happens when to much pressure is applied?

A

Work overheats

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11
Q

What is a side wheel grinder best used for?

A

Sharpening carbide cutting tools

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12
Q

What is the main use of belt grinders?

A

Grinding and polishing operations.

Good for deburring quickly after use of a cutoff saw

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13
Q

What are the 4 types of wheels?

A

Wire wheels-used to clean work piece

Buffering wheels-used to polish work piece to high lustre

Grinding disc-cut off operations

Sanding discs-light finishing

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14
Q

What are the two types of abrasives for grinding wheels?

A

Natural abrasives-crocus, aluminum oxide, emery, Diamond.

Manufactured abrasives-silicone carbide, cubic baron nitrate, synthetic diamonds.

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15
Q

What are the 4 properties of abrasives?

A

Hardness-the ability of a material to scratch another material

Heat resistance-the ability of a material to withstand heat without becoming dull.

Toughness-the ability of a material to resist impact and pressures

Friability-the ability of material to fracture under stress.

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16
Q

What are the three grits?

A

Course

Medium

Fine

17
Q

What is a bond?

A

Bond holds the grain together.

18
Q

What are 3 common bonds?

A

Vitrified-(V) speeds up to 6500 rpm

Resinous-(B) speeds from 9500 rpm and 16000

Rubber-(R) speeds up to 16000

19
Q

What are the 6 positions of wheel identification?
Acronym: AGGSBM ALL GOOD GRADES SHOULD BE MILLWRIGHTS

A 
A Position 1-abrasive type
G Position 2-grain size 
G Position 3-grade
S Position 4-structure or density
B Position 5-bond type
M Position 6-manufacture’s record
20
Q

What are the tools used to dress a wheel?

A

Mechanical dresser - lugs down on tool rest

Abrasive sticks

Abrasive wheels

Diamond dressers - very fine finish required

21
Q

When can you grind on the side of the grinder wheel?

A

Only if the wheel is rated for side grinding

22
Q

Nut on right hand side of grinder has which hand thread?

Nut on left hand side of grinder has which hand thread?

A

Right hand

Left hand

23
Q

Spark plate gap should be 1/16 to ____?

A

1/4

24
Q

What is the blotter wheel?

A

Paper attached to the side of the grinding wheel to protect the flanges from abrasive grits of the wheel and to display important information about the wheel. Also serve to compensate for uneven surfaces. Never mount a wheel without a blotters on both sides

25
Q

Aluminium oxide abrasives are indicated on the blotter by a letter A and are used for?

Silicone carbide abrasives are indicated by a letter C on the blotter and are used for?

A

Grinding steel

Grinding carbide and non ferrous metals

26
Q

When tightening grinding wheel why is it important not to over tighten?

A

Grinding wheels are brittle and break easily. Starting torque of the grinder tends to tighten the nut

27
Q

When dressing a wheel why is it important to always wear a mask?

A

Abrasive grinding wheels create harmful dust

28
Q

When a grinding wheel is glazed it means?

A

Abrasive particles have become dull making the wheel shiny.

29
Q

A loaded grinding wheel means?

A

Abrasive particles become jammed with material being ground. Where takes on colour of the material being ground

30
Q

What is truing a wheel?

A
31
Q

If vibration on the wheel persist after balancing what do you do?

A

Remove wheel and check shaft for runout and bearing condition.

Millwright Level 1 (24 decks)

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