Self Study

Question 1

What are sliding bearings?

Answer 1

Bearings where two surfaces move relative to each other without benefit of rolling contact.

Question 2

What does a shaft do?

Answer 2

the component rotates and transmits power from a driving device through a machine

Question 3

What is Turning and Boring used for?

Answer 3

To machine internal and external surfaces of components with rotational symmerty

Question 4

7 Turning/Boring operations

Answer 4

Turning
Facing
Parting off
Boring
Drilling
Form Cutting
Thread Cutting

Question 5

In Turning what is the swing?

Answer 5

The maximum diameter of work which can be rotated

Question 6

Typical accuracy of turning and boring?

Answer 6

0.01 mm but is dependent on material and diameter

Question 7

How does milling take place?

Answer 7

The workpiece is clamped to a movable table and the tool is rotated about either a vertical or horizontal axis

Question 8

What is milling?

Answer 8

Multiple point cutter removes metal normally to create a flat surface although free form surfaces can be created using computer and numerical control

Question 9

Accuracy of milling

Answer 9

typically 0.05 mm but depends on the size and material being machined

Question 10

What is drilling and reaming used for?

Answer 10

Create blind of through holes by cutting process.

Holes are drilled in rough machining and reaming gives the final finish to achieve close tolerances

Question 11

Explain the process grinding

Answer 11

Abrasive material removal which is generally a finishing process. It is only suitable for hard materials

Question 12

Typical accuracy of grinding

Answer 12

0.005mm

Question 13

Why do discontinuous chips occur?

Answer 13

The material fractures ahead of the tool, indicating a poor choice of cutting condition

Question 14

3 things about continuous chips

Answer 14

1. Represent the ideal cutting for ductile materials
2. Results in long tool life and good surface finish
3. Very long chips can be dangerous and difficult to handle so chip breaker are often employed to break the chip up, this reduces the chance of injury and makes the chips easier to dispose

Question 15

5 reasons coolants area used

Answer 15

1. to reduce friction
2. to reduce the tool/work temperature
3. to wash away chips
4. to inhibit corrosion
5. to reduce built up edges on tools

Question 16

4 desired characteristics of cutting tools

Answer 16

1. have high hardness
2. be tough
3. have excellent abrasion resistance
4. be able to withstand high pressures

Question 17

What is high speed steel used for and why?

Answer 17

single point tools and twist drills
mostly in job shop type environments where productivity rats are not high.
HSS retains its hardness up to 600C

Question 18

3 things about cast alloy tips

Answer 18

can be brazed or mechanically fastened to a holder
normally a high cast alloy which produces very hard carbides can retains its hardness up to 900°C
they are cast in ceramic mould because the material is difficult to machine

Question 19

4 Things about cemented carbide tips

Answer 19

Sintered from powder
Retains hardness up to 1000°C
Less brittle than cast alloy tips
commonly used where high production rates are required

Question 20

Define the clarification of task

Answer 20

functions and constraints are documented in a detailed design spec

Question 21

Define conceptual design

Answer 21

involves the establishment of function structures in the search for solution principles and their combination into design variants

Question 22

Define embodiment design

Answer 22

determines the layout and forms and develops the artifact in accordance with technical and commercial considerations

Question 23

Define detail design

Answer 23

lays down the final form, arrangement, dimensions and materials of all individual parts
manufacturing instructions are produced

Question 24

What are the elements of a design specification

Answer 24

Requirements
constraints
criteria
context of use
open remarks or questions

Question 25

Define abstracting

Answer 25

ignoring what is particular or incidental and emphasizing what is general and essential

Question 26

4 reasons the weighting an rating method bad?

Answer 26

1. subjective and arbitrary
2. numerical answers can be given too much importance. the number implies a precision that isn’t there
3. the multiplication makes the method sensitive to small changes
4. users an become good at making sure the rating give the answer they want

Question 27

What is shearing?

Answer 27

when a shape is cut from sheet metal by shearing the sheet between a punch and die

Question 28

Difference between punching and blanking

Answer 28

Punching the slug is discarded

Blanking the slug is retaining

Question 29

5 types of shearing operations

Answer 29

Parting
perforating
notching
slitting
lancing

Question 30

What do grip rings do?

Answer 30

improve the finish on the edge of a blanked part

it prevents movement of the sheet and allows the clearances to be reduced whilst producing a very smooth edge

Question 31

Three problems with sheet bending?

Answer 31

minimum bend radius
springback
bending forces

Question 32

define the minimum bend radius

Answer 32

the smallest radius which the sheet can be bent to without tensile fracture occurring on the outside of the bend

Question 33

Typical values of the minimum bend radius

Answer 33

when t is the thickness it varies from 0 to 6t