Machining

Question 1

Lathes:

Name 4 materials that can be used

Answer 1

Wood
Metal
Plastic
Ceramics

Question 2

Lathes:

What is a spindle? What tool is used to operate it?

Answer 2

> Holds the work piece in place

> Chuck tightens it

Question 3

Lathes:

What is the facing tool?

Answer 3

Squares end of piece my removing material radially

Question 4

Lathes:

What is the parting off tool?

Answer 4

Cuts off the end by cutting directly into the piece radially somewhere in the middle and allowing the end to fall off

Question 5

Lathes:

What is the drilling tool?

Answer 5

The work piece rotates whilst the drill bit stays still

Question 6

Lathes:

What is the boring tool?

Answer 6

Enlarges the internal hole diameter

Question 7

Lathes:

What is the thread cutting tool?

Answer 7

Moves across the piece at a constant speed to produce a thread

Question 8

Lathes:

What is the arithmetic mean roughness, its equation, its units and what tool is used and what is the symbol?

Answer 8

> This is a measure of the roughness of a surface
Ra = (1 / n) × SUM[i = 0 ⇒ n] (yi)
- n = number of samples
- yi = radius of sample point from mean surface radius
Units: μm
Tool: Contact profilometer
Symbol: Like a tick but with a line across to form a triangle and the roughness on top of the triangle

Question 9

Milling:

What is the headstock?

Answer 9

> Where the motor and gearing is held. Also where the tool is held.
It sets the speed of the tool

Question 10

Milling:

What are the different axes? What moves for each one?

Answer 10

> Table moves for x and y axis
Headstock moves for z axis
A adapter can be used to allow the workpiece to rotate in the b axis

Question 11

Milling:

What is face milling?

Answer 11

Creates flat surfaces

Question 12

Milling:

What is end milling?

Answer 12

> Perpendicular to work surface

> Makes trenches

Question 13

Milling:

What is cutting depth capability?

Answer 13

> The ability of the cutting tool to cut without deflecting

Question 14

Milling:

What is the slab milling tool?

Answer 14

> This is used to reduce the thickness of a workpiece by removing large amount of material
The putting direction is the opposite of normal milling

Question 15

What is a work holding device?

Answer 15

Holds parts with awkward geometries

Question 16

What is a jig?

Answer 16

> Holds work
Positions it on the machining tool
Guides the tool

Question 17

What is a fixture?

Answer 17

> Holds the work
Positions it on the machining tool
DOES NOT GUIDE THE TOOL

Question 18

What are the aspects of a fixture?

Answer 18

> Locators
clamps
Setting block (Holds onto work table)

Question 19

Cutting and chips:

What are the two ways of cutting?

Answer 19

> Orthogonal

> Oblique

Question 20

Cutting and chips:

What is orthogonal cutting?

Answer 20

> Tool perpendicular to cut direction

Question 21

Cutting and chips:

What is oblique cutting?

Answer 21

> Tool at an angle to cutting direction

Question 22

Cutting and chips:

What is are the three types of chips?

Answer 22

> Continuous
Discontinuous
Built up edges

Question 23

Cutting and chips:

What conditions produce a discontinuous chip?

Answer 23

> Small chip flow angle
Brittle material
Low cut speed
Thick chips

Question 24

Cutting and chips:

What conditions produce a continuous chip?

Answer 24

> Ductile material
High cutting speed
High chip flow angle
Thin chips

Question 25

Cutting and chips:

How is a discontinuous chip made?

Answer 25

By the chip facturing

Question 26

Cutting and chips:

How is a continuous chip made?

Answer 26

By not fracturing

Question 27

Cutting and chips:

What if discontinuous chips are made with ductile materials?

Answer 27

Then you are using a poor cutting method

Question 28

Cutting and chips:

What is the benefit of producing continuous chip?

Answer 28

> Good finish

> Long tool life

Question 29

Cutting and chips:

Describe built up edges

Answer 29

Material builds up on the ‘rake’ of the cutting tool

Question 30

Coolant:

What is the applications of coolant?

Answer 30

> Reduces friction
> Reduces temperature
> Stops corrosion
> Washes away chips
> Reduces built up edges

Question 31

What are some prerequisites before machining?

Answer 31

> Tool selection
> Depth of cut
> Cutting speed
> Feed
> What machine to use

Question 32

Tools:

What are the 5 types of tools?

Answer 32

> Single point (laithe)
> Multi point (mills)
> Drills
> Reames
> Taps

Question 33

Tools:

What are the main features that are important when selecting a tool type?

Answer 33

> Safety
> Time
> Quality
> Complexity
> Price

Question 34

Tools:

What are some aspects of a workpiece that affect tool selection?

Answer 34

> Hardness of workpiece
Abrasiveness of workpiece
Tensile strength of workpiece
Continuous or discontinuous chips

Question 35

Tools:

Name 6 important features of a tools material choice?

Answer 35

> Hardness (Harder than work piece)
> Operating temp range
> Toughness
> Abrasion resistance
> Pressure resistance
> Chemical inertness

Question 36

Tools:

What are 4 types of materials used for tools?

Answer 36

> Steel alloy
Cast alloy (Lots of carbon)
Cemented carbide
Ceramic tips

Question 37

Machinability index:

What is it?

Answer 37

The relative difficulty for a material to cut another material when compared with steel

Question 38

Machinability index:

What is the equation?

Answer 38

MI = ( Cutting speed for tool life of 20 mins / Cutting speed of SAE1112 Steel for 20 mins ) × 100

Question 39

What is feed rate?

Answer 39

How far the tool moves for one revolution of the part

Question 40

What happens if there is a high or low speed rate?

Answer 40

High: Affects the finish (makes it worse)
Low: Good for finishing operations (makes it better)

Question 41

What is affected by cutting speed?

Answer 41

> Tool wear

> Productivity (speed of production)