Miling

Question 1

What is the main purpose of the pilot hole?

Answer 1

Creating a starting hole in the material, to reduce the lateral force on the drill head (as it doesn’t drill down but only sideways enlarging the hole)

Question 2

describe what backlash is

Answer 2

Uncontrolled movement caused by clearances in the moving parts

Question 3

what is straddle milling

Answer 3

when multiple cutters are spaced out to cut both sides of a workpiece at the same time

Question 4

what is gang milling

Answer 4

you have a ‘gang’ of cutters set up to cut the workpiece at the same time

Question 5

Down Cut Milling ( ad vs dis )

Answer 5

Advantages:
- less workpiece lifting, especially in delicate or thin pieces (less moving due to the direction of cutting)
- reduces splintering, as the force acting compresses material downward
- less power is consumed due to less force being required to cut
disadvantages:
- higher chance of chip recutting (scratching) as there is less swarf removal
- backlash is a major problem, so high rigidity is required

Question 6

Up Cut Milling ( ad vs dis )

Answer 6

advantages:
- better surface finish, due to the upward motion removing the swarf better
disadvantages:
- Upward force causes more wear on the tools
- Tool sharpness is required due to the high forces involved
- chipping due to upward motion

Question 7

describe broaching milling

Answer 7

the tool doesn’t revolve but is pushed or pulled along the axis of the stationary workpiece chipping away material.

Question 8

problems with drilling

Answer 8

• poor heat removal
• poor accuracy/ finish
• swarf removal is difficult

Question 9

define swarf

Answer 9

fine chips or filings of material produced by a machining operation

Question 10

Push broaching vs Pull broaching

Answer 10

Pull broaching the tool being used can withstand higher forces but set is more complicated meaning this process is more time consuming

Question 11

what are the two types of milling machines

Answer 11

vertical and horizontal milling machines

Question 12

Formed surface vs Generated surface

Answer 12

Forming:
- The final component shape is created by a shaped cutting tool.
Gerenating:
- The final component shape is created by moving the cutting tool along a specific path.

Question 13

what is copy milling

Answer 13

The machine follows the original part with a tracer, with the movement being duplicated to generate a replica profile at the exact same time while tracing

Question 14

what is duplex milling

Answer 14

Motion is replicated on both sides of the machine, allowing simultaneous working of both sides of the workpiece, ensuring symmetry.

Question 15

what is a plano mill

Answer 15

Plano mills have multiple cutting heads that can operate independently, vertically, and or horizontally. This allows multiple actions to be carried out on the workpiece at once

Question 16

when would you use a centre drill

Answer 16

A center drill is used to create a precise starting point for drilling a hole or indentation at the center of a workpiece, ensuring accuracy and alignment for subsequent drilling or machining operations. Or for drilling a hole on the axis of a shaft to hold it between centers