CNC Machining

Question 1

why CNC machining

Answer 1

manufactures complex/imposible jobs (2D and 3D contours)
- improve quality and accuracy
- stabilize costs

Question 2

What does CNC mean

Answer 2

Computer Numerical Control

Question 3

Product quantity, Q
(annual quantity)

Answer 3

Low production 1 to 100 units
Medium production 100 to 10,000 units
high production 10,000 to millions of units

Question 4

Soft vs hard product variety

Answer 4

soft- small difference b/t products
hard - products differ a lot

Question 5

what are the three basic types of automation

Answer 5

1. hard (fixed) automation - fixed configuration
2. programmable automation - allows for diff parts
3. soft (flexible) automation - no lost production time when making changes

Question 6

what is computer numerical control (CNC)

Answer 6

A form of programmable automation in which
the mechanical actions of a piece of equipment
are controlled by a program containing coded
alphanumeric data

Question 7

what does the data represent in CNC

Answer 7

relative positions between a workhead (e.g., a cutting tool) and a workpart

Question 8

What does NC operating principle control

Answer 8

the motion of the work head relative to the work part and to control the sequence of motions

Question 9

What are the 3 components of a CNC System

Answer 9

1. Part program - commands to be followed (cad converted to this )
2. Machine control unit (MCU) - converts to assembly language (0 and 1)
3. Processing Equipment - does the sequence of processing steps

Question 10

What are the NC Coordinate systems

Answer 10

• 3 linear axes (x, y, z)
• 3 rotational axes (a, b, c)
  *do not require all 6 axes and rotational is used to access different surfaces

Question 11

What are the 3 basic categories of motion systems

Answer 11

1. point to point
2. straight cut control (continuous)
3. Contouring (continuous)

Question 12

what is the relation ship between speed and resolution

Answer 12

high speed - bad resolution
low speed - good resolution

Question 13

what are benefits of cnc

Answer 13

• Reduced non-productive time
  – Results in shorter cycle times
• Lower manufacturing lead times (cad to manufacturing process)
• Simpler fixtures
• Greater manufacturing flexibility
• Improved accuracy
• Reduced human error

Question 14

What are the 2 basic types of control in numerical control

Answer 14

1. open loop system (no feed back - used for simple shapes)
2. closed-loop control system (uses feedback to verify positions)

Question 15

what does an optical encoder do?

Answer 15

improves accuracy and resolution

Question 16

What do ball screws do

Answer 16

minimizes backlash

Question 17

What happens if u have more axis

Answer 17

You have less resolution and accuracy (u do get more movement tho) - cost increases too - reduces machining time

Question 18

interpolation idk

Answer 18

moving in 2 axis does not result in a straight line