Precision Machining Technology - Section 8 - Unit 1 - CNC Basics

Which coordinate system uses an angle and a distance to identify the a position?

Polar Coordinate System

What is another name for the Cartesian coordinate system?

Rectangular Coordinate System

Explain the benefits of using the incremental programming system verses the absolute system.

Repetitive motions can be more easily computed and programmed.

What is the name of the character that ends each line of code?

Semicolon

What is the name for the type of motor used to drive CNC axes that is also capable of recording axis position?

Servo Motor

Supposing a programmer, using absolute mode, mistakenly entered z-3.689, when he or she intended to enter z3.689? Describe what would happen, and how far the actual position would be from the intended position.

The tool would move in the -Z direction instead of the +Z, likely resulting in a collision with the workpiece or table.

Explain the purpose of the safe-start portion of a CNC program.

To cancel all modal codes that may be left over.

Briefly describe a ball screw and a linear guide.

A ball screw is a screw and nut assembly running on ball bearings. A Linear guide is a way and carriage which which run on ball bearings.

What is an ATC?

Automatic Tool Changer

What is a modal code?

Codes that remain active until canceled.

Explain the benefits of using the absolute programming system versus the incremental system.

Errors will not accumulate, generally simpler to program.

List four G-codes and describe their function.

G1 = Feed in straight line. G0 = Rapid positioning. G91 = Activate incremental programming. G2 = Clockwise arc

List four M-codes and describe their functions.

M8 = Coolant On. M9 = Coolant off. M3 = Spindle motor forwards. M9 = Spindle off.

What is an MCU?

Machine Control Unit