Chapter List

Part Overview

PROGRAMMING DATA

CNC machine tools need numerical data in order to control the motion (relationship) between the cutting tool and the workpiece in accordance with the dimensions on a part print. Other numerical data can set feeds and speed rates, define tool identification numbers, and miscellaneous functions related to machining the part. The combination of all the numerical data, in a sequence understood by the machine CNC controller, is called the part program.

Computer Numerical Controls use standard microelectronics modules developed especially for computer hardware. CNC controllers, through one or more microprocessors, can perform the mathematical calculations necessary for complicated moves. Modern CNCs can store a large number of programs and provide displays of tool paths and simulation of the machining operation.

The programmer's function is to take information from an engineering drawing and convert it into data that the control unit of the machine tool will understand. To do this conversion successfully, a programmer must have a good knowledge of machining operations and sequences, workholding methods, metal properties, cutting tools, and cutting speeds and feeds. The programmer must also understand the various codes and functions used in computer numerical control (CNC) so that accurate parts can be produced in the minimum amount of time. It is very important that there be a close liaison between the product engineer, the drafter, and the machine tool operator to ensure that the correct product is produced to the proper size.