Based on the component drawing, a lot of informations are needed to be fed into the control unit for processing and machining. The informations include dimensions, shape, cut- ting speed, feed, depth of cut, sequence of operations, tool and work material. The said informations should be fed into the machine control unit in an acceptable form. Preparation of the instructions in the above form is known as programming.
A series of instructions describing the part to be produced in an acceptable form to the control unit or computer is known as part program. Generally part programming is done by the following methods.
- Manual part programming
- Computer assisted part
APT (Automatically Programmed Tools), ADAPT, EXAPT, SPLIT, PROMPT are some of the high level languages used for writing NC programs.
Advancements in NC Machines
After the modern micro-processor based computers took control of the NC system, the technology in this field has grown tremendously. Following are two major advancements of NC system.
- Direct Numerical Control (DNC)
- Adaptive Control (AC)
Direct Numerical Control (DNC)
A manufacturing system in which several NC machines are connected to and controlled by a remotely located main frame computer, is known as Direct Numerical Control. The basic constituents of the system are
(i) Main frame computer (ii) Bulk memory
(iii) Nerwork system and (iv) NC machine tools.
DNC system eliminates the need of separate machine control units, input media like punched card and tapes. This system looks after the scheduling of work of all the NC machine tools. The required network system may be a LAN (Local Area Network) or a WAN (Wide Area Network).
Adaptive control is a system in which an important feature of decision making is employed during machining. When a component is being manufactured, some important process variables like torque, force and temperature are measured. These values are compared with established limits. On comparison, the process of production is modified by the adjustment of cutting speed, feed and depth of cut. This system enables cost effective, quality and high rate of production.