Monday, December 3, 2007

What is CNC machine??

CNC MACHINE

Computer control programmers and operators use computer numerically controlled (CNC) machines to cut and shape precision products, such as automobile parts, machine parts, and compressors.

CNC machines include machining tools such as lathes, multiaxis spindles, milling machines, laser cutting, water jet cutting, and wire electrical discharge machines (EDM), but the functions formerly performed by human operators are performed by a computer-control module. CNC machines cut away material from a solid block of metal, plastic, or glass—known as a workpiece—to form a finished part.

ADVANTAGES USING CNC MACHINE

CNC good at making small numbers of compicated shapes but CNC doesn't impose such restrictions, though to get nicely radiused corners, you might have to change tools, to make the last pass.


HOW TO GIVE INSTRUCTION TO CNC MACHINE TOOL??

A line in a G-code file can instruct the machine tool to do one of several things. G-code is a common name for the programming language that controls NC and CNC machine tools. Developed by the Electronic Industries Alliance in the early 1960s, a final revision was approved in February 1980 as RS274D.

sample of G-code:



Code Description
G00
Rapid positioning
G01 Linear interpolation
G02 CW circular interpolation
G03 CCW circular interpolation
G04 Dwell
G05.1 Q1. Ai Nano contour control
G05 P10000 HPCC
G10/G11 Programmable Data input/Data write cancel


THE MOVEMENT OF THE CNC MACHINE

Some machine tools can only do this in XY, and have to accept changes in Z separately. Some have two further axes of rotation to control the orientation of the cutter, and can move them simultaneously with the XYZ motion. Lately 4, and 5 axis machines have become popular. The 2 additional axies allow for the work surface or medium to be rotated around X and Y. For example, a 4-axis machine can move the tool head in XY and Z directions, and also rotate the medium around the X or Y axis, similar to a lathe.This is called the A or B axis in most cases.










HOME MADE CNC MACHINE
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A CNC Milling Machine











A CNC Turning Center









CNC panel Siemens Sinumerik










Siemens CNC panel




source: wikipedia.org, bls.gov, sheldonbrown.com