Mumbai University > mechanical engineering > Sem 7 > CAD/CAM/CAE

Marks: 5 Marks

Year: Dec 2015

The most common Contouring motion used in APT programming, and these statements specify the tool path continuously throughout the motion.

They make use of three surfaces: (a) drive; (b) check; and (c) part surfaces.

Drive surfaces represent the surface along which the vertical edges of the tool will follow. Part surfaces specify the surfaces the tip of the tool will follow. And check surfaces describe where the tool will come to rest after it has completed the motion of the current step.

There are four locations for the tool to stop with respect to a check surface. These four possibilities each have their own modifier words.

The TO modifier stops the tool when the first surface of the tool would come into contact with the check surface. The ON modifier stops the tool where the center point of the tool would come into contact with the check surface. The PAST modifier stops the tool where the last surface of the tool would contact the check surface. And the TANTO modifier stops the tool at the point of circular tangency with the edge of the tool.

The initial contouring motion statement is the GO/TO, which defines the initial drive, part and check surfaces. It takes the form: GO/TO, drive surface, TO, part surface, TO, check surface.

An example would be:

GO/TO, L1, TO, PL1, TO, L2

Specifying that the tool should use line L1 as the drive surface, plane P1 as the part surface, and line L2 as the check surface.

Continuing contouring motion statements are given from the vantage point of a person sitting on the top of the tool. The motion words are: (a) GOLFT; (b) GORGT; (c) GOFWD; (d) GOBACK; (e) GOUP; and (f) GODOWN.