Page 499 - Sensors and Control Systems in Manufacturing

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9.6.2 The Machining Program
The machining program is described in terms of sequences:
1. Clamp drill 1.
2. Set X to 10 and Y to 15.
3. Drill at cutting speed 2.
4. Set X to 95.
5. Drill at cutting speed 2.
6. Unclamp drill 1, clamp drill 2.
7. Set Y to 45.
8. Drill at cutting speed 1.
9. Set X to 10.
10. Drill at cutting speed 1.
11. Remove workpiece.

The positioning data, cutting tool information, and the required
cutting speed must be identified to accomplish any machining opera-
tion. Usually, the technological data such as speed and feed are
included in the tool data sheet. Tool number, speed, feed, and direc-
tion of rotation together form a unit. The feed speed has been omitted
in the preceding program; this decision has been left to the operator.
If the process is to proceed automatically at a later date, this informa-
tion will have to be added.
The positioning data is always referenced from the origin of the
coordinates. In this case, this is always the point of intersection of the
reference lines for the dimensioning of the drawing. The positional
information was therefore given in absolute form and can be pro-
grammed in absolute dimensions.
The information can also be provided relative to the current posi-
tion, which is entered as the x value, and a new value added for the
next position. This is called incremental positioning data. The incremen-
tal positioning data may be expressed as follows:
1. Set X + 10, Y + 15.
2. Set X + 80.
3. Set Y + 30.
4. Set X –80.

Choice of the most suitable method often depends on the dimen-
sioning of an engineering drawing. Sometimes incremental and abso-
lute specifications of positional data are mixed. Then, obviously, it is
necessary to describe the type of data in question.