EXAMPLE

EXAMPLE 1 : NC PART PROGRAMMING

 Aim : Holes of diameter 20mm and 10 mm are to be drilled at positions B and C respectively, on a rectangular plate.

 Let us first recall the steps we will follow if the holes are to be drilled on a traditional way.

  1. First we take edge A as reference

  2. Mark positions of holes B and C as (20,80) and (90,25) respectively

  3. The centers are punched

  4. Drill of 20mm diameter is put in the spindle

  5. Point B is positioned under the drill

  6. Drill rotation is started and feed is given.

  7. The operation is continued till the hole is drilled to full depth

  8. The drill is retracted

  9. The drill is taken out and replaced by another drill of 10mm diameter

  10. Point C is placed under the drill

  11. Drill is rotated, feed is given

  12. Drilling is done

  13. Drill is retracted

  14. Work is removed from the table.

We can write a NC program for the above operations as follows: 

N001 G92 X0 Y0 F0

N002 G90

N003 G81 X20000 Y80000 Z-68000 R-48000 F100 T01 M03

N004 G80 Z0 F0 M05

N005 G81 X90000 Y25000 Z-68000 R-48000 F100 T02 M03

N006 G80 Z0 F0 M05

N007 X150000

N008 M30

Meaning of the program:

N001 G92 X0 Y0 F0: this instruction will make the machine register corner A of the work piece as (0,0) in the control system: the operator shifts work piece such that the corner A is under the spindle. 

N002 G90: this will instruct the machine to follow absolute system, taking A as reference point. 

N003 G81 X20000 Y80000 Z-68000 R-48000 F100 T01 M03

 This line will call the canned cycle for drilling; specify the point for drilling (B: (20,80)), and the vertical distance to be traversed by the spindle and the distance for rapid traverse. Also this will give instruction about feed, tool (diameter 20mm) and spindle start. 

N004 G80 Z0 F0 M05

This will cancel the G81 cycle and bring the tool to Z0 position at zero feed with spindle rotation stopped. * 

N005 G81 X90000 Y25000 Z-68000 R-48000 F100 T02 M03

This line will again initiate canned cycle for drilling, specify new position for drilling (C: (90,25), the vertical distance to be traveled, rapid traverse distance, feed, tool (diameter 10mm). Also it will instruct to start the spindle. 

N006 G80 Z0 F0 M05: will provide information as explained previously (*). 

N007 X150000: Job is removed from the table. 

N008 M30  End of tape (Program).

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