Question

An aluminium component is to be machined on a vertical CNC milling machine. The original stock material is a flat piece having dimensions of 125 x 105 x 10 mm³. The top and bottom surfaces of the finished component are not machined in this operation. All other surfaces and features need to be machined. The finished shape has three Æ20-mm holes machined right through and a slot is machined to a depth of 5 mm. The outside dimensions of the finished item are 120 x 100 x 10 mm³.

The CNC program portion below performs all the machining operations including the finishing cut around the periphery, the three holes as well as the machining of the slot.

A Æ20-mm slot-mill is used for all the machining operations.

1. From the information given above and by analysing the CNC program below, determine the final shape of the finished component. Draw a diagram of the object showing all the relevant dimensions.                              (20 marks)    

2. Indicate clearly on your diagram in part (a) where the “program zero” is best located for this job. How is the “program zero” indicated in the CNC program below?                                            

                                                                                                                                              (5 marks)     

3. List any machining instructions that would be needed for the machine operator including each setup and how the job would be held to the machine table. Describe briefly what change you would need to make to the program below to allow each setup and clamping method to be properly implemented by the machine operator. (10 marks)     

     G00 - rapid feed                                                              M00 - end of program

     G01 - linear interpolation                                              M03 - spindle start

     G02 - circular interpolation in CW direction               G90 - absolute co-ordinates         

     G03 - circular interpolation in CCW direction                F - feed rate in mm/min

                                                                                                                                                               

                                                  

N0005 M03

N0010 G90 G00 Z50.0

N0020 G00 X20.0 Y20.0 Z10.0

N0030 G01 Z-12.0 F100

N0040 G00 Z10.0

N0050           Y80.0

N0060 G01 Z-12.0

N0070 G00 Z10.0

N0080           X100.0

N0090 G01 Z-12.0

N0100 G00 Z10.0

N0110           X20.0 Y50.0

N0120 G01 Z-5.0

N0130           X100.0

N0140 G00 Z10.0

N0150           X-10.0 Y-10.0

N0160 G01 Z-12.0

N0170           X50.0

N0180           Y20.00

N0190           X130.00

N0200           Y90.00

N0210 G03 X110.00 Y110.00 R20.0

N0220 G01 X10.00

N0230 G03 X-10.00 Y90.00 R20.0

N0240 G01 Y-10.0

N0250 G00 Z50.0

N0260 M00

Answer 1

廾ere M03 is spindle stat Goo is Rapid avevse R20.0 0 O 8o 50 2D 5D 130 Block Number urn