CNC Punch... Poor finish!!

[JamesH]

I'm using a EUROMAC punch with RADAN software. When i am punching especiallly 3mm sheets, the finish is terrible. It is so ragged and holes sometimes dont look like holes. for 1mm and 1.5mm sheets i am using 0.3 CL dies. For 2mm and 3mm i am using 0.6 CL dies. Am i doing something wrong in regards to the programming and tooling or is it something wrong with the machine etc? I check the punches and dies regularly and also sharpen on a regular basis. Any help would be much appreciated.

[angelw]

Originally Posted by JamesH

I'm using a EUROMAC punch with RADAN software. When i am punching especiallly 3mm sheets, the finish is terrible. It is so ragged and holes sometimes dont look like holes. for 1mm and 1.5mm sheets i am using 0.3 CL dies. For 2mm and 3mm i am using 0.6 CL dies. Am i doing something wrong in regards to the programming and tooling or is it something wrong with the machine etc? I check the punches and dies regularly and also sharpen on a regular basis. Any help would be much appreciated.

Hi James,
Poor finish on the actual shear surface is generally caused by:
1. poor finish of either, or both the Punch and Die
2. excessive clearance between the Punch and Die
3. Blunt cutting edged of either, or both the Punch Die

Excessive clearance can have a profound effect on the cut finish, with material type and thickness being major considerations when determining the best clearance. Generally, you won't go far wrong using 16% of the sheet thickness as the clearance amount.

Spraying the sheet with penetrating oil or kerosene also helps, particularly in sticky material like aluminum and mild steel.

Regards,

Bill