Hi,

I need to machine through holes, 0.25mm diameter, approx. 2.5mm deep
I need to machine approx. 4000 of such holes. Those holes are located in a single row array. The pitch c/c is 0.4mm.
These holes will be drilled in a die. There will be approx. 30 dies manufactured a year.

I consider drilling those holes in brass (CZ121), mild steel (of average characteristic) and 316 stainless steel

1. My options for brass is micro-milling (least expensive, possible micro hole surface finish problem), EDM hard-tool (probably dearest option, high finish quality),

2. My options for mild and stainless steel - EDM hard-tool.

I also considered micro laser machining, however, I have been informed by a company which provides micro laser machining, that they cannot penetrate a material deeper than 1mm.

I would be very obliged for any suggestions.

Thank you.