Brass CDA360 Material Hole Finishing Problem

[TCLB]

Hi, can anybody help me to solve the finishing problems of the hole(Dia 1.05*Depth 6mm Thru hole). As the holes are critical, need to view under 20x micro-scope.

Presently, cutting condition : Horizontal Milling m/c, with water base coolant.
Drill reamer is used, cutting at the speed of RPM5000, Feedrate: 100mm/min
Problems encounter:
1) very fine powder formed at the side of the hole wall (can't remove by air blow).
2) Entering portion encounter double tone ie 2 difference type of colour tone.
(Surface Rough at start about 0.5 to 1mm length)
3) Tested to Brush thru the wall with Micro-abrasive Bush, scratches formed.

[gibbsman]

see next post

[gibbsman]

I believe your problem is too slow of a feedrate. Reamers need approximately 1/4 of the drilling speed for the same material and a fast feedrate. I would try 4600 RPM & about 200 to 300 mm/min, this is assuming that you are using a 4 flute reamer. You should also only be leaving about .006" on dia. for reaming.

[TCLB]

Thanks for you help ==>gibbsman, finishing result much much better. Do you have any idea to remove the tiny particle (look like tearing chip) in the holes ? As this particle turn to become tiny nodules after plating.