Tool marks

[jfrandsen]

What is considered a "tool mark" when your using mil-standards? MIL-HDBK-454B to be clear. Do they expect a polished surface when they say no tool marks?

[ctate2000]

Impossible to make a part with no tool marks. Even lapped parts have tool marks, they are miniscule but they are there. To be accurate and proper they should specify a surface finish. A stated finish requirement is measureable, 'no tool marks' is subjective and not measurable.

IMHO 'no tool marks' means hit it with the paper and shine it up.

If you can't make it right, make it bright. They gonna check the ugly ones first.

CT

[roninB4]

Originally Posted by ctate2000 If you can't make it right, make it bright. They gonna check the ugly ones first. CT

That's funny only because it's true, they DO check the ugly ones first.


He's also correct that the customer should have specified a surface finish if they have a finish expectation. All methods do leave a mark of some sort so I wouldn't go any further with the job until the expectations are clearly stated. If you don't then it will be their option to scrap your parts and you'll have to eat the material costs.


Look up "surface finish" or RMS on the internet before you talk to them so you'll sound more knowledgeable than they seem to be. "No tool marks" is the language of those that don't know what they want.

[dertsap]

it only specifies bearing surfaces http://www.google.ca/url?sa=t&source...o4SfLctQVaMDbw

4.3 Bearing assemblies. Bearing assemblies should be free of rust, discoloration, and imperfections of ground,
honed, or lapped surfaces. Contacting surfaces should be free of tool marks, gouge marks, nicks, or other surfacetype
defects. There should be no detrimental interference, binding, or galling.

[ctate2000]

I understand the intent, however I think it is much better practice to specify a surface finish.

I make aerospace parts. We specify a 32 microinch finish for bearing surfaces. I we find a nick, gouge or other imprefection we run the profilometer across it. If the reading comes back over 32 the part is rejected.

I love these discussions, the make me think. Ouch,I will be sore for a week now. I don't get to think much these days, we are a copy and paste outfit.

[dertsap]

Originally Posted by ctate2000 I think it is much better practice to specify a surface finish.

from a manufacturing stand point it is simple common sense to specify a measurable surface rather than some idiot saying its no good because its got a spot on it