I am a project manager. The parts that I had machined (6Al 4V Ti) exhibit a smeering pattern. There is no surface finish call out on these particular parts except in areas noted that must be 32 and 63. The 32 and 63 finishes are fine, it's the smeery finish that is being called into question. i need some advise.
1. Where there is no surface finish call out on the print, what is the surface finish standard that i am safe to assume is acceptable. I thought it would be 125.
2. Does a smeered finish in 6Al 4V TI constitute rejectable condition on unspecified finish?
3. Can re machining these areas clean up the smeered look?
These parts where secitioned and macro photos show no indications of cold work or surface deteriation under 250X. There are no surface cracking or other indications that came though during penetrant inspection.
My customer wants to reject these parts due to the lack of "good workmanship". If there is no surface finish call out on the supplied print I think they should accept the parts. Any thoughts would help.
Sincere thanks to any responses.:
Not to be a 4 legged hoofed pack animal but would you pay for them?
If it isn't a machined finish, and specified or not if I was your customer I would expect a machined finish that could consistently be measured to a tolerance unless noted otherwise. As it was said by another poster without pictures who can really give an opinion, but if you place yourself in the customer's place when you look at the parts that should tell you if you need to ship them or not.
As to the customer's rejection what is the usage of the part? Is it visible in the final assembly? We machine a lot of castings for John Deere Commercial and Turf Care. If there are blemishes in enough castings that are visible after final assembly they will reject a whole shipment, sometimes 500 castings. Despite having a profile tolerance on cast surfaces of 1.5mm they will reject a casting that just doesn't look pretty enough despite it's being in tolerance and we quickly issue a RMA and hustle to replace the shipment while we wait on the return to arrive for sort. Ultimately we strive to satisfy the customer's expectations not just to machine parts that are technically correct.
Last edited by Shotout; 05-03-2009 at 12:22 AM. Reason: Remove quoted text
Suppose you were an idiot and suppose you were a member of Congress. But I repeat myself.
what the final finish is at your stage depends on the operation used, the customer should have some say if the aestetics of the part cannot be achieved, and should be negotiated.2. Does a smeered finish in 6Al 4V TI constitute rejectable condition on unspecified finish?
Yes, you can remove material, buff, grind etc ,,,,but the finished component must still meet dimensional requirements3. Can re machining these areas clean up the smeered look?.
I would check deeper to see if there are general standards applied to the drawing, or to additional notes. Ti parts can be a biitch to get a good acceptable finish if conditions are not spot-on, or if cutting corners to meet quote times etc.My customer wants to reject these parts due to the lack of "good workmanship". If there is no surface finish call out on the supplied print I think they should accept the parts.
If no standard is given, then fault would lie in both ball-courts, negotiate, invite him into the group to work out an acceptable fix to the problem. He may know of a quick solution.
The smearing look to the finish is called "grain tearing" The primary culprit is running the tool too long in cut and shearing action is reduced to a tearing action. To eliminate this I left a bit more material for finishing and insured I had a proper sharp positive insert for finishing and didn't try to take the whole part in one pass.
As to whether or not it is acceptable would pertain to the engineering specs provided by the customer and of course the application. Most of the parts I've seen it on were high speed turbine impellers which was acceptable in the salt water pumps, but not acceptable in the turbine power plant applications. Acceptance would be stress related more than cosmetic. Application of the part is the key element, hope to have helped some. But there are times when only the customer can give the right answer.
IH v-3 early model owner
Basically, Titanium is hard to machine metal, and if your customer doesn't knows or don't want to know this, your position is bit tough.
In our part of the world there goes a saying, The cutomers expects "Japan Quality, Fedex Service at China Price". Just evaluate whether your customer falls into this catagory and if so, run away from them.
Titan Engineering, Singapore. Titanium Metal & Alloy suppliers.
A poet knows no boundary yet he is bound to the boundaries of ones own mind !! ........