Aesthetic Surface Finish Callout (Black Delrin)
Aesthetic Surface Finish Callout (Black Delrin)
(OP)
Hello Everyone,
I was hoping to get some input on the surface finishes applied to parts for aesthetic purposes. I have been running into problems when ordering Black Delrin from shops as they meet specs but don't look very good. From what I gather, a surface call-out can look different depending on the method used (if I specify a 64 Ra surface it can look very different if that is achieved through grinding or milling.) My question is, for parts that you want to have a nice aesthetic look, without worrying about functionality, what call-out do you use? Additionally, is roughness not necessarily what makes a part aesthetically pleasing (should I be more concerned with the sizes of valley's / lay direction)?
Thanks in Advance,
Dan
I was hoping to get some input on the surface finishes applied to parts for aesthetic purposes. I have been running into problems when ordering Black Delrin from shops as they meet specs but don't look very good. From what I gather, a surface call-out can look different depending on the method used (if I specify a 64 Ra surface it can look very different if that is achieved through grinding or milling.) My question is, for parts that you want to have a nice aesthetic look, without worrying about functionality, what call-out do you use? Additionally, is roughness not necessarily what makes a part aesthetically pleasing (should I be more concerned with the sizes of valley's / lay direction)?
Thanks in Advance,
Dan





RE: Aesthetic Surface Finish Callout (Black Delrin)
The first thing you need is a surface comparator, so that you know what the finishes you are specifying, look like. In my opinion, a 16μin finish looks good. A 64μin finish does not.
Can you grind Delrin?
Ask your fabricator what he can do.
--
JHG
RE: Aesthetic Surface Finish Callout (Black Delrin)
In past days as a machinist, I've had customers complain about rough or ugly parts because they still could see the machining/tooling/cutter marks on the surfaces. It didn't matter that they were well under 32μin, well beyond their requirements. They didn't want to see tool marks on the bare metal (aluminum).
Perhaps what you should require is that "No cutter/tooling marks allowed on finished surfaces" and they can figure out how to make that happen. Whether it's with abrasives, different cutting strategy, different cutter insert geometry, or a post-machining process such as Scotch-Brite or sanding or something... let the suppliers find their best way.
Even parts with a very smooth surface roughness can still look "displeasing" to some due to manufacturing processes.
RE: Aesthetic Surface Finish Callout (Black Delrin)
To me, the ugliest feature of black (or natural) Delrin parts is the porous core that appears at the center of rounds and the midplane of plates. The porosity is unavoidable; it's related to Delrin being a condensation polymer, or something like that. The only solution is to buy grossly oversized stock, so you throw away the core, e.g. for a planar part that's ~1" thick, start with 2-1/2" plate and sawcut the blanks down the middle.
Mike Halloran
Pembroke Pines, FL, USA
RE: Aesthetic Surface Finish Callout (Black Delrin)
I will specify the "no tool marks", that seems like it should clear things up. Thanks for the additional info! I'll keep Delrin's porous nature in mind if I need to be particular about a part.
Much Appreciated!
Dan
RE: Aesthetic Surface Finish Callout (Black Delrin)
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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
RE: Aesthetic Surface Finish Callout (Black Delrin)
if you know what method works best for you, you can specify the exact manufacturing method on the finish symbol or drawing notes. e.g.: 32µin grind, you can be as specific as you want in the drawing notes.
lightweight, cheap, strong... pick 2
RE: Aesthetic Surface Finish Callout (Black Delrin)
"Art without engineering is dreaming; Engineering without art is calculating."
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RE: Aesthetic Surface Finish Callout (Black Delrin)
I have seen the same as you.
A good ref table: Link
Chris, CSWA
SolidWorks '15
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