Surface finish as a percentage of form requirement
Surface finish as a percentage of form requirement
(OP)
A coworker may have inherited this generic set of drawing notes (attached) but this one is dubious to me.
Per note 6 the entire part has a generic surface profile requirement of 0.8 mm (this changes between parts, but the note is ubiquitous). This is relatively generous in my opinion, but that's irrelevant to the question. Per note 5 preceding that the surface roughness requirement is "RA NOT TO EXCEED 4% OF FORM REQUIREMENT. CUT OFF VALUES PER ASME B46.1-2009, TABLE 3-2"
Am I right to understand this as a Ra of 32 (μm)? We are talking about relatively compact machined parts here, 3.2 would be generous, 32 seems almost nonsensical. Mind you this this particular part also has a callout of "E-POLISH ASME BPE SF6" which would reduce that finish requirement to 0.64 but that's irrelevant to the question since that is not present on every component.
Side note: I've never seen note 3 be relevant yet, but I suppose it must apply somewhere in our drawings.
Per note 6 the entire part has a generic surface profile requirement of 0.8 mm (this changes between parts, but the note is ubiquitous). This is relatively generous in my opinion, but that's irrelevant to the question. Per note 5 preceding that the surface roughness requirement is "RA NOT TO EXCEED 4% OF FORM REQUIREMENT. CUT OFF VALUES PER ASME B46.1-2009, TABLE 3-2"
Am I right to understand this as a Ra of 32 (μm)? We are talking about relatively compact machined parts here, 3.2 would be generous, 32 seems almost nonsensical. Mind you this this particular part also has a callout of "E-POLISH ASME BPE SF6" which would reduce that finish requirement to 0.64 but that's irrelevant to the question since that is not present on every component.
Side note: I've never seen note 3 be relevant yet, but I suppose it must apply somewhere in our drawings.
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