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Industrial standards for 180 grit polishing

Hi,
I am buying ornamental stainless steel square tube for our use.
Although suppliers confirm that they supply polish to grit 180, we are seeing variations from same or different source. What is the limitation according to industrial standard?
I am curious to know to be able to spec out my limits in details so that the variation is not too drastic. How can I verify and coordinate with the supplier if there is a industrial spec.
Please help.

Koh Cheng Yong
Buyer - Singapore
2005

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Suggest you revise your 180 grit specification to either an Ra, RMS, or Rz. The application or how the grit is worked in relationship to the tube will effect the finish.

AF Kenton
retired business owner - Hatboro, Pennsylvania
2005

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2005

Mr Kenton,
Thank you for the suggestion.
Maybe you can help me to understand what is equivalent Ra Value for the polish grit 180 finish. What is the range for this industry standard i.e tolerance.
Thank you and have a nice day!

Koh Cheng Yong
- Singapore

Your question has already been correctly answered by Mr. Kenton. This new question although, is equivalent as asking what is the standard speed at which baseballs have to be thrown. Obviously there is no such standard. When specifying surface finish attributes, physical measurements must always be preferred. Customers are concerned about the end result not how it was achieved. I would suggest that you make several coupons, identify which ones suit your customer, measure them and adopt them as your standard.

Guillermo Marrufo
Monterrey, NL, Mexico
2005

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Thank you G for your added thoughts. Maybe we should also say that given the same grit, Ra, RMS, or Rz, the finish may not have the same physical appearance because of the application of equipment and/or how the energy is applied to the part. Meaning, a typical 18 RMS can have a satin or polished appearance, again depending upon the process and energy forces.

AF Kenton
retired business owner - Hatboro, Pennsylvania
2006

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2006

The Specialty Steel Industry of North America (SSINA) has finish descriptions, including visual samples, on their website, http://www.ssina.com, which may help.

Finishes vary with product form and supplier:
"Polishing is available on round, square and rectangular tubing. On round products it is typically circumferential but some polishers can longitudinally polish. Other shapes are longitudinally polished."

Best to give both numerical value & samples, as recommended above.

Ken Vlach [deceased]
- Goleta, California
Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.