Andron Stainless

Mechanical Polishing

Mechanical Polishing

Andron Stainless provides the industrial array of precision polishing and finishing for sanitary stainless steel products. Within various industries related to metal working, polish terminology varies causing considerable confusion. This information is meant to define and outline our interpretation of these different polish terms.

Polish Combinations

1 - Unpolished
3 - Polished on the inside only or ID
5 - Polished on the outside only or OD
7 - Polished on both the inside/outside or ID/OD

304/304L Standard Polished Finish 32Ra ID / 32Ra OD
316/316L Standard Polished Finish 25Ra ID / 32Ra OD

When calling out a polish type on our coding system, it is defined as a polish combination. There are four different polish combinations.

We determine our polish finish using the Ra scale. Ra is defined as roughness average and is the most accurate measure of surface finish roughness. We measure the Ra using a surface roughness tester or profilometer. Often times the desired level of polish is called out in terms of grit. Below is a chart to cross reference grit to Ra.

Ra µin / µm Grit Rms µin / µm
43 - 48 / 1.09 - 1.22 120 48 - 54 / 1.22 - 1.37
30 - 35 / .76 - .89 150 34 - 39 / .86 - .99
23 - 28 / .58 - .71 180 26 - 32 / .66 - .81
15 - 20 / .38 - .51 240 17 - 23 / .43 - .58
9 - 13 / .23 - .33 320 10 - 15 / .25 - .38

Often used is the biopharm industry codes. These codes are also defined below.

Surface Finish Code ID / OD Finish (Maximum Ra Allowed) BPE Designation
PX Unpolished / Unpolished SF0
PZ Unpolished / 32 Ra SF0
PC 20 Ra Mechanical / Unpolished SF1
PF 25 Ra Mechanical / Unpolished SF2
PB 30 Ra Mechanical / Unpolished SF3
PL 20 Ra Mechanical / 32 Ra SF1
PT 25 Ra Mechanical / 32 Ra SF2
PQ 30 Ra Mechanical / 32 Ra SF3
PD 15 Ra Mechanical & Electropolished / Unpolished SF4
PG 20 Ra Mechanical & Electropolished / Unpolished SF5
PK 25 Ra Mechanical & Electropolished / Unpolished SF6
PM 15 Ra Mechanical & Electropolished / 32 Ra SF4
PO 20 Ra Mechanical & Electropolished / 32 Ra SF5
PO 25 Ra Mechanical & Electropolished / 32 Ra SF6

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We offer a complete line of fittings, valves, tubing, pumps and accessories.

Our products are made from the highest quality raw materials. In addition to our line of fittings and valves, Andron has extensive capabilities for manufacturing custom parts to your specifications.

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