How do I achieve a 240 grit finish on stainless steel?
Why can nobody tell you what a 240 grit finish actually looks like? Metal fabricators have for many years been frustrated when they receive their ‘finished’ stainless steel from their steel supplier. On both tube & flat stock the grain finish can vary widely.
Requesting a 240 grit finish has become a generic term for ‘a nice satin finish’, but how do I achieve it? Below is a quick guide to the most common products we recommend to achieve a 240 grit satin finish on different metal surfaces:
Stainless Steel Handrails and Balustrading:
If joints are welded & you want a 240 grit finish then we strongly encourage the tig process which leaves a neat weld which can be ground away in one action with the RCD rapid combi flap disc. RCD discs will leave a smooth finish without creating any flat spots on the tube. That will leave a finish that just needs to be blended in with the original finish to leave the clean burr free finish your customers will love. The fastest way to achieve this is using the Cibo Finitube machine which will wrap up to 270 deg around the tube in one action.
We recommend a simple two stage belt sanding process:
Stage 1 Create a consistent grain finish with the new ceramic range FF87 P120 or P150 belts. This will also remove any remaining damage and marks and create a consistent grain in the surface of the tube.
Stage 2 Blend the surface with the RC2 / medium surface conditioning belts. a light dressing over the surface will remove any burrs and blend with the existing tube finish.
Box Section Stainless Steel Tubes:
Often only 25 or 50mm wide the main need to re-finish this surface is where welding has occurred. The simplest way to achieve this is to use our Time Saving Kit set 1 process for removing the weld to leave a finish that is easy to re-brush working on the Finipower variable speed grinder.
Time Saving Kit: TSK/01 (see separate application guide for this process). Kit 1 contains all the products you need to remove the weld, refine the finish and put a fine mitre cornered satin finish on a box section fabrication.
The basic process uses P100 ceramic discs to remove the weld, trizact discs are then used to refine the finish and the final grain finish is put on with our FMCM combination flap brushes.
If working on larger quantities of box section or even angle that needs re-graining you could also consider the Garboli DUO machine which will process box section up to 150mm in width.
Large Area Stainless Steel Sheet Panels (hand held process):
Large stainless steel sheet sections are normally finished in the mill on continuous strip processes which product a very consistent finish with a very short grain fleck in the surface. This can be very hard to match in a hand held operation.
The ideal machine to use which will give the closest blend finish is the Finimaster Pro. With the larger 5” diameter wheels and soft inflatable tyre contact wheel it is possible to create a consistent finish without chatter marks.
Coarser belt preparatory work may be necessary but for applying the final finish we recommend:
Stage 1 Re-creating the grain is best done with the Trizact 337DC A300 belts
(AFS part no: 337DC/A300/385X100)
Stage 2 Blend the surface finish with the FMTM 180 grit wheels to remove any edge lines
(AFS part no: FMTM/180/120110)
Large Area Stainless Steel Sheet Panels (free standing machine process):
There is no doubt that the ideal way to create a 240 grit grain finish on stainless steel is with a wide belt sander or a long belt / pad sander machine. At this point there is a vast range of product options available dependent on the particular finish you are matching or the components you are working on.
We would recommend you give us a call if you are looking to engineer the correct process for this application.
Product options for wide belt or long pad sander belt sanding can vary from P60 grit paper belts through to the more high tech 3M Trizact and surface conditioning materials which will give a high quality and very consistent finish.
Recommendation: On the pad sanders – FF87 P80 grit semi flexible ceramic abrasive belts. The high performance cut from the ceramic abrasive gives a great durability and excellent finish.