Removing Defects from a Hot Rolled Substrate.
As much as we would like to remove every single defect from material sent into us for polishing it should be recognised that there are certain types of material that have inherent defects from their production process. Typically a plate of Hot Rolled stainless steel will have more surface defects than the equivalent size and thickness that has been cold reduced. The subsequent rolling in the production of the plate does give a very different finish. However we polish Hot Rolled plate on a daily basis and most surface defects can be removed with a grained polish such as a Dull Polish or, for a finer finish, polished to a 1K with a final surface measurement of less than 0.5¾m. Unfortunately there are occasions when the defects are too frequent and too deep to give a final product that is suitable—please see the example below. Here you can see severe bands of pitting and scale in the material that will not be removed by mechanical polishing within a sensible time frame.
Reflective and Decorative finishes by their very nature don’t remove surface defects which is why Hot Rolled plate is not suitable for these finishes. Here you can see what the surface pitting looks like if a grained finish is applied which is generally unsuitable for most requirements even with additional pre-grinding of the surface.
Your Partner in Polishing www.professionalpolishing.co.uk
The white areas measure over 0.2mm below the average surface of the plate meaning to remove these defects the 8mm plate would need to be reduced to 7.8mm or more. This of course does not take into account any more defects that may be revealed as the surface is reduced.