Polishing ‘Duplex’ grades. The Duplex ‘revolution’ has been under way for some while now and there is increasing demand for this versatile product for many applications. Whilst I say ‘revolution’ it has been more of a gentle uprising really. We all know that our industry is one where old habits die hard. Witness the fact that almost everyone still refers to grades by their ‘old’ BS1449 classification such as 430, 304, 316 etc. As Duplex gains in popularity so we at PPS have been involved in polishing to a wide range of finishes on assorted thicknesses. The as received condition is usually a ‘Hot Rolled’ product and our experience is that there is no significantly greater incidence of surface defects than is found on Austenitic grades. By carefully selecting grades of abrasive in a sequence of ‘grit’ sizes we are able to replicate our full range of finishes from a Coarse Ground [1G finish] through to measured Ra finishes as fine as 0.4 micron Ra. Duplex material performs in a similar manner to Austenitic materials during the polishing process so the specifier need have no fear that material will have a visually unacceptable appearance. Whilst the majority of Duplex material we process falls into the ‘plate’ category we have occasionally had occasion to apply polished finishes to ‘sheet’ which we have received in the Cold Rolled condition. In sheet form all the ‘Dull’ polished finishes produced via abrasive media are achieved by the same process as on Austenitic and Ferritic grades but when Bright / Mirror polishing is involved there is a greater need to consider the standard of substrate before polishing as extra time is needed to produce the desired level of reflectivity. When considering the attributes of Duplex material the specifier will obviously take into account the functional requirements at the design stage. Once it is established that Duplex is a suitably cost effective material for the application involved the client can have confidence that the experience we have at Professional Polishing Services will ensure that a superb polished finish will put the final touches to the project.
Written by Peter Davies, Professional Polishing Services Ltd.