When a heat transfer roll is being engraved or textured, make sure that the outer shell is made from a seamless tube, either by using a seamless pipe tube or a seamless forging for rolls that are larger than 24 in./diameter. If the outside shell of the roll is made from a rolled-and-welded plate or tube, the weld area will not etch or engrave at the same texture as the base metal of the shell. Typically the weld seam of a rolled and welded tube has a totally different metallurgy, and usually the welded area is much harder than the base metal on either side of the welded area.
Tim Womer is a recognized authority in plastics processing and machinery with a career spanning more than 35 years. He has designed thousands of screws for all types of single-screw plasticating. He now runs his own consulting company, TWWomer & Associates LLC. Contact: (724) 355-3311; firstname.lastname@example.org; twwomer.com