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Strip Building Techniques

widespread acceptance. Many end users specify the strip building method for covering their rollers due to quality and performance advantages.

Using the ‘flat’ method of application, there are few limitations. The process has been successfully used for covering rollers up to 100 inches/ 2.5M in diameter and over 50 feet/ 15M in length. These rollers have many end uses, including high quality printing.

Of the flat methods discussed, which one offers the best assurances against defects? Which method would be preferred for building high quality printing rollers?

That method would be stackbuilding. (Ref. diagram at the beginning of this article.) Stackbuilding is a name coined by John Slotten, a former part owner of Valley Roller Co. It refers to ‘stacking’ multiple wraps of thin extruded elastomer strip on top of itself by increasing the percentage of strip overlap more than 75%. This is done by changing the spin/travel ratio so that more revolutional or orbital wraps of polymer are made in an inch of travel movement. Wraps up to 12 revolutions per inch are possible, but 6-8 are more common. The theory is that each orbital wrap with the applicator head passing over the applied strip, produces more stitching and knitting action resulting in a densely packed layer of elastomer that can be up to one inch in thickness.

For best results, thinner extruded rubber strip is used to allow for more revolutions per inch. Obviously, if the strip size was ¼”/ 6.35mm x 1”/25.4mm, the total applied thickness at (8) revolutions per inch of travel would be approximately 2 inches/ 50.8mm. This is more than enough for most purposes. Cut the strip thickness to 1/8”/ 3.175mm and the applied thickness becomes (1) inch/ 25.4mm or if the strip thickness becomes 1/16”, the applied wall thickness becomes ½ inch/ 12.7mm. This may be a little extreme but try it and see what you get relative to quality of the finished product. Cut a section with a knife and look at the bonding area and throughout the covering thickness. Throw the sample in the autoclave (forget about tape wrapping) and examine it after curing. Grind a section and look at the surface. You might be surprised.

Some operators like to use enough applicator head pressure to cause a rolling ball or bubble ahead of the applicator head that assures maximum benefit of the system. This bubble is good indication that stock is being moved and compressed at the point of application, giving maximum quality benefits.

Of course, stackbuilding may not be the best technique in all cases, but there are situations where it more than justifies the extra trouble. It can be somewhat compound dependant and for many end uses, it simply is not necessary. On the other hand, if you

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