| The roll-forming machine, outfitted with 16 different rollers, bends 6.5-in.-wide steel into corrugated profiles used to test out a new grain silo design. |
Grain-silo manufacturer Westeel Corp., Winnipeg, Canada, roll-forms galvanized steel on rollers machined from polyurethane boards. The company's 14-pass forming machine uses a series of rollers to transform steel coil strips into 6-in.-wide, 0.04-in.-thick corrugated shapes. The polyurethane rollers let designers form prototype parts faster and cheaper by eliminating eight weeks of milling time usually needed when making conventional hardened steel rollers.
The polyurethane material -- Ren Shape 5166 -- is manufactured by Ciba Specialty Chemicals, East Lansing, Mich. To make the rollers, laminates from two 4-in.-thick boards are bonded together with adhesive and rough cut to shape. CNC lathes running at speeds of 1,600 and 10,000 rpm, respectively, rough and fine-cut the 16 different roller shapes needed to from the corrugated structure.
Metalforming processes such as drawing, stretchforming, and hydroforming also use dies made from machinable polyurethane. Ren Shape 5166 has an ultimate compressive strength of 9,500 psi, a tensile strength of 4,875 psi, and a notched Izod impact strength of 0.46 ft-lb/in.
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