UHMW Wearstrip Span Calculator

Wearstrips under a modular belt are beams on steel cross-supports, and the case that sizes them is not the product load. It is an operator leaning on the belt. This calculator solves the point-load deflection of a rectangular plastic rail continuous over its supports, tells you the longest support spacing that meets your stiffness class, and derives the end overhang you can run before the cantilever tip sags or the rail overstresses at the last support.

Material matters more than most people expect. Virgin UHMW loses stiffness in a hot washdown and creeps under sustained load, so the solver applies a temperature knockdown to the flexural modulus and runs a separate creep stress check on the distributed belt-plus-product load. Lubricated UHMW keeps the stiffness and cuts friction by roughly forty-five percent, which the belt pull calculator picks up directly.

How it works
  • Continuous over supports: δ_point = P·L³ / (110·E·I) for the operator load and δ_UDL = w·L⁴ / (185·E·I) for belt and product.
  • End overhang is solved, not entered: the cantilever length whose tip deflection (including back-span rotation) meets the stiffness class, then capped by bending stress at the last support.
  • Temperature knockdown reduces E for washdown conditions; a creep allowable governs sustained loading.
  • Material table: virgin UHMW, UltraLube #321, food-grade HDPE, acetal (never under an acetal belt), and PET-P with typical handbook values to verify against the supplier datasheet.

Free, no login. Your inputs are saved in this browser. Values are engineering references — verify against manufacturer data and applicable codes before a final design.

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Questions engineers ask

Why is wearstrip span sized on an operator rather than the product?
The governing load on a slider-bed rail is a person leaning on the belt: a point load far larger than the distributed belt-plus-product weight. The calculator solves point-load deflection for a rail continuous over its supports, then checks the sustained belt-plus-product load against creep.
How far apart can the supports be under UHMW wearstrip?
It depends on the rail cross-section, the stiffness class you hold, and the temperature. Virgin UHMW loses stiffness in a hot washdown, so the calculator knocks down the flexural modulus before solving the longest span and the end overhang.
Can acetal wearstrip run under an acetal belt?
No. Like-on-like acetal wears quickly, and the material table flags it as never used under an acetal belt. Virgin UHMW, lubricated UHMW, food-grade HDPE, and PET-P are the usual choices.

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