Cometech QC-638 Vertical Rebound Resilience Tester | Rubber Elasticity | ASTM D2632 | Free Drop Hammer Method | PTS Lab UAE

Overview

The Cometech QC-638 Vertical Rebound Resilience Tester measures rubber elasticity by the free vertical drop hammer method per ASTM D2632 — one of the simplest and most repeatable methods for characterizing rubber resilience in both R&D and production quality control.
A 28-gram hardened steel hammer is manually lifted to 400mm and released; it falls vertically and rebounds off the clamped rubber specimen, with the rebound height read directly from the graduated scale beside the guide rod.
To eliminate break-in effects and obtain a stable result, the first three impacts are used as conditioning drops (not recorded), and the average of the 4th, 5th, and 6th rebound heights is taken as the final rubber elasticity value — following ASTM D2632 protocol exactly.

Working Principle

The hammer is guided by a low-friction vertical slider rail to ensure a true vertical free-fall trajectory — any lateral deviation would introduce error into the rebound height measurement.
The specimen is clamped in an adjustable holder that positions the rubber surface precisely at the hammer's zero reference point; the fixing screw locks the holder at the correct height once specimen thickness is accounted for.
The rebound scale beside the guide rail is graduated in 4mm divisions; readings are taken with line-of-sight perpendicular to the scale, retaining one decimal place, to minimize parallax error.