ASTM D1646 Specimen Cutting Die (Lower)

ASTM D1646 Specimen Cutting Die — Lower Half (CCSi-D1646-LN)

The CCSi ASTM D1646 Lower Die produces one half of the two-piece specimen required for Mooney Viscometer testing under ASTM D1646, the standard covering rubber viscosity, stress relaxation, and pre-vulcanization behavior.

Mooney testing works by embedding a rotor inside a rubber specimen and measuring the shearing torque that resists its rotation — Mooney viscosity — along with how that torque decays once rotation stops (stress relaxation) and how it climbs if the compound begins to vulcanize during the test itself (pre-vulcanization). None of that is possible with a single solid puck of rubber; the rotor has to sit inside the material, which is why the specimen is built in two halves that combine into a sealed capsule around it.

This lower half is the piece that makes that possible: it’s die-cut with a centrally located orifice sized for the rotor shaft to pass through cleanly. Paired with the solid upper disc, the two halves press together under the Mooney die’s heat and pressure to form one continuous mass around the rotor.

Combined volume across both halves is specified at 25 ± 3 cm³, which means the mass of each cut specimen needs adjusting to ± 3 g once you know the material’s density — get the density wrong and the volume calculation drifts along with it.

CCSi manufactures both halves in-house from American tool steel, wire-EDM finished for resharpenable, dimensionally stable service over the die’s working life. The matching solid-disc upper half is sold separately as the ASTM D1646 Specimen Cutting Die (Upper).