Plastic, Duroplast (Phenolic PF), black shiny finish
Bushing: Technopolymer plastic (Polyamide PA)
design plastic ball knobs.
EN 319.1 ball knobs do not require a thread on the shaft.
During mounting, easy blows with a soft hammer are sufficient to drive the knob into place; the shaft end should be slightly rounded or chamfered (30°).
The bore is conical which guarantees a firm press on operation.
The polyamide bushing provides good holding force even with a shaft tolerance of h11. The knobs are resistant to vibrations and may be re-assembled any time.
Maximum heat resistance of plastic knob: 110° C (230° F).