The worms are case-hardened; the bore and worm flanks are ground. Standard worm gears are made from VL22, a copper-zinc alloy with aluminium, silicon and manganese additives. This is a special quality within the group CuZn40Al2 according to DIN 17660, developed for sliding purposes (new according to EN: CuZn37Mn3Al2PbSi-S40). The aluminum content gives it very high chemical resistance properties.
Plastic worm gears
Owing to their poor thermal conductivity, plastic worm gears are only suitable for low sliding speeds of < 1.5 m/s and medium tooth flank loading. The worm must be hardened and must have ground flanks.
Plastic worm gears have around 60% of the torque capacity of comparable bronze worm gears (this applies for use with mineral grease).
Bronze worm gears
Cu Sn 12 DIN 1705
Relatively soft material with good wear resistance: suitable for high sliding speeds.
Cu Sn 12 Ni DIN 1705
Relatively soft material with very high wear resistance: suitable for very high sliding speeds.
CuAl10Fe3 Mn2 DIN 17665 / 17672
Relatively hard anti-friction materials for high loads and relatively low rotational speeds.
Please find more details at our Worm gear set catalog.