PMB is a series of premixed copper-tin-lubricant powders to provide low, medium and high growth control based on the needs of the bearings manufacturer.
This ready-to-use family of copper-tin-lubricant premixes is specifically designed for the manufacture of oil-impregnated sintered bronze bearings and structural parts. A series of interrelated grades is available, each having controlled dimensional change properties, which enable the parts producer to obtain desired dimensions during sintering, while maintaining good microstructure, optimum strength and interconnected porosity for required oil content.
Our PMB line is a graduated series of standard free-flowing bronze premixes composed of homogeneous mixtures of copper powder, tin powder and lubricant ready for direct use in the compacting press. These premixes are commonly referred to as 90/10 mixes (90% Copper, 10% Tin) and are available in six standard grades with related dimensional change characteristics.
The grade selection is based on the dimensional change desired as influenced by part density, part size or configuration and production sintering conditions.
Is the standard grade in this family. All other grades offer specific growth values relative to this grade.
Lowest growth 90/10 mix designed to give 1.0% less growth than PMB-8 when sintered at 1530°F (832°C).
Low growth 90/10 mix designed to give 0.5% less growth than PMB-8 when sintered at 1530°F (832°C).
The standard 90/10 mix designed to give nominal growth during sintering at 1530°F (832°C) when processing into P/M self- lubricating bearings under normal production conditions.
High growth 90/10 mix designed to give 1.0% more growth than PMB-8 when sintered at 1530°F (832°C).
Highest growth 90/10 mix designed to give 1.5% more growth than PMB-8 when sintered at 1530°F (832°C).
Low Temperature Sinter Grade
Bronze premix powder is a press ready bronze powder composed of mixtures of elemental copper and tin metal powders and lubricant. The 302 premix contains 3/4% added lubricant.
The 302 grade is designed to be sintered at 1365°F to 1455°F (740°C to 790°C) to produce bearings with good ductility and high strength. The premixes are noted for consistent dimensional control, designed to give -0.9% radial shrinkage at 750°C (1380°F) and are suited for the manufacture of small bearings. The fine porosity and smooth surfaces minimize running noise.
The above grades conform to the following industry and military standards for oil-impregnated sintered bronze bearings.
- B438, Grade 1, Type I
- B438, Grade 1, Type II
- B255, Type I
- B255, Type II
- Type I
- Comp A