SCM offers several grades of blended powders, which contain prealloyed 90/10 bronze powders to meet the expanding needs of bearing manufacturers. The prealloyed bronze powders offer unique characteristics in powder flow, sintering properties, porosity development, and surface appearance.
AB Grades are press-ready, 90/10 bronze powders composed of substantially prealloyed bronze powder and admixed lubricant. These grades are designed for use in manufacturing microbearings, which are very small bearings typically weighing less than 1 gram. These are used in audio and video equipment, computer hardware and other electronic equipment.
These grades have the following advantages:
- Excellent green strength
- No compositional segregation
- Free flow
- Fine porosity and smooth surface appearance
- Low distortion and low hourglassing
- Tight tolerances on sized bearings
- Low noise in bearing operation
The basic grade in this family is grade AB-MBX1. This type of powder is preferably sintered at lower temperatures, 1300°F to 1400°F (704°C to 760°C), and longer times than the standard PMB premixed bronze powders.
MAB Grades are press-ready 90/10 bronze powders composed of a mixture of prealloyed bronze, copper, tin, and admixed lubricant. These grades are designed for the manufacture of oil-impregnated bearings which have a propensity to hourglass during sintering, e.g., bearings with flanges, thin walls and/or high length-to-diameter ratio. The MAB grades are available as a family of grades that exhibit low, medium and high growth, much like the PMB premixes, to meet the needs of the parts manufacturer. Lower growth grades include MAB-0 and MAB-6; the medium growth grade is MAB-12, and the higher growth grades are MAB-18 and MAB-24. These grades are designed for sintering at or near 1530°F (832°C) like the PMB premixed bronze grades.
Their specific advantages include:
- Low hourglassing and low distortion
- No tin burnout, smooth surface appearance
- Free flow to facilitate fill of deep die cavities