Plastic balls are manufactured from standard and speciality polymer resins in sizes from 3/32" (2.381mm) to 5" (127mm). Balls above 1" (25.4mm) are manufactured from extruded rod.
Plastic balls are a cost-effective substitute for metallic balls in low load bearings. They are also used as agitators in aerosol spray cans, lightweight check valves, medical diagnostics and a wide variety of other applications.
Tolerances to +/-0.0005" (+/-0.0125mm) are possible for certain materials such as nylon and acetal. Surfaces can be tailored from rough to highly polished finishes.
The following chart shows comparisons between the five main types.
| Acetal (Delrin) | Polyamide (Nylon 66) | Polyethylene Low Density | Polyethylene High Density | PTFE | |
|---|---|---|---|---|---|
| Physical Properties | |||||
| Specific Gravity | 1.42 | 1.13-1.15 | 0.910-0.925 | 0.941-0.965 | 2.14-2.20 |
| Water absorption, 1/8" thick specimen, 24h saturation (%) | 0.25-0.40 | 1.0-1.3 | <0.01 | <0.01 | <0.01 |
| Dielectric strength, 1/8" thick specimen, short time (V/mil) | 500 (90ml) | 600b | 450-1000 | 450-500 | 480 |
|
|||||
| Mechanical Properties | |||||
| Tensile strength at break (psi) | - | 12.000b 11.000c | 600-2300 | 3100-5500 | 2000-5000 |
| Elongation at break (%) | 25-75 | 60b 300c | 90-800 | 20-130 | 200-400 |
| Tensile yield strength (psi) | 95000-12.000 | 8000b 6500c | 800-1200 | 3000-4000 | - |
| Compressive strength (rupture or yield) (psi) | 18.000@10% | 15.000b(yld.) | - | 2700-3600 | 1700 |
| Flexural strength (rupture or yield) (psi) | 14.000 | 17.000b 6100c | - | - | - |
| Tensile modulus (103 psi) | 520 | - | 14-38 | 60-180 | 58-80 |
| Compressive modulus (103 psi) | 670 | - | - | - | 60 |
| Flexural modulus(103 psi) | 380-430 | 420b 185c | 8-60 | 100-260 | 80 |
| lzod impact. Ft-lb/.in.of notch (1/8" thick specimen) | 1.3-2.3 | 0.8-1.0b 2.1c | No break | 0.5-20 | 3 |
| Hardness Rockwell/Shore | M94 | R120b M83b | D40-51 | D60-70 | D50-55 |
| Thermal properties | |||||
| Coef. of linear thermal expansion (106in./in/oC) | 100 | 80 | 100-2220 | 110-130 | - |
| Deflection temperature Flexural load oF @264psi | 255 | 167b | 90-105 | 110-130 | - |
| @66psi | 338 | 474b | 100-121 | 140-190 | 250 |
| Thermal conductivity 10-cal.-cm/sec-cm2-oC | 5.5 | 5.8 | 8 | 11-12 | 6.0 |
| Grade | Sphericity | Tolerance | Surface | ||
|---|---|---|---|---|---|
| 0.0005 | 0.0125 | +/-0.0005 | 0.0125 | Polished | |
| 0.0005 | 0.0125 | +/-0.001 | 0.025 | Polished | |
| 0.001 | 0.025 | +/-0.002 | 0.050 | Unpolished | |
| 0.005 | 0.125 | +/-0.005 | 0.125 | Unpolished | |
Design by logologo