20mm Wheel White Plastic Crown Gears Compact With 28 Z Straight
Teeth
Plastic wheel crown gears with crown body shape , the straight
teeth with bigger reference circle are placed on side surface and
another side surface has a smaller gear with different reference
circle , directions of both gears are contrary . the number of
teeth and reference circles are different as well .
Material
Wheel crown gears are made from plastic nylon PA 66
Technical Data
Including Modulus , Number of Teeth ,Outside diameter ,Root
diameter ,reference circle ,depth of tooth ,tooth addendum ,tooth
dedendum ,pitch ,teeth thickness and pressure angle .
| Modulus | m | 0.5 |
| Number of teeth | z | 28 |
| Outside diameter | da | 15 |
| Root diameter | df | 12.75 |
| Reference circle | d | 14 |
| Depth of tooth | h | 1.12 |
| Tooth addendum | ha | 0.5 |
| Tooth Dedendum | hf | 0.625 |
| Pitch | p | 1.57 |
| Teeth thickness | s | 0.8 |
| Pressure angle | ɑ | 20° |
Unit : mm Big gear in duplicate gears
| Modulus | m | 0.5 |
| Number of teeth | z | 8 |
| Outside diameter | da | 5 |
| Root diameter | df | 2.75 |
| Reference circle | d | 4 |
| Depth of tooth | h | 1.12 |
| Tooth addendum | ha | 0.5 |
| Tooth Dedendum | hf | 0.625 |
| Pitch | p | 1.57 |
| Teeth thickness | s | 0.8 |
| Pressure angle | ɑ | 20° |
Unit : mm Small gear in duplicate gears
Precision
Level 9 based on ISO standard .
Application
Plastic crown gears are mainly used to derailleur and clutch for
toy items , they are also used for following items as fittings with
light load .
▲ Household appliances
▲ Official appliances
▲ Car
▲ Timing device
▲ Micro electric motor
▲ Camera
▲ Instruments and meters
Performances
| Physical Performance |
| Density ( g/cm3) | 1.14 |
| Water absorption % | 3 |
| Shrinkage % | 1～2 |
| Mechanical Property |
| Tensile strength MPa | 60～80 |
| Elongation at break % | 2.2 |
| Bending strength MPa | 100～120 |
| Modulus of elasticity for bending MPa | 2000 ～3000 |
| Notched Impact Strength(J/m) | 60～100 |
| HR hardness | 118 |
| Electrical Performance |
| Dielectric constant | 1.63 |
| Arc resistance sec | 130～140 |
| Specific volume resistance Ω·cm | 1.83×1015 |
| dissipation factor | 100～400 |
| Dielectric strength(kV/mm) | 20～30 |
| Thermal Performance |
| Normal working temperature ℃ | 80～120 |
| Brittle temperature ℃ | -30 |
| Melting temperature ℃ | 252 |
| Pyrogenic decomposition temperature ℃ | 350 |
| Matin heatproof ℃ | 50～60 |
Features
▲ Small volume
▲ Light weight
▲ Compact structure
▲ Long transmission torsion
▲ Automatic slip resistant
We make more plastic gears with different specifications for many
fields in industry , please contact us if you are interesting in
any gear , we are able to develop customized plastic gears as well
.
