Plastic gear commonly used materials

1. POM

Easy to injection molding, good dimensional stability, high strength, good ductility, wear resistance, corrosion resistance, moisture resistance. It is the main material of plastic gear.

2. PA6/PA66/PA46

High strength, wear resistance, but moisture absorption leads to dimensional instability. It expands as it absorbs water. They are mainly used for heavy load transmission.

3. TPE

It's an elastic material, which means it absorbs shock and reduces noise in transmission.

4. ABS

It is mostly used for low-end applications with low cost.

5. PC

As an amorphous polymer, PC has good dimensional stability in the injection molding process, it can be molded into the shape of the mold cavity with a small amount of shrinkage.

6. PPS

It is a rather expensive material that has good dimensional stability, but also has mechanical strength and durability.

7. LCP

Good dimensional stability, high precision, resistance to 220¡æ high temperature, chemical corrosion resistance.

Our Guangzhou OTEM Engineering Plastics Co., Ltd. has more than 20 years of experience in the production of plastic gear, with more than 2,000 square meters of physical plant, professional production equipment and professional design team, can bring you satisfactory products and services.

Gear process

1, gear milling

The shape of the teeth is completed on the main components to achieve the required dimensional accuracy.

2, gear tooth

The gear shaper is completed at the main part of the gear, so that the tooth shape of the gear meets the requirements of the variable blade type gear.

3. Gear pulling teeth

The specified broach knife is inserted into the main part of the bevel gear, and the cutting part is broached to achieve the requirements of accurate tooth shape and slight broach mark.

4, gear grinding

The designated grinding wheel is placed on the main part of the bevel gear, and the gear surface is roughed through orderly grinding to increase the surface hardness and wear resistance of the gear.

5, gear grinding

The designated grinding wheel is placed on the main part of the bevel gear, and the gear is finely ground to change the edge form of the gear to achieve the perfect processing effect.

Plastic gear repair method

1, hot melt repair method

Hot melt repair is a common method to repair plastic gear. First of all, the damaged part of the gear needs to be cleaned, and then heated with an electric soldering iron. The plastic strip of the same material needs to be melted and filled into the damaged part. After evenly filled, it can be cooled. The advantage of this method is that the repaired gear has high strength and no strange noise. The disadvantage is that the repaired gear will have a certain deformation, which may affect the accuracy of the gear.

2, use glue repair method

Glue repair method is a simple and effective repair method. First of all, the surface of the damaged part of the gear needs to be polished smooth with sandpaper, and then the special plastic glue is applied to the damaged part, and the glue can be filled evenly until dry. The advantage of this method is that it is simple and easy, and does not require too many tools and materials, but the disadvantage is that the strength of the repaired gear is low and it is easy to be damaged again.

3, tooth replacement repair method

Tooth replacement repair method is a relatively complex repair method, suitable for gear damage is serious or not suitable for other methods of repair. This method requires the use of professional fitter equipment and parts. First of all, it is necessary to remove the damaged gear, and find the same specifications of the gear, and then use professional equipment to grind off the damaged gear teeth, and then the new gear is processed and installed to the original position. The advantage of this method is that the accuracy of the repaired gear is the same as that of the original gear, but the disadvantage is that professional equipment and technology are required and the cost is high.

Factors affecting the noise of plastic gear transmission

1, gear type has an impact on the noise, the noise of the helical gear is lower than that of the spur gear

Different types of gears, due to their different geometric characteristics, will have different forms of meshing process. For example, under the condition of the same load and speed, through many application cases, it can be found that the noise of the helical gear is 3 ~ 10dB lower than that of the spur gear;

2, the gear pressure Angle has an impact on the vibration level and noise frequency of the gear

In order to transmit a certain amount of power, F must be kept at a fixed value. If the pressure Angle a is increased, the normal force Fn of the tooth surface must be increased, which will increase the pitch line impulse and meshing impulse on the actual tooth surface with friction, resulting in the increase of vibration and noise level. Although the error of gear center distance does not affect the exact meshing of involute tooth profile, its change causes the periodic change of working pressure Angle. For example, the eccentricity of the gear on the shaft will be changed by the rotation frequency of the gear to change its center distance, which is bound to adjust the frequency of the vibration and noise of the gear transmission, and the amplitude of the modulation will depend on the size of the eccentricity.

3, the impact of gear contact degree on gear noise, increasing the contact degree can reduce vibration and reduce noise

The gear teeth change in varying degrees when the load is transferred. In this way, at the moment of entering and disengaging, the meshing impulse along the direction of the meshing line will be generated, resulting in torsional vibration and noise. If the average number of instantaneous teeth is increased, that is, the degree of contact is increased, the load can be distributed on more teeth, so that the unit pressure of the tooth surface is reduced, so as to reduce the deformation of the gear teeth, improve the impact when entering and disengaging, so as to reduce the torsional vibration and noise of the gear drive. As can be seen from the application case, when the contact degree increases from 1.19 to 2.07, the noise is reduced by 4dB at 1000rpm and by 6dB at 2000rpm.

For the helical gear, the contact degree can be increased by changing the helix Angle ¦Â and the tooth width b, and it can be greatly exceeded by the spur gear, but the helix Angle should not be too large, otherwise it will cause axial vibration. Increasing the number of teeth, increasing the coefficient of tooth top height or reducing the pressure Angle can increase the contact degree, reduce vibration and reduce noise.

4, gear pitch, tooth shape, gear eccentricity and other gear accuracy has an impact on noise

Gear noise is greatly affected by gear accuracy, and an important part of reducing gear noise is to improve gear accuracy. For gears with low accuracy, any other noise reduction measures will often encounter a futile situation.

Gear machining product quality requirements

1, the precision of gear processing tooth shape must meet the specified technical requirements.

2, the plane shape and surface shape of the gear should conform to the position and size requirements shown in the drawing.

3, the gear surface is sharp and no rust, the surface roughness should meet the requirements of the requirements, the surface smooth.

4, the gear should be tested after processing to ensure that it can be used normally after processing and meet the performance requirements of the design requirements.