2.2.5 Noise and Vibration
When the chain engages the sprockets, it will definitely make noise (Figure 2.21). This is caused by several factors:
- The chain roller strikes the sprocket tooth bottom.
- There is space between the roller and the bushing; the roller makes noise by its elastic vibration (in the case of thin rollers, like S-roller).
- Sprockets vibrate.
- The fluid held between each part (usually air or lubrication oil) makes shock sounds.
Figure 2.21 Noise Occurs when the Chain Engages the Sprocket
Take for example, an RS80 transmission roller chain and a sprocket with 16 teeth operating at a speed of 123 rpm. (The chain speed is 50 m/min.) In this case, the noise at a point 30 cm from the sprocket will be: with no lubrication, 65 dB (A); with lubrication, 57 dB (A).
According to the data given above, the noise made by the chain engaging the sprocket can be predicted. Please contact the manufacturer.
There are some steps you can take to lessen the noise level.
- Decrease striking energy:
- Use a sprocket with many teeth. This reduces the impact velocity while maintaining the same chain speed.
- Operate the chain at slower speeds.
- Use smaller chain to decrease the chain's weight.
- Buffer the effects of the impacting parts:
- Lubricate at the bottom of the sprocket tooth and the gap between the bushing and the roller.
- Use specially engineered plastic rollers. (This will also decrease transmission capability. There is virtually no decrease in sound if you change to an engineered plastic sprocket.)
If we compare noise from chains and sprockets with other transmission machine parts like belt and pulley or toothed belt and pulley, we find:
- Belt noise is less than the other two. Compared to a flat belt, a toothed belt makes a high frequency noise during high speed.
- Usually, chain transmission is smoother than gear transmission. The chain also differs in that there is no increase in noise level as it wears and elongates during use.