What are some outstanding design/ construction features in a chain drive, and how do they contribute to higher productivity?
Chains are versatile components used in power transmission, conveying, and lifting applications, transmitting power in compact spaces. They come in many standard and made-to-order (MTO) styles, with a wide range of base materials, special coatings, and attachments. Different types operate in challenging environments (including temperatures from -270°F to more than 1,000 °F), resist corrosion, oil, grease, and other contaminants, and function in direct contact with food products and in extreme conditions.
One particular type — roller chains — can be purchased in bulk, such as 100-foot reels, and cut to length. They easily incorporate attachments and convey, index, and position, among many other tasks.
How can designers achieve higher productivity from the chain drives they place in machines?
Following a manufacturer's selection procedure ensures proper wear and fatigue life, whereas improper selection causes premature wear or component failure, leading to costly downtime, property damage, or even personal injury.
Going the opposite direction and choosing a chain larger than the manufacturer's recommendations offers increased bearing surfaces, reduced PSI contact pressure per load, and improved wear life. Larger chains also permit carrying increased loads when operating requirements change.
Once an application enters the field, an improperly selected drive is difficult and expensive to correct. Retrofitting can be time-consuming, difficult, costly, and sometimes physically impossible due to space constraints.
What can end users do to ensure higher productivity from the chain drives on their machines, and how does this help?
A properly selected and manufactured chain drive depends on regular maintenance. End users should periodically inspect drives for potential problems before disabling the chain system. Maintenance, such as regular lubrication (except on self-lubricating roller chains), and replacing worn components (chains and sprockets), prevents premature wear and maximizes service life.
Before operating, check:
- Connecting plates, clips, and cotter pins for correct installation
- Chain slack for proper adjustment
- Chain path and surrounding area for interfering objects, such as chain cases; then remove them.
Before beginning full operation, turn on the power and check:
- Sound: There should not be strange noises and the chain shouldn't touch the case
- Vibration: Look for excessive chain vibration
- Sprocket-chain interaction: Be sure the chain doesn't climb over the sprockets
- Sprockets: The chain should separate smoothly from the sprocket
- Chain articulation: Chain articulation should be smooth
Once in operation, chains should be inspected monthly.
First, stop the drive and take the necessary precautions to prevent unexpected start-ups or a release of other stored energy. Then:
- Measure the chain's wear elongation
- Inspect for external cleanliness, lubrication, corrosion, damaged link plates or other components
- Monitor excessive sprocket-tooth wear
- Observe the flex of the chain and spin of the rollers; tight joints or rolls indicate problems
- Look for cracks in the link plates
- Probe rollers for cracks
- Check for pin rotation or gaps between the plate and pins
- Examine link plate edges for excessive wear
The chain should be replaced if any of these conditions exist or when its measured elongation exceeds 2%. Roller chain damage is unlikely during operation if the proper type and size are selected.