Roller chain can have a significant impact to downtime
Roller Chain can keep your production and profitability moving in the right direction. The Roger Brown Co. offers these suggestions for plants that want to achieve the longest service life and greatest returns possible from their chains.
Chain elongation (“stretch”) is the increase in measured chain length due to wear between the pin and bushing. The chain articulates as it goes around the sprocket and the pin wears on the bushing to the point that the length of the chain pitch elongates. It is recommended to replace your chain when the wear results in elongation that exceeds 3%. Use a chain-wear measurement tool to easily calculate this elongation. Diamond Chain Company provided the below table and and knowledge for this article.
Alignment
Use a level to verify that shafts are parallel.
Confirm sprocket axial alignment with a straightedge or laser tool. Axial alignment is correct when there are no gaps between sprockets and the straightedge. Normally, it is good practice to align the sprockets as close to the shaft bearing as possible. For long center distances, use a taut cord, or wire long enough to extend beyond each of the sprockets.
Lubrication
Maintain a film of lubricant between the pins and bushings to minimize chain-wear elongation and increase service life.
- Manual lubrication: Oil is applied with an oil filler or brush on the slack side of the chain. Apply at fixed intervals (usually about every 8 hr.) or as often as necessary to prevent the bearing areas from becoming dry.
- Drip lubrication: Oil from an oil cup is dripped onto the chain. Apply 5 to 20 drops of oil/min. for every strand of chain based on the chain speed.
- Oil-bath lubrication: The chain is installed in a leak-free casing. Chain should be submerged in oil 1/4-to 1/2-in. deep. If submerged too deep, the oil may overheat and lose effectiveness.
Tensioning
- Adequate slack should be maintained for effective roller-chain operation. Excessively tensioned chain may reduce chain life.
- Check chain tension to be certain the slack span has 4-6% mid-span movement in horizontal drives and 2-3% in vertical drives.
- If vibration occurs, due to high chain speed, install a guide.
- If the center-line is vertical, install an idler, which functions to eliminate extra slack. If the driving shaft is on the lower side, an idler must be installed.
