The Importance of Conveyor Alignment: How to Align a Metal Conveyor Belt

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belts
conveyor
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Has your car ever had a misaligned tire? If so, you know how difficult it can be to keep your car centered in your lane. In addition to the added frustration to your drive, it can also wear out your tires faster. This same principle applies to metal conveyor belting. Every part of the conveyor, from the end rolls to the supporting rolls, must be level and parallel. If the conveyor is misaligned, the belt becomes difficult to track and it can stretch unevenly. Once a belt is stretched unevenly, it no longer is in optimal working condition, creating unplanned downtime and unnecessary expenses. A way to increase your belt’s longevity is to keep it tracking and stretching evenly. The steps below outline how to properly align your conveyor. 

You will need the following tools:
•    Surveyor’s transit
•    Carpenter’s level
•    Chalk and chalk line
•    Tape measure
•    Plumb bob
•    A piece of rigid steel (2 x 2 box tubing, or angle iron). The steel must be long enough to extend from the conveyor centerline out to an open area on the side of the conveyor
 

Level All of the Rollers

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First, use a carpenter’s level to level all rolls to an accuracy of + or – 1/32”. The end goal of the alignment is to position the main head and tail rolls parallel to each other and perpendicular to the conveyor center line. The other auxiliary rolls must be adjusted to be parallel to these main rolls.

Define the Center Line of Your Conveyor

Choose one end of the conveyor to start on. For long and enclosed conveyors, use the center line measurement of the opening to the enclosure as a beginning reference mark. Using a rigid piece of steel, transfer the center reference mark of the opening to an open area next to the conveyor. Use a plumb bob hanging from the steel to mark this on the floor for reference (position 2 in diagram). The line should be far enough from the conveyor to allow focusing of the transit. The outside center line is located by repeating the transfer of the reference center mark to the area outside of the conveyor. There is now a reference line (called outside center line) that is parallel to the conveyor’s theoretical center line.

Set up the Transit

Set up the transit in position 1. Accurately sight the transit on position 2 and rotate the transit 90 degrees to sight across the end roll (see diagram). Use this sighting to make a mark on the floor on the opposite side of the conveyor. Move the transit off of position 1. Using a chalk line, make a line between this new point and position 1. This line is now perpendicular to the outside center line and parallel to the desired end roll position. Next, set up the transit on position 2 and sight on position 1 (see diagram). Swing the transit 90 degrees and using this sighting make a mark on the floor on the opposite side of the conveyor. Move the transit off of position 2. You now have a second line perpendicular to the outside center line and parallel to the desired end roll position.

Align the Head and Tail Pulleys

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For each end, using the above established lines, measure from the line to the rolls on both left and right sides of the roller. This can be done by hanging a plumb bob off the end roll and measuring this mark back to the line. Ensure that both measurements are equal. If they are not, adjust your rollers within the bearings to equalize.  Repeat this process at the opposite end.  Your head and tail pulleys are now parallel to each other and perpendicular to the center line of the unit.

Align the Snub Rolls

Align the remaining rolls (snub, take-up, return pass) to the end rolls.  This can be done by measuring from the main end rolls back to the rolls needing to be aligned. To avoid errors, measure directly from the end roll to the roll being aligned.  An alternative method would be to repeat the measurement process that was done on the head and tail pulleys using the 2 parallel lines created in step 3.  The end goal is to ensure all rolls are parallel to each other and perpendicular to the conveyor center line.

Note: do not pin these secondary rolls in place. In some cases, they are used to track the belt. On new conveyor belts and/or when a new belt is being installed, all support rolls should be aligned parallel with the end drums before the belt is installed.

Final Inspection and Recommendations

After the alignment of the rollers, a final inspection should be done where the following items can be reviewed, if applicable:
  • Inspect all rolls for roundness, free turn bearings, and run-out accuracy as they rotate. 
  • If the drive roll is lagged, check it for wear. 
  • The counter-tension roll should be restricted to uniform parallel motion. The take up system should operate as a single mechanism. Canting will stretch the belt edge and make tracking almost impossible. 
  • Make sure all rails, skids, hearth plates and herringbone supports are smooth, flat and parallel with the end rolls. 
  • Sharp edges and abrupt corners should be removed since scraping will shorten the belt’s life. 
  • Check that nothing is touching the belt edge that might drag on the belt. On applications where edge sensing is required, limit the force to one pound. 

Your conveyor is now aligned and ready for continuous operation. By following these steps you should be able to avoid future misalignments. 

To learn more about our diverse portfolio of conveying products, visit rexnord.com. For technical questions and support, call 1-866-REXNORD to talk to one of our technical experts.

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Mike Franzoni

Mike is an Application Engineering Manager with Rexnord's Food team. He has been with the company since 2016, but has spent more than 15 years with Cambridge International in application engineering and technical support for metal conveyor belt products. Mike graduated with a Bachelor of Science degree in Mechanical Engineering from the Rochester Institute of Technology.