Why Do My Sanding Belts Keep Breaking?

Sanding belts seams rarely fail, despite the friction and high-speed flexing that comes with regular and/or aggressive use. While older belts may be more prone to breaking under wear and tear, a newly purchased abrasive should last you a long time. If it doesn’t, you need to investigate what’s causing all of these belt seam failures.

In this blog, the experienced abrasive technicians atRed Label Abrasives outline common causes for sanding belt breakdown and the steps you can take to avoid each issue.

Improper Manufacturing Process

When belt joints are manufactured incorrectly, they can break. The manufacturer may not have used the right heat setting when they pressed the belts together to cure the tape, glue, and backing together. It could also be that the belt was not scuffed properly before it was taped and glued, meaning a small amount of the joint was not sanded off to ensure a proper adhesion. 

If a lot of belts by the same manufacturer are breaking during use, manufacturer error may be to blame. The manufacturer may have a guarantee on their belts or a return policy you can use to exchange the defective belts for new ones. 

Too Much Pressure on the Belt Sander During Use

If you run your belt sander with too much or too little tension pressure, you may experience tracking issues, belt folding, belt tearing, and joint failure. Your belt's ideal tension pressure will depend on whether it has a paper, cloth, or polyester backing. Below are some general guidelines.

• Paper backing – 45-55 psi

• Cloth backing – 55-65 psi

• Polyester backing – 65-85 psi.

Belt Is Not Being Run in the Right Direction

One thing you should check to prevent premature belt joint breakage is the belt's recommended direction. While most tape jointed belts are designed to be bidirectional (they work well when going both directions), others are only unidirectional. If your belt joint is unidirectional, you'll want to make sure that your belt is traveling in the right direction, or else it can come apart at the joint.

Note: Allsanding belts manufactured and sold by Red Label Abrasives are bidirectional, so you won’t have to worry about this issue impacting product performance. 

Excessive Loading

If your belt popped, it might have been due to excessive loading of the material being sanded. Occasionally, particles caught in the machine or a wide variation in the thickness of the workpiece can cause too much pressure and snap the belt. If this is the case, take appropriate steps to minimize load during sanding. 

Improper Temperature Control During Storage

Sanding belts that are well cared for can last for one or two years if they are stored away from moisture, condensation, excessive cold, or excessive heat. All of these factors can contribute to joint deterioration, so store your belts in a climate-controlled environment.

Belt Is Older Than a Year

You should purchase belts that you expect to use within eight months to a year, and store them under recommended conditions. If you haven’t used them past that point, consider cutting them up for use during hand sanding applications. 

Incorrect Belt for the Application

If your belt breaks during use, it's possible that you are not using the correct type of belt for your application. Paper backed belts are often chosen over cloth belts due to their smoother finish and lower price point, but they are much more fragile than cloth belts, so they are more prone to breaking during certain applications. If you’re working with metal or carrying out heavier stock removal, use a cloth belt instead.

Improper Belt Tracking

When a belt is not tracking properly on the machine, it will slide off the rollers or misalign while running. When tracking is incorrect, your sanding belts will prematurely wear out and break. Belt tracking issues can result from problems with the laser eye, tension pressure, belt cut, removal rate, improper abrasive storage, or uneven rollers, so run through each of these scenarios to see if you can pinpoint the problem.

Workpiece Imperfections

This is one of the easiest issues to address. Belts can break if the workpiece being sanded has a nail, staple, or other imperfection protruding from the surface. You’ll want to inspect your workpieces before they are sanded to make sure they don’t contain any pieces that could snag and tear the belt.

Should You Repair a Broken Sanding Belt?

Your sanding belt has broken during use. Should you try to repair it or is the damage irreversible?

While a repair job appears to be the most economic option, it probably won’t work. There’s no strong or safe way to replicate the heat-activated adhesion that manufacturers employ, so determine what caused the belt to break and then cut it up for your hand sanding jobs.

How Do You Keep Your Belts Running as Long as Possible?

 If you want to prolong the life of your belt, start by keeping your belt sander well-maintained and in good working order. Next, make sure your belts are running with the right amount of tension and achieving optimal removal rate. You’ll also want to confirm that you’re running through the proper grit sequence each time and that you are using the best abrasive material for your application. All of these factors will extend the life of the belt.

Do You Have Questions For An Abrasives Specialist?

One of the first steps you can take to prevent belt breakage is to source the highest-quality abrasives. For over 35 years, Red Label Abrasives has been providing a wide range of industries with thesanding belts and other abrasive products they need to achieve excellent results. Feel free tocontact us if you have questions about how to get the most out of your product. We’re here to help!