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Troubleshooting High/Lows on Orbital Welds

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I’m seeing an increase in the number high/lows in my welds – how do I correct this?

The easiest thing to do is to swap weld heads with someone when they’re not looking, but that really doesn’t solve the problem. Actually, you can usually figure this out pretty quickly. There are a handful of things to check (from most to least likely reasons):

  1. Mismatched or worn out collets
  2. Poor quality collets to begin with.
  3. Problem with the weld head itself
  4. Ovality of the tube
  5. Tube ends aren’t being prepped properly.

Since you’re getting a more gradual increase in the number of tubes/fittings not lining up, it’s probably not mismatched collets. Usually, a mismatch will either always cause the problem, or never cause a problem.

Click here for a more detailed write-up on this issue.

Sooner or later, every orbital welder sees has to deal with unacceptable misalignment of their tubes or fittings in the weld head. It can either be a high/low between the tubes, a gap – even when the tubes are butted together in the head — or both*.

The good news is that troubleshooting an orbital welding problem is fairly easy. In 99% of the cases, it boils down to one of six different things. These are listed from most likely to the least likely culprit.

  1. Mismatched Collets – Pairs of collets may look like a match, but if you’ve got multiple pairs of the same sizes/styles, the pairs can become mismatched. If you’ve got the old style AMI collets, you’ll see that they’re scribed with 2 sets of numbers. These were machined/matched sets. Just like any other set, if these numbers don’t match, the collets will not provide proper alignment.
  2. Worn Out Collets – Eventually, even the best collets will wear out to the point where they don’t provide a snug fit for the tube. A sloppy fit means it’s time for a new set.
  3. A certain brand of pre-spring loaded style collets – We’re not going to name the manufacturer, but if you have them, you’ll quickly notice that they’re not worth their weight in salt.
  4. Ovality – Sometimes the tube is out of round. The larger the diameter and the thinner the wall, the more likely this is to become an issue.
  5. Ends not prepped properly – If your collets are good, but you’re seeing a gap, then your tube might be out of square.
  6. Weld head problem – If your equipment is cared for to even a reasonable level, then a problem with the head is surprisingly rare. When problems do occur it is usually a broken line-up pin, worn jaw hinges, or a worn weld head housing. If you’re renting orbital equipment from a reputable shop, then these potential points of failure are typically checked & serviced if necessary prior to putting back into rental inventory.

*The “rule of thumb” / defacto industry standard tolerance on high/lows is 10% of the wall thickness.

Troubleshooting High/Lows on Orbital Welds was last modified: February 5th, 2014 by admin

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Since 1998, Critical Systems, Inc. (CSI) has been providing Gas Cabinet, Valve Manifold Boxes & Gas Abatement Systems (Gas Cabinets and Gas Scrubbers, etc.), and Orbital Welding Rental, Lease, Repair and Training Services related to process tool facilitation for Semiconductor, Biotech, Pharmaceutical and related industries. Company headquarters are in Boise, ID USA, with additional locations in Shrewsbury, PA USA – Draper, UT USA – and our new European Sales and Service center in the Netherlands.