Roll Forming Machine Troubleshooting: Cutoff Length Tolerance
Today we are disucssing about roll forming machine troubleshooting: Cut Length Tolerance! It is a very common question that many users may have during their operation of a roll forming machine. To well understand this question, we must be aware of the difference between two cut methods of roll forming machines.
As we know a roll former usually cuts the roll formed profiles automatically according to required lengths and quantities through PLC control system. However, some roll formers measure the length via a counter or an encoder, and some other roll forming machines require manual measurement of cut length instead of an encoder. After the required cut length is measured and the position switch is set up manually at the right spot, roll forming production starts.
Fixed-Length Cut
This cut method is named as fixed-length cut. It’s not as automatic as multi-lengths cut or encoder-cut, but it rarely cuts in any tolerance, which is why there are still many operators or plant managers prefer such cut method, even though each shift of production can only produce one cut length. To cut a different length every time, the roll forming machine needs to be powered off, and the operator remeasures the length and sets up position switch at a different place.
Encoder Cut
Encoder-cut works in another way. It’s fully automatic and all the operators need to do is just input the required lengths and quantities through the HMI, the counting and measuring jobs are left to the machine itself. Each shift of production, it can cut up to 20 different lengths fully automatic with no need to stop the machine.
An ecoder-cut machine measures length via the counter, i.e. ENCODER. An encoder is pushed tight on the roll fromed sheet, and rotates as the roll formered sheets moves forward. During this roll forming process, the control system records how many circles the encoder rotates, calculates out how many meters the roll formed sheets move forward (easy math job), stops the machine and cut the sheet when the required length of the roll formed sheet is reached. This is exactly how an enoder-cut machine works.
Roll Forming Machine Troubleshooting
Back to the question at very begining, why is there cutting length tolerance after a roll forming machine is correctly set up? We need to do a roll forming machine troubleshooting and find as a matter of fact, this issue-cut tolerance, comes from an encoder-cut roll forming machine.
- On one hand, as production goes on day by day, the encoder is pulled loose and may slip on the roll formed sheet, instead of rotating. Sliping causes error on the result of length calculation (the perimeter of encoder cannot be calculated correctly). As a result, there will be cut tolerance for the roll formed sheets.
- On the other hand, a roll forming machine usually roll forms different thickness materials, and change of that may also cause encoder not rotate normally and to the end cut tolerance occurs.
Whenver cut tolerance takes place, do the below quick check.
- If no materials have ever been replaced, check whether or not the encoder works functionally.
- If different materials have been replaces, check carefully the surface of the sheet and whether or not the encoder slip on the sheet.
- Check PLC control system, if any default numbers about cut tolerance adjustment have ever been changed.
SOLUTION
- Try to adjust the numbers about cut tolerance according to the manual provided by roll forming machine.
- Adjust the postion of encoder.
- Change a new encoder and reset the numbers.
- Try to order a roll former with an innovated encoder, laser encoder for example
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Frequently Asked Questions
Why does an encoder-cut roll forming machine develop cutting length tolerance even though it was set up correctly? ›
Tolerance issues in encoder-cut machines typically result from encoder slippage on the sheet surface. Over time, the encoder can become loose and fail to rotate consistently, causing miscalculations in length. Additionally, changing material thickness can affect encoder traction. For fixed-length cut systems, tolerance is rare because measurement and cutting positions are manually fixed, but production is limited to one length per setup.
What should I check first if I notice a cut length tolerance problem on my roll former? ›
Start by determining if you recently changed material thickness or type. If you did, inspect the encoder’s contact with the sheet to see if slipping occurs. If material hasn’t changed, verify the encoder is functioning correctly and securely mounted. Also check your PLC control system for any altered tolerance adjustment settings. Unusual wear on the encoder wheel or contamination on the sheet surface can also contribute to measurement errors.
Can material thickness changes cause cut tolerance issues, and if so, how do I compensate? ›
Yes, changing material thickness can affect how tightly the encoder presses against the sheet. A different thickness may change the effective diameter where the encoder contacts the material, or it may not provide enough resistance for proper rotation. Some machines allow you to adjust the encoder arm or spring tension. Always re-verify accuracy after a material change and re-calibrate the length measuring system according to your machine’s manual.
What are the practical alternatives if frequent cut tolerance errors are hurting my production quality? ›
If repeated encoder adjustments don’t solve the problem, consider whether a fixed-length cut setup would work for your production runs, since this method inherently has minimal tolerance. Alternatively, you could replace the standard encoder with an updated type, such as a laser encoder system, which eliminates physical contact and thus avoids slippage issues. Discuss these options with your roll forming machine manufacturer to see which approach fits your production volume and profile needs.
How does the cut method affect my ability to produce multiple profile lengths without stopping the machine? ›
The cut method directly determines your flexibility. With a fixed-length system, you must stop production, manually reposition the limit switch, and restart to change lengths—only one length is possible per run. An encoder system allows you to input up to 20 different lengths per shift via the HMI, and the machine switches automatically without stopping. This makes encoder systems ideal for diversified orders, though they require proper encoder maintenance to maintain accuracy across all cuts.
What regular maintenance should I perform on the encoder to prevent cut length tolerance drift? ›
Periodically verify that the encoder is tightly secured and its wheel is clean, without any dust or metal debris buildup. Inspect the wheel surface for flat spots or wear, which can change its effective diameter and cause measurement errors. Confirm the encoder remains perpendicular to the sheet for full contact. A simple routine check of the encoder and its cabling every production shift can prevent most tolerance drift problems before they affect your cut lengths.
