Improving Cutting Accuracy and Repeatability
on Cut-to-Length Lines by Replacing Contact Wheel Encoders with a Non-contact Laser
Understanding the Problem
Many manufacturing processes use contact wheels with encoders to measure the speed and length of the product during production. However, in many cases, this does not provide the desired outcome because the product being measured is either soft, sticky, coated in oil or subject to rapid acceleration or deceleration.
This can lead to inaccurate measurement and on some processes, the traditional contact wheels require constant maintenance to ensure reliable measurement. This can be due to particle pick up on the wheel changing its effective diameter or wear of the wheel or the supporting mechanism. For operations where a continuous product is cut to shorter lengths, the final lengths can very often be longer than they should be resulting in the manufacturer giving away a percentage of their total yearly production.
Measurements conducted on various processes have discovered that very often the typical measurement error with a contact wheel encoder is in the region of 2-5%. However, the error is not constant and will vary depending on the product being measured, the line speed and the surface coating.
This inconsistency makes it difficult for the process engineer to account for these errors in the control system. Therefore the actual accuracy will vary depending on the product that is being produced. On some process lines, an encoder is connected to the drive roll and this is used as the reference for length control. As the drive rolls primary function is to push or pull the material through there is always an inbuilt slip with this type of measurement method.
LaserSpeed® Pro Solution
The LaserSpeed® is a direct replacement for a contact wheel and encoder system, improving the accuracy and repeatability of the measurement. As the LaserSpeed® is unaffected by the product surface condition, oil coating, whether the surface is wet or dry, the accuracy and consistency of measurement are much better than can be achieved by a contact wheel encoder.
The LaserSpeed® will achieve an accuracy of better than ±0.03% and a repeatability of ±0.02% irrespective of the product or conditions. Furthermore being non-contact the gauge is maintenance-free resulting in lower running costs. LaserSpeed® is used on many cut-to-length applications where a flying shear or saw is used in process to cut a continuous product to shorter lengths.
Connecting a LaserSpeed®
The LaserSpeed® has a full quadrature output just like a regular rotary encoder. The pulse rate can be configured by the user to emulate the rate of the existing encoder. This means that the existing control system does not need to be changed or reprogrammed. Once connected, an existing line will benefit immediately from the improved accuracy of using the LaserSpeed®. In some cases, a 2-5% improvement in cutting accuracy has been achieved.
The LaserSpeed® Pro can be used on all types of cut-to-length line to replace an existing rotary encoder, including:
LaserSpeed® gauges have no moving parts and are permanently calibrated resulting in significant time and money-saving.
What Our Customers Say…
We wanted to improve the accuracy and repeatability of the automated length cutting operation on our Agnati corrugator. From the first meeting, it was clear that LIMAB have a lot of experience in this area and they replaced our mechanical encoder with a LaserSpeed®. The implementation of the LaserSpeed® has enabled us to achieve our original goal and it has ultimately improved the quality of the products that we are supplying to our customers.
Shaun Coombs – Engineering Manager
If you would like to find out whether a LaserSpeed® could improve your production processes, then please do get in touch.