Every converter of flexible packaging is faced with the challenge of producing high-quality products that meet exact customer specifications. Ultimately, converters need to ship the correct amount of product to customers and avoid material over-supply or under-supply situations to remain profitable. But it’s not that easy when the manufacturer is using a mechanical, contact-type measurement method to control the length and speed of product on the production line.
The good news is that there is a non-contact, laser-based measurement technology available that enables converters to achieve the highest level of measurement accuracy. This non-contact technology is being used in a variety of flexible packaging applications to precisely measure product length and speed, control cutting operations and regulate differential speed in lamination processes, to name a few. And, converters are realizing significant benefits in product quality, productivity, and bottom-line savings.
Contact Methods Pose Measurement ChallengesMany manufacturers still use mechanical methods, such as contact wheel encoders or pulses off the drive, to measure length and speed to ensure they are processing the correct amount of product or to trigger a specific production action. But these contact methods are subject to slippage and calibration changes caused by variations in the roll or wheel diameter due to dirt build-up and wear. For example, mechanical contact encoders can cause length and speed measurement inaccuracies by as much as 2 percent or more depending on the application. A 2 percent inaccuracy on a 20,000 foot roll means 400 feet of uncertainty. This translates into a significant amount of money in unnecessary expense.
Non-contact encoders use a unique, laser-based measurement technique without contacting the product. This measurement system is permanently calibrated and has no moving parts to wear out. It works by projecting a unique pattern on the product’s surface. As the product moves, light is scattered back to the encoder. This information is translated into product speed and pulses are produced to determine the product length – independent of shape, surface or color. The pulse output (pulses/unit) is then sent to a control system, such as a , to trigger actions such as length counting, product positioning, cutting control, printing and other tasks. Length and speed measurements are captured with better than +/-0.05 percent accuracy, +/-0.02 percent repeatability.
Accuracies and InaccuraciesMany manufacturers depend on the accuracy of their drive speeds or contact encoders to accurately apply coatings to materials or to control the speed of two or more materials coming together during the lamination process. But materials typically exhibit a certain amount of slippage on the drive roller based on texture, product composition or tension. A contact encoder attached to the drive roller or riding on the product has the same problem, causing measurement and calibration issues. Placing a non-contact laser encoder at each critical measurement point along the line enables the manufacturer to accurately control the tension and speed of the lamination line.
Measurement inaccuracies caused by contact encoder slippage or mechanical issues can throw off cutting systems, causing synchronization issues between the fed material and the cutter. Implementing a non-contact laser encoder provides a non-contact, slip-free method to measure the product length and speed with near 0.05 percent accuracy. This non-contact method improves cut-to-length control, reduces waste and enables the production of higher quality products.
The non-contact laser encoder is steadily becoming the standard measurement technology for many common manufacturing applications involving flexible packaging, and is quickly replacing mechanical contact-type measurement techniques. The benefits of length and speed measurement accuracy offer converters a real competitive advantage. Those companies that adopt this high-precision measurement technology will quickly realize dividends in improved product quality and increased productivity with substantial cost savings.