Irwindale, CA . . . NDC Infrared Engineering will introduced a revolutionary new measurement strategy for differential coat weight at CMM 2005.
Called “SPOT-ON™”, this new X-Ray coating weight gauging solution provides the most accurate differential coat weight measurement available today.Preliminary results of several installations of this new NDC control algorithm have shown significant, documented improvements, including 4 times greater coat weight accuracy and 3 times better measurement resolution, allowing much closer control to the edge of the web. This tighter control over the entire web translated into significant material savings and scrap reduction. “SPOT-ON has been developed by NDC to better measure coat weight on substrates, regardless of what substrate is being used,” said Hector Marchand, NDC Vice President of Marketing.
“It completely accounts for base substrate effects to assure that only the coat weight is measured. This greatly improves the measurement capabilities and accuracy of our basis weight sensors, such as our X-Ray transmission sensor.”In 2002, NDC introduced its X-ray transmission basis weight sensor to excellent market acceptance. Among its advantages over traditional beta gauges are significantly greater precision, higher resolution, and reduced sensitivity to web flutter and gauge transmitter / receiver alignment. This resulted in quick acceptance of the sensor in extrusion and textile markets.
The only issue with the sensor was its increased sensitivity to material composition (such as mineral and metallic additives), which made it more difficult to achieve stable calibration in a process where substrate composition can change run-to-run, product-to-product, such as converting. To meet this challenge, NDC developed the SPOT-ON coat weight measurement strategy.
How It Works
Three things can affect the performance of a differential coat weight gauging system:1. Variability in basis weight of the substrate (if the base gauge measures the substrate at a different spot than the final gauge) 2. Differences in signal outputs of the two sensors 3. How the coating weight calculations are made (to separate base effects from coating effects)Simple differential gauging systems don't account for these variances, and as a result, their measurement accuracies suffer tremendously.Accounting for the variances in substrate weight can be handled through a process called same spot measurement.
With same spot, the two scanning sensors are carefully coordinated through high-resolution digital pulse encoders, so that the second gauge waits until the precise moment that the material that was scanned by the base gauge reaches it, and then it takes its measurement on the exact same spot of the web. Scan speed is locked digitally to line speed to insure that same spot is maintained even if web speed changes. Most modern gauging systems employ this important feature.However, accounting for the differences in signal output of nucleonic gauges is problematic. No two nuclear sources are identical, and since they are sealed passive devices, the only option is to try to compensate for the signal differences through software modeling.
There are always significant compromises with this approach.With X-Ray sensors, the energy output of the transmitter can be precisely regulated via a digitally-controlled power supply. This offers two key advantages over the beta gauge: first, the signal does not deteriorate over time as a beta gauge does due to half-life, and second, the substrate and total gauge outputs can be exactly matched to insure that no errors occur from this source.Finally, with these matched sensors in place and measuring the exact same substrate, base stock effects can be "zeroed", and a very accurate coat weight calibration can be applied completely independent of base substrate composition.
The NDC SPOT-ON coat weight algorithm includes these three key features: digitally controlled same spot measurement; digitally matched sensor output; and a coat weight algorithm that is completely insensitive to the base substrate. This model has been tested on several coating lines, including an adhesive coater used for conversion of film and paper substrates, as well as an extrusion board coater used for the manufacture of liquid packaging products. All of these diverse installations enjoyed superior coat weight measurement and control performance when compared to differential beta gauges. The NDC SPOT-ON coat weight measurement strategy is available on the company's 8000 and Pro.Net control systems.
SR710 Gauge Delivers Accurate On-line Measurement of Coat Weight
Also featured at CMM will be NDC’s new SR710 near infrared (NIR) on-line measurement gauge, which offers accurate and reliable measurement of thin layer organic coatings applied to shiny substrates including metal or metallized materials such as polypropylene, paper or board. SR710 offers manufacturers unprecedented control of organic coatings for better consistency and more effective use of expensive raw materials. As a result, the new gauge will provide manufacturers with a return on investment in weeks or months rather than years.SR710 is optimized for measurement of organic or aqueous coatings applied to a reflective substrate.
It is designed for use in the packaging industry where organic coatings are used for their barrier properties.The new SR710 is the latest in a series of ‘lacquer-on-foil’ gauges from NDC Infrared Engineering. While traditional NIR and nucleonic systems have struggled to achieve this difficult measurement, NDC Infrared Engineering’s technology still offers the most accurate on-line solution for organic coat weights less than 20gsm. This is because of optical interference, which causes massive variations in light levels and heavily distorts other infrared sensors’ results.
SR710’s unique optical system design eliminates these problems to offer much superior precision, repeatability and stability of measurement.On-line measurement and control of coat weight provides faster start-up times, better process control, and reduction in expensive raw material usage/wastage, resulting in significant cost savings. Furthermore, SR710 provides early warning of defects such as narrow streaks caused by die blocks even at fast cross web scanning rates. Measurement stability of ±0.003 gsm.
SR710 enables data to be collected at ultra high speeds with a minimum data collection period of three (3) msec. All measurements are robust to the operating environment and are therefore unaffected by ambient lighting, temperature and humidity variations. The signal to noise ratio is excellent.SR710 can be supplied as a measurement system with integrated scanning frame, profile display and data logger, or as a stand-alone gauge with advanced communication options.
About NDC Infrared Engineering
NDC Infrared Engineering offers the world's most extensive range of non-contact sensors and systems for measurement of moisture, fat, protein and continuous web processes variables such as coat weight and film thickness.The group's range of complementary measurement technologies for the web industry includes infrared absorption, beta transmission, gamma backscatter, X-ray fluorescence and transmission, laser caliper and UV absorption. Applications include blown film, cast film, paper, foil and film converting, pulp and paper, nonwovens, rubber and plastics sheet materials, tire production and plastic pipe manufacture.
Products range from hand-held, portable devices for QA checks, to complete on-line system solutions for continuous precision measurement and process control.The group is the world market leader in the design and manufacture of near infrared (NIR) sensors and systems for on-line and off-line analysis and measurement.
The NIR product range includes instruments for monitoring fat, moisture and protein content in food; moisture, nicotine and total reducing sugars in tobacco products; alcohol content and specific gravity of beer; film thickness, barrier layers and coat-weight in plastics; paper and board, foils and sheet steel.Other products in the NDC Infrared Engineering portfolio include a microwave system for measuring the moisture content of paper and a wide range of hardware and software accessories for the sensor and system ranges. All products are CE marked.NDC Infrared Engineering is headquartered at Irwindale, California in the USA and Maldon, UK in Europe.
Operating companies in Germany, China and Japan provide local support to key world markets, and NDC Infrared Group is presented in more than 60 countries worldwide by a comprehensive network of specialist distributors.NDC Infrared Engineering is a Spectris company, an international company specializing in high value-in-use process control solutions.Visit their website at www.ndcinfrared.com