On-line measuring systems are essential tools in any extrusion line. When it comes to accurate determination of concentricity and wall thicknesses, however, they do not provide the highest possible accuracy needed to minimize compound consumption. More and more companies determine their wall thicknesses, concentricity, ovality etc. utilizing digital off-line measuring and data collection systems such as the KSM manufactured by ACM AB (
www.acmab.com) of Sweden.
The most important item to understand is that the OFF-Line measurements are by no means a way to replace ON-Line measurements. The main difference between the 2 systems are the amount of measurements which are conducted and to what detail each system can accurately determine the true insulation values. On-Line equipment uses only 2-3 axes to measure the insulation, and it averages values over a set of readings. The offline version takes an infinitely more accurate digital image of the actual sample slice, utilizing an average of 300, or more, measurements to obtain a detailed and precise result of the sample, no matter how complex the shape may be.
Willy Hauer
www.howarequipment.com 
