A good thickness control starts with good gauging.
Want to make money twice?
No one but a copper producer would understand how this odd question could be put in relation to thickness gauging. Because, he is actually rolling money, or more precisely, the strips used to produce the coin blanks. At the same time he has to earn money on this activity! The coin strip material must be produced effectively, at low cost, with high quality and with tight thickness tolerances.
The alloys used for coin are often putting special demands on the gauging systems. Copper alloys containing aluminium as an alloying component (i.e. “Nordic gold”) are very difficult to measure accurately with X-ray systems. Strip used for coin production is normally both thick and hard. This often leads to slightly bent strip edges during rolling, a condition that causes problems for a contact gauge measuring very close to the edge.
Gauge control is always crucial in strip production. The demands for narrow thickness tolerances are higher for coin material than for most other types of strip. One reason for these demands is the use of coins in different kinds of vending machines. A good thickness control starts with good gauging. The gauge is the eye into the process! Not even the best and most advanced control system can do anything if the information from the process is incorrect or unreliable. As being the eye to the process, the gauge will necessarily be in direct contact with the process and will be exposed to the fury of the rolling process. The gauge must survive in this environment without the need of extensive maintenance and more; it must measure thickness with the best accuracy achievable.
The Millmate Thickness Gauge (MTG) from ABB is based on the patented Pulsed Eddy Current (PEC) technology. It is a non-contact gauge without the drawbacks of common systems based on X-ray, isotope or contact measurement. The PEC technology is totally unaffected by any material but metals. The MTG will therefore measure true strip thickness even in the harshest environmental conditions. It is also insensitive to changes in material properties and does not require any information about the rolled alloy. Closer thickness tolerances are made possible by this new gauge that measures as accurately in production as in the laboratory.
Companies around the world have installed the MTG system and have realized that this gauging system opens new possibilities to improve their competitiveness. Strip thickness accuracy is improved and as a bonus the costs for calibration and maintenance are significantly reduced. A number of these companies have decided for a general change in gauging technology and have already installed several MTG systems in their plants.