Success with new process

To meet the high requirements, Polydec uses two demagnetization systems from Maurer Magnetic in Grüningen. Frédéric Nicolet commissioned the first of the two systems over ten years ago and the second a few months ago. "Initially, we demagnetized with a tunnel coil. We slowly pulled the parts through the coil by hand in an aluminum container," explains Frédéric Nicolet. "The process was very time-consuming. We had to employ an extra person to do it, who did nothing else from morning to night. Nevertheless, the parts were not properly demagnetized at the end." Over time, the production volumes increased, the effort involved became greater and the quality of the demagnetization began to suffer. Polydec therefore looked for a better solution. And found it in 2006 in the form of a new technology from Maurer Magnetic. The company had developed and patented the Maurer degaussing technology just a few years earlier. Frédéric Nicolet and Polydec became early adopters of this demagnetization process - and the two companies became partners.

Both companies focus on high quality made in Switzerland and are family-run SMEs. Despite a manageable number of employees, both companies serve the global market with their products. "I met Mr. Maurer at the Control trade fair in Stuttgart," recalls Nicolet. "I told him about our problem. He invited me to come to Grüningen with a box of our bulk material, where we discussed and experimented to determine the optimum demagnetization process. Maurer Magnetic then built a demagnetization system for us using the new degaussing technology. When Mr. Konrad, our patron, saw the new system, he said: "This is the best machine I have ever seen! It only has one button and it works," he says and laughs. Since the new system was commissioned, the entire production has been 100 percent demagnetized.

Why demagnetize?

Nicolet explains why demagnetization is so important: "Demagnetization is a quality feature. The first time we demagnetize is after machining, because chips can stick to the parts, which would hinder their function. After hardening and polishing, we separate the parts from the polishing stones using a magnet. This again leads to residual magnetism, which attracts particles and contaminates the parts. Further operations and checks as well as washing the bulk material also have a magnetizing effect. So we demagnetize our parts up to four times."

Residual magnetism can also cause problems in handling and conveying processes. If parts are not demagnetized, they can become misaligned in the sorting machine, for example, or stick to the measuring rollers. Faults can also occur in the final process step, the inspection with the optical inspection machine.

Nicolet explains: "Visual inspection is very important in order to meet the high quality requirements of our customers, because as part of quality assurance, the machine must be able to photograph every single part and analyze the images." However, demagnetization no longer causes him any headaches: "It's incredibly quick. One employee loads up to 20 boxes, each containing 300,000 parts, onto a trolley and has them demagnetized in 20 minutes. That's no problem with the Maurer Magnetic system."

A few months ago, Polydec ordered a second demagnetizer from Maurer, the MM VE-4. The old system had reached its capacity limits due to the high production figures. If too many boxes are demagnetized too quickly one after the other, the coil becomes too hot, explains Nicolet. "It's also a risk to work with just one demagnetization system: If it were to break down for any reason, it would stop our entire production."

Albert Maurer, Managing Director of Maurer Magnetic, explains how the Maurer degaussing process works: "Polydec needs very high field strengths for demagnetization because its products are ferromagnetic components made of alloyed or hardened steel in bulk. A coil in continuous operation, such as the tunnel coil used at the beginning, cannot come close to achieving such field strengths. Maurer degaussing technology works with a strong and precisely controlled pulse. The short duty cycle of the pulse of a few seconds prevents unnecessary heating of the coil. Thanks to the FMT Field Multiplicator Technology we use, an incredible amount of energy is saved despite the high demagnetization performance."

Thanks to the pulse demagnetization process with FMT in combination with high-performance capacitors, this design of the MM VE-4 demagnetization system achieves a very high field strength of 305 kA/m. The air cooling with radial fan shortens the cycle time, which is typically 10 to 30 seconds. Maurer adds: "The pulse enables demagnetization in a matter of seconds without having to move the workpiece. This is what makes the method so precise and therefore process-capable; the error rate is negligible. The pulse saves energy and costs. In addition, fewer personnel need to be deployed."