A degreasing process’s energy use and CO2 emissions have been nearly cut in half thanks to a joint project involving Freudenberg Sealing Technologies and its sister company SurTec. The process
is part of the pretreatment of Simmerring® metallic parts in Weinheim.
The process – low-temperature washing – is a familiar concept. In today’s washing machines for homes, low-temperature detergents are capable of removing red wine and oil spots from trousers, shirts and sweaters energy efficiently. “This basically works like a standard household washing machine,” said Project Manager Dr. Stanislaus Schmidt, Technology & Innovation.
Today the pretreatment of the metal only has to heat the washing solution to 40 or 45 °C (104 to 113 °F) to degrease them. Until now, the bath had to be maintained at a minimum of 65 °C (149 °F). This decline of more than 20 °C (36 °F) translates to a decrease in energy use and CO2 emissions of about 50 %. This not only benefits the climate – it lowers energy and production costs as well. The new special chemical cleaning agent used for the pretreatment comes from SurTec.
Fewer Chemicals Needed
Degreasing is the first step in the phosphating process for the metal parts (see box). It takes place at all FST facilities and their suppliers and is based on the same model everywhere – which means this approach can save energy at other sites. “I have already presented this approach to our facilities in Europe. An evaluation is underway. And we have already carried out pretests in the United States,” Schmidt said.
The experts in Weinheim have already left these stages, including extensive testing at the laboratory level, far behind. The 45-degree solution has been proving itself since last summer. “This is a very stable process. The coating with a binding agent afterwards runs just as well as it did in the past,” said Thomas Schwöbel, who oversees the pre-products unit. Schmidt added: “We see no difference in the performance. We even need fewer chemicals than before.”
Aside from huge energy savings, Schwöbel can cite a range of other benefits of using low-temperature degreasing with the SurTec cleaning solution. Unlike a household washing machine, the washing agent is not pumped away as wastewater during the process. Instead, it is used again and again in each washing cycle for up to three months, benefiting the environment. But that means it has to be regularly de-oiled one floor below.
“A froth always formed when the previous detergent was used. It was not something we wanted,” Schwöbel recalled. Additional safety measures were needed to protect employees, machines and the environment. Extra cleanup was also required to prevent wear and the deterioration of pumps and intakes.
The froth is now gone, and so is the annoying work associated with it. “We have it all under control,” Schwöbel said. The new system offers yet another advantage: At low temperatures, there is a noticeable reduction in the amount of evaporation from the solution.
Metal Parts Pretreatment
A strong bond between metal carrier parts and elastomers is of crucial importance for the quality and longevity of a Simmerring®. With metal parts pretreatment, the surface of the already stamped and formed blank is prepared for a lasting bond, first with phosphating and then with a coating.
The process is divided into various successive steps. The metal parts start out as bulk material in perforated drums. In Weinheim, based on the diameters, they contain up to 20,000 rings. The drums are successively dipped into various baths during a largely automated process.
The first process step is degreasing. Here the drawing oils from the stamping and metal operation are removed – at first with a less-than-complete cleaning in the first bath. The “second run” takes place next. As part of a project to save energy, Freudenberg Sealing Technologies (FST) was able to reduce the washing temperature and, thus, the energy use associated with the two 1,500-liter (396-gallon) degreasing baths significantly.
To round out the process: The other steps are called pickling, activating, phosphating, passivation and drying. “We are also testing ways to improve the pickling and activating baths to boost sustainability,” said Dr. Stanislaus Schmidt. The metal rings are coated after the phosphating step.
