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July/August Feature

Auto Parts Maker Develops New Welding Technique

By Karen M. Koenig

Monaco-based Mecaplast has developed a new process whereby polyamide air inlet distributors ca
With mirror welding, it is possible to produce 3D welding surfaces. The assembly areas are melted from contact with hot surfaces, then assembled under pressure.
n now be produced by mirror welding. The technique is used to make air inlet distributors for Mercedes BR 900 Series Actros four- and six-cylinder engines. The material used in the distributors is a Bayer Durethan BKV H2.0 6 polyamide strengthened by glass fiber.

Prior to this, polyamide air inlet distributors were vibration welded. Unlike vibration welding, which involves rubbing the pieces against each other to the point of melting and interpenetration, mirror welding involves melting the assembly areas through contact with a hot surface prior to assembly.

For its development of the technology, Mecaplast received the AEI Tech 2001 Award at last March’s SAE exhibition.

“This new weld technology gives us the freedom to design polyamide parts. The difficulty before in working with polyamides was because of polyamide’s high temperature melting — the material becomes ‘liquid’ but the viscosity is low. It also allowed a very short assembly time. The entire process — melting, hot plate withdrawal and joining — can take just a few seconds,” says Stéphane Firecka, development manager, in the Lens, France office.

“These problems are now eliminated,” he adds. “We can also produce 3D welding surfaces. With vibration welding, you are limited to 2D welding surfaces because of the pressure index needed for applying equal pressure around the weld,” he added.

According to Mecaplast, other benefits include:

• The ability to “design a welded joint that is narrower locally, allowing access to the locking screws and the production of parts that take up less space or are easier to integrate into the engine;”

• The opportunity to “weld the areas of parts that are not held by the welding tool, such as internal ribs, that are generally deformed by vibration;” and

• A greater mechanical resistance for parts under high pressure stresses, such as turbo engine distributors.

“With vibration welding, we saw a number of limitations: in movement between parts, the friction process, flash concern, dimension limits; limitations in polyamide use, and the high melting point combined with fast crystallization and low melt viscosity of the materials,” he adds
“Customers are now asking for very clean parts. This is a very clean process and doesn’t produce any plastic dirt.”


Manufacturing and Testing Components at the Lens, France Facility

Incorporated in 1955 in Monaco, Mecaplast began operations to manufacture automotive components for companies such as Peugeot.
Stephane Firecka shows some of the equipment in the testing area. At the facility are: vibration cells, a traction machine, an electric engine block and equipment to test the effect of water, including moist air on filters and the effect of infrared light of heat on the materials.
More than 80 percent of the company’s business continues to be dedicated to the automotive industry, supplying under the thermoplastic and thermoset hood applications, interior components and body applications, including door components. Sales in 2000 were $320 million.

In addition to the Monaco facility, the company has expanded its operations to include production facilities in France, as well as a testing facility in Lens. The company also has an office in Michigan.

The Lens facility is dedicated — 100 percent— to underhood applications. Among the products offered are thermoset and thermoplastic rocker covers made from 30 percent glass-filled nylon, used for gas engines, not diesel. “We are the European leader for thermoplastic rocker covers,” says Stéphane Firecka, development manager. “In the United States, rocker covers are generally thermoset, not thermoplastic. We have the capability to manufacture both.”

Other products include fluid management systems such as air/water/oil filters, cooling systems and cooling tanks, and air emissions components including the hose/resonator intake manifolds and air filters. Products such as the intake manifolds are injection molded using lost core technology. However, with the new welding technology developed by Mecaplast, the company can reduce the number of parts made through lost core.years. “We can create the whole module and assemble all the functions. We can also manage the whole process, from production through testing,” says Laurent Guilly, calculations manager.

Testing involves calculation of the acoustic levels and temperature ranges inside each part. “We’re also interested in free dynamics — calculations on the entire engine, including power, torque, efficiency, noise, 3D calculations to show pressure drops in the system and to understand the structure of time lines,” Guilly adds.

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Plastics Machining & Fabricating
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