Jaguar vibration dampers feature elastomer-metal hybrid designJaguar vibration dampers feature elastomer-metal hybrid design

Some car components really do keep a low profile. You'd only notice how they function if they weren't there. Vibration dampers are a good example, reducing unwanted vibrations produced by engines and drivetrains.

Winkelmann Automotive (Ahlen, Germany) is a development partner and system specialist when it comes to vibration and how best to dampen it. Vibration dampers are further enhanced by the use of elastomers. In the case of a decoupled pulley which has recently been developed for Jaguar, two elastomer components help boost vibration damping performance.

To be precise, the component is a torsional vibration damper with an integrated, decoupled belt pulley. This assembly, comprising 10 metal parts, is supplemented with a pressed EPDM rubber ring and a hybrid, bonded EPDM-Metal part. The assembly weighs a total of 2.99 kg. The elastomer components weigh 180 g. The part can be exposed to temperatures as high as 140 °C.

Horizontal machines from thermoset injection machine supplier Maplan are deployed for manufacture of the rubber rings. The high-precision EPDM rings are vulcanized to very tight tolerances in a fully automatic process on a horizontal MHF 2600/460 machine using multi-cavity molds by tooling specialist Peta Formenbau. Very precise wall thicknesses are essential to ensure true running pulleys. These wall thicknesses are automated inline and continuously checked offline by means of reference samples.

Winkelmann has also focused on increasing production output. The trick here has been to vulcanize the rings in double width and then radially cut them inline, creating two rings which are then transported to the tempering oven for further treatment. The cutter for this process is from KAMtec. "The automation and double-width rings have proven themselves as an economical and reliable manufacturing solution. This way we could avoid stack mold technology and thus achieve highest quality with low tooling costs," says Michael Metzinger, from the development department for elastomer technology at Winkelmann.

The horizontal Maplan MHF 2600/460 machines possess full-size heating platens to maintain temperatures of both halves of the mold. The fully insulated heating plates are also insulated on the sides, to direct the maximum heat energy to the molds and minimize losses. This enables precise heating of the cavities and is also used for the cold runner heating plate. CoolDrive II drive technology is applied for the main drive and parallel drive. The DCI heating technology deployed works with controlled pumps where the heating and cooling requirements are accurately adjusted to meet process needs by means of an integrated control algorithm. Typical overshooting when heating and undershooting when cooling, a phenomenon that regularly occurs in practice can therefore be effectively prevented.

In addition, rubber-metal composite parts for decoupled belt pulleys are manufactured as bonded vibration dampers. These are produced on a vertical MTF 2600/280 ergonomic machine from Maplan with "molds again supplied by Peta Formenbau. Vulcanized bonded vibration dampers mean unrestricted geometries for the elastomer components and are particularly suitable for high and complex frequency vibration loads. "In order to manufacture these hybrid components, the sheet metal parts are coated with a bonding agent before being inserted into the mold which is then injected with elastomer material," says Metzinger. "The quad-cavity molds from Peta Formenbau have eight valve gate nozzle cold runners - four cavities each with two injection points per molded part.

In the final expansion phase of the manufacturing plant, six vertical Maplan elastomer machines have been deployed at Winkelmann in Ahlen. By means of intelligent needs-based control of the flow rate, energy consumption of the DCI heating and cooling units on the Maplan MTF 2600/280 machines has been reduced by up to 80 % while at the same time considerably improving quality control. The CoolDrive servo-hydraulic technology provides additional performance for rapid drying cycle times with even less energy requirements. This is more environmentally friendly and lowers production and unit costs. The servo-hydraulic system, in this case additionally fitted with a parallel drive unit for even faster cycle times reduce energy consumption for the drive by up to 50 % with the same reduction in drying cycle times. Noise emissions have also been halved (-10dB).

Each production cell is equipped with a Fast Double Shuttle for the manufacture of rubber-metal hybrid parts with inserts. The shuttle features twin guides to fit the shuttle plate. The same twin guides can also be found on the knock-out bars on the clamp side hydraulic ejector. A special feature of this solution is that two identical shuttle plates alternate between the machine and the external station. The advantage of the "Fast Double Shuttles" is that both shuttle plates can be moved at the same time, i.e. while plate A is being removed from the machine, plate B can be placed in the machine. This together with a newly developed, extremely fast servo drive concept means a considerable reduction in loading times, compared to conventional shuttle plate shifting. Another feature of the Fast Double Shuttle is a hydraulically-actuated ejector including a dockable heating plate. The external heating plate prevents the shuttle plate from cooling down when outside the machine. The finished rubber-metal parts are ejected from the shuttle plate so that they can be easily removed by the operator.