Non-anaerobic silicone beading has gradually replaced solid gaskets on powertrain assembly lines. Christoph Denis-Bosio of Kremlin Rexson Sames explains the importance of application for the solution’s better performance
In 2016, a total of 90m engines and 90m gearboxes were produced for light passenger vehicles the in 371 engine plants and 309 transmission plants worldwide. Another 3.2m engines were manufactured for medium and heavy commercial vehicles at 117 plants around the globe. The OEMs themselves make up the huge majority of engine manufacturers. For gearboxes, however, large tier suppliers are responsible for one-third of worldwide production, providing their wares to assembly lines of OEMs everywhere.
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Manufacturers of engines and gearboxes have a critical application in their production lines: non-anaerobic silicone beading. Solid gaskets have been gradually replaced over the past ten years ago due to the many benefits of non-anaerobic silicone beading. One such benefit of this liquid gasket is that it can be applied by robots on horizontal as well as vertical surfaces, on a very flexible path, which reduces the need to stock specific solid gaskets. On the performance side, the liquid gasket reduces hydrocarbon emissions due to the reduced seal gap.
Overall, the quality of the bead brings high reliability and long life to the final component. But, to achieve such a quality and volume of production, the manufacturing process is highly automated.
Customer requirements call for an uninterrupted and regular bead and no excess of material. This means that the entire system should be dispensed with precision and the bead should be continuous. Moreover, the system must inform the responsible operators and supervisors that the station is functioning correctly.
Typical powertrain gasketing solutions installed at several OEMS and tier one suppliers consist of a ram unit for silicone pumping, up to a multi-axis robotic system. They include a high level of regulation or electrical dispensing units.
One benefit of a liquid gasket is that it can be applied by robots on horizontal as well as vertical surfaces
The first level of this solution is the silicone extrusion pumping and transferring system. With double or single ram and follower plates available for 20-litre and 60-litre drums, ram pumping is available with options such as automatic crossover for double ram, a safety piloting system and roller plates for easy drum installation. A large range of pumps can be installed for high-pressure ratio or high flow.
The high precision of the dispensing is a must and, to that end, the bead-volume dispensing unit is controlled by a PLC.
The Regulex dozing unit is electrically driven and is designed to enable very accurate dispensing of the non-anaerobic silicone. Regulex can dispense a constant or variable bead diameter, at constant or variable speed. Some safety modules can be added, such as a vision system for bead regularity control.
For additional installation management, a touchscreen control bay pilot features such as a heated zone, pump start-and-stop, pressure regulation and runaway protection.
Some installations work on an automated basis, though not a robotic one. In that case, the standard solution includes a similar ram pumping system but regulation is performed by a high-precision product regulator at low pressure. An automatic gun dispenses the silicone and while accuracy is high, it is not at the level of the robotised system.
Ease of maintenance and cleaning at each step is another key point for users. The simplicity and efficiency of a product chamber make it easy to work with, including an excellent precision of dispensing. Regulators that are low shear have a fast response time but are easy to maintain. As a material, stainless steel pumps are highly robust and very efficient.
Kremlin Rexson Sames is a turnkey system supplier of dispensing systems, manufacturing dispensing equipment, from manual and automatic applicators to a wide range of pumps and machines for fluid handling, dosing, mixing and dispensing.