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.
With the popularity of personalisation among today’s car-buying customers, OEMs are looking to their painting lines to provide assistance. There will always be challenges for painting lines around lower running costs, higher quality, simpler installation, more flexible and robust equipment and, of course, environmentally-friendly processes. Anticipating this trend, Sames has been working on waterborne paint application technologies.
Waterborne application choice How do we electrically charge waterborne paint which, as everyone knows, is a conductive material? The paint must be insulated from the supply to prevent short circuit issues. Sames proposes not one, but two solutions. The first one is the patented Accubell technology, which allows charging of the whole sprayer within the canister full of paint. Already more than 1,000 atomisers with this technology are painting cars and bumpers all around the world. The second solution is the external charge, known as indirect charge. The electrostatic charge is made by ionisation. The paint droplets are electrically charged by passing in front of electrodes, which are external to the sprayer. In this case, the paint feeding system remains ground wired. For the customer, that means no need to modify the existing paint circuit. Moreover, the investment costs are limited when switching from an existing solvent installation to a waterborne one.
How to get over the limitsIf electrodes get dirty during production, the electrostatic charge becomes less effective. Cleaning operations are indeed compulsory. The paintshop’s productivity is not as it should be. Therefore, to eliminate this external charge’s drawback, Sames innovates with two technologies. The first one is on electrodes. They are now equipped with two pins instead of one.
“This dual pin technology showed great results during trials made at Sames’ paint application centre: “250 cars could be painted without cleaning the sprayers or their electrodes,” explains R&D manager Eric Prus. This outcome enables even for a high capacity paintshop to produce quietly between each break.
The second technology brought on external charge atomiser comes from Sames internal charge atomisers: the full range of bell cups 50mm and 80mm with its dual shaping air for super wide pattern (SW). Designed with the patented Hi-TE technology, the EX80 cup allows customers to meet the highest finishing results. The size of droplets is between 6% to 11% smaller, compared to previous bell cups. That helps for better colour matching results and quality (no mottling and stripping issues). The SW air shrouds are controlling the pattern with the dual shaping air management. The fixed ratio of air flow between straight air and vortex air gives a robust pattern. The total air flow and cup speed can vary to adjust a width of pattern from 300mm to 500mm. An additional benefit of these SW air shrouds is a shorter spraying distance which reduces the transfer efficiency of around 4%.
A brand new atomiserSaving paint is also possible in the atomiser itself: an integrated colour change bloc helps to save paint, solvent and time. A new external charge atomiser within multi-trigger technology will be available for 2017. Depending on the process, the new PPH 707 EXT MT embeds six high runner colours block for coloured primer station, or four high runners for unlimited colour configuration of base coat station. For limited number of colours, all paint hoses supply directly the atomiser which manages a 5.6sec colour change with only 4cc ofpaint loss.