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WITHOUT LUBRICATION AND WITH EXPLOSION PROTECTION: HEPCOMOTION’S HDS2 SYSTEM IN ACTION IN THE AIRCRA
Sonplas are a leading German manufacturer of assembly and test stands. They supply turn-key solutions in the areas of fuel injection, electro-mobility, aviation technology and security systems in the automotive sector.
In this case, Sonplas were commissioned to design a test stand for hydraulic testing and measurement of customer-specific fuel pumps for aircrafts under variable test and ambient conditions. Since these pumps are used in aircrafts they are subject to especially rigorous test regulations. Sonplas was looking for a gantry system that would be suitable for use with highly flammable substances and would function properly for a long time regardless of the highly degreasing effect of the fuel.
The application:
The role of pre-feed fuel pumps on an aircraft is to take in kerosene using a snorkel and feed the substance to the main fuel pumps. Because of their critical role in aircrafts, it is essential that pumps function properly at all time, making a well-constructed test system essential to guarantee perfect performance later on. In order to mimic the real life scenario as much as possible, Sonplas wanted to realistically map all of the potential pump positions in its test stand. It therefore needed to build an adjustable test platform which required a multi-axis gantry unit. The combination of the customer’s desire to test components at flow rates of 0.5 – 900 litres a minute and the comparatively high level of automation required presented an additional special challenge in the construction process.
A further requirement was that system components were required to run perfectly even without lubrication – quite a challenge since the target system life for the test station was 20 years! However, avoiding lubrication was necessary to ensure electrical grounding would be possible without problems; a key pre-requisite to meet the requirements of ATEX explosion protection directives.
Initially, Sonplas considered using traditional components and existing solutions from the automotive industry to build the test station, comprising of a complete turnkey-solution including a driven axis unit, similar to the ones traditionally used in the car industry. However, this approach was ultimately ruled out since the fire resistant qualities of the component materials could not be fully determined.
The solution:
After exploring all options, Sonplas decided to use bearings and slides from HepcoMotion’s HDS2 heavy-duty range, which can carry loads of up to 68000N. Specifically, they used corrosion-resistant V-bearings and narrow track rollers jointly with surface hardened guide rails to construct an XYZ-gantry system.
In doing so, Sonplas was able to a very stable and shock-resistant construction while also making it possible to test specimens directly on the test apparatus. To check if HepcoMotion´s bearings would be up to the mark in terms of corrosion resistance, Sonplas performed a seal test on them: the bearings were placed in the kerosene substitute for several days. The results were perfect – HepcoMotion´s bearings showed no signs of corrosion. An additional crucial feature for the system was that HepcoMotion´s bearings perform well even without lubrication. However, naturally, if used without lubrication, wear is greater and so it was critical that HepcoMotion´s bearings can also easily be replaced in order to maintain the full functioning of the test stand in the long-run. So the aimed at 20 year life span of the test stand was achievable. Currently, the station is at the endand has been in operation to their complete satisfaction since mid-2019.
