Cleaning of Mechanical Precision Parts for Clean Room Assembly
NTS Mechatronics B.V. in Eindhoven assembles mechatronic systems for the medical, semiconductor, graphic, solar and Nano industry amongst others. Here, all aspects of high quality and innovative service come together. By focussing on process stability, NTS Mechatronics B.V. distinguishes itself from others in the market.
High precision and strong quality control during the entire assembly process contribute to this success. This also includes efficient part cleaning in an automated industrial cleaning line before assembly. The parts made from stainless steel, aluminium, titanium or plastic are highly contaminated after machining. In order to remove oil, coolant, finger prints, particles etc., the parts are thoroughly cleaned in an aqueous ultrasonic cleaning system. This system has been developed and built for this specific application by FinnSonic Oy. Kemet provides guidance during the entire process, from the very beginning to the installation and operation, complete with training for the users.
Roy Loonen, Project Manager at NTS Mechatronics B.V., explains: “The parts must be completely free of any contamination before they can be processed further.”
Thanks to three different cleaning combinations – consisting of the steps ultrasonic cleaning and rinsing – different detergents can be applied. This allows an effective cleaning of a wide variety of materials and contaminations. This is necessary to satisfy the high expectations of customers, namely a top quality clean assembled product. After ultrasonic cleaning and rinsing two more rinsing steps follow in DI-water (so called demineralised water) of high quality. These rinsing steps, together with mechanical agitation, permit an effective removal of detergent residues and other impurities.
Next the parts are carefully dried in the hot air dryer. To prevent recontamination in this drying step, incoming air is filtered through a HEPA-filter.
An open area in front of the dryers gives NTS Mechatronics B.V. the flexibility to extend the machine in the future, should cleaning capacity or cleaning quality so require.
In order to achieve consistent and high level results, an automatic PLC-controlled transport system was selected. This enables NTS Mechatronics B.V. to follow up the set process times precisely. With an intuitive touch-screen different cleaning programmes can be selected and compiled.
The stability of the cleaning and rinsing fluids is of great importance for the cleaning quality. As a result all cleaning tanks are equipped with surface skimming, filtration and automatic dosing of both water and detergent. The rinse tanks are automatically refreshed so that each part will be optimally cleaned again.
To profoundly clean all holes and chambers of very complex parts, Kemet integrated a step in the machine where parts can be repositioned for a second cleaning in which difficult to reach surfaces are cleaned as yet. This turning station also allows removal of rinse water accumulations from parts in order to optimize drying.
Automatic conveyors for loading and unloading the cleaning line allow a very ergonomic and user-friendly system.
Limited load of the clean room
An ultrasonic cleaning line consisting of nine tanks generates a lot of heat and water vapour. In order to minimize the load of the clean room, the work is carried out in three zones.
The first zone is a separate area of the clean room. There, parts to be cleaned are positioned in the baskets. In turn the baskets enter the machine via the load conveyors. Due to the overpressure of the clean room in relation to the closed housing of the machine, heat and water vapour will end up in the area as little as possible.
All cleaning tanks of the cleaning line are situated in the second zone. The completely closed housing with extra seal limits air leaks between the machine and clean room to a minimum. Warmth and vapour, generated by the machine, are continuously released outward. All peripheral devices for fluid treatment are located in the technical room next to the clean room.
The third zone is situated right next to the hot air dryer. To prevent heat transfer to the third area of the clean room, the unload conveyor is equipped with an automatic shutter. In this way the space where the cleaned parts end up can be kept in an excellent condition easily.
Roy Loonen concludes: “Kemet was selected as supplier due to their proactivity in thinking along with the processes and adjusting the cleaning line according to NTS Mechatronic B.V.’s wishes. The final breakthrough was the price/quality ratio compared to other suppliers.”