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Process Cleaning Magazine
© 2012
AMT-The Association For Manufacturing Technology
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PC FEATURE
This aqueous cleaning system, used at a heavy industry plant for cleaning large fuel and hydraulic tanks, is specially designed for washing, rinsing and drying of complex parts with difficult-to-reach internal features.
The rotary drum front loading spray wash system is designed to combine mechanical, thermal and chemical energy sources to fully and effectively impinge all areas of the components needing to be cleaned with the heated spray wash solution.
With this manually loaded system at an automotive manufacturer, the operator locks a V8 engine block into position in the inner cage, then pushes the cage into the wash chamber. Blind holes and hard-to-reach areas are successfully cleaned.
When it comes to cleaning components during any inter-stage or final stage manufacturing process, component parts often need a high-precision clean both inside and out. Moreover, just as engineered parts are increasing in complexity, so the required standard of precision cleaning is becoming higher and more specific. Add to this restricted time factors, cost effectiveness, environmental issues, ergonomic pressures and legislative requirements, and it is not surprising to find that many manufacturers are faced with a real challenge when it comes to sourcing an effective cleaning system that can match all of industry’s modern demands.
Historically, manufacturers have often considered solvent cleaning as one of the most trusted and efficient methods of cleaning complex components. The high and consistent standard of cleaning that can be achieved and the speed with which this is reached has long made solvent cleaning a popular choice.
However in recent years, significant legislative changes have left manufacturers facing increased pressure to follow strict procedures, replace equipment, and rethink their entire cleaning process. This has become costly and time consuming. As a result, many manufacturers have completely turned away from solvent cleaning, and instead have been sourcing cleaning processes that are considered safer and simpler.
Aqueous-based cleaning is undoubtedly a logical alternative. However, where highly complex engineered components are concerned, traditional aqueous-based cleaning is not without limitation. While immersion-style aqueous cleaners and ultrasonic tanks will certainly ensure a thorough wash inside and out, manufacturers can be left with the problem of drainage and drying, especially if the component has a tendency to retain the wash solution inside.
Similarly, a spray-wash-type aqueous system is highly effective at achieving exceptional levels of cleanliness. However this will only work if every area of the component is reached with the cleaning solution. Problems can arise if the parts have difficult to reach internal areas. Fluid from these systems can also become trapped, creating drying problems.
The Development
With all of these problems in mind, Tony Grayson, technical director of Technowash Ltd., set his sights on developing a new style of aqueous wash system specifically for these complex component parts. He says, “We noticed a trend in inquiries, particularly from the automotive industry, where customers were complaining that they simply could not find any one machine in the marketplace that could fulfill all of their requirements.”
These inquiries were from customers with highly engineered parts, containing blind-hole areas and internal areas that needed to be cleaned and dried to a high standard all while meeting the correct environmental, health and safety criteria. The machine needed to be cost-effective and meet very tight process cleaning times.
Technowash established that an adaptation of a standard aqueous spray wash system could provide the most likely solution. “Aqueous spray wash cleaning is able to provide a highly effective and quick precision clean if all the required elements are combined correctly,” Mr. Grayson continues. “We soon realized that by totally rethinking one of the general principles, we could offer an impressive solution to this problem.”
The Technology
Aqueous spray-wash cleaning works essentially by combining mechanical, thermal and chemical energy sources. The total energy required is the sum of all these energy sources combined over a given period.
Conventional automated aqueous spray wash cleaning machines incorporate a wash chamber that contains spray bars and spray jets. Component parts are placed in a basket located inside the wash chamber.
The chemical energy source comes via the wash solution contained in the machine’s fluid tank, which is normally made up of a percentage of aqueous-based detergent mixed with water. The wash solution is heated to provide thermal energy, and is then driven by the wash pump out of the spray jets. The mechanical energy source is traditionally either from the spray bars, which are rotated around the component basket, or the component basket itself, which is completely rotated around the spray bars.
The overall key to successful component aqueous washing is in combining these elements in such a way that all areas of the components end up fully impinged by the heated spray wash solution both quickly and effectively.
Aqueous spray wash systems also have the facility to rinse and dry components by using the same principles.
The difference with the Technowash machine comes from the manipulation of the mechanical energy—the rotation element. The traditional component basket is substituted for a full component cage, which is specifically engineered to lock the particular component(s) in place. The inner cage is then transferred inside the wash chamber (either automatically or manually) and locked into a second outer cage, forming one secure unit. Spray jets are strategically placed around the wash chamber both above and below the cage. The entire cage is then rotated.
By rotating the entire cage, the component part itself is also fully rotated, so wash solutions can easily reach all sides and all internal areas. The cage can be stopped in varying positions during the cycle, further aiding fluid drainage and allowing concentrated drying of troublesome areas. The speed of the cage rotation is fully adjustable and bidirectional, ensuring cycle times to be as economical as possible.
The System in Action
The rotary aqueous wash system has proven successful in a number of manufacturing applications during the past several years, particularly with customers who have medium to large, highly engineered component parts. In one case, Technowash supplied a large, heavy industry company with an automated rotary system to wash and rinse fuel and hydraulic tanks. The tanks in question are large and heavy, and the cleaning specification is high, particularly for the tank internals.
The system requires full automation, and the cycle times must be efficient. Technowash took the new rotary drum system concept and adapted it to fit into a front-loading spray-wash system. The individual fuel and hydraulic tanks are locked securely into the inner cage, which is automatically transferred to the wash chamber and locked into the outer cage. The machine is controlled by a tailored PC program and fitted with touch-screen controls that provide operators with full control over the wash and rinse cycles.
To aid the washing of the inside of the tanks, a fast-fill system quickly pumps wash solution directly into the fuel tank. The cage system rotates the tank while more spray wash solution is pumped through high velocity spray jets. At varying points, the cage is stopped to allow the tank to fully drain away fluid. Rinse stages commence with an initial fast fill followed by full rotation of the cage.
At the end of the wash cycle, an automated process opens the door, transfers the cage out of the machine, and brings the cage to rest at the load/unload position.
To accomodate the scale of the tanks being washed and the high level of cleanliness required, this particular machine is fitted with an intensive series of filtration units, which effectively removes all soluble and insoluble particles from the wash solution (down to one micron particle size) and allows the wash solution to be continuously re-circulated around the machine.
Cleaner Engines
In another example, an automotive manufacturer was in need of a cleaning system to wash, rinse and dry V8 engine blocks to a final clean standard. The engine blocks need to be cleaned inside and out, and contain blind holes and hard-to-reach areas.
The rotary front loading spray-wash system installed at this facility uses simple manual loading. The operator locks the engine block into position in the inner cage and then simply pushes the cage inside the wash chamber, locking it into the outer cage.
The wash cycle commences once the machine door is closed. The cage rotates bi-directionally while the machine goes through wash, rinse and dry cycles. All areas of the engine block are successfully washed and thoroughly dried. Once the wash process is finished, the door is opened and the cage can be unlocked and pulled back out of the machine for unloading.
The Future
Company leaders at Technowash are pleased with the developments of the rotary wash system and are convinced it can help resolve cleaning issues in a wide assortment of applications involving complex components with difficult-to-reach areas. Mr. Grayson concludes, “Having engineered a unique technology that allows full rotation of any shape or type of component part, cleaning parts via traditional aqueous wash techniques has suddenly gotten a lot easier. Our customers can now have a water-based machine that will clean to the standard they need, yet still meet other environmental and ergonomic criteria.” PC