The first installation of a MecWash Millennium parts washing machine has now proven itself as central to the cleaning processes at one of the world's leading pneumatic component manufacturers. The unit is used intensively within one of the dedicated "focus" facilities at IMI Norgren's Lichfield plant. It is located ahead of assembly and storage areas and handles parts from approaching 60 machines, 30 of which are high volume. Not only is it achieving unprecedented levels of cleanliness - to a level beyond the capabilities of small individual washing units that have been attached to some of the machine tools - but it is also helping to reduce the risk of mechanical handling damage while increasing operational cost efficiency and environmental protection.
The company's Fittings Division produces, in the main, brass components, the majority of which are destined for the commercial vehicle sector of the automotive industry for safety critical braking and auxiliary applications which clearly calls for the highest levels of component cleanliness and damage control.
The core machining processes leave components coated in mineral oil and swarf or in some cases soluble oils - much of which, with brass components, can be chipped and clogged. Until the installation of the MecWash Millennium, this was mostly removed using a multi stage process of spinning and riddling or by subcontract cleaning. The installation of the Millennium has significantly reduced in-house and sub-contract costs, component handling requirements have been rationalised and both stock level demands and production delays reduced.
At the heart of the Millennium installation is a rotating drum within which the components are located and then subjected to flood and spray wash then rinse and both hot air and vacuum drying processes. The individual products are held in a series of specially designed mesh baskets, themselves part of the MecWash project, which are central to the efficiency of the overall operation. Chris Jones, Manufacturing Engineer at IMI Norgren, explains why -
"Components are collected at the machining stations directly into the wash baskets submerged in machining oil which provides an important degree of protection for the parts as they exit down the chute into the basket," he says. "From each location they are transported on special pallets to the central wash area and hand loaded onto a roller conveyor that feeds into the Millennium machine, although the installation has been designed for adaptation to automatic loading if required. The unit currently offers six programme sequences depending upon component type at a typical throughput rate of just 2½ minutes per basket.
"Because the same baskets locate into the rotating drum - in batches of eight - there is now no reason for components to be tipped or removed from their containers at any point between machining, washing and their eventual arrival at our dedicated semi-automated wash basket to tote pan controlled transfer installation where batch loads are created for onward plating, assembly or storage. Significantly," he adds, "the baskets themselves are cleaned as part of the operation, removing the risk of cross-contamination."
The importance of the role played by the Norgren designed basket is enhanced by an integral jetting system built into the lid within the wash chamber. This allows the efficiency of the cleaning process to be maximised - IMI Norgren estimate up to a 40% improvement on previous methods - because the basket mesh does not restrict the wash flow. Moreover, the same manifold is then used to direct the hot air drying process onto the components.
Further benefits of the basket design are noted through a reduction in handling weight, better damage control by the use of adjustable height lids and direct oil recovery at the machining process compared with tote pans which collected oil in the base. "The overall result sees components cleaned to better than 20 microns. The Millennium machine has been designed to be adapted for five microns if required," points out Chris Jones.
Collection of the high level of swarf that is removed from each component is simplified in the MecWash Millennium machine by the use of a multi strainer basket system and supporting settlement tank - significantly, this also enables the components to be cleaned without the need for spinning and riddling. The damage caused by the previous processes had high associated costs, scrap and re-work. The facility uses six removable strainers which are simply emptied and cleaned each day to protect the wash and rinse tanks from contamination. In turn, this has led to a reduction in the need for regular dumping of the cleaning solution tanks which itself has contributed to operational efficiency. This is significantly enhanced by the inline filtration and a MecWash Aqua-Save built into the Millennium installation at IMI Norgren - designed to remove machining oils that emulsify into the wash solution. This allows clean water to be returned to the rinse tank and overflow back to the wash tank, maximising the quality of both.
This is further endorsed by the use of an auto-dosing system which ensures the optimum chemical content of the solution is maintained - in this case MecWash supplies AC40 detergent which also, importantly, helps to brighten the brass. The system has run without a single requirement for solution dumping during the first twelve months of operation with consequent savings in downtime, water, energy and effluent disposal costs.
"Because this process also produces de-mineralised water," continues Chris Jones, "there is a marked reduction in the risk of the brass components staining - always an aesthetic consideration with this material. We are ISO 14000 accredited so the use of this type of system is clearly important from both environmental and production efficiency points of view."
The Lichfield Fittings Division operates a total of some 60 machining stations and the majority now feed directly into the MecWash Millennium. The unit has been located centrally within the premises alongside an existing MecWash Midi cleaning system which has provided a highly effective centralised cleaning process for selected machining operations over a number of years. This latest investment, however, has now allowed the organisation to deliver cleaning levels that match increasingly stringent requirements both internally and from the company's range of
"From all points of view - efficiency, economy, the environment and, ultimately, quality," concludes Chris Jones, "the investment in the MecWash Millennium has been highly successful and its versatility will allow it to play a key role for many years to come. As an organisation, we are committed to improving our performance and quality standards on an ongoing basis and this installation is clearly an important step in this direction."