Job: Cleaning system for battery tray components | Challenge: Strict customer requirements and integration into high cycle times of existing production lines | Implementation: FLOWTRONIC® H-V-HD system | Process: Horizontal conveyor line in 5 process chambers and 3 drying zones
PURIMA develops intelligent FLOWTRONIC® system for the automotive industry.
A fully automated and integrated into the customer’s infrastructure integrated cleaning system for components of battery trays, which are used as fixed components in e-vehicles PURIMA, the Porta Westfalica-based expert for industrial component cleaning, has successfully implemented a cleaning system for a major customer in the automotive industry. Along a production line, these are first machined and deburred and then require thorough cleaning. And then require thorough cleaning which completely removes both remaining traces of oil and chips. After cleaning, the tub components are transported further and welded together. On the one hand, the cleaning plant was designed according to strict process requirements of the customer and on the other hand seamless and under realization of high cycle times into the customer’s production line.
Complex cleaning material - well thought-out process details.
freedom from chips and stains, complete drying of the cleaning material, a surface tension of at least 36 mN/m and a high cycle time – these are, in a nutshell, the requirements that the customer placed on the aluminum components to be cleaned. To meet these requirements, PURIMA decided to construct a so-called FLOWTRONIC® H-V-HD system made entirely of stainless steel – a cleaning system that treats the cleaning material along a horizontal conveyor line infive aqueous process chambers and three drying zones.
The aluminum components of the battery trays vary greatly in size and shape very strongly: small parts positioned in baskets, elongated hollow chamber profiles and large-dimensioned base plates must be reliably transported through the cleaning system. This presented some challenges for PURIMA’s innovation: To ensure a high cycle time in a fully automated process, the company therefore developed universal goods carriers for all tub parts, which are processed by robots with a Precision of ± 1 mm are deposited at a defined place on the product carrier and pass through the entire production cycle. Within the treatment zones, it was also necessary to ensure the optimum positioning of the merchandise supports within the system: this is controlled by a PLC control system in all cleaning stages.
Furthermore, the parts to be cleaned have a high high weight and, in the case of the base plates, are very large: a merchandise support must therefore be designed for a a capacity of up to up to 300 kg; it must also and must also accommodate workpieces with maximum dimensions of maximum dimensions of 1,600 x 2,000 mm. can be accommodated. Not least due to the size of the material to be cleaned and the cleaning chambers and drying zones adapted to the process, the resulting plant has an overall size of total size of 30,000 x 5,500 x 5,000 mm.
But how does the fully automated system recognize which of the possible component types need to be moved into the system and cleaned? – To make this possible, the reading of an RFID tag so that information about the items to be cleaned is processed directly in the control system and transferred to all cleaning stages according to shift-register programming. This ensures that the correct treatment program is the correct treatment program for each is activated for each group of workpieces.
Constant water quality through digital condition control and treatment system.
The customer has optimal water quality at the production site and therefore operates the purification plant with city water. The heating of the plant basins, each with a filling volume of 5 m³, is carried out by means of heating elements in protective tubes and district heating the maximum heating time must not exceed two hours. To ensure that the target temperature of 60° C can be maintained at a constant level in all cleaning baths and that the district heat can be optimally utilized, outside the tanks there are plate heat exchangers and automatic control valves are installed outside the tanks.
Despite good initial quality, the supplied water must be constantly monitored and optimally filtered. Therefore, at the customer’s request, a manual bath check is carried out during pre-cleaning, in which the water is chemically checked, while an automatic determination of the water quality is carried out during the rinsing stages of cleaning. In addition, the cleaning process is carried out according to a full-flow filtration using special filters, constant filtration of the water in the circulation system is ensured: The material to be cleaned is thus only exposed to water that meets the customer’s specifications. If the required conductivity values are exceeded, an automatic water exchange takes place. Automatic water exchange.
All wastewater from the purification plant is treated in a water treatment plant located in the rear part of the plant. The task of the 50 m² separate plant is to treat wastewater chemically and physically so that it can be discharged into the public sewer system.
The spraying process with heated media produces vapors that are discharged to the outside by vapor condensers via the roof of the production hall. Outside through the roof of the production hall . The condensation water is recirculated. An electrical height control also ensures continuous monitoring of the tank levels.
Safe accessibility and easy operation.
The plant extends over three levels: While the lower levels contain filtration and pumping technology, the upper level is accessible for maintenance work, for example, and is secured with a railing. In order to be protected against leakage, the plant has a collection tray, just like the water treatment plant. All plant information is also passed directly to the customer’s software system and can be retrieved at any time. The system also has the possibility of external access, so that remote maintenance activities can be carried out.
Five treatment stages plus hot air drying meet high purity requirements.
After a loaded universal goods carrier is delivered to the receiving station of the cleaning system via the customer’s conveyor system and the RFID tag is read, it is transported to the cleaning system.
Now begins the process of the first pre-cleaning stage. The cleaning medium is applied, and – as in all other cleaning stages – the spray registers are always aligned with the product carrier in the best possible way. The impact takes place from the side or from above, as required, and in addition, the tip registers oscillate: This ensures that the components and the hollow chambers inside them are treated with the cleaning medium over their entire surface. The cleaning medium accumulating at the inclined bottom of the chamber runs back into the storage tank in each cleaning chamber due to gravity. Accumulating chips are collected in an inlet pocket in the storage tank in the first cleaning step and isolated from the tank via a screw conveyor and discharged into a trough provided for this purpose. Furthermore, dirt particles in each cleaning stage are effectively removed by appropriate filter units from the process medium and collected in filter bags or cartridges provided for this purpose. After completion of the first cleaning stage, the machine cycles one step further.
Also in the second pre-cleaning step a cleaning medium is also applied in the second pre-cleaning step. In contrast to the first cleaning process, the components on the product carrier are blown off with air by high-pressure fans during transport to the next chamber in order to avoid liquid pockets and minimize carryover into the next process medium. Pre-cleaning is finished at this point and the machine clocks one step further. Now follow three rinsing steps . In the rinsing chambers, corresponding components are each exposed to rinsing water instead of a cleaning medium and blown off at the end of the process, as in pre-cleaning stage two.
To ensure that all parts leave the plant completely dried, the items to be cleaned are blown off in three successive drying zones with hot circulating air from powerful high-pressure fans after completion of the three rinsing stages and finally delivered to the unloading station.
The goods carriers are transported by conveyor chains. All process chambers of the cleaning system are separated from each other by tightly closing lifting doors, so that carryover of the process liquids into the subsequent chambers is prevented. As soon as a product carrier has passed through all treatment stages, it can be transferred to the unloading station and passed on to the customer’s welding process.
Perfected triad of automation, cleaning efficiency and easy handling.
The cleaning plant of the special plant specialist PURIMA was able to meet the customer’s requirements in every aspect. Thanks to many well thought-out details, such as the ingenious product carrier concept, intelligent workpiece recognition as they pass through the system, or the multi-stage, automated cleaning and drying process, a residue-free cleaned product carrier is delivered to the unloading station of the system as specified every 100 seconds. In the horizontally arranged process chambers, targeted loading of the product carriers ensures that even critical areas are reliably cleaned, rinsed and dried. To reduce heat losses and minimize carryover of aqueous media during treatment, all cleaning steps are separated from each other by tightly closing lift doors – this also reduces ongoing operating costs. The system also enables long bath service lives in the cleaning and rinsing basins due to the lifting doors and the multi-stage blow-off or drying processes. Overall, the system is also designed to be user-friendly and safe, and ensures traceability of all process parameters at all times by recording all data and feeding it back to the customer’s system. Wastewater is reliably treated to high standards by a comprehensive filtration system and an additional treatment plant. All in all, a fully automated cleaning of the complex aluminum cleaning material tailored to the customer’s specifications has finally been made possible and a smooth integration into the ongoing finishing process has been achieved.