“No Contaminants < 30 µm” – A Demand Perfectly Met
Vibratory finishing with subsequent part washing represents a process combination that meets ever-increasing cleanliness specifications. By matching the right equipment these requirements can be easily fulfilled in linked, fully automatic processes as well as in stand-alone systems.
A subcontract company offering comprehensive vibratory finishing and shot blasting subcontract services was given the challenge to deliver a part with no contaminants >30 µm . Operating more than 25 mass finishing and shot blasting machines, the manager of the workshop stated, “With Rösler we have found a supplier who offers a comprehensive test facility and always assists us with professional advice”. When the job shop received an order for treating a new automotive part, besides vibratory finishing the part also required washing, to meet stringent cleanliness requirements. The finished surface had to be free of abrasive particles <30 µm and metallic particles <600 µm. Residual contaminants per part could not exceed 1,5 mg. Meeting these specifications required a custom engineered washing solution prior to, as well as after the vibratory finishing process. The manager continued, “We decided to choose Rösler equipment because of our excellent experience with their equipment and service, and because we felt that working with a single source supplier would be the best way to find the best process solution”.
During the first ‘washing cycle’ prior to vibratory finishing residual oil and coolants from the previous manufacturing stage are removed from the part‘s surface, minimising the carryover of contaminants into the vibratory finishing process. This washing cycle takes place in a compact continuous feed spray washing machine with a cleaning, rinse and blow-off station from where the parts are directly transferred into the vibratory finishing system. Because subcontractors require a great deal of operational flexibility, finished parts are manually placed into the subsequent fine washing machine. Four parts must be placed side by side in optimised positions. They pass through the different processing stations; ‘washing 1’, ‘washing 2’ and ‘rinsing and passivation’ at a speed of 0.5 m/min. During the process the parts are exposed to different types of cleaning liquids from above and below. The pressure and volume for the upper and lower spray nozzles can be individually adjusted for every processing station. After each station the parts are exposed to an intensive blow-off that helps minimise the carryover of cleaning and passivation liquids to the next station before the washed parts are dried with hot air.
To safely meet the cleanliness specifications the washing machine, completely built from stainless steel, is equipped with an oil skimmer and a high performance filter system with mesh sizes from 200 down to 20 µm. The part unload station is located in a clean room.
“Since the system was installed we have been working for several customers requiring a similar cleanliness levels and we are comfortably meeting these specifications”, continues the manager. In order to document the cleaning results the company also created a laboratory for analysing the residual contaminant values on parts.
For further information on washing installations please visit www.rosler.com
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