Ultrawave ultrasonic cleaning system installed in brake manufacturing specification

An ultrasonic cleaning system from Ultrawave has been incorporated into the manufacturing process at Continental Teves Small Series plant in Ebbw Vale, South Wales. The site, part of Continental Automotive Systems manufactures a wide range of high quality brake callipers for use in the automotive industry. As a supplier to most of the big names in the international car market, the site manufactures thousands of units each day. The ultrasonic cleaning system was incorporated into the specification to improve the manufacturing process and has led to cost savings and a reduction in energy requirements.
The manufacturing process of brake callipers requires parts to be machined and zinc plated prior to assembly. After acid pickling and 5 minutes in a de-rusting solution, smut can be left on the surface of parts causing poor coverage in the zinc plating stage. In addition the de-rusting solution can lead to flash corrosion of parts. In order to minimise this and ensure uniform coverage of zinc plating, power is increased in the plating process. These problems mean that more costs are absorbed in both fluid and energy usage during the cleaning stage.
Ultrasonic technology was recognised as a potential solution to this cleaning problem. Ultrawave were brought on board to provide a system which could be added to the process. Ultrawave have been manufacturing ultrasonic cleaning systems for over 15 years and in that time have developed detailed knowledge and acquired valuable experience of ultrasonic technology. Ultrawave can manufacture bespoke systems, tailor made to meet customers exact requirements.
Continental Teves already had a 7,500 litre tank which they were using for the cleaning process. In order to incorporate ultrasonic technology into the tank, Ultrawave submersible transducers were used. In total, Ultrawave supplied fourteen 1.5KW transducers which are located around the sides of the tank. Additionally, 7 transducers are deployed in the centre of the tank, producing ultrasonic activity in a 360 degree direction. In total 31.5KW of ultrasonic power is generated.
Ultrawave supplied 21 PLC controlled generators to power the transducers. Housed in a purpose built cabinet, the PLC system uses a controller, pre-programmed at Ultrawave. The variable factors of the system can be programmed including cycle time, heat and ultrasonic power, ensuring the process is tailored to exact requirements.
Ultrasonic cleaning utilises high frequency sound waves, transmitted through a liquid medium. These sound waves create an activity in the liquid called cavitation. This occurs as the sound waves pass through the liquid, causing the formation of microscopic bubbles which are forced to expand. Once they reach a size where they can no longer support their own density, the individual bubbles implode. These implosions are cavitation.
The cavitational process creates a scrubbing effect within the liquid as the fluid surrounding the bubble rushes in to fill the remaining space. Where the onrushing fluid comes into contact with the surface area of the item, any contamination is brushed off. The action is similar to that of microscopic scrubbing brushes gently agitating debris off the surface area of any item immersed in the tank. It is this process which allows the complete surface area of the immersed item, including difficult to penetrate box joints, hinges and threads, to be effectively cleaned in every cleaning cycle.
The ultrasonic technology in the Continental Teves system successfully removes the smut from the brake callipers after the acid pickling stage. Following this, parts are still soaked in a de-rusting solution but the concentration of the cleaning fluid has been reduced from approximately 20% to less than half this amount. In addition the operating temperature of this solution has fallen by 20 degrees Centigrade.
As well as reducing energy usage, the addition of the ultrasonic cleaning stage provides improved part quality results. The improved plating coverage has led to a reduction in the zinc wastage in the plating process while faster coverage in the low current density areas has sped up the overall process. The flash corrosion has also stopped now that ultrasonics is used.
Philip French, the Works Chemist at Continental�s Ebbw Vale plant stated that �the ultrasonic system has provided reduced costs, reduced energy and reduced rejects. Chemical and heating costs have drastically dropped and incorporating an ultrasonic system has provided greater stability to the process. The success experienced with the Ultrawave ultrasonic system has seen the use of ultrasonics included as an alternative to electro-cleaning in the Continental specification for zinc plating.
As well as submersible transducers and generators, Ultrawave can design and supply bespoke systems for a wide range of complex cleaning requirements. With a wealth of experience in ultrasonic cleaning, the company has supplied systems to a wide range of companies in industries such as aerospace, orthopaedic implant manufacture and motor racing. Hollow tubes, pharmaceutical tablet presses, cylinder heads and turbines and hollow medical instruments such as spinal taps have all been cleaned in Ultrawave ultrasonic machines. This flexibility combined with the high quality of Ultrawave's precision ultrasonic cleaning equipment sees the company supplying cleaning systems to more and more satisfied customers.
As published in Finishing Magazine July/August 2007 www.finishingmagazine.co.uk
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