Component cleaning
May 1st 2006 Hardide Coatings, the technology-driven metals-coating company has installed a 'best-practice' solvent based component cleaning process that will enable it to maximise its surface preparation efficiency while continuing to exceed environmental and safety regulations
Hardide is a patented surface engineering technology which combines ultra-hardness, low friction and chemical resistance for use with steel, hard alloys and other materials. The Hardide process involves applying a binderfree tungsten carbide coating produced by CVD (chemical vapour deposition) which creates a dense homogenous structure around the base material which vastly prolongs the life of the component. Due to the deposition process, Hardide can coat complex shapes including 'out-of-sight' surfaces uniformly and smoothly without the need for subsequent treatment.
The company services a global market of customers that have high wear and corrosion requirements in sectors ranging from oil & gas and aerospace to general engineering, valves and pumps.
A new surface cleaning process has been installed combining both an enclosed technology solvent cleaning system and the SAFE-TAINER system, a closed-loop delivery and handling system for the safe management of chlorinated solvents on the site. The result is a complete process where the NEU-TRI E solvent is completely enclosed throughout the entire process, thus significantly minimising the operators' exposure to the product.
Chlorinated solvents continue to be a preferred option in many areas of metal cleaning where high quality surface cleanliness and dryness is important. This will persist even though the use of chlorinated solvents in component cleaning is being further controlled by the Solvent Emissions Directive Regulations ('SED Regulations'), requiring its use to be minimised to a maximum of 1 tonne per year unless a special permit under a solvent reduction scheme is granted.
Many companies, like Hardide, are finding that the 1 tonne limit is achievable through the use of the SAFE-TAINER system.
According to Hardide's operations manager Stephen Guse, health and safety has always been their top priority, so as changes to their in-house processes required new investment in component cleaning it was the ideal opportunity to take a completely new approach. "We wanted to continue using trichloroethylene as this gives us the level of cleanliness we need before we apply a nickel strike to the surface prior to the tungsten carbine layer.
But we also wanted to make this process more efficient and ensure that there was no risk to people, spillage or unacceptable environmental implications."
A new enclosed-technology solvent metal cleaning and drying system was designed and manufactured by Layton Technologies, one of few companies in the UK with experience in building machines to handle a wide range of solvents and other cleaning chemistries.
The design of the machine ensures that the cleaning process is carried out deep inside an enclosed system where parts are transported automatically by a sophisticated internal handling system. The complete process, which takes just minutes, is fully programmed with a visual display indicating each step of the process. The on-board electronics can be remotely monitored and managed through a built-in modem link.
The SAFE-TAINER system was introduced at the same time to manage the safe storage and handling of the solvent. It includes two separate specially designed double-walled containers; one for the storage of fresh solvent and one to receive spent material.
Inside each lockable container is a 216.5 litre drum safely housed to avoid damage or spillage. Portable and integrally bundled, it facilitates the safe and simple on-site storage and transfer of solvent. With a few simple connections, fresh and waste solvent transfer and storage is simply and safely achieved within a virtually sealed system.
Based on the consumption of solvent since the new system was installed last year, it is expected that the total annual usage will be less than two drums, which is less than half the exemption limit of 1 tonne that will be required by 2007. This lean solvent regime will mean both savings for the company and Responsible Care for the environment without compromising the high standards of surface cleanliness and final coating integrity.
Solvent maintenance
Stephen Guse also monitors the stability of the solvent, which helps the company to extend the service life and consumption of the trichloroethylene. "We regularly sample the material in the machine to check cleanliness and use a test kit to analyse its acidity. That way we can maintain the integrity of our cleaning operation and minimise solvent usage," he said. The rising concentration of oils, fats, cutting oils and their decomposition products, which are removed from metal surfaces in the cleaning operation, slowly degrade chlorinated solvents. In enclosed cleaning systems higher temperatures may cause these contaminants to decompose further, causing acidification of the solvent, which can significantly reduce its working life. In response, a stabiliser concentrate is added.
Hardide is confident that the combined SAFE-TAINER system and the Layton enclosed-technology cleaning system represent best practice in low usage, low emissions, and health and safety.
"Compared to previously available plants our new equipment gives us a robust and controllable process with minimum risk to operators and working environment," concludes Stephen.
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