TTI acts on SED

TTI Group is the first heat treatment business in the UK to respond to the Solvents Emissions Directive (SED) legislation by installing an EVT hermetically sealed solvent degreasing system.

Formerly known as Senior Heat Treatment, TTI is part of the materials technology division of Aalberts Industries and has nine sites in the UK. All these sites are ISO 9001-accredited, and specific sites also have other approvals such as NADCAP aerospace accreditation.

According to Martin Dyson, TTI Regional Sales Manager: ‘TTI Group set up a project team to review the effectiveness and costs of component cleaning systems, whether existing systems or possible alternatives, and to assess the future costs and regulation of available systems. It concluded that for heat treatment processes such as nitriding, Nitrotec and vacuum treatment, where the effectiveness of the pre-process cleaning is of paramount importance, the only cleaning process that satisfies the laid-down criteria is solvent degreasing.’

This led to a partnership developing between TTI, EVT Eiberger Pfohler and EVT’s UK distributor, IB Industries of Bolton. The outcome of their discussions was the installation in January 2007 of a hermetically sealed Trichloroethylene solvent system with a charge size of 1600mm x 1600mm x 1500mm and a charge weight of up to a maximum of four tonnes, making it the highest capacity degreaser trike degreaser in a UK heat treatment facility. This has provided TTI Telford with the equivalent capacity to its nitriding facility using a solvent spray and vapour process, with a regenerating carbon absorption system removing the last traces of solvent from the chamber prior to the finish of the cleaning cycle.

‘The decision to choose EVT was based on the system’s capability to satisfy new legislation, its robust design and its compact size,’ said Martin Dyson. ‘It is also energy-efficient and operationally effective by delivering the desired hourly throughputs. These features combined with a competitive price, a bespoke design offering low maintenance costs, and UK-based after-sales service and support made the decision relatively easy.’

The spraying system is said to be optimally adjusted for the work pieces and it is also effective in rinsing off solids such as swarf and splinters.

After the spray process the solvent is in a dirty state and is pumped directly from the cleaning chamber to the distillation to recycle the solvent to be available for the next load. The solvent vapour is led into the working chamber where the solvent vapour condenses on the cold parts and degreases even the most complicated of shapes with the smallest of drill-holes.

This has provided TTI Telford with the equivalent capacity of their open top degreaser using a solvent spray and vapour process for all parts which need nitriding or heat treatment.

A regenerating carbon absorption system removes the last traces of solvent from the chamber prior to finishing of the cleaning cycle. For adherence to the legal regulations, the system is equipped with a concentration measuring instrument, which monitors the solvent concentration in the working chamber at regular intervals. Only after falling below the concentration value legally designated of 1g/m³ air the opening of the sliding door is possible.

If the activated carbon of the adsorption unit is saturated with solvent, it can be regenerated automatically by hot air in operation with the circulating air.

In order to keep the oil rate of the solvent small and thus the cleaning quality high, the distillation of the solvent is indispensable. The oils brought in usually have a high boiling range and remain therefore in the distillate swamp. This can be disposed off emission free in the gas pendulum procedure in the safetainer system.