A specially designed finishing system with heated paint application has been installed by Hodge Clemco as part of a major upgrade in production facilities at the works.

Benefits include a reduction of at least 15 per cent in paint costs, improved environmental working conditions and increased productivity as a result of faster drying times.

The Derbyshire company manufactures a wide range of waste containers and skips, most of them finished in corporate colours and varying in size from 2m³ to 50m³. Using a two-shift system, output is about 100 a week.

The existing extraction system was nearing capacity, and there were concerns over the ability to maintain environmental standards. Also, the need to allow up to 12 hours for paint to dry during the winter before containers could be moved out of the paint shop was creating a potential production bottle-neck.

The system designed by Hodge Clemco includes Graco heated air-assisted airless paint spray equipment and a three-bay extraction plenum on one wall of the paint shop to leave the maximum amount of clear floor space.

Instead of using thinners, the Graco application equipment heats the paint to a temperature of 50°C to achieve the required viscosity at the spray gun nozzle. Because temperature is constant and controllable in all conditions, very consistent finishes can be achieved, whatever the temperature in the workshop.

The model used is a President 30:1, which has a maximum fluid working pressure of 210 bar with a fluid flow of 3.6 litres/min. Paint generally takes about five minutes to reach temperature for spraying, and a twin-pipe design returns any paint not applied back to the container during spraying.

The Graco equipment has allowed our client to take advantage of a one-coat compliant polyurethane paint which has low VOC levels and gives a 75 micron dry coat — 150 microns when wet. The new system has reduced paint costs by around 15 per cent. The annual bill for the site is £500,000.

A further benefit has been the virtual elimination of solvents on the site, apart from relatively small quantities of cleaning solvents for cleaning, as the viscosity of the paint is maintained consistently by temperature.

Potential throughput has also increased because the paint dries in less then half the time of conventional material. In cold weather finished containers had to be kept inside the factory for up to 12 hours to make sure the finish was not damaged. Because the paint is now applied hot and undiluted, it dries fully in a maximum of three hours so containers can be moved into the outside yard more quickly, leaving space for the next.

Maximising usable working space in the paint shop, which has a floor area of 1300m², was also an important factor in the design of the extraction system. In order to leave as much of the floor as possible clear of obstructions, three PEC 3500 Enviraclean dry filter extraction chambers were installed on one wall, with ducts rising vertically through the roof 15 metres above.

Each PEC 3500 consists of an open-fronted extraction chamber with paint arrestor media fixed to the front and measures 3500mm wide, 1000mm deep and 3000mm high. Steel mesh supports the CPA filter media, which is made from multi-layered, multi-density polyester with an average removal efficiency of 99.5 per cent and a high paint-holding capacity.

Each chamber produces an air flow of 16,000 cfm (27,200 m³/hr), with a duct venting exhaust air into the atmosphere, compliant with EPA regulations, through a high-velocity weather cowl.

Between the extraction chambers are two 2.4m high light modules set into 3m x 1m galvanised panels and housing florescent light fittings. The design of the whole installation allows three skips at a time to be in position for painting.

The extraction system has produced clear improvements in the finish achieved in the paint shop, said Ian Salmon. ‘In the old paint shop we used to get dust settling on the paint before it had dried, but the new extraction system is so efficient that this is not a problem any more’. The system also enabled the company to comfortably meet current standards for emissions and working conditions for operators, he said.