Specialist plastics coating machine

Citation

(2000), "Specialist plastics coating machine", Anti-Corrosion Methods and Materials, Vol. 47 No. 6. https://doi.org/10.1108/acmm.2000.12847fad.008

Specialist plastics coating machine

Specialist plastics coating machine

Keywords Gravatom Engineering Systems, Linings, Plastics, Cylinders

Gravatom Engineering Systems Ltd has developed the Falcon coater, a specialist plastics coating machine that applies linings to the inside of fire extinguishers at a reported through-put of up to 360 units an hour (Plate 4). According to Gravatom, when measured against previous traditional coating technologies the Falcon accomplishes in 20 minutes what previous coaters completed in a day.

Plate 4 The Falcon coater

At the development stage, the Falcon's increase in through-put over traditional coaters attracted funding from the UK Government, through a SMART award which sponsors engineering projects of outstanding technical merit. Now complete, the technology behind the new Falcon has important ramifications for other industries that require internal linings on cylindrical parts.

Fire extinguisher manufacturers seek to increase through-put and decrease consumption of the thermoplastics material used in linings. To reduce material consumption, the lining must be as thin as possible and the Falcon reportedly achieves this by using an innovative electrostatic spray technique rather than a traditional gravity fed method of coating. Falcon's manufacturers consider that this ability to control the lining's thickness, coupled with the fast through-put, allows savings to be made on heating, powder consumption and manpower, while increasing production.

A number of different size cylinders can be coated by the Falcon. On machine start-up, the cylinder model is selected from a touchscreen and the whole machine is automatically configured to the operating parameters of that particular cylinder. The variable parameters include aligning the spray nozzles to the centre line of cylinder axis, setting the spray pattern of the servo controlled spray lances and the powder spray cycle time. By altering the nozzle flow rate, speed of traverse and dwell of the spray heads, the coating thickness can be adjusted in any area of the cylinder.

For quality control purposes the exact quantity of powder deposited on each cylinder can be ascertained through a weigh-check-and-balance system. This system functions by weighing each cylinder at a station prior to entry into the coating oven and simultaneously recording the weight and location within a data acquisition system. After powder spraying, the cylinder is re-weighed to check that the increase is within a predetermined tolerance. As a safety measure, in the event that an operator has not loaded enough cylinders, the weigh system will detect a cylinder absence and prevent powder spraying from starting.

Although electrostatic spraying technology had already been successful with polyesters, the Falcon uses a new plastic powder. This self-adhesive, AFFF resistant coating powder was specially developed by Plascoat for the protection of water/foam extinguishers and is stated to meet all EN.3 requirements. It is used by major manufacturers, and is believed to be resistant to all known foaming agents.

Further details are available from Engineering Systems Ltd. Tel: +44 (0) 1489 896010; Fax: +44 (0) 1489 894382; E-mail: Dbarker@gravatom.com; Web site: www.gravatom.com