Heraeus infrared drying tunnels in new Land Rover paintshop
Heraeus infrared drying tunnels in new Land Rover paintshop
Keywords Automotive industry, Heraeus, Infrared, Paints
Energy-efficient,precisely controlled, short wave infrared drying tunnels, designed and built by Heraeus Noblelight Ltd, of Bromborough, Cheshire, form a central part of the new state-of-the-art, £110 million Paintshop 21 at Land Rover's factory at Solihull (Plate 1).
The Paintshop 21 represents one of the largest automotive engineering projects to have been carried out in the UK over the past 20 years. It is also said to be the largest and most environmentally advanced paintshop in Europe, being four years ahead of EC environmental legislation.
Paintshop 21 will handle all Land Rover vehicles, from the new Freelander to the well established Defender and has allowed production capacity to be increased from 45 units per hour in the old paintshop to 75 units per hour.
The complete project has been managed by Haden Drysis International and the drying systems installed in the 30,000m2, three-storey building reflect the latest drying technology.
All Land Rover models are designed for rugged, off-road use, which means that paint specification and application is extremely rigorous. Pretreatment, involving cleaning,phosphating, chromic passivation and rinsing is followed by electrocoating to provide primary corrosion protection, before the primer coat is applied. Drying,using a combination of radiant and convected heat, is the preferred method after each of these stages but, to achieve optimum energy-efficiency and productivity,short wave infrared has been combined with a hot air system to effect rapid and consistent drying of the water-based colour coat.
Plate 1 Vehicles passing through the Heraeus infrared drying tunnels at Land Rover's new Paintshop 21
Water-based paints are being increasingly specified on environmental grounds. Unfortunately,water-based paints, traditionally, have proved more difficult to dry than solvent-based alternatives. However, the affinity of infrared radiation for water allows these problems to be overcome.
The infrared drying ovens at Land Rover are divided into ten side zones and 16 roof zones, each of which is individually controlled by means of thyristors to ensure that the maximum amount of water is flashed off the colour coating before final drying in a hot air oven.
Each of the side zones is fitted with two pairs of horizontally mounted, 1.5kW short wave emitters,directed at the left and right side of the vehicle body. All emitters feature integral gold reflectors to maximise forward radiation and efficiency. To save energy, each pair of emitters is turned down to 10 per cent power, by means of a thyristor, once a vehicle passes through on a conveyor. In addition, a pair of 6kW, vertical emitters is fitted between three of the side zones and these are angled to provide a direct radiant, drying effect on the rear of each vehicle as it passes. Each bank of horizontal emitters acts on a given part of the vehicle bodywork, which for this purpose is split into a sill zone, a lower middle zone,an upper middle zone, a lower top zone and an upper top zone, providing a total of 50 independently controllable zones.
The horizontal surfaces of the vehicle are heated in the 16 roof zones, each of which features three 4kW short wave infrared emitters, with thyristor controllers regu-lating output as required. Optical pyrometers at the end of the tunnel take temperature measurements at defined points, to ensure that the correct heating profile is being achieved.
Two short wave infrared ovens have been installed, one on each of the twin paint lines. A third system is dedicated to the Defender and this can also be used as a repair facility.
Details from Heraeus Noblelight Ltd, UK. Tel: +44 (0)151 343 0545; Fax: +44 (0)151 343 9883.
