The Web for Automotive Professionals & Car Enthusiasts

MINI History

MINI History

Plant Summary  Facts   Assembly  Paint Shop   Body Shop   Logistics 
Quality & Engineering Center

BMW Oxford Plant : Paint Shop

The paint shop was built in 1997 to the highest environmental and process standards. When it was under construction, it was the second biggest building programme in the UK - after the Millennium Dome. It is the most modern and flexible facility of its kind in the UK.

Customers are able to order their MINI in a range of colors and with the distinctive, contrasting roof color of the MINI COOPER models in white or black. As a result there has to be a fast color-change facility to paint each car to match the color combination specified by the customer, as part of the comprehensive options and body derivatives which are available across the MINI range.

To meet these production requirements Mini-Mix and Micro-Mix paint systems have been installed, which result in fast color changes between individual body shells, eliminating the need to "batch" paint a number of cars in the same color before switching colours.

The eight-stage process starts with pre-treatment. This washes the bodyshell to remove all debris and then coats it with zinc phosphate to improve corrosion resistance.

This is followed by the electropaint stage where the body is immersed in a large tank of paint with an electric charge applied, typically 300 volts and 800 amps. This causes the paint to be attracted to the whole structure, inside and out and is critical in the corrosion proofing of the vehicle. This form of painting is very efficient and more than 90 per cent of all paint is used directly on the car. The residual paint is returned to the main tank and washing liquids are cleaned and reused. The car is then baked in an oven to cure the paint.

During the surfacer process specific colours are applied to the bodies to enhance the final colour coat and for further protection. The surfacer is applied to all visible surfaces, inside and out with electrostatic equipment to improve transfer efficiency of the paint. The type of paint used has a high solids content and also improves resistance to stone chips. Following this process the car body is baked in an oven.

The final colour coat application is applied by both manual application and automatic spray machines. To prepare the car for painting any imperfections are first removed by light sanding. Any dust is removed firstly by compressed air and then by wiping the body with a sticky cloth. As a final cleaning process the body passes through a "feather duster machine". This is similar to a car wash, but with sets of feathers mounted on rollers which rub gently against the car, removing all traces of dust. The colour coat paint is water-based, using an emulsion of micro gels, dispersed in an aqueous solution. Infrared is used to drive the water off within the paint film.

The clear coat gives the body a uniform gloss through a special grade of paint called 2K, which uses a catalyst to cure the paint and to minimise overall solvent emissions. A further heat treatment follows the clear coat.

The contrast roof facility uses a simple robotic system to apply a white or black roof, as specified by the customer to MINI COOPER bodyshells after the main colour has been painted.

Cavity wax is applied as the final stage in the corrosion resistance process to all hollow sections where water could collect. The bodyshell is heated to make the wax fluid and then rocked back and forth to ensure the wax penetrates all critical areas.

Throughout the paint process stringent quality standards are imposed and inspection takes place under special, intense lighting conditions. The location of each bodyshell is known through a camera tracking system which reads the car's individual barcode.

This also allows orders to be changed and production sequences to be altered to give maximum manufacturing flexibility. The total time taken to protect and paint the bodyshell is 10 hours.

(July 10, 2001)

top