4.1 – Keeping it clean
When it comes to cleanliness, the Paint Shop leaves nothing to chance. Maintaining a spotlessly clean, dust-free environment is critical to the quality and consistency of each car’s paint job.
Floors are covered in dust-beating plastic and overhead walkways are wrapped in webbing. There are air showers to remove dust from clothers and sticky floor mats pull grit from the soles of shoes. Walls of running water collect fine airborne particles while humidifiers spray a fine mist to keep the air clear and clean.
All staff in the Paint Shop wear lint-free suits and hair caps. What’s more, their gloves and protective steel toe cap boots are white, because it is more effective in displaying dirt. But most impressive of all is the time the team here spends preparing the bare metal shells for painting.
4.2 – Body in white
The cars arrive as bare metal shells just 37 minutes after the final welding spots are applied. This is a state referred to as a ‘white’ body. It takes up to 15 hours to treat each new Toyota vehicle in the Paint Shop, a process that begins by passing the bodyshells through a series of dip tanks designed to stop corrosion. This dipping cleans and prepares the metal for painting, and provides protection in areas vulnerable to corrosion and damage.
Section manager Pete Dennis talks us through the process in the following video.
4.3 – Anti-corrosion
The first dip tank cleans and degreases the metal. The second contains a phosphate liquid that prepares the shell for electro-deposition. The final stage in this initial process is immersion in the electro-deposition tank, which has 800 volts passing through it and gives the car its principal anti-corrosion coating. Strangely, although the electro-deposition bath is filled with a liquid, the car emerges dry to the touch.
The bodyshell is then moved on a carrier into an oven where it is baked at more than 200 degrees centigrade for up to two hours. Oven baking helps cure the paint, making it harder and more resistant to scratches and chips.
Once cooled, each vehicle undergoes its first Paint Shop quality inspection. This is carried out under powerful fluorescent lights, which makes imperfections easier to spot. These tunnels are busy places, where line workers are frequently joined by engineers and senior managers on Genba walks.
4.4 – Hidden quality
Back on the production line, each car is made watertight. Up to 73 metres of sealant is applied along panel joints where rain or moisture could potentially enter. While the sealant plays an important practical role, its finish needs to look good too. Which is why up to 12 metres of sealant is applied and finished by human hand instead of an automated robot, with Paint Shop members sculpting and shaping the product with precision.
Adding the sealant is a skilled task. Members undergo a six-week training programme to ensure they are proficient before joining the team. The accuracy of the entire process means that each Toyota built at Burnaston comes with a 12-year anti-corrosion warranty and three-year guarantee against surface rust.
4.5 – Protecting the future
In addition to sealant, robots are used to apply coats of damping material in key areas of the body to reduce vibration and noise when the car is driven. Heavy-duty stone guard material is also applied to the underbody, protecting this most vulnerable part of the car from damage.
Humans take over to add sealant to areas of the car such as the lower doors and sill seams. This is carried out in a sunken pit area, so the job can be comfortably carried out with minimal reaching or stretching. Members are also responsible for the sealing bead that goes around the doors and cabin.
Owners won’t be able to see most of these protective measures but they are vital for keeping their car free from corrosion or water damage. The bodyshell is now ready for the first stage of the painting process, the primer coat.
4.6 – Flash finish
The primer coat is primarily applied by robots. However, manual spraying is used for hard-to-reach areas such as the fuel filler surround and parts of the interior that will be visible when the cabin is fitted. After oven baking, a further quality inspection takes place before the car is ready for the next stage – the application of the top coats that give each Toyota its finished colour.
Top coats are applied by robots in a dust-free enclosure to reduce the risk of contamination. Complementing the robots is a team of skilled sprayers who add extra paint to critical areas by hand. A short burst of heat called a ‘flash off’ ensures any moisture is removed from the base coat before the clear lacquer coat is applied.
4.7 – Final inspections
Once the final clear coat is in place the vehicle is again heat-treated in an oven, this time for 50 minutes. Before passing to the next stage of assembly, every car undergoes two quality inspections.
The first check is for any minor defects that can be rectified immediately. The second more intensive inspection is carried out by two Paint Shop members, who will only allow perfect quality to be passed on to the next teams.
4.8 – End of the run
Before moving into the Assembly Shop, the jigs that held the doors, bonnet and boot slightly open during the painting process are removed and wax protection is injected into vulnerable body cavities. Black stonechip protection is also applied inside the wheel arches.