Geneva was a bit of an interruption, but we are finally back to document the build of Agera RS chassis #7128.
When we last covered Build#128, the car was at Station 2 where the first fitting of the all the body panels was made to the tub chassis built at Station 1. From station 2, the car is split into several pieces and activity starts in several different areas of the factory. We’ll cover it all in the coming weeks but in summary – the exterior panels go to station 3 for paint preparation, the engine is built and tested, the front and rear subframes are built and various carbonfibre parts are manufactured and sent for polishing (which is where the painted panels go, too).
We have a LOT to catch up on!
Let’s start back at Station 2, where the exterior panels have been fitted and aligned for the first time.
Before the car is dismantled and scattered around the factory, our paint-preparation crew moves in to start some of the preliminary work.
The first task is to begin sanding the body while it’s still assembled. This is preliminary sanding only but it provides a basic matching surface for the next part of the process. 144 individual pieces of sandpaper were used for this initial rubdown. Yes, I counted them.
Once this first sanding is done, our eagle-eyed painters come over and start marking out the stripes and the areas where the car will transition from paint to clear carbon. This car will have a stripe down the side as well as clear carbon over the top of the car. All of this marking-out work is done by hand and eye. It has to be this way because the panels themselves are hand made and will have tiny inconsistencies from car to car.
Jerry and Micke use a thin painters tape to mark the edge of the lines. The precision is amazing and takes years of experience to master.
Having marked out positions for the stripes and the transition, the appropriate areas are masked off and sprayed in grey while the car is still all together. These lines will be used as reference points once the panels are removed and taken to Station 3 for preparation.
Preparation – Carbon Parts
Our carbon parts are generally finished in one of two ways – ‘painted’ finish, or a polished raw carbon finish.
‘Painted’ parts have a clear epoxy coating that is part of the manufacturing process. That clear coating is left in place and then polished before the part is used in the car. The result is a deep, reflective shine, especially on parts like the intake plenum with it’s air-flowed curves and bumps.
Polished raw carbon parts have that clear epoxy coating sanded off prior to polishing. What you’re left with is raw carbon fibre with a beautiful, satin look and feel.
‘Painted’ parts go straight to polishing after manufacture but polished raw carbon parts need some time in the sanding room first. What follows is a look at the level of detail we go into when preparing polished raw carbon parts for our cars.
What you see below are the fins that will make up part of the venturi at the rear of the car. They sit under the rear of the car so they won’t be seen much. The fact that they’ll go unseen by 95% of the people who ever see the car doesn’t mean we skimp on the preparation, however. These parts still undergo the full sanding and polishing regime.
They’re being sanded with a 600-grit pad in this photo.
What you see above is the second sanding. The first sanding was with 500-grit paper (which you can see in the bottom right corner). Before these parts are finished and ready for polishing, they’re sanded again with two different types of 800-grit paper.
….. then 1200-grit,
…….. then 1500-grit,
and finally……. 3000-grit.
123 pieces of sandpaper were used in all – and that’s just for these four fins that will hardly ever be seen.
And after all this, they still have to be polished.
Every carbon fibre part on a Koenigsegg spends time in the polishing room before being fitted to a car. Below we have the cover that sits over our Triplex suspension damper at the rear of the car. Parts are generally polished with one of a number of rotary tools we have available – larger pads for larger parts and small, fine pads where appropriate.
Parts and panels generally spend around 200-300 hours in the polishing area, on top of 600-800 hours in paint/preparation, which you’ll see below.
Preparation – External Panels
The general method of preparation for paint involves a combination of sanding, blocking and clear coat. The exterior panels, separated from the chassis at Station 2 for individual preparation, are sanded first with 180-grit paper and then a coat of clear is applied to build up the surface.
This basic first step underpins everything you’re about to read. Sand, build. Sand, build. Carbon fibre has an imperfect surface with tiny pits that need to be built up until the surface is consistent. The sanding smooths the surface, the clear coat builds it up for the next bout of sanding.
We use either 240-grit or 320-grit for sanding after the first clear coat. We then block-sand with 400-grit and machine sand with 600-grit. The block sanding ensures that surface is flat. Then we clear coat it again.
This process – 400-grit block and 600-grit machine sanding followed by clear coat – is repeated until the surface is deemed to be OK for paint. That can be between 3 and 6 repeat cycles. For those of you not doing the numbers in your head, that means the raw carbon fibre panels received from Station 2 will have between 4 and 7 clear coats applied to them before they go into the booth to be painted properly.
That’s the basic process. Of course, it varies for each car according to the state of the carbon when we begin, as well as the intended paint finish. A clear carbon car will need more time than a car with a painted colour. As it happens, this car has a combination of both coloured paint and clear coated sections.
Agera RS Chassis 128 will have spent about 800 hours at Station 3 by the time the car is fully prepared and then painted.
If you calculated the time spent just painting the car – actually applying paint and clear coat to the various body parts – it would add up to maybe 2% of those 800 hours. As is the case with the application of paint to anything – preparation is the key. Sanding, blocking, masking. It’s all critical and it’s all quite time consuming.
Most of that preparation has been done in the photos you’ve seen above. Hours and hours of sanding prepare the panels for what will be a four-stage final paint process:
1. Body colour
2. Metallic effect (body)
3. Metallic effect (stripes)
4. Clear coat
Note: photos below are in black and white. We’ll show the finished colour later in the series, when all the panels are reassembled.
#7128 received 4 coats of base body colour. It then received 2 coats of effect for the body, 2 coats of effect for the stripes and then a final regime of clear. The car stays in the booth at 65 degrees C for an hour at the end of each stage.
That was the paint program for #7128. Each car is different and we keep painting – checking progress at every stage – until the job is done. Customers receive a sample of their paint finish when the options for the car are being selected. In the photo below, you see Micke checking progress against the colour sample. This happens throughout the entire painting process.
In this case, there are two separate metallic stages, one for the base colour and separate stage again for the stripes.
The stripes are covered during the first metallic effect coat and you can see the masking being removed, below.
Again, for those not doing the mental math, we’re talking about at least 11 coats in the paint stage, plus the 4-7 coats of clear involved in the preparation of the car beforehand. And in between each stage of the process the panels will be sanded again to ensure a consistent surface and finish.
Below, you can see that all the masking has been removed and the clear carbon centre section of the car is now visible. That means the metallic effect coats are finished and the whole car is being clear coated.
Where to from here?
The panels will go to polishing, where they’ll spend another 200-300 hours along with other carbon fibre parts to be used on the car.
The tub chassis proceeds to station 5, where it’ll receive wiring and the front/rear subframes. And that means it’ll have an engine!
We’ll be back to talk about the engine build soon.