Carbon – how we make carbon fibre parts

Every part we make, whatever the material, starts with a car. The car arrives at our headquarters in Wojnicz, and a specialist scans the body with a 3D laser scanner. The device reads light reflected off the bodywork and builds a highly detailed digital model from it. No unbolting, no drilling, no interference with the car at all.

This scan is the foundation for everything that follows. In carbon, there’s no room for “more or less”. A part that has to sit against the bumper along its entire length must be based on the dimensions of a real car – not on photos or someone else’s product.

The designer works on the 3D model. Their job is to bring two worlds together. On one side, accuracy counts: the part has to fit the bodywork perfectly. On the other, aesthetics count: a splitter, diffuser or spoiler should continue the car’s lines, not fight them.

With carbon, the designer also has to think about one more thing: how the part will be made. The shape has to allow the fabric to be laid into the mould and the finished part to be taken out again. A good carbon design looks great on the car and can be produced without any compromise on quality.

Once the design is ready, it’s time to bring it into the real world. CNC milling machines cut the working moulds straight from the 3D model. This is the first moment the project becomes something you can touch.

The working moulds aren’t used to make the parts that go to customers, though. They are the pattern from which the production moulds will be made. That’s why their surface has to be perfect. Any imperfection would be carried over to the carbon mould and then to every part that comes out of it. That’s why the working moulds are milled for several days, and in some cases more than ten – all so that their shape is flawless.

The production moulds – the ones in which the parts will actually be made – are created on the working moulds. We make them from the same material as the products: carbon. We cover the working mould with carbon fibre and then cure it in a special oven until the material takes on its final shape. A production mould always consists of two parts – a lower and an upper one – with a space between them. That space will soon become a carbon splitter.

Why a carbon mould? Because it has to withstand the conditions inside the autoclave and keep its shape at high temperature and pressure. A mould that deformed even slightly would mean parts that don’t fit. That’s why there’s no room for shortcuts at this stage – it’s an investment that pays off with every single piece.

We work with prepreg – carbon fibre fabric that comes pre-impregnated with resin. This keeps the fibre-to-resin ratio always the same, and the finished part is strong while weighing very little. Prepreg is a demanding material – we store it in industrial freezers so the resin doesn’t start reacting too early.

A plotter cuts patterns from the roll of prepreg – pieces of fabric in precisely defined shapes. The cutting pattern comes straight from the digital model, so each piece has exactly the size and shape needed in that particular spot in the mould. The machine cuts precisely and consistently, which means less waste and the same quality in every part.

Now comes a stage that can’t be automated. The cut pieces have to be laid into the mould by hand, layer by layer. It takes enormous precision and a feel for the material. How the pieces are laid determines both the strength of the part and the look of the visible weave. A piece of fabric laid at a slight angle will show on the finished product.

Lay-up takes place in specially prepared rooms with their own air circulation and filtration. Any speck of dust that got between the layers could leave a mark on the surface. That’s why we care about cleanliness as much as precision.

Once all the layers are in place, the mould has to be prepared for the autoclave. We cover the laid-up part with film fitted with a pressure valve and connect hoses to the valves. This creates a sealed package from which the air can be drawn out.

From the outside this stage looks unremarkable, but it matters enormously. How well the film seals determines whether the pressure will press the layers together evenly across the whole surface during curing. Even a small leak could ruin hours of lay-up work.

The autoclave is the heart of carbon production. This is where prepreg turns into a hard, strong part. Inside, the temperature reaches 120°C and the pressure 6 bar. For comparison, that’s more than twice the pressure in your car’s tyres – and for many hours.

Under these conditions the resin flows through the entire structure, the layers bond into a single whole, and any air that could weaken the part is forced out. Depending on the part, curing takes anywhere from several to several dozen hours. This is exactly the stage that sets autoclave carbon apart from cheaper alternatives, where a thin layer of fibre is applied over plastic purely for looks. With us, the pattern on the surface isn’t a wrap. It’s the structure itself.

When curing is complete, the package comes out of the autoclave. We remove the film and carefully take the part out of the mould. It’s always a special moment – for the first time you can see how the weave has turned out and whether everything went to plan.

The mould goes back into rotation, is thoroughly cleaned and degreased, and is ready for the next part. The demoulded piece already has its final shape and strength, but it’s still a long way from being a finished product. Now those irreplaceable human hands come back into play.

First comes sanding. The edges have to be trimmed and the surface prepared for the next stages. It’s done by hand, because every part has its own corners and transitions that a machine can’t reach with the right touch.

Then it’s time for polishing and lacquering. The lacquer protects the carbon and brings out the depth of the weave, while polishing gives the surface its smoothness and gloss. Lacquering is done in our professional paint shop. The end result is a mirror-smooth surface and a weave that looks as if it’s set under glass.

The finished part goes through quality control. We check the surface, the edges and the weave, because only a flawless product should reach the customer. The part is then protected for transport so it arrives in exactly the same condition as when it left our hall.

A mounting kit matched to the specific product also goes into the box. Only then is the parcel ready to ship – from Wojnicz to customers all over the world.