Daniel, Michael and Martin attaching carbon fiber
During the last weeks Christophe, Daniel, Martin and Michael have been working in a company called APC Composites (or simply APC) in Luleå, which is a long-term supporter for various student projects. The quartet has been busy doing the monocoque for the prototype – a hard shell that substitutes the need for a normal chassis/coach in the car. This is common in Formula 1 cars, for instance.
The work consists of putting layers of carbon fiber and a sandwich material (sponsored by DIAB) on top of a mould that we’ve designed. Once finished with a layer, the material has to harden in an oven before the next layer can be put on. This process repeats a couple of times until all layers are present.
Polishing the mold before lacquering
This job has received a bad reputation from previous year’s projects. First, it’s an unhealthy environment with fibers and dust particles all over. Second, the task is kind of boring. Third, it’s easy to do simple mistakes, and these mistakes tend to be catastrophic and lead to a lot of extra work. And last, previous year’s students have made a lot of simple mistakes, which meant that they practically lived at APC for a few weeks. This was something we knew already from the start.
So, how did it go this time? Let’s illustrate it with a story from the 18th of March. This is my (i.e. Kristian’s) depiction of what happened.
During the project group meeting at the 18th, I raised my hand to volunteer as an oven guard at APC. This means nothing more than just sitting close to the oven and make sure nothing unexpected happens. The APC quartet was to finish their work of the day at 18:00. Then Anders would come and guard the oven, and at 22:00 I would relieve him. I would then stay put until 03:00 and the arrival of the third guard, Kristofer. Since I was a bit tired from working I decided to go home and get some sleep.
Christophe, Michael and Daniel during production at APC
When I arrived at 22:00, Christophe, Daniel and Michael – who were supposed to leave 18:00 – were still there. They were way behind schedule, and when Anders left after an hour or so, the work continued. They applied the last layer of carbon fiber, then put a protective screen on top of it, then a wool-like surface to distribute the load, and – finally – they began to mount a big plastic vacuum bag to keep the form intact while in the oven. Working with the bag is kind of easy if the mould is somewhat flat, but as the shape had grown more complex with time, it proved out to be quite difficult. At around 00:00 we decided to take a break.
At 00:30 we continued working on the vacuum bag, and around 01:00 we thought the bag to be ready. We spent some time transporting the mould to the oven, and then we had to wait for it to warm up. As we turned on the vacuum we heard a noise indicating that our plastic bag was leaking somewhere. This meant turning the oven off, fix the leaks and heat ut up again.
Sealing the vacuum-bag with a sticky substance called "dogmeat"
At 02:15 we made another try. There were some minor leaks then as well, but they were easily taken care of. But as we did this, we turned the oven off again, and as the mould cooled down some layers settled faster than others and they detached from one another. This meant that we once again had to turn the oven off, take away the vacuum, fix the layers to one another with clamps, reheat the oven again, and once again apply the vacuum. When Kristofer came to relieve me, we were still in the process of clamping the layers, and as I left around 03:30, Christophe, Daniel and Michael (who were supposed to leave at 18:00) were still working, and had been since 08:15 that morning.
Unfortunately, this wasn’t the only time things didn’t go as planned. Even though they had a “better safe than sorry” approach and made very few mistakes, the quartet spent days, evenings, nights and weekends for three weeks at APC until they were finished last Friday. And, fortunately, it looks great! We’re currently attaching other parts to it and making the last few modifications of the exterior, and so far it really looks promising.
We wish to thank Dr. Sauli Vasara who sponsored us with the physical examinations that are required to work at APC. Maybe because of him, the quartet is still fit for fight physically – although the work may have created some mental scars.
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