Hi, I'm Jan from VelomobileWorld.com and today I want to answer a video, or let's say a question from a video ... Dagmar van Dusschoten put it below on the video Alpha 7 number 2 or My Alpha 7 number two, he asked, could you make some videos about how you make the bodies. I think he asked the question how you make the composite shells, spoiler alert, I will not tell all the details, the devil is in the details, so I tell you in big lines how we do it, we will show you some things, we will go in the workshop and yeah, show you in big lines how we make the bodies or shells, let's go.
Here you see GT molds, this morning it's now already like a quarter past eleven, so when they came in at six, the first thing is they cleaned the molds, they waxed it and after the waxing it stayed like a half hour to evaporate the wax and then in the spray booth they sprayed a thin layer of gel coat over it, this thin layer of gel coat will cure today and tomorrow they will start lamination, so on day one they clean the molds and wax it, they put gel coat in it and in the first day we cut at "croire" (tailoring/cutting), I don't know the english word for it, we cut the fibers according to a pattern, let's go there.
So here we are at the cutting department and as you can see we have all kind of different rolls, here we have glass fiber 390 grams, here 200 grams glass fiber, this is 160 grams carbon fiber, here below I have a 200 grams fiber, here we have some Innegra fibers, some glass, some Aramid fibers, some special carbon, here some other carbon fibers.
We have a suction table here, so we pull out the carbon fiber, we put here the cutting template over it and a very fine dust gets free and we have a suction table, so that little fine dust gets directly sucked away, filtered and become filtered back. So that's all for day one, let's go to day two.
Here you see the front wheel well for the GT, I take this as example because I want to film everything today, not in the whole process, so what they do, they put epoxy resin here first on it, then they put according to their instructions the carbon fibers, glass fibers on it and they impregnate with epoxy and that's all what I want to tell about it, there are of course a lot of secrets which I don't want to tell, but that's kind of the structure, you put resin, carbon fiber, resin, that's it, sounds very easy, it's not.
One of the details which went wrong in the beginning was the curing, we had very much problems that we couldn't control the heat up slope, we couldn't control the maintenance, the curing slope and the cooling slope, so we had very much problems, then I invested quite some money in proper ovens and PLC to control the machine.
So one thing we have, we have a sensor here, so we know the door is closed and ... so we have a door of like, I think it's like 40 centimeters thick, with isolation.
Here we have airflow ducts, they blow in hot air here and they suck it out here, so we have ... it goes diagonally through the oven, we measured in the beginning when we set it up also in different places if the temperature is here, here and here approximately the same, um after we adjusted a bit the airflow and we made an average because sometimes you have here a big shelf with small parts, here a velomobile, here again is a big shelf with small parts, so you have more airflow, but we made a bit an average and also when it's not heating the airflow goes from there to there so we have some um ... yeah, the air is constantly flowing so we have a proper homogene temperature here, um well we have the sensor to check if we are good and we have a tolerance of like one degree plus minus the indicated slope temperature, so we have maximum one degree plus minus fluctuation. Right now we have the door open and so that ruined a bit the cycle, so let's go out and start again.
So after it was in the oven, this right now is still soft, because it's the first day of the week and I don't have finished parts, so if this part is cured in the oven they pull it out, there is some cutting lines in the mold, a little scratch, so at the finishing department they know, okay I have to cut according this line, after they are finished they ship it to our painting department and painting department will be another video. So this is kind of how we make bodies, parts from composites and I will tell you some details about carbon fibers back in the office.
I brought a little piece of carbon fiber and as you can see it's very thin, but it has a lot of strength, but it has strength only in one direction, in the direction of the fiber, so if I do bent it there's no resistance at all or if I compress it there's no resistance at all, so in the lamination you have the carbon fiber, is woven like this and it's impregnated with the resin, so if you push it like this the strength comes from the resin and if you bend it, the outside ... for example you have multiple layers, I don't know if you can see it, you have multiple layers and if you bend it like this only the outside layer will be pushed, will be tested on pulling, but the inside will be compressed, so here the resin will be doing its job and here the fiber. The best thing is to bring this a little bit from each other and we do this by adding Innegra between it and Innegra is a material... it's a kind of nylon, a kind of nylon and the good thing of Innegra, it brings the distance between the layers a bit further away, which gives you more bending resistance. Also carbon fiber transforms heats very well, so if the sun is shining on top of your velomobile, the heat will come straight on you, so Innegra isolates this, also it reduce the noise a bit and um, the biggest important thing is if there is an impact and there is Innegra between it, the chance of cracking it completely, is very much reduced.
Yeah, these are all the secrets that I want to tell, there are many many I don't want to tell because I learned them partly from Daniel, partly because we made a mistake and we have found a solution.
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