from my own AoA experience, I can say that "telegraphing" is more a case of a proper use of resin, curing and post cure, polyester and vinyl resins are much more prone to this than epoxy(which costs a lot more, like 3-4 times more expensive than polyester), and the better you compress the laminate, the less it may show, because it has to do with fibers having enough flexible (resins, some more than others, even cured, are still flexing/streching) material between them to move aroundmarcush. wrote:one important point is:
for weight savings composite ,not carbonfibre is what is driving the weight down.
In fact a glassfibre skin can be made lighter than carbonfibre ,which is very hard to get a closed surface with no telegraphing ..
so a nomex paper core with glass skins is what you need to make a ultralight panel.
I´d guess most of the cf use in car production is just a matter of being fancy.It´s a bit like the EV vehicle hype.
MORE!! I NEED MORE OF THIS IN MY LIFE!Nando wrote:Do they use similar machines in F1 cars like this one? Hypnotizing to watch
amazing!Is it nearsighted of me? Maybe, in the sense of that's the status quo. I call it like I see it. The pattern that I see incidentally is that those are all premium or high cost manufacturers whose target demographic are people with high amount of disposable income, who are willing to dispose of even more of it if attracted by some fancy new widget or "performancey thing" they can be sold on. I would not put them under the title of "efficiency-oriented" OEMs. Tata Motors I could see being under that umbrella - appeal to broad market, get the most you can for the least cost. How much CRFP are they using, or how much is in other broad market cars? Toyota Corolla? Nissan Sentra? Renault Clio?aussiegman wrote:That's a very cynical and myopic view of the situation I think.Jersey Tom wrote:Only reason it's used is for marketing.
If it gave no benefit other than marketing then its usefulness would be limited and we wouldn't be seeing the recent expansion in it use. Companies like Audi, Porsche, Mercedes and BMW (see a pattern there, cost and Euro based design where efficiency is the primary driver) now have used composites in their production cars.
jz11 wrote:from my own AoA experience, I can say that "telegraphing" is more a case of a proper use of resin, curing and post cure, polyester and vinyl resins are much more prone to this than epoxy(which costs a lot more, like 3-4 times more expensive than polyester), and the better you compress the laminate, the less it may show, because it has to do with fibers having enough flexible (resins, some more than others, even cured, are still flexing/streching) material between them to move aroundmarcush. wrote:one important point is:
for weight savings composite ,not carbonfibre is what is driving the weight down.
In fact a glassfibre skin can be made lighter than carbonfibre ,which is very hard to get a closed surface with no telegraphing ..
so a nomex paper core with glass skins is what you need to make a ultralight panel.
I´d guess most of the cf use in car production is just a matter of being fancy.It´s a bit like the EV vehicle hype.
autoclaves only advantage is the additional pressure you may put on the part to compress the laminate more, everything else, like curing temp and post cure can be achieved without the pressure chamber
and I have no idea how you can make a lighter skin from glass than from CF with the same strength properties (I already explained that telegraphing is a non-issue with CF), it just makes no sense to me at all
on the other hand, if you want to go the cheap/easy way, spray or hand lay up is the way to go, and this is where you go for glass + polyester or vinyl resins (CF will not work well with these resins, saturation is sort of an issue), but these parts are in no way structural or lightweight compared to aluminum, or even steel counterparts, good for prototyping or low volume production though
I also think that the people who have never worked with composite laminates might imagine this to be a wonder technology that makes manufacturing complex things very easy, it is not actually, there are many tricks to get consistent good results even in low volume production of complex geometries, especially when the parts get small and have tight radiusses, on the other hand you have hydroforming, which has made it quite easy to shape metal (alu/steel) in almost any imaginable shape with easely repeatable success and is very adaptable to high volume production
Autoclave cured composites mostly benefit from having a better fiber fraction than vacuum bagged/oven cured laminates. There is little difference in the cure cycle times between the two processes, but ovens are cheaper than autoclaves, and much larger parts/tools can be used with ovens versus autoclaves.g-force_addict wrote:Maybe FIA should give some rewards for teams that use out of autoclave carbon fiber parts?
In order to allow opportunity for smaller teams and to smooth carbon fiber transition to every day cars.
Some say autoclave only adds a minimal strength increase at a huge cost and delay:
BMW are shifting towards introducing more and more carbon on their cars, their plan together with SGL is to mass-produce carbon fiber.Jersey Tom wrote:Is it nearsighted of me? Maybe, in the sense of that's the status quo. I call it like I see it. The pattern that I see incidentally is that those are all premium or high cost manufacturers whose target demographic are people with high amount of disposable income, who are willing to dispose of even more of it if attracted by some fancy new widget or "performancey thing" they can be sold on. I would not put them under the title of "efficiency-oriented" OEMs. Tata Motors I could see being under that umbrella - appeal to broad market, get the most you can for the least cost. How much CRFP are they using, or how much is in other broad market cars? Toyota Corolla? Nissan Sentra? Renault Clio?aussiegman wrote:That's a very cynical and myopic view of the situation I think.Jersey Tom wrote:Only reason it's used is for marketing.
If it gave no benefit other than marketing then its usefulness would be limited and we wouldn't be seeing the recent expansion in it use. Companies like Audi, Porsche, Mercedes and BMW (see a pattern there, cost and Euro based design where efficiency is the primary driver) now have used composites in their production cars.
There are plenty of high strength-to-weight materials out there. Various alloys of steel meet that bill very well, as well as aluminum. What is the advantage of fiber reinforced materials? I'd say primarily it's the directionality you can achieve. High strength or stiffness in one orientation at the expense of another by taking advantage of an anisotropic material. What specific applications on a broad market consumer car can stand to be substantially improved by composites?
There's a time and a place for carbon. I don't see the screaming needs for it on OEM application, and I do maintain that a primary use for it at the moment is just for marketing. Just the same as absurdly wide and low profile tires and large bead diameter wheels.
Consider it like this: If you need to produce say 100K unibodies per year, that requires spitting one out about every 5 minutes. It would take about 4 hours to lay-up and cure a composite chassis part under the best of circumstances. So this would require around 48 duplicate sets of tooling for each part. This tooling cost would be prohibitive for any automotive application.browney wrote:I would have thought that repair and defect testing/monitoring would be one of the big reason why you wouldn't make many parts of a car out of carbon fiber. It would be a big change for the local body shop.
Body panels that are designed just to be thrown away could be made out of plastics if they could produce good colour/finish in a reasonable time though.
Cycle times are the limiting factor .As i understand the Mclaren Tub manufacturing process is incredibly quick.BMW are possibly the leaders in the mass production having done big roof panels for the M3 since some years now in cooperation with SGL .riff_raff wrote:Consider it like this: If you need to produce say 100K unibodies per year, that requires spitting one out about every 5 minutes. It would take about 4 hours to lay-up and cure a composite chassis part under the best of circumstances. So this would require around 48 duplicate sets of tooling for each part. This tooling cost would be prohibitive for any automotive application.browney wrote:I would have thought that repair and defect testing/monitoring would be one of the big reason why you wouldn't make many parts of a car out of carbon fiber. It would be a big change for the local body shop.
Body panels that are designed just to be thrown away could be made out of plastics if they could produce good colour/finish in a reasonable time though.
