I recently developed a huge interest in the carbon fiber tubs that are used for the formula 1 chassis. I know that many teams use female moulds and lay pre-preg carbon fiber, kevlar, etc in them and then bake them but i want to know more. If anyone knows a more detailed process of how they do this, or just give me some insight into the process I would love to know. Some questions i have are...
1. Would they make the female moulds to the outside dimensions and work their way in?
2. How are they able to prevent the outside shape of the tub to be repeated as the layers of carbon fiber are layed? (ie the exterior shape of the front nose is irregular and the center shape ends up to be a perfect rectangle)
3. How do they make the air intake above the driver? At some point do you think they use a block that is the shape of the intake and then continue to lay the carbon fiber down around it?
4. How would they implement the vaccum around the mould?
5. I saw two pictures of an f1 chassis disassembled slightly, one of an arrows at their website and one of a mclaren at dailyf1. Both show a small hole on the top side of the nose, I assume to get to suspension pieces, but the rest of the chassis seems to be solid (around the foot well). Wouldnt it be difficult to change suspension pieces with such limited room?
6. Do they use other carbon panels along the nose and cockpit area to cover up the main tub? Or is that the actual tub we see?
6.5 What is the max number of layers do you think they lay in the highest stressed area? What do you think the min number of layers used is in one area?
7. If they use a carbon fiber tub how is the floor of the chassis integrated? Is carbon fiber easy enough to go back and install the floor after preliminary work?
8. Would they use small strips of carbon fiber or larger ones?
9. What patterns would they lay the pieces of carbon fiber in for optimal strength and torsional rigidity?
10. Is it possible to do any of this with a cheaper and heavier weight carbon fiber in someone's garage?
11. How well would a chassis work with carbon fiber that is not Pre-preg and cures at room temperature?
12. Could a chassis be developed to accept an engine that is not a stressed member?
13. Could it be possible to attach, say, a 355 f1 engine with a chromemolly sub frame to this type of tub, along with the f1 tranny and diff, or are the latter components too bulky?
14. What is the curing time for a carbon fiber tub?
15. How long do you think it would take to complete a carbon fiber chassis?
16. Does anyone know of any websites that gives any insight to the process or any books that might help?
Thank you all for your input. I just found this website and i am addicted already. I think that everyone has had very good thoughts about the technology involved with the sport. Thanks again.
carbon fiber tub production
Started by
ferrarifan2000
, Oct 16 2000 01:28
7 replies to this topic
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#2
rainern
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Posted 16 October 2000 - 21:11
The book : THE MODERN FORMULA 1 RACE CAR by Nigel Macknight is quite detailed in how to produce the tub itself.
As the book was printed in 1993 it is not the latest in technology but it still gives a detailed general understanding about the manufacture of carbon-fibre tubs.
Rainer
As the book was printed in 1993 it is not the latest in technology but it still gives a detailed general understanding about the manufacture of carbon-fibre tubs.
Rainer
#3
rainern
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- 64 posts
- Joined: September 00
Member
Posted 16 October 2000 - 21:21
FROM THE McLAREN SITE :
Everyone's heard of carbon fibre, but what exactly is it - and why is it so important McLaren cars?
Words: Peter McSean
Curious question: What's the difference between a rayon shirt and a Formula One car? Well, you probably couldn't get Mika Hakkinen into a rayon shirt. Other than that, there's not much in it: they start life one and the same.
Ninety per cent of an F1 car (by volume) is made of synthetic materials called composites, and of these, 90 per cent are carbon fibre. And the carbon fibre used in all F1 cars starts out, believe it or not, as rayon or acrylic fibre.
Rayon, a cellulose fibre, or polyacronitrile (PAN), an acryclic fibre, is initially wound on to frames and heated to 250°C. The fibres are then put in a crucible and heated to 2,600°C.This carburises the contents, producing pure carbon or graphite. These fibres are woven in a criss-cross pattern and impregnated with resin. Every strand is only 0.1mm across (the width of a human hair) and contains 3,000 filaments. "We use about four main weaves," says Dave Hawke, the manager of McLaren's composites department, "and we have different resins for different parts of the car, according to whether they are structural,aerodynamic or subject to intense heat: for instance, close to the exhaust or around the brakes of the car."
Rolls of impregnated carbon fibre, known as 'pre-preg', are stored at -18°C to give them a shelf life of six to eighteen months; at room temperature it's only three days. And you don't want to waste this stuff. Says Hawke: "A single ply of carbon fibre can cost maybe £300 per square metre, and some of our components can use up to 60 plies of it." A carbon fibre component begins its life on the screen of the CAD system. A pattern is derived using computerised numerical control (CNC) and is finished by hand, then painted to give an ultra-smooth finish (every blemish will show up on the finished component). A carbon fibre mould is made from the pattern and it is this that is used to lay up the actual component. In the laminating department, the plies of carbon fibre are cut to shape and laid in the mould to the specifications of computer drawings before the part enters an autoclave for curing. It is then trimmed, assembled and painted en route to the race mechanics. McLaren has a fast turnaround, but it's still a lengthy process. "A front wing will take about three days, and a completely new component about 11," says Hawke. "Laminating alone can take two hours for a simple bracket and two weeks, working day and night, for a chassis." So why use carbon fibre? Because it is light, strong and stiff. "Relative to weight, it's about five times as stiff as steel and up to four times as strong," explains design engineer Stephen Taylor. "Without it, we simply couldn't pass the stringent crash tests in force today." McLaren's MP4 of 1981 was the first F1 car to use a carbon fibre chassis. Then a "space-age step forward", as Ron Dennis said, composites are easier to work with today. Whilst in 1981 the tub of the MP4 was made in five sections by US aerospace specialist Hercules Inc, today's MP4-13 consists of just three sections and the McLaren engineers make them in-house.
By its nature, carbon fibre is strong in some directions and weaker in others. In sensitive areas of the car, McLaren supplements carbon fibre with other composites - the bullet-proof Kevlar for deflectors, and an energy-absorbing fibre specially prepared for car noses. So could these eventually replace carbon? Well, not in the near future. Whilst scientists in aerospace are experimenting with boron fibres, the most promising technology is hollow fibre, which reduces carbon's tendency to buckle. It's good news to Taylor: "Mm, could be useful.
Everyone's heard of carbon fibre, but what exactly is it - and why is it so important McLaren cars?
Words: Peter McSean
Curious question: What's the difference between a rayon shirt and a Formula One car? Well, you probably couldn't get Mika Hakkinen into a rayon shirt. Other than that, there's not much in it: they start life one and the same.
Ninety per cent of an F1 car (by volume) is made of synthetic materials called composites, and of these, 90 per cent are carbon fibre. And the carbon fibre used in all F1 cars starts out, believe it or not, as rayon or acrylic fibre.
Rayon, a cellulose fibre, or polyacronitrile (PAN), an acryclic fibre, is initially wound on to frames and heated to 250°C. The fibres are then put in a crucible and heated to 2,600°C.This carburises the contents, producing pure carbon or graphite. These fibres are woven in a criss-cross pattern and impregnated with resin. Every strand is only 0.1mm across (the width of a human hair) and contains 3,000 filaments. "We use about four main weaves," says Dave Hawke, the manager of McLaren's composites department, "and we have different resins for different parts of the car, according to whether they are structural,aerodynamic or subject to intense heat: for instance, close to the exhaust or around the brakes of the car."
Rolls of impregnated carbon fibre, known as 'pre-preg', are stored at -18°C to give them a shelf life of six to eighteen months; at room temperature it's only three days. And you don't want to waste this stuff. Says Hawke: "A single ply of carbon fibre can cost maybe £300 per square metre, and some of our components can use up to 60 plies of it." A carbon fibre component begins its life on the screen of the CAD system. A pattern is derived using computerised numerical control (CNC) and is finished by hand, then painted to give an ultra-smooth finish (every blemish will show up on the finished component). A carbon fibre mould is made from the pattern and it is this that is used to lay up the actual component. In the laminating department, the plies of carbon fibre are cut to shape and laid in the mould to the specifications of computer drawings before the part enters an autoclave for curing. It is then trimmed, assembled and painted en route to the race mechanics. McLaren has a fast turnaround, but it's still a lengthy process. "A front wing will take about three days, and a completely new component about 11," says Hawke. "Laminating alone can take two hours for a simple bracket and two weeks, working day and night, for a chassis." So why use carbon fibre? Because it is light, strong and stiff. "Relative to weight, it's about five times as stiff as steel and up to four times as strong," explains design engineer Stephen Taylor. "Without it, we simply couldn't pass the stringent crash tests in force today." McLaren's MP4 of 1981 was the first F1 car to use a carbon fibre chassis. Then a "space-age step forward", as Ron Dennis said, composites are easier to work with today. Whilst in 1981 the tub of the MP4 was made in five sections by US aerospace specialist Hercules Inc, today's MP4-13 consists of just three sections and the McLaren engineers make them in-house.
By its nature, carbon fibre is strong in some directions and weaker in others. In sensitive areas of the car, McLaren supplements carbon fibre with other composites - the bullet-proof Kevlar for deflectors, and an energy-absorbing fibre specially prepared for car noses. So could these eventually replace carbon? Well, not in the near future. Whilst scientists in aerospace are experimenting with boron fibres, the most promising technology is hollow fibre, which reduces carbon's tendency to buckle. It's good news to Taylor: "Mm, could be useful.
#4
Doug
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- 12 posts
- Joined: October 00
New Member
Posted 18 October 2000 - 03:04
The MacKnight book is a excellent pictoral reference, as stated above. It's a bit pricey, but well worth the investment.
This link has some pictures from the book and discusses some of the major issues related to composite monocoque construction.
http://acatc.ame.ari...oject/colin.htm
I'll take a stab at some of your questions. **Note all answers are AFAIK, I'm not some composites guy working for McLaren or anything.
1. Would they make the female moulds to the outside dimensions and work their way in?
--> For the monocoque, yes.
2. How are they able to prevent the outside shape of the tub to be repeated as the layers of carbon fiber are layed? (ie the exterior shape of the front nose is irregular and the center shape ends up to be a perfect rectangle)
--> I'm assuming that you're refering to the 'sculptured' shapes on some of the monocoques? (Such as the area directly in front of the Jordan cockpit.)
One could make such areas and have a uniform internal cross section by using additional layers or an appropriate filler material to build up the sculpted area. It would all depend upon the structural requirements for that specific region of the tub.
3. How do they make the air intake above the driver? At some point do you think they use a block that is the shape of the intake and then continue to lay the carbon fiber down around it?
--> From pictures it appears that the 'air intake' is acutally composed of the roll over hoop, the 'snorkle' that fits ontop of the engine and slots into the roll over hoop, and, of course, the external bodywork.
4. How would they implement the vaccum around the mould?
--> Plastic vacuum bag material sealed around the edges of the mould, so as to place the layed-up pre-preg under vacuum. Inside the vacuum bag, a breather layer is used to insure the vacuum is fairly uniform. A special vacuum fitting is used to connect external hoses and draw the vacuum inside the bag.
5. I saw two pictures of an f1 chassis disassembled slightly, one of an arrows at their website and one of a mclaren at dailyf1. Both show a small hole on the top side of the nose, I assume to get to suspension pieces, but the rest of the chassis seems to be solid (around the foot well). Wouldnt it be difficult to change suspension pieces with such limited room?
--> Haven't see many up close pictures to see how cramped the torsion spring suspension components are inside the tub. I'd assume they are a lot more difficult to work with than the top-mounted coil overs used a few years ago.
6. Do they use other carbon panels along the nose and cockpit area to cover up the main tub? Or is that the actual tub we see?
--> It's mostly the actual tub.
6.5 What is the max number of layers do you think they lay in the highest stressed area? What do you think the min number of layers used is in one area?
--> That's probably a pretty closely guarded secret within each team.
7. If they use a carbon fiber tub how is the floor of the chassis integrated? Is carbon fiber easy enough to go back and install the floor after preliminary work?
--> The under tray and rear diffuser are separate pieces that are fastened to the tub/engine. As for the floor of the monocoque, that is accomplished by constructing the tub from two halfs (see MacKnight).
8. Would they use small strips of carbon fiber or larger ones?
--> Varies with structural and shape requirements.
9. What patterns would they lay the pieces of carbon fiber in for optimal strength and torsional rigidity?
--> same as 8.
10. Is it possible to do any of this with a cheaper and heavier weight carbon fiber in someone's garage?
--> Sure. Do a search on the web to see that there are a number of homebuilders that build bike frames, etc. from fibre reinfored materials. Larger projects might be prohibited due to cost.
11. How well would a chassis work with carbon fiber that is not Pre-preg and cures at room temperature?
--> I think the advantage of pre-preg is increased consistency in the final material after proper lay-up and consolidation. (ie., more reliable mechanical properties, etc.) Manufacturing processes that use pre-preg still require paying attention to details, as well.
12. Could a chassis be developed to accept an engine that is not a stressed member?
--> Yes, but would it be as efficient? (ie., added weight for the 'clip' that the engine would be mounted to)
13. Could it be possible to attach, say, a 355 f1 engine with a chromemolly sub frame to this type of tub, along with the f1 tranny and diff, or are the latter components too bulky?
--> Isn't that the general design layout for the F50?
14. What is the curing time for a carbon fiber tub?
--> Will depend on material and actual manufacturing conditions.
15. How long do you think it would take to complete a carbon fiber chassis?
--> I can't see the tub alone taking any more than a week. Assuming the mould is ready.
16. Does anyone know of any websites that gives any insight to the process or any books that might help?
--> see above[p][Edited by Doug on 10-18-2000]
This link has some pictures from the book and discusses some of the major issues related to composite monocoque construction.
http://acatc.ame.ari...oject/colin.htm
I'll take a stab at some of your questions. **Note all answers are AFAIK, I'm not some composites guy working for McLaren or anything.
1. Would they make the female moulds to the outside dimensions and work their way in?
--> For the monocoque, yes.
2. How are they able to prevent the outside shape of the tub to be repeated as the layers of carbon fiber are layed? (ie the exterior shape of the front nose is irregular and the center shape ends up to be a perfect rectangle)
--> I'm assuming that you're refering to the 'sculptured' shapes on some of the monocoques? (Such as the area directly in front of the Jordan cockpit.)
One could make such areas and have a uniform internal cross section by using additional layers or an appropriate filler material to build up the sculpted area. It would all depend upon the structural requirements for that specific region of the tub.
3. How do they make the air intake above the driver? At some point do you think they use a block that is the shape of the intake and then continue to lay the carbon fiber down around it?
--> From pictures it appears that the 'air intake' is acutally composed of the roll over hoop, the 'snorkle' that fits ontop of the engine and slots into the roll over hoop, and, of course, the external bodywork.
4. How would they implement the vaccum around the mould?
--> Plastic vacuum bag material sealed around the edges of the mould, so as to place the layed-up pre-preg under vacuum. Inside the vacuum bag, a breather layer is used to insure the vacuum is fairly uniform. A special vacuum fitting is used to connect external hoses and draw the vacuum inside the bag.
5. I saw two pictures of an f1 chassis disassembled slightly, one of an arrows at their website and one of a mclaren at dailyf1. Both show a small hole on the top side of the nose, I assume to get to suspension pieces, but the rest of the chassis seems to be solid (around the foot well). Wouldnt it be difficult to change suspension pieces with such limited room?
--> Haven't see many up close pictures to see how cramped the torsion spring suspension components are inside the tub. I'd assume they are a lot more difficult to work with than the top-mounted coil overs used a few years ago.
6. Do they use other carbon panels along the nose and cockpit area to cover up the main tub? Or is that the actual tub we see?
--> It's mostly the actual tub.
6.5 What is the max number of layers do you think they lay in the highest stressed area? What do you think the min number of layers used is in one area?
--> That's probably a pretty closely guarded secret within each team.
7. If they use a carbon fiber tub how is the floor of the chassis integrated? Is carbon fiber easy enough to go back and install the floor after preliminary work?
--> The under tray and rear diffuser are separate pieces that are fastened to the tub/engine. As for the floor of the monocoque, that is accomplished by constructing the tub from two halfs (see MacKnight).
8. Would they use small strips of carbon fiber or larger ones?
--> Varies with structural and shape requirements.
9. What patterns would they lay the pieces of carbon fiber in for optimal strength and torsional rigidity?
--> same as 8.
10. Is it possible to do any of this with a cheaper and heavier weight carbon fiber in someone's garage?
--> Sure. Do a search on the web to see that there are a number of homebuilders that build bike frames, etc. from fibre reinfored materials. Larger projects might be prohibited due to cost.
11. How well would a chassis work with carbon fiber that is not Pre-preg and cures at room temperature?
--> I think the advantage of pre-preg is increased consistency in the final material after proper lay-up and consolidation. (ie., more reliable mechanical properties, etc.) Manufacturing processes that use pre-preg still require paying attention to details, as well.
12. Could a chassis be developed to accept an engine that is not a stressed member?
--> Yes, but would it be as efficient? (ie., added weight for the 'clip' that the engine would be mounted to)
13. Could it be possible to attach, say, a 355 f1 engine with a chromemolly sub frame to this type of tub, along with the f1 tranny and diff, or are the latter components too bulky?
--> Isn't that the general design layout for the F50?
14. What is the curing time for a carbon fiber tub?
--> Will depend on material and actual manufacturing conditions.
15. How long do you think it would take to complete a carbon fiber chassis?
--> I can't see the tub alone taking any more than a week. Assuming the mould is ready.
16. Does anyone know of any websites that gives any insight to the process or any books that might help?
--> see above[p][Edited by Doug on 10-18-2000]
#5
TNSFH
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- 2,466 posts
- Joined: June 00
Member
Posted 18 October 2000 - 17:50
There is now a new process for making carbon/fibre structures that is making the use of same cheaper and faster to produce.
Instead of weaved mats, a multi-axis machine tool lays individual fibers, coated in epoxy, by the thousands over a mold, mandrel or form. First in one direction until the form is covered, then in the opposite direction. Layer upon layer, each layer criss-crossing the other until the desired thickness is attained. Then the form is baked in an autoclave.
I know this tool is in wide use in the aerospace industry and it can only be a short time before it is used in racing.
Saw it on the History Channel just last night.
Instead of weaved mats, a multi-axis machine tool lays individual fibers, coated in epoxy, by the thousands over a mold, mandrel or form. First in one direction until the form is covered, then in the opposite direction. Layer upon layer, each layer criss-crossing the other until the desired thickness is attained. Then the form is baked in an autoclave.
I know this tool is in wide use in the aerospace industry and it can only be a short time before it is used in racing.
Saw it on the History Channel just last night.
#6
Doug
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- 12 posts
- Joined: October 00
New Member
Posted 18 October 2000 - 18:29
I think that process is called "filament winding".
Cheers!
Cheers!
#7
blkirk
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- 319 posts
- Joined: March 00
Member
Posted 18 October 2000 - 19:00
Filament winding is a continuous process. It has been in use for quite a while ( > 10 yrs.) for making pipes and pressure tanks. The fibers are run in a continuous strand around the form similar to a roll of twine.
Tape laying (the process TNSFH brought up) is a bit like using thousands of pieces of fiber-reinforced packing tape to make a part. The robot head moves around laying strips of fibers on the mold in any direction, location, and distance needed.
Tape laying (and filament winding for that matter) can make parts with slightly better strength-to-weight ratios than parts made with woven mats. However, either way you go, the time and expense of curing the part in an autoclave is still going to control production.
Tape laying (the process TNSFH brought up) is a bit like using thousands of pieces of fiber-reinforced packing tape to make a part. The robot head moves around laying strips of fibers on the mold in any direction, location, and distance needed.
Tape laying (and filament winding for that matter) can make parts with slightly better strength-to-weight ratios than parts made with woven mats. However, either way you go, the time and expense of curing the part in an autoclave is still going to control production.
#8
Doug
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- 12 posts
- Joined: October 00
New Member
Posted 18 October 2000 - 20:09
Tape laying does fit the description much better.
Thanks for the info!
Thanks for the info!
