Automotive

Plastic engine parts could lead to lighter cars

Plastic engine parts could lea...
Demonstration model of the experimental engine with lightweight cylinder casing (Photo: Fraunhofer ICT)
Demonstration model of the experimental engine with lightweight cylinder casing (Photo: Fraunhofer ICT)
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Demonstration model of the experimental engine with lightweight cylinder casing (Image: Fraunhofer ICT)
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Demonstration model of the experimental engine with lightweight cylinder casing (Image: Fraunhofer ICT)
Demonstration model of the experimental engine with lightweight cylinder casing (Photo: Fraunhofer ICT)
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Demonstration model of the experimental engine with lightweight cylinder casing (Photo: Fraunhofer ICT)

Recent government requirements for greater fuel efficiency have led to lighter cars hitting the market, but there's only so much that can be shaved off the body and chassis. To find further weight reductions, a Fraunhofer project group is developing ways of building engine cylinder blocks that are partly plastic.

Lighter engines that can still do the job of their heavier cousins have been around since the first aluminum engine blocks were introduced in the 1960s. Going one step further with plastic has been on the drawing boards since the 1980s, but plastic parts able to withstand engine heat and stress could only be made in small volumes and at great cost.

The approach taken by the Fraunhofer project group for new drive systems (NAS) was to create an experimental engine using fiber-reinforced plastic suitable for injection molding instead of aluminum.

"We used a fiber-reinforced composite material to build a cylinder casing for a one-cylinder research engine," says Lars-Fredrik Berg, project leader and manager of the research area Lightweight Powertrain Design at NAS. "The cylinder casing weighs around 20 percent less than the equivalent aluminum component, and costs the same."

Fraunhofer says that using plastic not only allows for lighter vehicles, but provides the added advantages of reduced fuel consumption, less noise, and less heat radiated from the engine. However, achieving this meant overcoming problems with heat and vibrations.

"First we looked at the engine design and identified the areas subject to high thermal and mechanical loads," says Berg. "Here we use metal inserts to strengthen their wear resistance."

Other problems the project faced was getting the plastic to bond well with and expand like metal, redesigning engine parts to keep heat away from the plastic, and making the plastic hard and rigid, yet also capable of withstanding contact with oil, petrol, glycol, and water coolants.

The project eventually settled on a glass-fiber-reinforced phenolic resin of 55 percent fibers and 45 percent resin that uses granulated thermoset plastics in an injection molding process. The glass fibers are already mixed with the liquid resin, which is injected and hardens in the mold. The trick was sorting out the details of the process to obtain the best results while eliminating many of the finishing operations needed for metal parts. Carbon composites can also work and are lighter, but are more expensive.

Fraunhofer says that a prototype of this engine will be presented at this year’s Hannover Messe this month, and that the project is now working on a multi-cylinder engine.

Source: Fraunhofer

19 comments
Tom Lee Mullins
I think that is a creative solution. With some saying gas prices will go up, reducing weight - no matter how small - will help with better MPG.
William Sywyk
Don't forget about them charging the same price for plastic as they do for metal, and the parts wearing down and breaking easier.
Gavin Roe
phenolic plastic engines would be a environmental nightmare
S Michael
Will the car manufacturers still want us to pay outrages prices for "Plastic" cars. Rip off .... When is the public going to wake up at the outrages prices they are paying for cars. Here's an idea... don't advertise on every radio, television. Commercials cost billions, Cut that out and lower the price of cars..
Mindbreaker
The aluminum is recyclable those plastics are not. Stick with the aluminum or try titanium alloys. There are any number of ways to alloy metals...surely there is an alloy that is better than that plastic in weight and performance.
I think the metal powders that are compressed into objects are the best approach...that allows a wide variety of possible alloys and beyond with very little waste. Lasers melting powders are also interesting.
Who is going to buy a car with a plastic engine? Ceramic maybe...plastic? That is going to encounter resistance.
If plastic is so strong, where are the plastic screws and nails? When a plastic screw can cut through sheet steel like your clothes washer is made out of (self-tapping), I will take it back. A good ceramic could probably do that, but it might be too brittle and thus vulnerable to shock. We forget how great this stuff called metal is.
Electric is where it is all going anyway. You are working on horse buggies.
SuperFool
Plastic makes things lighter, but it absolutely fixes their duration of usefulness because the stuff is susceptible to temperature, vibration, & uv. I could only get behind this if the specs were downloadable to 3d printers (some day when pigs fly, the cost of 3d printers go down, and auto manufacturers decide maintenance is better than selling a new car for $20k every 10 yrs)
Nicky Hansard
Na I don't like this. I'm all for imrproving materials for new areas but I think some things should just be left to metal e.g. especially when it comes to temperature and oils. How about making carbon fibre cheaper and making chassis's/car bodies from that and/or increasing spending on research into electric cars.
Thomas Lewis
Plastic ?repairs,warpage,inserts pulling out,cracking,plastic tends to breaks down.I rather see some type of carbon/kevlar etc which would hold up much better If we could come up with faster ways to produce carbon parts,printing,vacuum forming etc.I've seen race cars with carbon fiber driveshafts,gearboxes,transaxles etc, The cost would have to come way down and the quality would have to improve a lot other wise its just another nightmare for consumers.
johnflood
Why not use the same plastic to produce the car body panels , maybe even the chassis
Catweazle
The first Honda Formula 1 car in the 1960s used nylon for the gears in its transmission, and plastic inlet manifolds have been in use on production cars for years.