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7 comments

Forged Wheels vs. Cast Wheels

Posted February 05, 2010 6:00 AM by CarDomain

The new RT-S wheels from Weld Racing are made from forged-billet to offer significant weight and performance advantages over wheels that are cast or constructed from standard billet. The following comes from the company's press release.

"Forged wheels have numerous advantages over cast wheels and non-forged billet wheels. A cast wheel is made from A-356 Aluminum that is melted and poured into a mold. This material is only 60% as strong as 5000 or 6000 series alloys that are forged into shape. In addition the cast A-356 is brittle and porous. Not exactly properties you want in a wheel, especially in a high performance application!

A billet of aluminum alloy that is not forged to approximate shape before machining does not have grain running from center to rim like spokes on a wheel. A forged billet, done correctly, does. This prevents de-lamination failures that can occur during high loads in a pure billet wheel. The forging process also increases the surface density of the wheel improving durability further. With a stronger material you can use less to build the wheel reducing its weight as much as 40% and still have a more durable wheel."

Would you buy forged wheels for your car?

Visit CarDomain.com

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#1

Re: Forged Wheels vs. Cast Wheels

02/05/2010 9:40 AM

"Would you buy forged wheels for your car?"

That's all the factory offers for my car and I would not use anything else anyway.

However, for basic transportation is it overkill. Even police cars use steel wheels. So it depends on the application.

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#2
In reply to #1

Re: Forged Wheels vs. Cast Wheels

02/05/2010 3:29 PM

I agree, physical properties differences would be the only improvement......but why?

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#3

Re: Forged Wheels vs. Cast Wheels

02/06/2010 9:22 AM

Spin formed/forged aluminum wheels are superior to cast product in terms of strength, ductility and avoidance of porosity. This is due to avoidance of surface flow imperfections and internal grain structure and alignment. The nature of the alloy(s) used in forging also presents a more ductile failure mode (and generally higher tensile strength) than a typical casting in case of impact ... so you get a dent rather than a fracture when you hit that big pothole in the road. The functional advantage of aluminum (and moreso magnesium at 1/3 less weight than aluminum) over steel is less unsprung mass. Less unsprung mass improves steering and handling response (with some improvement in braking and a slight gain in fuel economy) due to lower moment of inertia.

I would choose (spin) forged over cast aluminum wheel product. In either case there should be radiographic evidence of good product at the supplier to allay any concerns about product quality. The value proposition always points to steel if performance and looks is not a factor.

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#4

Re: Forged Wheels vs. Cast Wheels

02/07/2010 3:05 PM

Many years ago a leading German car magazine tested light alloy wheels for weight savings over standard steel wheels. They compared the same size wheels/tyres.

Only 2 makes actually saved weight, BMW & Merc, all the rest were actually heavier...

If you then take into account the fact that most light alloy wheels are bought also wider that the steels they replace........!!!

They just look nicer......

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#5
In reply to #4

Re: Forged Wheels vs. Cast Wheels

02/07/2010 3:24 PM

As an engineer I object to the anecdotal data summary from the magazine. Engineering analysis of vehicle dynamics/unsprung mass would argue otherwise... but only if design is optimized to take advantage of the opportunity for weight reduction. You can overdesign any solution especially if the overdesign of typical sections (hence added weight) is a result of concern with consistent properties of product as manufactured (cast vs forged).

As a consumer I suspect the overview from Mr. Germany is valid unless handling performance and response is an important factor.

Drop/spin-forged magnesium wheels would make a difference (on the order of 1/3 the weight of steel wheels) ... ask the guys on the Formula 1 circuit.

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#6

Re: Forged Wheels vs. Cast Wheels

04/07/2010 1:44 AM

i have no vanity, the wheels are there to eep the chassis from rubbing along the road, and to give the gearbox somthing to turn, so pressed steel wheel will do for me.

it depends on what your going to use car for, going to and bac from wor anything round would do.

racing and putting high torque and sideways thrust when cornering then you need maximu strengh.

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#7
In reply to #6

Re: Forged Wheels vs. Cast Wheels

04/07/2010 7:44 AM

You may have to clean out your Keyboard, your K and X aren't coming through

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