Speaking of Precision Blog

Speaking of Precision

Speaking of Precision is a knowledge preservation and thought leadership blog covering the precision machining industry, its materials and services. With over 36 years of hands on experience in steelmaking, manufacturing, quality, and management, Miles Free (Milo) Director of Industry Research and Technology at PMPA helps answer "How?" "With what?" and occasionally "Really?"

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Seven Advantages of Friction Welding

Posted September 21, 2010 9:33 AM by Milo

Friction welding is an ideal method to join dissimilar metals - cost, quality, and strengthwise.

Ideal for dissimilar metals

Here are 7 advantages of Friction (inertial) welding:

  1. Easily joins dissimilar metals. This means the ability to use more expensive corrosion resisting materials where needed, and less resistant but sufficiently strong materials where there is no need- ON THE SAME PART.
  2. The full surface of the cross section is made up of both metals, airtight and absent of voids.
  3. Friction welds are higher strength than other means of joining.
  4. Friction welds often cost less as there are no consumables like filler metals fluxes etc. (This would be the bottom line for most businessmen, but I chose another, see # 7 below.)
  5. Friction welds minimize the Heat Affected Zone (HAZ).
  6. Friction welding minimizes the need to clean furnace residues from the entire part, post welding.
  7. The ability of a designer to optimize material choices by using friction welding cannot be overstated.

Airbag systems rely on friction welding for assembly.

I produced truckload quantities of 1050 modified steel for an automotive half shaft application, the friction welding process made this a highly reliable part despite the high carbon content and different material between the alloy steel forged end assembly and the carbon steel shaft.

This welding process is ideal for pumps, process mixers, and other applications where a portion of the part needs to be food safe or chemically resistant, but the remainder of the part does not. The photo below shows an electrical industry bimetallic (copper and aluminum) application.

Friction (inertial welding) lets the engineer put what s/he wants where they want it!

Frictional welding is a controlled process where two components are frictionally bonded by the heat and mechanical displacement of each material's being melted and re-fused amongst the melt products at of the other. The bond that is created by the mechanical intermixing and solidification of the two metals is strong and free from voids and porosity. It can be cost effective and offers design engineers many more options than other methods.

Friction or inertial welds are a key process for attaching precision machined components to other parts like shafts or bodies or forgings.

My thanks to Stuart Short at Inertia Friction Welding at IMTS for chatting with me about this not so well known joining process.

Airbag Dummy photo.

Editor's Note: CR4 would like to thank Milo for sharing this blog entry, which originally appeared here.

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#1

Re: Seven Advantages of Friction Welding

09/21/2010 11:21 AM

At a company I used to work for we used to friction weld pump shafts. Mild steel at the bearing end and high nickel/chrome alloys (Hastelloy and duplex ss type materials) at the 'wet' end. Never ever had a problem, and it was quite fascinating watching the welding process. I don't know if there are any videos about? In the old days they had two seperate shafts pinned together.

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#2

Re: Seven Advantages of Friction Welding

09/21/2010 11:24 PM

I have used a similar approach a number of times to bond dissimilar plastics together for making odd fittings for special applications.

I learned it form a old plumber that showed me how to bond two plastic pipes together that don't have a common glue or other simple method of connecting them otherwise.

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#3
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Re: Seven Advantages of Friction Welding

09/22/2010 8:37 AM

Friction Welding is under-utilized in the US. The most important aspect of friction welding is controlling the variables. RPM, Pressure, and displacement are only the beginning. Second friction time and deceleration time is important to monitor as well.

The current trend now is to graph the variables. By comparing the graphs from lot to lot, one can determine if the welder is performing as it did during initial testing.

Like all welding, material defects can be amplified by friction welding. A percentage of the welds should be ultrasonic tested just to insure material defects do not exist in the material.

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#4

Re: Seven Advantages of Friction Welding

09/22/2010 8:45 AM

Very cool (even if it does have a HAZ). Air bag systems also use projection welding to attach a burst or rupture disc to the inflation gas source. We design and build these welding systems that produce leak proof welds around the entire disc in a few milliseconds.

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