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TWI Bulletin, March - April 2009

Case Study: Urgent need for titanium preforms - prompt delivery delights customer

Huge material savings, low cost tooling, excellent weld properties and reduced production times were just a few of the favourable aspects of linear friction welding (LFW) which prompted one of TWI's clients to get in touch.

The Midlands based engineering business Thompson Friction Welding wanted TWI to make several preforms by joining large blocks of raw material to second and third blocks. The process, sometimes known as solid-phase additivemanufacture, allows complex shapes to be manufactured without the wastage of excess material normally associated with machining from solid block, casting or forging.

There was an added dimension of urgency. The parts were needed in time for the fast approaching Farnborough Air Show.

The merits of preform manufacture by LFW are numerous:

  • Typical applications include components that are currently machined from solid blocks of high value materials. By LFW of preforms both the quantity of material which is turned into swarf, and the machining time, can be drastically reduced.

  • Feasibility studies in a range of titanium alloys have already shown that excellent weld properties can be achieved. The tensile and fatigue properties are comparable to those of the parent metal.

  • The process window for good quality LFW in titanium allows is generally very large.

  • The LFW approach also allows the inclusion of dissimilar titanium alloys at defined locations in the component. So the part can in effect be 'tailored.'

  • Example parts have been produced by LFW which clearly demonstrate the material savings possible.

So the LFW process's potential for reducing production costs is huge. It's a highly repeatable process which has its roots in blisk manufacture, joining blades to disks. The development of low cost LFW machines has broadened inrecent times and the process can now be considered for many more applications than were available a decade ago.

To learn more about TWI's linear friction welding capability contact Adrian Addison.