Sodi-Tech EDM machines complex probe bodies

EDM is used for the machining of complex, hardened steel probe bodies used to measure critical factors in jet engines such as pressure and temperature.

Sodi-Tech said that there is constant pressure to reduce aero engine testing cycles to minimise costs and bring forward the revenue earning part of the engine's life.

To measure critical factors such as pressure and temperature, one leading aero engine OEM manufactures special purpose probes that feature an array of sensors for recording and checking different engine attributes.

Coventry, UK-based Hi-Tech Aerospace Components machines of the complex, hardened steel probe bodies.

Hi-Tech does work for companies like Rolls-Royce, MTU and BF Goodrich and has specialised in aerospace machining since its formation in 1981.

The company is also AS 9100:Rev 3B accredited and has NADCAP (National Aerospace and Defense Contractors Accreditation Program) approval from the USA.

Hi-Tech is NADCAP approved to undertake wire, die sink and hole drilling EDM operations, something that few other tier 2 suppliers in the UK can claim, said Sodi-Tech.

Hi-Tech Aerospace Components using a combination of die sink and the latest high specification CNC Sodick wire erosion machines to machine the probe bodies.

"We process a lot of exotic materials, including titanium, which is particularly difficult to machine using EDM techniques," said Hi-Tech co-director Bob Duffin.

"Sometimes we might only be producing a GBP 250 feature on a component worth GBP 3,000.

However, the feature in question might specify tolerances as tight as 0.005mm, which puts a lot of pressure on the operator and the performance of the machine".

* Die sink, hole and wire erosion machines - Hi-Tech Aerospace Components' Coventry facility operates a number of die sink, hole and wire erosion machines.

The latter, of which the company has eight, are all Sodick models that have been supplied by Sodi-Tech EDM.

The latest is an AQ300L wire EDM purchased at the UK's MACH 2008 machine tool exhibition.

The machine's linear motor technology provides instantaneous servo time that maximises cutting efficiency.

Since there are no ball screws or couplings, backlash is totally eliminated, which provides several advantages including improved positioning and cutting accuracy, while delivering smooth and vibration free table movement.

Hi-Tech uses the AQ300L to machine the aero engine probe bodies in batches of around 40-off.

The shaft-like components are approximately 200mm in length and feature a series of 'chimneys' at one end that accept the different sensors required by the customer.

The parts arrive as turned blanks before a wire EDM roughing operation is performed on the Sodick.

The part is then transferred to a die sink machine for the machining of one particular feature before it comes back to the AQ300L for finishing operations.

Finally the probe body has a few finishing details produced on another die sink model, which are followed by polishing.

Dimensional tolerances are in the region of 0.05mm.

The probe bodies, which have a net value of approximately GBP 1,200 each, take approximately two to three days to produce.

"Although we've been manufacturing these engine probes for a while now, new variants are always being introduced to keep us on our toes," said Duffin.

"Our expertise and quality accreditations are also helping us win plenty of new business.

I think we can now rightly call ourselves one of the largest EDM subcontractors in the West Midlands, if not the country.".

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