EDM for fir-tree profiles

18 Feb 2019

Engineering capacity news posted by Andy Sandford

A new wire erosion machine at Derby subcontractor Promach 3D is producing fir-tree profiles on special tooling for a critical aerospace application.

The Sodick ALC 400G is its second machine from Sodi-Tech EDM and has been purchased to boost capacity and keep up with customer demand.

Established in 2004 by Matt Fazekas with little more than a three-axis vertical machining centre and a laptop for CADCAM software, Promach 3D has grown into a 12-employee business turning over in excess of £1 million per annum. The company has created a strong niche by focusing on bespoke projects for high-end markets, the principal one being aerospace. Typically, the parts, tooling and assemblies manufactured by Promach 3D are complex in design, with high tolerance and surface finish demands.

Offering three- and five-axis CNC milling, CNC turning and general toolroom manual machining, the company recently sought to increase its wire EDM capacity. Promach 3D had installed a Sodick AG600L in 2012, but in order to meet the demands of an increasing order book, wanted to add another machine.

“We recently introduced an additional facility in Derby, and decided to invest in a second wire EDM, not just to increase capacity, but to take advantage of the latest technology,” explains Mr Fazekas. “Our existing wire EDM is six years old and technology has moved on. Although we looked at the whole market, due to the reliability and functionality of our AG600L, we returned to Sodi-Tech EDM. The ALC 400G was the right machine for our requirements, largely thanks to its versatility and high specification. As a subcontract business, we never know what will come through the door tomorrow, so we have to be prepared and continue to offer high-end solutions.”

Having made the decision to purchase the machine at MACH 2018, the subsequent months since installation have seen the ALC 400G hard at work.

“We won an aerospace contract that in the first instance involved liasing with the customer to assist with the design-for-manufacture of stainless steel tooling that helps automate the coating of turbine blades,” explains Mr Fazekas. “From the outset it was clear that, due to the complexity of a key feature, wire EDM was the only way it could be made effectively and efficienty.”

Machining high-precision components and tools has been the mainstay for Promach 3D since the beginning. As the business has expanded so has the complexity of jobs, with the client list following suit. Promach 3D quotes on projects which other engineering companies tend to avoid, typically due to the challenging nature of the parts and materials to be machined.

The turbine blade root holder, as the part is known, is a case in point. An intricate fir-tree profile is the prominent feature of the tool, which is used to clamp the turbine blade into position at its root end, ready for coating.

As a company, Promach 3D has evolved over the years, from producing one-off jigs and fixtures, to small batch production and anything in between. This trend is predicted to continue, as evidenced by the root holders. The company is currently working its way through batches of 150-off, for three types of root holder, with more variants set to follow.

“We designed a fixture to EDM 20 root holders at a time on our new Sodick ALC 400G, typically running lights-out over a 12-hour cycle time,” says Mr Fazekas. “The AWT [automatic wire threading] technology of the Sodick machine is excellent, which means we can leave it to run assured of its reliability. If we need to run the machine over a longer unattended period, we can use the Sodick Jumbo wire feeder for a full weekend’s worth.”

Promach 3D, which is accredited to ISO 9001:2015, employs a one-cut strategy on the root holders, as the quality of the Sodick ALC 400G means a single cut is more than sufficient to meet the tool’s requirements for tolerance and form.

“We seem to be picking up more and more work, which is encouraging as we have seldom touted for business since forming 14 years ago,” concludes Mr Fazekas. “Our growth has been pretty consistent in the years since the financial crisis ended in 2010. In fact, last year we reached £1 million turnover for the first time, which is a nice milestone, and one that prompted us to invest in additional machinery and people."