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Tool Life, Scalability Drives New Thinking in Machining

Peter Loetzner
By Peter Loetzner CEO, EMAG LLC

With larger turbine components, compared to automotive and aerospace, plus assembly challenges, new machining technologies are gaining popularity. The conventional milling and broaching techniques in turbine blade machining, with the high tooling costs and abrasive flow issues, are fast fading, as modern assembly methods continue to drive machining tolerances to new heights. More precision is needed for the stack-up process, so companies are turning to new techniques such as electrochemical machining (ECM) as a scalable method for single disc to blade and rotor production.

Today, ECM is a viable means of production, especially when materials such as Inconel are involved, as it produces residue-free output of precision components. No tool touches the part, the material properties remain unchanged, warping or material stress is eliminated and there is no need for secondary finishing operations, in most cases.

ECM technology, for those unfamiliar with it, involves the anodic dissolution of metal in a highly controlled environment. All types of metallic substrates can be subjected to ECM, which has particular upsides in the working of high-alloyed, nickel- or titanium-based materials, as well as pre-hardened materials. As a contactless process with no heat input to the substrate, ECM produces no tool wear, mechanical surface stress, micro-fissures or need to deburr.

In the ECM process, better parallelism is maintained, with a faster overall time to part. With recent advancements in fluid chemistries, the long-standing safety concern over carcinogenic materials has been minimized. Machine demand for this category has increased four-fold in the last two years.

It is an exciting time in the energy sector, as young engineers entering the field are accepting of this new technology and driving its implementation in many areas of production.

From a practical standpoint on the factory floor, ECM equipment has virtually no tool wear, occupies a smaller footprint and produces no surface impact on the part (another misconception of the past). The result has been a rapid increase in the use of ECM by both the energy and aerospace sectors, where larger workpieces often presented considerable challenges for the conventional milling and broaching techniques used in the industry.

ECM now offers the market a competitive solution to part production at a lower overall cost. With the growth of blade requirements in all sectors of the energy market, from gas to solar and hydro, there is a noticeable transition occurring from the old mill/broach solution to alternative manufacturing techniques such as ECM, a trend we expect to continue.

Further, the growth of large gearboxes in the industry for oil, gas and water pumping are driving an increase in threading machines, especially the inverted verticals, which permit an optimum chip flow.
As cost becomes an ongoing challenge, more automation will achieve higher quality levels, plus this automation will allow those quality levels to be maintained on lower quantity runs with cost containment, due to the labor savings.

Work cells are making some inroads in the manufacturing process at most energy-related equipment companies and their supply chain partners. This trend will require a new look at cloud-based data gathering, customized app development to track production data and edge technology, the fast-emerging bridge between that data gathering and the cloud, with a particular emphasis on cybersecurity and data sharing issues.

Complementing this trend will be the increased need for advanced machine and line controllers for the parallel gathering of information and the integration of robotics, transfer mechanisms, and other automation. Plus, as tool quality in the market continues to improve, better feeds and speeds will result, regardless of the machining techniques used.

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