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At ELE we know the importance of achieving complex engineering solutions, especially when it comes to manufacturing processes. Non- traditional methods of drilling and machining provide cost effective solution, high quality for intricate cooling systems, including those in the aerospace and gas turbine production industries.

One such intricate and effective drilling technology is Shaped Tube Electrolytic Machining or STEM as it is more commonly referred to. While there are other drilling techniques, such as capillary, laser and fast hole, STEM still offers a way to create clean, multiple, round and shaped, accurate holes with large depth-to-diameter ratios.

Making small, precision holes in metal has always been a challenge for manufacturers. A popular option is electrical discharge machining, although this is an efficient method of manufacture it does have some drawbacks one of them being that it produces sparks and creates precipitate in the hole being drilled. STEM is more often used because it doesn’t have this problem and there is less consequent tool wear and therefore reduces tooling costs.

The Benefits of STEM

Compared to other manufacturing and tooling processes, STEM delivers major benefits to many industries, such as:

  • It can produce round and shaped holes including radial edge, film cooling, and platform holes with large depth to diameter ratios.
  • It is still one of the most versatile deep drilling technologies in the world.
  • It can be used to drill multiple holes at the same time, reducing time and cost.
  • It produces less stress on materials and can be used on some of the hardest metals that are used in manufacturing, across the board, today.
  • It can handle numerous drilling profiles with depth ratios of up to 300 to 1 with diameters as small as 0.5mm.
  • Because it uses an acid electrolyte process, it can handle hard metals with a high degree of precision, quickly and with little waste.
  • The process delivers fast metal removal with low thermal and mechanical stress.

How Does Shaped Tube Electrolytic Machining Work?

STEM drilling was developed primarily to handle large depth-to-diameter ratios, a requirement for many industries and manufacturing processes including those in aerospace. These deep holes cannot generally be drilled in the conventional way without some form of waste, expense, or reduced quality and accuracy of the drilling. Other processes such as ECM tend to create precipitates which then hamper the electrolytic flow path of the bore preventing the deep drilling that is often a prerequisite for manufacturing industries. Stem drilling achieves deeper hole depth to diameter ratio’s by using an acid electrolyte – making it ideal for hardened materials such as nickel-based corrosion resistant metals, where depths of 300:1 can be achieved.

Areas of Use

STEM is used extensively in areas such as jet engines and industrial gas turbine; products like HPT turbine blades, nozzle guide vanes and heat shields, where small holes, starting at 0.05mm diameter can be created for cooling, with high precision in multiple arrays. A major benefit of Shaped Tube Electrolytic Machining is that several holes can be drilled simultaneously reducing manufacturing time and costs. Furthermore in  processes where the designer demands no re-cast layer,  something that the EDM process cannot provide, as it can weakening the surrounding material an issue and can in some cases initiate parent metal cracking , STEM does provide a fast and accurate solution to this issue.

How can we help you?

At ELE we combine a range of manufacturing technologies to deliver the best outcome for each of our clients. Processes such as STEM, allow ELE to deal with a wide range of complex designs and materials to a very high degree of precision.



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