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Electrical discharge machining (EDM) has long been the answer for high accuracy and demanding machining applications where conventional metal removal is difficult or impossible. The time has now arrived for it to also be equipped with intelligent features. Contributed by Makino

Makino Moving Towards Intelligent Control Of Electrical Discharge Machining

Moving Towards Intelligent Control Of Electrical Discharge Machining

Electrical discharge machining (EDM) has long been the answer for high accuracy and demanding machining applications where conventional metal removal is difficult or impossible. The time has now arrived for it to also be equipped with intelligent features. Contributed by Makino

Generation Z (born from mid-1990s onward), also known as the iGeneration, grew up with touch screens such as smartphones and smart televisions, as compared to Generation Y (born between 1980s and mid-1990s) that grew up with computers that were not “smart” yet.

When Generation Z starts their careers in the manufacturing industry, they will expect manufacturing technologies—such as electrical discharge machining (EDM)—to be smart as well. Companies have been working to ensure that its young operators are equipped with the right knowledge on machining technology.

Eliminating Anti-Rusting Hassle

It is common knowledge in the industry that leaving metal workpieces submerged in a water-based dielectric fluid for an extended period of time will cause it to rust.  To prevent rusting, two traditional solutions include adding anti-rust agent to the fluid, or turning to the sandblasting process.

A supplier of EDM machines, Makino recently introduced a third option called the ProTech approach, whereby a cathode electrode plate is placed into the work tank and linked with a 15 volt power supply, rendering the circuit automatically active when the work tank is filled with fluid. With this approach, operators need not monitor the process nor replace any parts; or clean the tank post-process. This approach can be applied to steel products, and also to protect the surfaces of carbide and aluminium products.

Auto-Lock—Simplifying Maintenance Procedures

In wire cut maintenance, there are two carbide energising plates in the upper and lower heads of the machine that has to be moved at fixed distances. To index the energising plate with a measuring device, the operator places it on a mounting table but this could result in insufficient space to access and adjust it.

In such cases, the operator might delay this maintenance procedure, which may cause a higher chance of the wire breaking and or even a reduction in cutting performance. With an auto lock system, all an operator would need to do is to rotate the indexing knob once and will know if they have tightened or loosened the knob by listening to the sound of an audible click.

Intelligent System Features

Moving Towards Intelligent Control Of Electrical Discharge Machining

The auto lock system lets the operator know if they have tightened or loosened the
knob by listening to the sound of an audible click.

Intelligent features in manufacturing systems are essential for manufacturers to move forward—especially when the younger generation (such as Generation Z) enters the workforce—and information relating to the shop floor should be easily accessible to operators on any digital device.

The information that can be made available online could range from an operation manual explaining machine functions, to video tutorials on machine maintenance. Moreover, by connecting the manufacturing process to a network system, it enables operators to check the machine status whilst away from the factory floor and to also send instructions to the machines via remote control when needed.

Selecting The Right EDM Technology For Hole-Drilling Applications
According to a white paper by Makino, advancements in EDM technologies can offer several advantages over traditional manufacturing methods. For example, the EDM drilling process can reduce lead-times by eliminating the need for secondary post-machine operations by producing burr-free hole features with greater precision. In addition, EDM processes are unaffected by the hardness of workpiece materials, making it an effective solution for a wider variety of applications.

Aerospace Requirements

The aerospace market encounters its own unique blend of hole-production requirements. The most common hole features seen in modern aerospace applications are known as film cooling holes. These hole features are machined directly into the leading and trailing edges of blade and vane segments used within jet engines, and serve a critical role in providing cool airflow through the hollowed centre of these parts.

Aircraft blade and vane components commonly feature high volumes of film cooling holes as well as shaped hole features known as diffuser shapes. Production requirements for these holes typically range in diameter from 0.5 mm to 1.5 mm, with average accuracy tolerances of ±0.050 mm. As EDM drilling is a thermal process, attention must be paid to the impact of the process on the metallurgical quality of the workpiece. The heat affected zone (HAZ) and recast in the material around the drilled hole typically have a maximum allowable value under 0.050 mm. These characteristics have led to development of several new EDM hole-drilling technologies that emphasise speed over precision, such as multi-sided part positioning and back-strike prevention.

Difference Between Dielectric EDMs Types

Despite the growing variety of EDM hole-drilling technologies available on the market, there exist two primary machine platforms, oil dielectric and water dielectric, which offer very distinct performance characteristics.

  • Oil Dielectric EDMs: Oil is used to provide the highest accuracy and best surface-quality holes. It is typically reserved for precision machining or special applications not possible with the tolerances and surface finish of water machines.
  • Water Dielectric EDMs: Water, typically deionised to control conductivity, is an effective and inexpensive dielectric fluid that is the most commonly used in EDM drilling machines. Water is a suitable choice when the workflow calls for a dedicated process machine, one that drills only holes, and requires the fastest possible machining speeds.

When choosing the right machine to get—whether oil- or water-based—below are key features to look out for:

  • Capacity for fine-hole EDM drilling and standard sinker EDM operation on a single machine.
  • The ability to quickly change from one EDM method to another.
  • Smallest hole size capability.
  • Accuracy capability.
  • Tool-change capability.
  • Flush pressure capability.

The right tool is needed for the job, and both water- and oil-based EDM hole-drilling machines certainly offer potential capabilities for producing small holes. The imperative is to accurately determine the needs and choose the machine with the performance and characteristics best suited for the work for maximum productivity and process efficiency.

 

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