In recent months, the Graphel Carbon Products Engineering Department has fielded questions concerning Sinker EDM and Wire EDM.  Sinker EDM machines have dimensioned graphite parts that create the opposite shape in the workpiece through electrical discharge.  Wire EDM machines use a wire to cut the shape into the workpiece through electrical discharge.  Many companies use both types of machine and Graphel Carbon Products wanted to put together an article discussing Sinker EDM and Wire EDM. While both methods have unique advantages, in this article, we will focus on the advantages of Sinker EDM over Wire EDM. Here are six advantages Sinker EDM has over Wire EDM.

1. Accuracy and Precision: The accuracy and precision of both machines can be the same.  Wire EDM has a more challenging time holding tighter tolerances as the workpiece thickness gets taller.  You can do finishing skim cuts to offset this disadvantage if the finished part isn’t removed from the raw material stock.  It depends on the application.  Skim cuts in Wire EDM do take additional time. In Sinker EDM, the electrode is in direct contact with the workpiece, allowing for precise and intricate machining. This makes it ideal for applications that require tight tolerances and complex shapes. The critical advantage sinker EDM has over wire EDM is that it can EDM blind cavities where wire EDM must cut through a part.  That is often the differentiating factor in deciding if a part is wire cut vs. sinker. Additionally, Sinker EDM can produce complex 3D shapes where wire EDM can’t.
2. Surface Finish: Sinker EDM produces a better surface finish than Wire EDM. The direct contact between the electrode and the workpiece allows for a smoother, more polished surface. This is crucial in industries such as aerospace and medical, where high-quality surface finish is essential.
3. Machining of Hard Materials: Sinker EDM is particularly effective in machining hard materials such as hardened steel, carbide, and exotic alloys. The direct contact between the electrode and the workpiece enables efficient material removal, even from tough and heat-resistant materials. On the other hand, Wire EDM may struggle with such materials due to its reliance on a thin wire for cutting.
4. Versatility: Sinker EDMs can handle more significant parts than wire EDMs. Wire EDM machines have limits on how tall the workpiece material can be.  The taller the part is, the longer it takes to cut and the less accurate the cut will be if skim cuts can’t be made (the wire tends to “bow” more as the part gets taller due to the distance increasing between the wire guides).
5. Reduced Material Waste: Sinker EDM produces less material waste than wire EDM. The direct contact between the electrode and the workpiece allows for precise material removal, minimizing the amount of material that is wasted. This can result in cost savings, especially when working with expensive materials.
6. Time Efficiency: Sinker EDM can sometimes be faster than Wire EDM. The direct contact between the electrode and the workpiece allows for efficient material removal, reducing machining time. This can be advantageous when working on projects with tight deadlines or high production volumes.

Higher changeover rates can be attained with sinker EDM because changing out electrodes is quick (mainly when standardized tooling is used, like System 3R) vs. having to feed wire through a workpiece if internal features are being wire cut from a part.

EDM Sinker offers several advantages over Wire EDM, including superior accuracy and precision, the ability to machine hard materials, greater versatility, reduced material waste, and time efficiency. However, it’s important to note that the choice between Sinker EDM and Wire EDM depends on the specific requirements of the project and the materials being machined.

If you have additional questions on Wire EDM or Sinker EDM, please contact Graphel Carbon Products. Our Engineering Department can help you choose the correct graphite material, design or redesign your electrode, and suggest the proper tooling for your EDM machine. Contact Graphel on Live Chat Chat With Us • Graphel to talk directly.