In precision manufacturing fields such as mold making, semiconductors, and aerospace components, Electrical Discharge Machining (EDM) is an essential process.
Among the many factors influencing EDM performance, EDM oil plays a particularly critical role.
Far from being a simple lubricant, EDM oil is a high-performance fluid that must maintain a delicate balance between insulation and cooling ability.

1. Insulation — The Foundation of Stable Discharge

EDM works by applying voltage between the electrode and the workpiece across a tiny gap, melting and vaporizing the metal through electric discharge.
Here, the insulating property of EDM oil is vital.

• Function 1: Prevents unwanted discharge (short circuits)
  If insulation is poor, direct contact may occur between the electrode and workpiece, causing short circuits and surface damage.
• Function 2: Enables precise discharge control
  Proper insulation ensures consistent discharge timing, improving surface finish and dimensional accuracy.
• Function 3: Enhances micro-machining quality
  In micro-EDM or die making, stable insulation helps generate uniform sparks, resulting in superior surface quality.

In short, EDM oil acts as an insulating medium, blocking unnecessary current flow and ensuring that discharges occur only when and where they are intended.

2. Cooling — The Hidden Hero That Controls Heat and Sludge

During discharge, the temperature between the electrode and workpiece can reach several thousand degrees Celsius.
At this stage, EDM oil provides cooling and flushing functions that are essential for a stable machining environment.

• Function 1: Controls heat and prevents deformation
  Strong cooling capability minimizes electrode wear and thermal deformation of the workpiece.
• Function 2: Removes sludge efficiently
  Fine metal particles generated during discharge are quickly flushed away, maintaining discharge stability.
• Function 3: Maintains surface quality
  Effective sludge removal reduces surface roughness and prevents micro-cracks.

3. The Key Is Balance Between Insulation and Cooling

However, insulation and cooling performance often work in opposite directions.

• Excessive insulation can slow down the machining speed because discharges occur less frequently.
• Too much cooling capacity can reduce insulation, causing unstable discharges.

Therefore, high-quality EDM oils are formulated to achieve the optimal balance between these two opposing characteristics.

Recent advancements in low-viscosity, high-insulation synthetic oils have improved both discharge efficiency and surface finish.
Moreover, environmentally friendly formulations featuring low odor, reduced mist, and controlled flash points are becoming increasingly popular in modern machining environments.

Conclusion: Machining Quality Begins with Fluid Quality

EDM is a complex process that involves electrical, thermal, and chemical interactions.
Thus, choosing the right EDM oil is not just about selecting a consumable — it is a key factor that determines process quality.

When insulation and cooling performance are well balanced, EDM oil can deliver greater stability, efficiency, and superior surface quality.

Dyna Co., Ltd.
Industrial Lubricant Solution
E-Mail : dyna@dynachem.co.kr
Web : dyna.co.kr/en/