Technical Reference
EDM Minimum Feature Size Guide Technical Reference
Minimum EDM feature size is controlled by electrode size, discharge gap, depth or height, material, flushing, stability, and the measurement method. A feature can be electrically machinable but impossible to support, flush, or inspect.
Quick Answer
Minimum EDM feature size is controlled by electrode size, discharge gap, depth or height, material, flushing, stability, and the measurement method.
Key Technical Points
What the Parameter Changes
A nominal micro size may be machinable but not measurable, flushable, or stable at the required aspect ratio. The consequence changes fit, function, or service performance for the Minimum Feature Size decision; it is not only a change in surface appearance.
How to Select It
Specify the finished feature and functional tolerance; do not define capability from electrode diameter alone. When planning Minimum Feature Size, apply the requirement only to the dimensions and faces that control fit, function, service life, or documented release.
What Can Go Wrong
A feature can be electrically machinable but impossible to support, flush, or inspect. Minimum size must be released together with depth, aspect ratio, edge radius, electrode or wire size, and the actual measurement capability.
Technical Context
Minimum feature size is limited by electrode stiffness, discharge gap, flushing access, depth-to-width ratio, wear, and the ability to inspect the result. A nominal electrode diameter alone does not prove the feature is manufacturable at the required depth and tolerance. This mechanism explains the limits and behavior that matter when planning Minimum Feature Size.
Feature-Size Decision Table
| Condition or input | Why it matters | What must be confirmed |
|---|---|---|
| Electrode or wire size | sets stiffness and contributes to kerf or corner radius | available size, wear, current capacity, breakage risk |
| Spark gap | adds to slot width or cavity offset | material, energy, pass, and machine technology |
| Depth or section height | changes flushing and deflection | aspect ratio, guide spacing, support, and inspection |
| Inspection method | sets the smallest feature that can be released | probe size, optics, magnification, datum, and uncertainty |
Surface Considerations
Assign surface, edge, and sub-surface requirements only where they affect function, and give each requirement its own acceptance method. For Minimum Feature Size, tie the accepted condition to the feature and inspection method named in the drawing.
Minimum Feature Size Drawing and Release Checkpoints
- Identify the controlled feature, material condition, access direction, and functional datum for this Minimum Feature Size decision.
- Separate dimensional requirements from texture, edge, recast, corrosion, fatigue, or post-process acceptance.
- State the inspection method, sampling or first-article requirement, drawing revision, quantity, and any documentation needed for release.
Limits and Better Alternatives
Main Limit
For EDM Minimum Feature Size Guide, the guide applies to the named technical decision and does not replace the drawing-specific review of geometry, material, setup, and inspection. When that boundary dominates, use a larger feature, shorter aspect ratio, Sinker or Micro EDM for a different access condition, or redesign the internal corner when the physical limit is not functional.
Consider Another Route When
Use a larger feature, shorter aspect ratio, Sinker or Micro EDM for a different access condition, or redesign the internal corner when the physical limit is not functional.
Practical Next Step
Assign surface, edge, and sub-surface requirements only where they affect function, and give each requirement its own acceptance method. Specify the finished feature and functional tolerance; do not define capability from electrode diameter alone.
What to Remember
Minimum EDM feature size is controlled by electrode size, discharge gap, depth or height, material, flushing, stability, and the measurement method. A numeric target is ready for release when its feature, conditions, allowance, and inspection method are explicit.
Technical Reference
Use the values as planning references and define the functional requirement on the controlled drawing.
Use This Guide to Prepare Your RFQ
Contact us when your drawing and requirements are ready for review.
- Drawing or part sketch
- Material grade
- Thickness / part size
- Quantity
STEP/STP, DXF, DWG, PDF, IGS/IGES or ZIP.
Confidential drawing review. NDA support available on request.
Frequently Asked Questions
Can Wire EDM make a zero-radius internal corner?
No. Wire radius and spark gap leave a finite internal radius.
Does smaller wire always improve the result?
No. It can reduce stiffness, speed, and stability.
What should be dimensioned?
Specify the finished feature, depth or height, radius, tolerance, and inspection method.
When should another EDM route be used?
Use Sinker or Micro EDM when access or feature scale differs from a normal through profile.