Process & Material
Beryllium Copper Small Hole EDM Drilling General Tolerance + Rough EDM Cut Finish Review
This Beryllium Copper Small Hole EDM page combines a General tolerance target with a Rough EDM cut surface target. These requirements must be planned together because finishing passes improve texture while also changing profile offset, cavity size, hole size, or edge geometry.
Quick Answer
For Beryllium Copper, ±0.025–0.050 mm and Ra 2.0–3.2 μm are achievable on selected Small Hole EDM features when electrode runout, flushing, breakthrough support, and the finishing sequence are planned together. Apply both targets from the same datum, and reserve the tightest values for the dimensions and faces that control function.
Key Quality Decisions
What These Targets Mean
On Beryllium Copper, ±0.025–0.050 mm controls the named dimensions and Ra 2.0–3.2 μm controls the named functional faces. In Small Hole EDM, diameter, straightness, wall condition, and breakthrough respond differently to electrode wear and finishing energy. The supplied condition adds a separate risk: heat-treatment condition and safe downstream handling must be identified.
Getting Both Targets Right
Use one machining and inspection datum. Apply ±0.025–0.050 mm only to dimensions that control fit, and Ra 2.0–3.2 μm only to functional faces. Plan electrode diameter, true path depth, aspect ratio, flushing, rotation, straightness, and breakthrough support. State the exact Beryllium Copper condition and the inspection method before releasing the result.
What Gets Missed
On a deep small hole specified at ±0.025–0.050 mm and Ra 2.0–3.2 μm, entry diameter can pass while exit diameter, straightness, or breakthrough position fails. The tolerance represents a broad size band, while the roughing craters and high discharge energy remain on the functional face; treating them as independent callouts can make the last finishing step destroy the dimension it is meant to improve. Inspect entry, exit, taper, straightness, and hole-wall condition after the final surface step. For Beryllium Copper, also account for this material-specific risk: heat-treatment condition and safe downstream handling must be identified.
How the Targets Interact
For Beryllium Copper, ±0.025–0.050 mm and Ra 2.0–3.2 μm are linked through the Small Hole EDM finishing route. Diameter, straightness, wall condition, and breakthrough respond differently to electrode wear and finishing energy. The release plan must bind material condition, geometry, datum, finishing stage, and measurement to the same named features.
Small Hole EDM Capability Reference
| What you're asking | What you can expect |
|---|---|
| Feature types | small through holes, deep holes, angled holes, cooling holes, vent holes, and start holes in hard or heat-resistant alloys |
| Tolerance | ±0.010–0.050 mm |
| Surface finish | Hole-wall finish is feature-dependent |
| Typical diameter | About 0.3–3.0 mm for ordinary planning |
| Depth driver | Depth-to-diameter ratio, straightness, and breakthrough |
| Main limitation | Very small diameter combined with extreme depth may require specialized equipment, staged electrodes, and dedicated metrology. |
Quality Target Reference
| Requirement | Planning range | What it means in practice |
|---|---|---|
| General tolerance | ±0.025–0.050 mm | Use one controlled EDM pass where geometry matters more than close fit. |
| Rough EDM cut finish | Ra 2.0–3.2 μm | Suitable for stock removal and nonfunctional surfaces where cycle time is more important than texture. |
Material Condition Reference
| Condition | What to expect | Watch out for | Surface notes |
|---|---|---|---|
| solution annealed | Use gentle fixturing and adjust energy for high conductivity. | Soft edges can mark or roll under poor support. | Keep contact, bearing, and cosmetic faces as separate finish requirements. |
| cold-worked | Balance work-hardening stress with wear compensation. | Thin sections can move and micro features can round as electrodes wear. | Inspect edge radius and functional texture. |
| age-hardened | Use conservative finishing on hard-drawn or aged stock. | Over-finishing can remove useful texture or shift contact dimensions. | Apply finishing only to functional faces. |
Tolerance & Surface Requirements
For Small Hole EDM at ±0.025–0.050 mm and Ra 2.0–3.2 μm, apply the finish only to the faces named on the drawing. On Beryllium Copper, use gentle fixturing and a finish strategy that protects contact, sealing or heat-transfer surfaces. Roughness does not replace recast, edge, corrosion, crack, or post-process acceptance where those items affect function.
Beryllium Copper Small Hole EDM Quality Checkpoints
- Mark the dimensions that actually need ±0.025–0.050 mm and use the same datum for machining and inspection.
- Circle the faces that need Ra 2.0–3.2 μm; leave nonfunctional surfaces at a practical production finish.
- State the Beryllium Copper condition, Small Hole EDM finishing strategy, measurement method, and any recast or edge requirement.
Limits and Better Alternatives
Main Limit
±0.025–0.050 mm and Ra 2.0–3.2 μm are selected-feature planning references for Beryllium Copper in Small Hole EDM, not unconditional whole-part guarantees.
Consider Another Route When
Use mechanical drilling for accessible easy-cutting material, laser drilling for suitable thin high-volume parts, or Micro EDM for smaller precision features.
Practical Next Step
Send the Beryllium Copper drawing with the Small Hole EDM features that need ±0.025–0.050 mm, the faces that need Ra 2.0–3.2 μm, the supplied condition, quantity, datums, and inspection method.
Practical Takeaway
On Beryllium Copper, plan ±0.025–0.050 mm and Ra 2.0–3.2 μm together for the selected Small Hole EDM features. Use one datum and one inspection plan, and apply the tightest values only where they control function.
Additional Project Information
Include application, destination and end-use notes together with the material, quantity and drawing requirements.
Project Details for Technical Review
Include application and end-use notes when they affect material, inspection, documentation, or export review.
- Process: Small Hole EDM
- Material: Beryllium Copper
- Drawing or part sketch
- Material grade
- Thickness / part size
- Quantity
- Tolerance and critical dimensions
- Surface finish or inspection requirement
STEP/STP, DXF, DWG, PDF, IGS/IGES or ZIP.
Confidential drawing review. NDA support available on request.
Frequently Asked Questions
Can Small Hole EDM hold the selected tolerance on Beryllium Copper?
Use ±0.025–0.050 mm as a selected-feature planning reference. The confirmed result depends on material condition and geometry. Process control covers electrode diameter, true hole depth, depth-to-diameter ratio, tubular-electrode wear, flushing pressure, breakthrough quality, and hole-wall inspection. Machining and inspection should use one consistent datum.
Should Ra 2.0–3.2 μm apply to every surface?
No. Apply the fine finish only to functional faces. Other areas can remain at a practical production finish, which reduces cycle time and avoids unnecessary processing.
How does the condition of Beryllium Copper affect both targets?
Beryllium Copper is age-hardenable copper alloy used for conductive spring and tooling features. The condition changes support, stress response, finishing energy, dimensional stability, and surface-integrity planning.
What should the drawing identify?
Identify the dimensions that need ±0.025–0.050 mm, the faces that need Ra 2.0–3.2 μm, the datums, the exact Beryllium Copper condition, the Small Hole EDM feature, and the inspection method. Machining and inspection should use the same datum scheme.