One of the most common reasons for delays and higher costs in wire EDM is a poorly prepared CAD file. The customer sends a file, the shop needs to fix it, the process is delayed and the price goes up. Good news: this is easy to avoid.
⚙️ Why Is the CAD File So Important?
The CAD file is the starting point for the entire wire EDM process. The CAM program in software such as PEPS CAM is generated from it. It defines the cut geometry and directly affects machining time. A bad file means the operator must fix it — increasing cost and lead time. The price difference between a good and bad CAD file can be 30–50%.
📐 Best File Formats
| Format | Use | Rating |
|---|---|---|
| DXF | 2D cutting | ✅ Best choice |
| DWG | 2D design | ✅ Good |
| STEP | 3D models | ✅ For 3D projects |
| — | ❌ Avoid | |
| Photos/Scans | — | ❌ Much more expensive |
🔍 Basic CAD File Preparation Rules
1. Closed Contours
Every element must be closed and continuous. A broken line or unclosed shape means the machine doesn't know where to cut.
2. No Duplicate Lines
Two lines in the same position or overlapping geometry cause double cutting, CAM errors and extended machining time.
3. Only Cut Geometry
Remove from the file: dimension annotations, construction lines, title blocks, text. The file should contain only the contours to be cut.
4. Scale 1:1
The file must be in 1:1 scale. A scale error leads to incorrect quotes and rework before production.
5. Units in Millimetres
Always work in millimetres and state this when submitting. Avoids mm/inch conversion confusion.
❌ Common Customer Mistakes
- Sending a PDF instead of CAD — the shop must recreate the geometry from scratch
- Incomplete drawing — missing critical dimensions or tolerances
- Overly complex geometry — unnecessary detail increases cost
- Missing technical information — material, thickness, quantity
💰 Impact on Cost
- Customer A sends a ready DXF with closed contours → production starts immediately → lower cost
- Customer B sends a photo of a part → shop creates CAD, checks geometry → cost higher by hundreds of £/$
🔧 How to Optimise for Wire EDM
- Simplify geometry — fewer arcs and details = shorter cut = lower cost
- Avoid sudden direction changes — the machine slows down at sharp transitions
- Match tolerance to requirements — ±0.01 mm is often perfectly adequate
- Consult before sending — a good EDM provider will advise on optimisation before production starts