How to Specify Angle Cuts on Ejector Blade Tips
Key Takeaway: Use angle-cut blade tips when the rib has a visible draft angle (≥3°). The blade tip angle should match the rib draft within ±1° to prevent drag marks. Standard angles: 5°, 7°, 10°, 15°.
Why Angle Cuts Are Needed
When a rib has a draft angle, the rib walls are not perpendicular to the ejection direction. A flat-tipped blade contacts the rib base at an angle, creating a shearing force that drags across the part surface during ejection. An angle-cut tip matches the rib geometry, converting the shearing force into a uniform compressive force that ejects cleanly.
Angle Selection Guide
| Rib Draft Angle | Blade Tip Angle | Surface Quality |
|---|---|---|
| 0–2° | Flat grind (no angle needed) | Excellent — no drag risk |
| 3–5° | 5° angle cut | Excellent with angle match |
| 5–10° | 7° or 10° angle cut | Good — match within ±1° |
| 10–15° | 15° angle cut | Good — may need radius transition |
| >15° | Compound angle (special order) | Requires 5-axis CNC machining |