Field note — toolroom
The die cavity job started breaking brass wire every forty minutes. Power and offset were unchanged. The upper guide had ovalized 0.04 mm and the dielectric filter ΔP was ignored for two shifts. Flush starved the kerf; tension hunted; the wire snapped where the cut needed precision most.
Wire EDM owns stable electrode geometry in a clean dielectric, not “auto wire” hope. Breakage is a process signal: diameter, tension, guide condition, and flush volume must stay in the qualification window.
Before you raise power or slow the cut
- Measure used wire diameter vs. spool certificate; mixed lots are MoC.
- Inspect upper and lower guides for oval wear and scoring.
- Confirm dielectric conductivity and filter ΔP against the recipe, not last week’s “looks fine.”
Rule
No overnight unattended run after three breaks in one setup without a signed root cause—guide, flush, or lot. Scraping another spool without fixing flush buys hours, not dies.