A mould that runs three shifts a day wears far faster than one that runs once a month. That is why calendar-based maintenance rarely fits moulds. The better measure is the number of shots, because wear on vents, ejectors, slides and parting lines follows the number of cycles.
What shot-based maintenance means
Each mould gets one or more maintenance intervals measured in shots, for example a light check, a full clean and a major overhaul. When the mould's shot count reaches the next interval, maintenance falls due, wherever the mould has been running.
Step 1: Build a mould register
For every mould, record its number, the parts it makes, the number of cavities, the standard cycle time, the machines it fits and its current shot count. If you do not know the current count, start from an estimate and correct it at the next overhaul.
Step 2: Set intervals with your toolroom
Intervals depend on the mould's construction, the material being molded and its history. Glass-filled or abrasive materials wear moulds faster; simple moulds need less frequent attention. Start with your toolroom's experience and adjust using the breakdown history you collect.
Step 3: Count shots from production, not by hand
The shot count should build up automatically from production entries or machine counters. Counting by hand on a card fails as soon as a mould moves between machines. When every production entry adds to the mould's count, the due date is always current.
Step 4: Record what was done
For each maintenance job, record the date, the shot count, what was done, the spares used and who did it. Over time, this history shows which moulds cause the most breakdowns and rejects, and where to invest in repairs or new tools.
Step 5: Link maintenance to quality
Flash, short shots and dimensional drift are often the first signs of wear. When rejects are booked by defect type against the mould, a rising reject rate becomes an early warning that maintenance is due.
What you gain
- Fewer unplanned mould breakdowns in the middle of an urgent order
- Fewer rejects caused by worn moulds
- A clear record of each mould's life and cost
- Better planning, because maintenance downtime is known in advance
What to check at each level
- Light check: clean vents and parting lines, check water channels for leaks, lubricate ejectors and slides, look for flash or damage on the parts.
- Full clean: take the mould off the machine, strip the moving parts, clean and inspect for wear, replace worn springs, seals and O-rings.
- Overhaul: repair or replace worn inserts, ejector pins and slides, re-check critical dimensions with first-off parts after re-assembly.
Keep the right spares
A maintenance plan fails if the spare parts are not available. Keep a list of critical spares for each mould, such as ejector pins, springs, seals and heater parts, record their use against the mould, and set reorder levels for the ones that wear out regularly.
Store moulds properly
Moulds that are not running still need care. Clean, dry and protect cavities before storage, record where each mould is kept and its shot count, and attach the last first-off approval so it can be set up quickly next time.
In Formezy, every shot booked in production adds to the mould's shot count, and preventive maintenance can fall due by shots or by date. See injection molding ERP or the molding process flows.
