Why this matters
Every hour of job change is an hour of lost production, and a poorly-executed changeover costs double — time during, plus scrap after. In most plants we visit, changeovers take 14–18 hours. The best run under six. That gap — eight to twelve hours per changeover, forty to eighty times a year per line — is usually the single largest pool of accessible productivity in the plant.
SMED, adapted for glass
Single-Minute Exchange of Die comes from stamping, not glass. Direct application does not survive first contact with a forming machine. But the core disciplines translate:
- Separate internal from external work. What must happen while the machine is down, versus what can happen while it is still running?
- Convert internal to external where possible. Mould prep, blank staging, forehearth setpoint reviews — all external if you pre-stage them.
- Streamline whatever remains internal. Parallel activity, choreographed sequencing, standard tool positions.
The choreography
A six-hour changeover is not one team racing. It is three to five roles running in parallel, handing off at specific moments, with a shared timeline everyone can see. We map it like a recipe:
- T-60 to T-0 (running): External prep — moulds staged, blanks prepped, forehearth setpoints pre-calculated, crew briefed.
- T0 to T+30 (shutdown): Controlled ramp-down, section isolation, heat-up cycle started for incoming moulds.
- T+30 to T+180: Parallel execution — mould swap, blank swap, forehearth re-tune, inspection setup reconfigured.
- T+180 to T+300: Restart ramp, first gob, first-hour yield monitoring.
- T+300 to T+360: Stabilisation and handover to production.
First-hour yield: the forgotten KPI
A fast changeover that produces scrap is not a win. We treat first-hour yield with the same discipline as minutes-to-complete. Two habits stick the most:
- First-hour target on the huddle board. If the crew cannot see it, they cannot own it.
- Defect coding in the first 20 minutes. Most defects after a changeover fall into 3–4 categories. Code them, track them, pareto them — you fix a different changeover each time.
The changeover standard that lasts
A bound PDF of the standard is dead on arrival. What lasts:
- A one-page visual timeline in the control room and the forming corridor.
- Role cards laminated at each station — two or three bullets per role per phase.
- A digital version (we build one; it is our Job Change Tool) that progresses live with the actual changeover.
Where to start
Do not start with the standard. Start with a video study of two or three changeovers. The improvement opportunities will name themselves. Draft a standard. Pilot it once. Adjust. Pilot it again. Only when you have two clean runs do you codify it — and even then, every crew's first run is a learning, not a failure.
What a typical engagement looks like
A typical changeover engagement runs 8–14 weeks: two weeks of video study and analysis, two weeks of standard drafting with the crews, six to ten weeks of piloted execution and iteration. By week 14, the plant has a written standard, a dashboard, and at least ten changeovers at the new target.