What to record after a mould change to reproduce a stable process

The mechanical part of a mould change is complete once the tool is installed, connected and ready. Process stabilisation continues: temperatures, flow rates, material condition, control programmes and injection settings must reach a combination that repeatedly produces conforming parts. Much of this work draws on the experience of the people who know the mould.

When that experience is scattered across different records, each new start-up may require earlier decisions to be partly reconstructed. A well-organised technical history distinguishes an approved condition, a provisional adjustment and a deviation requiring investigation.

Identify the reference configuration

The first record should describe the condition to be reproduced. Identify the injection moulding machine, mould revision, number of cavities in use, product, material grade and batch, and auxiliary equipment. Retain the approval date and the person responsible.

Setpoints need to be accompanied by information on auxiliary conditions. The temperature displayed by a controller, for example, represents either a setpoint or a measurement at a specific location; the actual material temperature and the mould’s heat-removal capacity may respond differently.

Record the start-up period

To investigate why one setup reaches stable production sooner than another, establish verifiable milestones: start of preheating, availability of the cooling system, first injection, first conforming part, quality approval and start of sustained production. Consistent time-recording criteria allow the plant to compare equivalent start-ups.

Cell energy measurements also help examine how long heaters, temperature control units, dryers and other auxiliaries operate during preparation. Comparing kWh requires a defined set of measured circuits and normalisation for production conditions. See energy measurement in the injection moulding cell.

Preserve decisions and the reasons for adjustments

The history should state which variable was changed, which symptom prompted the adjustment and how the process responded. Changes to holding pressure, speed, cooling time or mould conditions can affect dimensions, appearance, mass and cycle time in different ways. Measurements and acceptance criteria give these records their value.

Operators’ and technicians’ experience is essential for interpreting what happened. Photographs of defects, setup sequences and instructions reviewed with the team complement the signals acquired from the machine.

Compare results under equivalent conditions

A start-up involving a different resin, ambient temperature or level of cleanliness in the cooling circuit calls for careful interpretation. To assess an improvement, retain the previous condition, contextual differences, observation period and an independent quality check.

Standardisation can begin with one mould that has prolonged start-ups. After several production runs, the team can identify which records were useful and refine the procedure before extending it across the machine fleet.

Information to help build the system

• Machine, mould, product, material and recipe-version identifiers.
• A timeline of preheating, setup, approval and stable production.
• Auxiliary conditions: cooling, drying, material feeding and other services.
• Parameter changes, with the reason, responsible person and observed result.
• Quality evidence and the criteria used to approve production.

PM Tec Engineering, through its Industry 4.0 division, KERN IoP, uses production records and industrial monitoring alongside process engineering to investigate applications of this kind. Read more about preserving the knowledge of operators and technicians and documenting an injection moulding condition.

Related research: The state of digitalisation in plastics-processing SMEs, KERN IoP (2026).