New mold trial (T1) checklist: before mounting, on the machine, and afterward

The first trial (T1) is often the most expensive hour: the machine, operator, toolmaker and material all wait together. Preparation shortens this significantly.

1. Before mounting the mold

• Machine compatibility: Mold dimensions, tie-bar spacing, closed height, opening stroke, locating ring and nozzle radius.
• Tonnage and shot size: Is the required clamping force below the machine's capacity? Is the shot volume in a suitable range? (Clamping force calculation)
• Water circuits: Number of circuits, connection order, inlet/outlet markings, leaks. Pressure-test with water and visually confirm each circuit flows.
• Hot runner: Check heaters, thermocouples and cabling; heating up must be done in stages, and allow time for moisture to clear.
• Mold cleaning and lubrication: Remove rust-preventive oil, lubricate sliding surfaces.
• Raw material: Correct grade, drying complete, suitable dew point.

2. First steps on the machine

1. Set mold protection values to high safety (low speed, low force).
2. Open/close slowly at first; visually confirm no moving parts collide.
3. Set the hot runner and mold temperature and wait long enough.
4. Start with short shots (50%-75%-90%) and observe the fill balance; don't apply holding pressure on the very first shot.
5. Once filling is complete, set up the V/P changeover, then holding and cooling.

3. What to record

• Machine and screw diameter, nozzle, dosage, cushion, V/P changeover, speed profile, pressure limit.
• Melt temperature (measured with a probe), mold surface temperature, water temperature and flow rate.
• Fill time, holding, cooling, total cycle, part weight.
• Photos: The short-shot series and any defects.

4. After the trial

• Measurement report (critical dimensions, warpage, shrinkage).
• Defect list: location, type, probable cause; as a clear work order for the toolmaker.
• Mold cleaning, protective oil, storage.
• Print out the process sheet (set sheet) and add it to the mold's file. This is the starting point for the next production run.

Common mistakes

• Running the hot runner without waiting long enough (splattering if moisture is present).
• Trying full fill and holding in one go on the first trial, straining the mold and material.
• Making adjustments one after another without writing down what was changed.

Note: The list in this article is a general template. Combine it with the mold maker's instructions for your mold's specific requirements (hydraulic cores, valve gates, sliding parts).

The calculation tool helps you prepare tonnage, shot size and starting values before T1.