When our customers receive a new plastic mold to be proofed, they are always eager to try out a result earlier, pray for a smooth process to avoid wasting man-hours and causing confusion. Following are the tep-by-step guides on how to conduct a plastic mold trial.
1. Pre-Trial Preparation
● Review Mold Design & Specifications
Check the mold drawings, material selection, and part design (shrinkage, draft angles, etc.).
Confirm gate location, cooling channels, and ejection system.
● Inspect the Mold
Ensure the mold is clean and free of damage.
Verify that all moving parts (ejector pins, sliders, cores) function smoothly.
● Select the Right Machine
Match the mold size and tonnage requirements with the injection molding machine.
Ensure the machine’s shot capacity, clamping force, and plasticizing rate are suitable.
● Prepare Material
Dry the plastic resin if necessary (e.g., nylon, PET).
Set the correct melt temperature based on material specs.
2. Mold Installation
● Mount the Mold
Secure the mold onto the machine’s platens and align it properly.
Connect cooling lines and ensure no leaks.
● Set Up Process Parameters
Input initial settings (temperature, injection speed/pressure, cooling time, etc.).
Use recommended settings from the material supplier or previous trials.
3. Initial Trial Run (Short Shot Test)
● Perform a Short Shot
Inject a small amount of plastic to check flow behavior.
Identify flow marks, air traps, or filling imbalances.
● Adjust Parameters
Increase injection speed/pressure if the part doesn't fill completely.
Modify temperature settings if there are flow issues.
4. Full Injection & Process Optimization
● Run Full Cycles
Produce complete parts and check for defects (sink marks, warping, flash, etc.).
Adjust packing pressure and cooling time to minimize shrinkage.
● Optimize Ejection
Ensure parts eject smoothly without sticking or damage.
Adjust ejection speed, force, or add release agents if needed.
● Check Dimensional Accuracy
Measure critical dimensions against CAD specs.
Compensate for shrinkage by fine-tuning mold temperature or holding pressure.
5. Defect Troubleshooting

Defect	Possible Cause	Solution
Short Shots	Low injection pressure/speed, cold mold	Increase pressure/speed, raise mold temp
Flash	Excessive clamping force, over packing	Reduce injection pressure, check mold alignment
Sink Marks	Insufficient cooling/packing	Increase packing pressure, extend cooling time
Warping	Uneven cooling, high stress	Optimize cooling channels, reduce melt temp
Jetting	High injection speed	Reduce speed, modify gate design

6. Final Validation
● Run Stability Tests
Produce multiple batches to ensure consistency.
Monitor cycle time and part quality over extended runs.
● Document Settings
Record optimal machine parameters for future production.
Note any mold modifications needed (e.g., venting, gate adjustments).
● Customer Approval
Submit samples for approval before mass production.
7. Post-Trial Mold Maintenance
● Clean and lubricate the mold.
● Address any wear or damage observed during the trial.
SOMETOOL Team with about 60 experienced engineers, technicians and toolmakers are dedicated to pursuing customer satisfaction, if you need custom plastic mold, please contact us for your owm mold design and trial.