In the injection molding production of the refrigerator industry, mold replacement and debugging are key links to ensure product quality and production efficiency. This article will take the refrigerator mold as an example to introduce the full process debugging steps from mechanical action, process parameters to safety protection after the injection molding machine mold change is completed, helping operators quickly enter a stable production state.
1. Mould replacement confirmation content
Before starting debugging, first confirm whether the following mold change preparations are completed:
- The mold positioning and installation is completed, and the mold bolts have been tightened;
- Connect the cooling water pipe and let water flow through it to make sure the water path is unobstructed;
- The hot runner wiring is correct and the temperature control equipment is working properly;
- The ejector system is connected correctly and moves flexibly;
- The mold limit switch, electric eye and air pipe are connected intact;
- The production raw materials are adequately prepared and the drying temperature meets the standards;
- The electronic control system and hydraulic system of the injection molding machine operate stably without any alarm.
2. Initial mold adjustment and clamping force setting
1. Manually check the mold opening and closing action
Use manual operation to fully open the mold and slowly close it to make sure there is no interference or jamming. If there is any abnormality, check the mold gap or guide column lubrication immediately.
2. Start automatic adjustment of mold thickness
- Start the mold thickness adjustment function and appropriately reduce the mold thickness until preload is generated ;
- At this point, the clamping toggle system should begin to react and generate initial clamping force;
- Determine the clamping cylinder pressure by observing the clamping pressure gauge. The higher the pressure, the greater the final clamping force.
- Press the “Mold Thickness Return” button to adjust the mold back by more than 5mm, and then perform the complete mold closing action to ensure that the clamping elbow can be fully extended. At this time, there should be a slight gap between the movable template and the fixed template , and they should not be completely fitted to protect the precise structure of the mold.
3. Set up mold locking protection
- Adjust the low-pressure clamping stroke and pressure;
- Set the mold opening and closing limit positions;
- Verify whether the low-voltage protection is effective to prevent foreign matter from getting stuck in the mold and causing damage to the equipment.
3. Injection molding parameter setting and adjustment
After the mold action is debugged correctly, the injection process can be debugged:
1. Barrel temperature adjustment
Confirm that the temperature of each section of the screw meets the process requirements, and set the drying and barrel temperatures according to the type of plastic (such as HIPS, ABS, PP, etc.). For example:
- The temperature of HIPS refrigerator liner is generally set at 180–220°C;
- If flame retardant materials or two-component raw materials are used, the temperature of the latter stage should be appropriately increased to ensure fluidity.
2. Residue removal and pre-injection
- Completely eject the remaining plastic in the barrel;
- Check whether the material is discharged evenly and has a bright surface, and confirm that the melt is stable;
- Start the mold test with low pressure and low speed injection to observe whether the mold filling is smooth and avoid short shots and air marks.
3. Parameter fine-tuning (including the following contents)
- Injection speed and pressure : gradually increase until the mold is fully filled without short shots;
- Holding time and pressure : Adjust according to the shrinkage degree of the product to avoid shrinkage and deformation;
- Cooling time : set according to mold temperature and product thickness to prevent mold release deformation;
- Mould opening and closing speed : control it within a reasonable range to prevent mould collision and demoulding impact;
- Screw back pressure and metering stroke : ensure uniform plasticization of plastic and prevent air inclusion.
4. Product trial and confirmation before mass production
- Trial production of the first piece to check whether the size, flatness, screw hole positioning, etc. meet the refrigerator product standards;
- Confirm that the product has no flash, no welding marks, no bubbles, and no shrinkage;
- Check whether the ejector system ejects smoothly and whether demoulding does not damage the product surface;
- Adjust the mold temperature controller parameters to keep the mold temperature stable;
- After the product has been running stably for 30 minutes, the process parameters are fine-tuned for a second time and the final parameters are saved and archived.
5. Summary of Precautions
- After the mold is replaced, the water, electricity, gas, signal and other systems must be verified one by one;
- If the clamping force is set too high, it will cause damage to the mold, and if it is set too low, the product will flash. It must be adjusted accurately.
- Refrigerator liner products have a large structure, so the injection process needs to prevent defects such as shrinkage and corner collapse;
- Each mold is recommended to have standard debugging parameters to reduce the machine adjustment time;
- If the mold has automatic core pulling, cylinder or electric slider, its stroke, limit and protection devices should be tested separately to see if they are normal.
If you are using large molds such as refrigerator door or back panel, it is recommended that you pay more attention to key factors such as template parallelism, mold opening stroke buffer, core pulling timing control, etc. during the debugging process to avoid early damage to the mold and defective product batches.
If you need mold modification, process support or injection molding machine joint debugging services, please feel free to contact us. We have rich experience in refrigerator mold debugging and mass production, and can help you put into production quickly and stably.