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Three steps of injection molding machine adjustment

October 19,2022

In fact, the maintenance of injection molding machineis hard, but it is a process of continuous learning and progress.

 As long as you master the basic working principle and methods of injection molding machine, no matter what type of machine, you can explore a set of maintenance procedures to ensure the normal operation of injection molding machine.
Maintenance workers must first understand and master the contents of the operating instructions of the injection molding machine, the mechanical parts, circuits and oil circuits of the injection molding machine, the working process of the machinery, circuits and oil circuits of the injection molding machine in normal operation, and the inspection and maintenance methods of electrical components and hydraulic components. Clear the normal working state and abnormal working state, so as to avoid false judgment and false disassembly when free of charge.
So how to adjust the injection molding machine? How many steps are there?

The following Kejun Machinery will share with you the three steps of adjusting the injection molding machine:

First, confirm and prepare setting parameters before setting parameters.
1. Confirm whether the material drying, mold temperature and heating cylinder temperature are set correctly and can be processed.
2. Check the action and distance setting of opening and closing die and ejection.
3. The injection pressure (P1) is set at 60% of the maximum value.
4. Keep the pressure (PH) set at 30% of the maximum value.
5. The injection speed (V1) is set at 40% of the maximum value.
6. Screw speed (VS) is set at about 60RPM.
7. Back pressure (PB) is set at about 10kg/cm2.
8. Set the loosening and withdrawal at 3mm.
9. The position of pressure maintaining switch is set at 30% of the screw diameter. For example, a screw with a diameter of φ100mm is set to 30 mm..
10. Set the metering stroke slightly shorter than the calculated value.
1. Set the total injection time slightly shorter and the cooling time slightly longer.
Second, manual operation parameter correction
1. Lock the mold (confirm the rise of high pressure), and advance the ejection seat.
2. Shoot manually until the screw stops completely, and pay attention to the stop position.
3. Screw back feeding.
4. After cooling, open the mold and take out the molded product.
5. Repeat the steps (1) to (4) until the screw finally stops at 10% to 20% of the screw diameter, and the molded product has no short shot, burrs, whitening or cracking.
Third, the correction of semi-automatic operation parameters
1. Correction of metering stroke [metering end point] Increase the injection pressure to 99%, temporarily adjust the pressure holding to 0, adjust the metering end point S0 forward to the occurrence of short shot, and then adjust it backward to the occurrence of burrs, with the middle point as the selected position.
2. Correction of ejection speed: Return the PH to the original level, adjust the ejection speed up and down, find out the individual speed of short shot and burrs, and take the middle point as the appropriate speed [at this stage, you can also enter the parameter setting of multi-stage speed corresponding to appearance problems].
3. Correction of the holding pressure. Adjust the holding pressure up and down to find out the individual pressure of surface depression and burrs, and choose the middle point as the pressure maintaining.
4. Amend the holding time [or injection time] to gradually extend the holding time until the weight of the molded product is obviously stable.
5. Correction of cooling time. Gradually reduce the cooling time, and confirm that the following conditions can be met:
(1) The molded product will not be whitened, cracked or deformed when ejected, clipped out, trimmed and packaged.
(2) The mold temperature can be balanced and stable. A simple algorithm for cooling time of meat products with thickness over 4mm;
(3) Theoretical cooling time = s (1+2s) …… The mold temperature is below 60 degrees.
(4) Theoretical cooling time =1.3S(1+2S)……. The mold is above 60 degrees [S represents the maximum meat thickness of the molded product].
6. Modification of plasticizing parameters
(1) Confirm whether the back pressure needs to be adjusted;
(2) Adjust the screw speed so that the metering time is slightly shorter than the cooling time;
(3) Confirm whether the metering time is stable, and try to adjust the temperature gradient of the heating ring.
(4) Confirm whether there is dripping in the nozzle, pig tail or mold sticking in the main runner, and whether there is air mark in the finished product, and appropriately adjust the temperature of the nozzle or the loosening distance.
7. Multi-stage pressure keeping and flexible use of multi-stage firing rate
(1) Generally speaking, under the condition that the appearance is not affected, the injection should be carried out at a high speed, but it should be carried out at a lower speed before switching between gates and maintaining pressure;
(2) The pressure maintaining should be gradually reduced to avoid that the internal stress residue of the molded product is too high and the molded product is easy to deform.