Three steps of adjusting injection molding machine

In fact, the maintenance of the injection molding machine is difficult, but it is also a process of continuous learning and enterprising. As long as we master the basic working principle and basic working methods of the injection molding machine, we can explore a set of maintenance procedures to ensure the normal operation of the injection molding machine, regardless of various models.  

Maintenance workers must first understand and master the contents of the operation manual of the injection molding machine, be familiar with and master the mechanical parts, circuits and oil circuits of the injection molding machine, understand the working process of the machinery, circuits and oil circuits of the injection molding machine during normal operation, and understand and master the inspection, maintenance and use methods of electrical components and hydraulic components. Know the normal working state and abnormal working state, so as to avoid false judgment and false disassembly.  

So how to adjust the injection molding machine? How many steps are there? Let’s share the three steps of adjusting the injection molding machine:

1、 Before setting parameters, confirm and prepare to set parameters   

1. Confirm whether the material drying, mold temperature and heating cylinder temperature are correctly set 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. The back pressure (PB) is set at about 10kg / cm2.   

8. Set the release to 3mm.   

9. The position of pressure maintaining switching is set at 30% of the screw diameter. for example φ Set 30mm for 100mm screw.    

10. The metering stroke is slightly shorter than the calculated value.   

11. The total injection time is slightly shorter and the cooling time is slightly longer.

2、 Manual operation parameter correction   

1 lock the die (confirm the rise of high pressure) and advance the injection seat.    

2. Inject 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 formed product.   

• Repeat steps (1) to (4) until the screw finally stops at 10% ~ 20% of the screw diameter, and the molded products have no short shot, burr, whitening, or cracking.

3、 Correction of semi-automatic operation parameters   

1. The correction of exit speed restores pH to the original level, adjusts the exit speed up and down, finds out the individual speed of short shot and burr, and takes its middle point as the appropriate speed [in this stage, you can also enter the parameter setting of appearance problems corresponding to multi-stage speed].   

2. the correction of the metering stroke [measurement end point] increases the injection pressure to 99%, and temporarily represses the pressure to 0. The end point S0 is moved forward to short shoot and then transferred back to the burr, with the middle point as the selection.   

3. Correction of pressure holding time [or injection time] and gradually extend the holding time until the weight of molded products is obviously stable, which is an appropriate choice.   

4. Correction of holding pressure, adjust the holding pressure up and down, find out the individual pressure with surface depression and burr, and select the middle point as the pressure holding point.    

5. Revise the cooling time, gradually reduce the cooling time, and confirm that the following conditions can be met:

(1) Molded products will not whiten, bulge or deform when they are ejected, clamped, trimmed and packaged.

(2) The mold temperature can be balanced and stable. Simple algorithm for cooling time of products with meat thickness of more than 4mm:     

(3) Theoretical cooling time = s (1 + 2S)…… mold temperature below 60 ℃.   

(4) Theoretical cooling time = 1.3s (1 + 2S)…… the mold is more than 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 to make the metering time slightly shorter than the cooling time;   

(3) Confirm whether the metering time is stable, and try to adjust the gradient of heating ring temperature.   

(4) Confirm whether there is dripping at the nozzle, whether pig tail or die sticking occurs in the main channel, and whether the finished product has air marks, and properly adjust the temperature or loosening distance of the nozzle.   

7. Multi-stage pressure maintaining and flexible use of multi-stage firing rate   

(1) Generally speaking, the injection shall be carried out at a high speed without affecting the appearance, but at a lower speed before passing through the gate and pressure maintaining switching;     

(2) The pressure shall be gradually reduced to avoid too high residual stress in the molded products and easy deformation of the molded products.