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PU foaming machine failure and troubleshooting

Source: │ Datetime:2020-03-17

Weihua Machinery summarized the common faults and causes of 11 PU foaming machines in operation, and the corresponding troubleshooting methods have been listed. According to these guidelines,Prepare for your productivity.


pu foaming machine picture


Symptom: Pressure controller automatically jumps
Reasons and solutions for pressure controller automatic trip failure:
1. Stock solution has low temperature and high viscosity.
1. Increase the temperature of the stock solution, or start at a low speed, and then gradually increase the speed
2. The return line is blocked
2.Remove the dirt and impurities in the return line
3. Low preset pressure of pressure controller
3. Correct the preset pressure of the pressure controller

Symptom: The flow is unstable, and the original solution contains small bubbles, which can not reach the specified flow and pressure (or unstable).
Causes and solutions:
1. The feed line is leaking and the original solution contains small bubbles
1. Tighten the inlet and outlet pipes to make them sealed
2.The joint surface of the pump is not sealed or the gap between the shaft end face and the swing ring is too large.
2. Adjust the gap between the pump base and the pump body, such as: the front and rear covers and the cushion of the pump body
3. The inlet and outlet pipelines are blocked
3. Clean up and unblock the delivery and discharge pipelines
4.The pump wears a lot
4. Replace with new pump
4. Air leakage from the return pipe

Symptom: The temperature rises too high when the metering pump is running
Causes and solutions:
1.Feed line valve is not open
1. Open the feed line valve
2. Stock solution contains coagulum
2. Strengthen the original liquid filtration
3. Shaft end gland seal is too tight
3. Correctly adjust the sealing gland

Symptom: No material comes out when starting the injection switch
Causes and solutions:
1. No compressed air or insufficient pressure
1.Air pressure reaches 4-6.5kg / cm2
2. The solenoid valve is not energized or the solenoid valve is damaged
2. Connect the power supply and replace the solenoid valve with a new one if it is damaged.
3. Lack of oil in the cylinder, causing excessive friction between the plunger and the cylinder
3. Refuel the oil mister
4. The plunger is solidified by the residual liquid
4. Remove coagulum and refuel

Symptom: No cleaning and blowing
Causes and solutions:
1. The solenoid valve is not energized or damaged
1. Connect the power supply and replace the solenoid valve with a new one if it is damaged
2. No compressed air or insufficient pressure
2. Increase air pressure
3. Solenoid valve or cleaning blocked
3.Clean the solenoid valve or cleaning valve and strengthen the filtering

Symptom: Injection timing relay fails or cannot work
Causes and solutions:
1. Press the terminal loose
1. Fasten the terminal
2. Internal parts are damaged
2. Replace with a new relay
3.Reflow timer failure
3.Troubleshoot the timer

Failure phenomenon: the raw material foaming time is too fast, the mixer jacket is overheated (except for the formula), and the mixing is uneven
Causes and solutions:
1. Stirrer or stirring jacket has too much solidified matter
Remove coagulum
2.The installation position of the stirrer and jacket is incorrect
2. Adjust the installation position of the blender jacket
3.Motor reverse
3. Correct the motor steering
4. Unbalance of backflow and injection pressure
4. Adjust the raw material pressure to make it balanced
5. The motor belt slips, or the stirring shaft is solidified by foaming liquid
5. Tighten the motor belt or replace the belt with a new one to clear the stirring solidified matter, refuel and seal

Symptoms: The product is partially foamed unevenly, and some raw materials (isocyanates) are not completely reacted.
Causes and solutions:
1. A, B, C three-component blanking line speed imbalance (not simultaneous blanking)
1. Adjust the injection plug and gear to make the line speed equal (A, B, C blanks at the same time)
2.A and B component ratios are different
2. When measuring the ratio, the two components A and B must be the same

Failure phenomenon: unbalanced backflow pressure of raw liquid and injection pressure
Causes and solutions:
1. Stock solution pipeline is blocked
1.Clean the dirt in the original liquid pipeline to make the pipeline unobstructed
2.The discharge hole is blocked
2. Remove the solidified material
3. The diameter of the discharge hole is too large or too small
3. Adjust the diameter of the discharge hole until the pressure is balanced
4.Plunger shift
4. Adjust the plunger to the correct position

Symptom: Unstable proportion of stock solution
Causes and solutions:
1.The speed of the speed control motor is unstable
1. Repair the speed regulating motor to make it stable
2. The pipeline is blocked
2. Dredge the original liquid pipeline
3. The timing of the injection timing relay is inaccurate
3. Replace the timing relay

Failure phenomenon: leaking material of metering pump shaft oil seal
Causes and solutions:
1. Oil seal wear and aging
1. Replace oil seal or fill with sealing material
2. The oil return pipe is blocked or not connected
2. Dredge or connect the oil return pipeline

If the above 11 common faults still do not solve your problem, you can consider the PU foaming machine of Weihua Machinery. The PU foaming machine we designed has its own patent, stable performance, less maintenance, and Weihua Machinery is all The products are provided with product description guidance to eliminate difficulties for you.


tags: PU foaming machine failure, PU foaming machine troubleshooting method, PU foaming machine design.
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