How to solve 16 faults of plasticizing unit of injection molding machine?

Time:2023-03-09 10:37:20 / Popularity: / Source:

1, can not shoot glue

Nozzle is blocked by a foreign object. Check whether nozzle is blocked, clean or replace nozzle.
Glue nozzle is broken. Disassemble flange to check whether glue nozzle is broken, and replace glue nozzle.
Injection direction valve is stuck. Check whether directional valve has 24V voltage, and coil resistance is 15-20 ohms. If it is normal, valve is blocked. Clean valve or replace directional valve.
Injection piston rod is broken. Loosen tight nut of injection piston rod, check whether piston rod is broken, and replace piston rod.
Barrel temperature is too low. Check whether actual temperature reaches melting point temperature required for material, and reset barrel temperature.
Injection piston oil seal is damaged. Check whether piston oil seal is damaged and replace oil seal.
plasticizing unit 

2. sound of plastic injection is loud at the start

injection speed starts too fast. Observe change in starting speed of injection speed, and adjust injection flow rate.
There is air in oil circuit. Observe whether there is vibration in each action.

3. sound is loud when plastic injection is terminated and melt is transferred.

Action transition speed is too fast when shooting glue. Check whether injection glue has increased holding pressure, increase holding pressure, adjust injection series, and add melting time delay.

4. Amount of glue injection is unstable

Cylinder oil seal is worn. Observe pressure retention of pressure gauge and replace oil seal.
Rubber nozzle and rubber ring are worn. Detected with 2 injections of glue, replace three-piece glue dispensing nozzle.
Barrel worn. Use 2 nozzles to detect, disassemble material to check wear and tear, and replace glue barrel.

5. Semi-automatic without glue injection.

Advance of launcher is not terminated. Check whether travel switch in front of injection table or mold clamping is normal, check circuit and travel switch.
Disconnected. Check wiring and rewire.
Clamp to zero. When hinge is straight, position is 0, and zero position of electronic ruler is re-adjusted.

6. During semi/automatic operation, barrel temperature gradually exceeds set value.

Melt speed is too fast. Use a tachometer to test whether screw speed is too fast and reduce melt speed.
Excessive back pressure. Observe product, back pressure gauge value, and reduce back pressure as much as possible.
Screw and barrel friction. Remove screw and barrel, check wear condition, and replace barrel or screw.
Improper temperature setting. Check whether actual temperature is too low, and reset temperature.
Plastic is subjected to excessive shear heat. Check temperature rise in the front section and middle section, reduce melt speed and back pressure.

7. Screw sounds when glue is melted

Improperly installed drive shaft. Separate screw rotation to check if there is any sound, if so, remove plane bearing and reassemble it.
Plane bearing is bad. Separate screw to check if there is noise in rotating part, then replace plane bearing.
Screw is bent. Remove screw for inspection and replace screw.
Screw has iron filings. Disassemble screw for inspection and clean screw.
Check coaxiality of adjusting screw with a dial indicator. Beating of about 0.05mm is normal.

8, can not melt glue

Burnt bearing or drive shaft burst. Separate screw, re-melt glue and observe sound, and replace bearing.
Screw has iron filings. Separate screw and barrel, check whether screw has iron filings, and remove screw for cleaning.
Melt valve is clogged. Use hexagonal key to top valve core to see if it moves, and clean solenoid valve.
Melter motor is damaged. Separate melter motor, replace or repair melter motor when melter does not turn.
Burn out heating coil. Use a multimeter to check whether it is normal and replace heating coil.
Plug is loose. Check whether plug made of melt glue oil is in poor contact, connect plug tightly, and check whether there is a 24 power supply.
plasticizing unit 

9. Back pressure cannot be adjusted when melting glue

Defective back pressure valve. Increase back pressure of blanking material, check whether screw is backward, and clean back pressure valve.

10. Product has black spots

Screw has carbon deposits. Check, clean screw and barrel.
There is carbon deposit in barrel and auxiliary machine is not clean. Check feeder for dust, polish barrel and clean auxiliary machine.
Nozzle assembly is corroded. Check dispensing nozzle and replace dispensing nozzle assembly.
Flange and nozzle have carbon deposits. Clean up and replace.
Raw materials are not clean. Check raw materials, replace raw materials.
Temperature is too high, and back pressure of melt adhesive is too large. Check temperature of each section, cool down and reduce back pressure.

11. Poor color mixing of screw

Material issue. Check toner quality and replace material.
Temperature is too low. Check actual temperature and required temperature of material, and increase temperature.
Back pressure is too low, check back pressure and increase back pressure.
Mixing time is short. Extend mixing time or replace mixing head.
Speed is too low. Check screw speed and increase screw speed.

12. No glue pumping action

Great back pressure. Check spraying speed of nozzle when manually melting glue, and reduce back pressure.
Disconnected. Glue valve is disconnected.
Directional valve spool is not flexible. Press spool with an Allen wrench to check if it moves freely, and clean spool.

13. When glue is melted, motor swings the tail

Bad bearing. Observe whether there is any abnormal sound when glue is melted, and replace bearing.
Improper adjustment of inclined ball bearing. Observe whether drive shaft oscillates and re-adjust clearance.
Screw deformation. Separate screw to observe rotation of drive shaft and replace screw.
Copper sleeve of rear plate of injection table is worn, and two guide rods are deformed or fixing screws are loose. Observe whether copper powder is ground out of copper sleeve of second plate, and replace copper sleeve.

14. Glue shot twice

Aperture of nozzle is too small, and resistance is too large when glue is injected.
Heating ring of nozzle is damaged, check heating ring or replace it.
Check whether pressure flow output is switched off.

15. Reasons for screw breakage

Shot shift is not synchronized, adjust shot shift synchronization ±0.05
Injection cylinder is not synchronized, adjust synchronization of injection cylinder ±0.05
Raw material does not match performance of screw of injection molding machine.
Temperature did not reach melting point of material used.
Wait until temperature is just reached before turning screw.
If heating tube is burned out and does not heat, check whether there is an anti-cold function, and replace heating tube.

16, can not adjust mold

Mechanical level and parallelism are out of tolerance. Check with a spirit level and angle ruler to adjust parallelism and level.
Gap between pressure plate and die-adjusting nut is too small. Measure with a feeler gauge, adjust gap between pressure plate and nut, adjust gap between die nut and pressure plate (gap ≤ 0.05mm).
Burn nut to check whether nut can be rotated and whether there is iron powder coming out. Replace nuts.
Adjustment of upper and lower support plates. Remove lock nut of standoff to check and adjust adjusting nut.
I/O board is broken. Check whether there is a signal at output point on computer page, and repair electronic board.
Mold adjusting valve core is stuck. Remove the valve for inspection and clean the valve.
Mold adjusting motor is broken. Check the oil motor. Replace or repair oil motor.

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