Common problems and solutions of injection molding machines and molds

1、 Common problems of injection molding machine

1. No mold locking

① Check and repair the travel switch in front of the safety door.

② Check the 24v5a power supply in the electric box, replace the fuse and power box.

③ Check whether the valve element is stuck and clean the valve element.

④ Check whether the I / O board has output and whether the solenoid valve is charged.

⑤ Check whether the hydraulic safety switch is pressed and whether the mechanical lock lever baffle is opened.

2. The opening and closing machine is twisted

① Check whether the lubricating oil pipe is disconnected. If so, reconnect the oil pipe.

② The amount of lubricating oil is small, so it is recommended to increase the amount of lubricating oil. It is recommended that 50 molds be oiled once or enough lubricating oil be added manually.

③ Large clamping force, check whether the mold needs large clamping force, and adjust the clamping force lower.

④ Adjust the current of the amplifier board, check whether the current parameter meets the acceptance standard, and readjust the current value.

⑤ If the parallelism is out of tolerance, use a dial indicator to check whether the parallelism of the first and second plates is greater than the acceptance standard; Adjust the parallelism.

3. Wait a few seconds before opening the mold

① The starting speed is slow. Check whether the screw damping is too large and adjust the screw damping hole.

② The middle hole of the damping screw is too large. Check whether the damping of the y-hole screw is too large. Replace the damping screw with a thin center hole.

4. Crawling of unlocking die

① . the second plate guide rail and coring column are greatly worn. Check the second plate guide rail and coring column, replace the second plate copper sleeve and coring column, and add lubricating oil.

② The speed and pressure of mold unlocking are not adjusted properly. When the flow is set at 20 and the pressure is 99, the second plate of mold locking should not crawl. Adjust the flow proportional valve hole or pilot valve hole and adjust the linear current value of the proportional valve.

③ There is air in the pipeline and oil cylinder, and exhaust.

5. Unable to open the mold

① Increase the speed of unlocking die, and the pressure flow is too small and not adjusted properly. Check whether the speed and pressure of unlocking die are appropriate, and increase the pressure and speed of unlocking die.

② . the zero position of the electronic ruler of the mold locking is changed. Check whether the mold locking straightening machine ends at the zero position after twisting, and readjust the zero position of the electronic ruler.

③ Check whether the hinge is reversed.

6. Automatic production: the middle note die will become tighter or looser

① The internal leakage of the mode adjusting solenoid valve shall be checked to see if the solenoid valve is of “O” type. Replace the solenoid valve or check whether the solenoid valve is powered with 24V when it is not working. Mold master wechat: mujudaren

② Check whether there is mold adjustment action during manual operation, and check whether the valve is stuck.

7. When other actions work after mold locking, fully automatic and slow mold opening

① . the oil plate leaks. Check or replace the quick clamping valve and replace the oil plate.

② If the mold opening valve leaks, start the oil pump and stop the mold locking. Press the injection table or glue injection action to check whether the second plate moves backward. Replace the mold opening oil valve. Normally, the unlocking die does not move.

8. Only mold opening action during mold locking

① . connect the wrong line, check whether there is 24VDC to the valve, check the line and wiring.

② . if the valve is jammed or the valve element is installed incorrectly, check whether the valve element is installed incorrectly or blocked, reinstall the valve element or clean it. Under normal conditions, the mold unlocking action is immovable.

9. Poor mold locking

① . A and B holes are not adjusted properly. When the system flow is 20 and the pressure is 99, observe whether the mold locking action crawls and readjust or replace the valve.

② There is air in the oil circuit. Listen to the sound of air in the oil circuit, check whether there is air bubble in the oil, and exhaust.

③ Adjust the amplification plate by observing whether the current value of the ammeter is proportional to the rise and fall or the rotation speed.

10. Mold locking can not lift high pressure, exceeding the stroke

① . if the limit switch exceeds the limit, check whether the mold adjustment is appropriate and adjust the appropriate mold thickness; Check whether the motor is in normal condition.

② If the hydraulic limit exceeds the stroke, check whether the stroke position of the electronic ruler is appropriate, check whether the mold adjustment is appropriate, and properly adjust the mold forward.

11. Manual mold opening termination, semi-automatic mold opening termination

① If the mold opening valve leaks, operate after manually striking the injection table. Observe whether the second plate moves backward and replace the mold opening valve.

② Check the maximum stroke and pressure flow of the electronic ruler.

12. No thimble action

① . the limit switch of the thimble is broken. Use a multimeter to check whether the 24V proximity switch is on. Replace the ejector pin limit switch.

② . if the valve is jammed, press the ejector pin with a hexagonal key to check whether the valve element is movable, and clean the pressure valve.

③ . the ejector pin limit lever is broken. After the machine is stopped, take out the limit lever by hand and replace it.

④ . the thimble switch is short circuited. Use a multimeter to check the 0 voltage of the thimble switch to the ground, and replace the thimble switch.

⑤ The position of the electronic ruler is not set properly.

13. The ejector pin is out of control during semi-automatic operation

① The ejector pin plate is broken. Check whether the circuit is normal and the normal voltage is dv24v. Repair the ejector pin plate.

② . the line is disconnected. Comprehensively check the switch connecting line and the connecting line on the I / O board. Check the wiring and reconnect it.

③ Check whether the mold moves.

④ Check whether the sealing ring of cylinder piston rod is damaged.

14. Loud noise during mold opening

① The proportional linearity is poor, and the pressure and flow at the opening and closing time position are poorly adjusted. Check the oblique rise and fall in the parameters and adjust the oblique rise and fall in the parameters.

② The lubrication of the clamping machine hinge is poor. Check the lubrication of the coring column, the sliding foot of the second plate and the machine hinge. Increase the lubrication and the number of oiling.

③ If the mold clamping force is too large, check the mold clamping force when the mold is stressed, and reduce the clamping force according to the product condition. Check whether the time and position are appropriate.

④ The parallelism deviation of the first and second plates shall be checked. Adjust the parallelism error of the second plate and the head plate.

⑤ The setting position of slow to fast mold opening is too small and the speed is too fast. Check whether the position of slow mold opening to fast mold opening is proper and whether the slow mold opening speed is too fast. Lengthen the slow mold opening position and reduce the slow mold opening speed.

15. Semi automatic, with 2 mold locking actions

① . the mold locking valve element is not completely reset. Check whether the next action is too continuous after the mold locking action is completed. Increase the delay time of the next action.
2、 Fault problems and treatment methods of module adjustment

1. Unable to adjust the mold

① The mechanical level and parallelism are out of tolerance. Check with level and angle ruler. Adjust parallelism and level. (for large models, small models have little impact)

② The clearance between the pressing plate and the die adjusting wire is too small. Measure with a feeler gauge. Adjust the clearance between pressing plate and nut, and the clearance between mold adjusting nut and pressing plate (clearance ≤ 0.05m).

③ Burning nut: check whether the nut can rotate and generate heat and whether there is iron powder. Replace the nut.

④ Adjust the upper and lower support plates. Disassemble the locking nut of the support plate for inspection. Adjust the adjusting nut.

⑤ The I / O board is broken. Check whether there is a signal at the output point on the computer page. Repair the electronic board.

⑥ The mold adjusting valve core is stuck. Remove the valve for inspection. Clean the valve.

⑦ The mold adjusting motor is broken: check the oil motor. Replace or repair the oil motor.
3、 Fault problems and treatment methods of injection part

1. No glue injection

① The nozzle is blocked by foreign matters. Check whether the nozzle is blocked. Clean or replace the nozzle.

② The dispensing nozzle is broken. Disassemble the flange and check whether the rubber nozzle is broken. Replace the dispensing nozzle.

③ The glue injection direction valve is stuck. Check whether the directional valve has 24V voltage and coil resistance of 15-20 Ω. If it is normal, the valve is blocked. Clean the valve or replace the directional valve.

④ The rubber injection piston rod is broken. Loosen the nut of rubber injection piston rod and check whether the piston rod is broken. Replace the piston rod.

⑤ The barrel temperature is too low. Check whether the actual temperature reaches the melting point temperature required for the material. Reset the barrel temperature.

⑥ The oil seal of rubber injection piston is damaged. Check whether the piston oil seal is damaged. Replace the oil seal.

2. The starting sound of glue injection is loud

① The glue injection speed starts too fast. Observe the change of starting speed of glue injection. Adjust the glue injection flow and speed.

② There is air in the oil circuit. Observe whether there is vibration in each action.

3. The sound is loud when the glue injection is terminated and the glue is transferred

① : the action conversion speed is too fast during glue injection. Check whether the pressure maintaining is increased for the glue injection. Increase the holding pressure, adjust the number of glue injection stages, and add the delay of melt glue.

4. Unstable glue injection

① The oil seal of oil cylinder is worn. Observe the pressure holding of the pressure gauge. Replace the oil seal.

② The rubber nozzle and rubber ring are worn. Detect with two times of glue injection. Replace the three-piece set of dispensing nozzle.

③ The barrel is worn. Use the two-time nozzle to detect the wear, and then check the wear condition of the material remover. Replace the melt cartridge.

5. Semi automatic no glue injection action

① The advance of the shooting platform is not terminated. Check whether the travel switch in front of the injection table or the mold locking is normal. Check the circuit and travel switch.

② , disconnection. Check the wiring. Rewire.

③ And the mode locking is reset to zero. When the machine hinge is straightened, the position is 0. Readjust the zero position of the electronic ruler.

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

① The speed of glue melting is too fast. Use a tachometer to test whether the screw speed is too fast. Reduce the melt speed.

② The back pressure is too large. Mold master wechat: mujudalen observes the products and the back pressure gauge value to reduce the back pressure as much as possible.

③ Screw and barrel friction. Remove the screw and barrel and check the wear. Replace the barrel or screw.

④ Improper temperature setting. Check whether the actual temperature is too low. Reset the temperature.

⑤ The shearing heat of plastic is too large. Check the temperature rise of the front and middle sections. Reduce the rotation speed and back pressure of the melt adhesive.

7. Screw rings when glue is melted

① The transmission shaft is installed improperly. Separate the screw and check whether there is any sound. If so, remove the plane bearing. Reassemble.

② The plane bearing is damaged. Separate the screw and check the rotating part for noise. Replace the flat bearing.

③ Screw bending. Remove the screw for inspection. Replace the screw.

④ The screw has iron filings. Disassemble the screw for inspection. Clean the screw.

⑤ Check the coaxiality of the adjusting screw with a dial gauge. About 0.05mm runout is normal.

8. Unable to melt adhesive

① Burnt bearing or drive shaft burst. Separate the screw and re melt the glue and observe the sound. Replace the bearing.

② The screw has iron filings. Separate the screw from the barrel and check whether there is iron scrap on the screw. Remove the screw for cleaning.

③ . the melt valve is blocked. Top the valve core with a hexagonal key to see if it moves. Clean the solenoid valve.

④ The glue motor is damaged. Separate the glue motor, when the glue does not rotate. Replace or repair the glue motor.

⑤ The heating ring is burnt out. Use a multimeter to check whether it is normal. Replace the heating ring.

⑥ The plug is loose. Check whether the fuse oil plug is in poor contact. Tighten the plug. And check whether there is 24 power supply.

9. Back pressure cannot be adjusted during glue melting

① The back pressure valve is broken. Increase back pressure during blanking. Check whether the screw retreats. Clean the back pressure valve.

10. The product has black spots

① The screw has carbon deposits. Check and clean the screw and barrel.

② There are carbon deposits in the barrel and the auxiliary equipment is not clean. Check the feeder for dust. Polishing barrel and cleaning auxiliary machine.

③ The components of the dispensing nozzle are corroded. Check the dispensing nozzle. Replace the dispensing nozzle assembly.

④ There are carbon deposits on the flange and nozzle. Clean and replace.

⑤ Raw materials are not clean. Check the raw materials. Change raw materials.

⑥ The temperature is too high, and the back pressure of the melt adhesive is too large. Check the temperature of each section. Reduce temperature and back pressure.

11. Poor screw color mixing

① . questions between materials. Check the toner quality. Replace materials.

② The temperature is too low. Check the actual temperature and the required temperature. Increase the temperature.

③ The back pressure is too low. Check the back pressure. Increase the back pressure.

④ Short mixing time. Lengthen mixing time or replace with mixing head.

⑤ The rotation speed is too low. Check the screw speed. Increase the screw speed.

12. No glue pumping action

① Large back pressure. Check the speed of spray nozzle during manual glue melting. Reduce back pressure.

② , disconnection. The glue extraction valve is disconnected.

③ The valve element of directional valve is not flexible. Press the valve element with an Allen wrench to check whether it can move freely. Clean the valve element.

13. When the glue is melted, the motor swings its tail

① The bearing is damaged. Observe whether there is abnormal sound during glue melting. Replace the bearing.

② The inclined ball bearing is not adjusted properly. Observe whether the drive shaft swings. Readjust the clearance.

③ Screw deformation. Separate the screw and observe the rotation of the transmission shaft. Replace the screw.

④ The copper sleeve of the rear plate of the shooting platform is worn, two guide rods are deformed or the fixing screws are loose. Observe whether copper powder is grinded out from the second plate copper sleeve. Replace the copper sleeve.

14. Glue injection action twice

① The aperture of the nozzle is too small, and the resistance is too large when spraying glue.

② The heating ring of the nozzle is damaged. Check or replace the heating ring.

③ Check whether the pressure and flow output is changed.

15. Cause of screw breaking

① . the firing movement is not synchronized, and the firing movement is adjusted to be synchronized ± 0.05

② . the glue injection cylinder is not synchronized, adjust the synchronization of the glue injection cylinder ± 0.05

③ The raw materials do not match the screw performance of the injection molding machine.

④ The temperature does not reach the melting point of the material used.

⑤ When the temperature has just reached, turn the screw.

⑥ If the heating cylinder is burnt out and does not heat, check whether there is anti cooling function and replace the heating cylinder.
4、 Fault problems and treatment methods of hydraulic part

1. Hydraulic oil contamination

① Air is mixed in the oil. This is mainly due to poor tightness of pipe joints, hydraulic pumps and hydraulic cylinders. There are bubbles on the oil tank.

② Water is mixed in the oil. The oil will turn milky white. The main reason is that the cooler leaks water or the environment is wet. Mold master wechat: mujudaren

③ Solid impurities are mixed in the oil. It mainly includes cutting chips, welding slag, rust pieces and metal powder.

④ And colloidal substances are produced in the oil. The main reason is that the seal is eroded or deteriorated by the oil, resulting in the formation of colloidal substances in the oil, which often block the small holes.

2. What is the effect of temperature on the viscosity of hydraulic oil

① When the temperature rises, the viscosity of the oil decreases. The change of oil viscosity directly affects the performance and leakage of hydraulic system. (normal temperature is between 30 ~ 50 ℃)

3. Creeping fault

① Poor lubrication condition. “Stop – taxi – stop” appears. Increase the amount of lubrication.

② The hydraulic system is immersed in air. Exhaust is required.

③ Mechanical rigidity. Parts wear and deform, causing friction changes and creeping. Replace parts.

4. The oil pump rings after starting production for a period of time

① The quality of oil suction pipe is poor or the throat code is not tightened. Remove the filter screen and check whether it is deformed. Whether the oil suction pipe is layered. Replace the oil pipe and filter screen.

② The filter screen is not clean. Whether there are too many impurities in the hydraulic oil. Clean the filter screen.

③ Wear of oil pump: check the wear of oil distribution plate and rotor end face of oil pump. Replace the oil pump.

5. After the motor is started, the pressure gauge has pressure but no flow

① The Da board is damaged. Repair the Da board.

② The overflow valve is stuck. Remove the overflow valve for inspection, clean the overflow valve or replace the pressure gauge for inspection.

6. No pressure flow

① Check whether the rotation direction of motor oil pump is normal.

② Check whether there is oil leakage.

③ Check whether the pressure flow valve has current.

④ Check whether the pressure valve core with hexagon socket is pressurized, replace or clean it.



About Huizhou Dj Molding Co., Ltd

Dj Mold is a China mold maker of plastic molds- injection mold, die casting moulds, plastic blow molding, rotational molding, medical plastic injection molding, two shot plastic injection molding, insert molding, overmolding, metal injection molding, micro injection molding, powder injection molding, ceramic injection molding, liquid injection molding, husky injection molding, household mold, casting mold, die mold tool, custom molds, china moulds, rapid prototyping tooling, plastic prototyping tooling, punch press tooling, die and tooling for mobile/ cell phone parts, automotive parts, vacuum cleaners, rechargeable tools, telephones, copiers, computers, multimedia speakers, and many other electronic products and household appliances. And also a plastic product manufacturer, mold manufacturer China– plastic parts, plastic water tank, plastic balls, plastic containers, plastic buckle, plastic anchor, plastic hanger, plastic spoon, plastic pipe fitting, plastic tumble, plastic tableware, plastic cups, plastic bottles, plastic tray, plastic cosmetic container, plastic case, plastic food container, plastic chairs, plastic caps, plastic cap closure, plastic tubes, plastic water pipes, plastic knobs, plastic tubing, plastic utility boxes, plastic racks and so on.

Person: James Yuan
Company: Huizhou Dj Molding Company Limited
Add:  LongGang Village,LongXi Town,BoLuo County,HuiZhou City,GuangDong Province, China
Tel: 86-752-6682869
Email: [email protected]


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