Common Issues and Troubleshooting Methods for Blow Molding Machines
Bencheng Machinery2026-01-23 08:23:45
Poor transparency of PET bottles
Reason: 1. Heating temperature is too high; 2. Heating time is too long; 3. Compressed air contains moisture; 4. The injection molded tube itself is opaque; 5. Inappropriate embryo tube design; 6. The inflation ratio is too small.
Exclusion method: 1. Cooling down; 2. Shorten heating time; 3. Use a dryer to remove water; 4. Improve the quality of embryo tubes, select materials, and increase the dryness of raw materials; 5. Improve embryo tube size design; 6. Reduce the diameter of the embryo tube.
PET bottle shows pearl luster and whitening
Reason: 1. The heating temperature is too low; 2. Uneven wall thickness of embryonic tube; 3. The thickness of the embryo tube is too thick, and the heating penetration is insufficient.
Exclusion methods: 1. Heat up or slow down the revolution speed; 2. Improve the quality of embryo tubes; 3. Reduce the thickness of the embryo tube, or try raising the outer cover of the heating device to increase the surface temperature dissipation of the embryo tube.
PET bottle bottom water outlet position offset
Reason: 1. Start blowing too early; 2. The stretching rod did not descend to the bottom; 3. The stretching rod is offset from the centerline of the bottle shaft; 4. Uneven thickness of embryo tube wall or uneven injection density; 5. Uneven heating.
Exclusion methods: 1. Delay the blowing time or increase the descent speed of the stretching rod; 2. Adjust the position of the magnetic pole switch; 3. Adjust the position of the stretching rod; 4. Improve the quality of embryo tubes; 5. Improve heating conditions or check for any issues with embryo tube rotation.
Uneven wall thickness of PET bottles
Reason: 1. The stretching rod is not located at the center of the embryo tube; 2. Asymmetric blowing holes with varying pore sizes; 3. The stretching ratio is too low or the inflation ratio is too small; 4. The embryo tube does not rotate in the heating furnace; 5. Uneven wall thickness of the embryo tube or uneven injection density.
Exclusion method: 1. Adjust the position of the stretching rod; 2. Adjust the position and aperture of the blowing hole; 3. Increase the stretching ratio or inflation ratio; 4. Check the rotation device; 5. Improve the quality of embryo tubes.
The upper part of the bottle is too thick
Reason: 1. The upper temperature is too low; 2. The position of the mold exhaust hole is too far from the upper part; 3. The stretching ratio is too low; 4. The inflation ratio at the top of the bottle is too low; 5. The speed of the stretching rod is too slow.
Exclusion method: 1. Upper heating; 2. Adjust the position of the exhaust vent; 3. Increase the stretching ratio; 4. Change the shape of the bottle; 5. Adjust the speed of the stretching rod.
The bottom of the bottle is too thin
Reason: 1. Start blowing too early; 2. The bottom temperature is too high; 3. The bottom of the embryo tube is too thin.
Exclusion method: 1. Delay the start time of blowing air; 2. Reduce the bottom temperature; 3. Increase the thickness of the bottom of the embryo tube.
The bottle mold line is obvious
Reason: 1. Insufficient clamping pressure; 2. The sealing time is too early; 3. Mold issues; 4. The size of the embryo tube mouth does not match the mold fit.
Exclusion method: 1. Increase the clamping pressure and adjust the clamping strut angle (<5 degrees); 2. Position of the switch for the rear moving mold closing stroke; 3. Repair the mold or check the assembly position of the mold, such as whether the guide column is loose or whether the mold is not tightly pressed; 4. Repair the fitting position of the mold teeth.
Roll up or accumulate material at the bottom or bottleneck of the bottle
Reason: 1. The delayed blowing time is too long; 2. One roll, one good; 3. The temperature at the material storage area is too low; 4. The unstable air pressure during the action affects the descent speed of the stretching rod.
Exclusion methods: 1. Shorten the delayed blowing time or reduce the descent speed of the stretching rod; 2. Reduce the gas volume on one side of the bottle; 3. Increase the heating temperature at the location of the embryo tube; 4. Add a gas storage tank to the operating gas source, or shorten the gas supply pipeline.
Stretch perforation at the bottom of the bottle
Reason: 1. Insufficient temperature, no penetration; 2. The delay stretching time is too long; 3. The stretching ratio is too large; 4. The bottom of the embryo tube is too thin; 5. The stretching rod head is too sharp.
Exclusion method: 1. Heating; 2. Shorten the delay stretching time; 3. Reduce stretch ratio; 4. Improve the design of the bottom of the embryo tube; 5. Round and stretch the rod head.
Bottom explosion of bottle
Reason: 1. The delayed blowing time is too short; 2. The delay in mold opening time is too short; 3. The temperature is too high; 4. The exhaust valve is not functioning.
Exclusion methods: 1. Extend the delay blowing time or increase the descent speed of the stretching rod; 2. Extend the delay in mold opening time; 3. Cooling down; 4. Clean the exhaust valve with gasoline.
The bottom of the bottle is not full
Reason: 1. The temperature at the bottom of the bottle is too high; 2. Insufficient or uneven exhaust holes at the bottom of the mold bottle; 3. The stretching rod has not reached the bottom; 4. The design of the stretching rod head does not conform to the shape of the bottom of the embryo tube; 5. Insufficient blowing pressure; 6. Insufficient flow of blowing valve; 7. Poor design of bottle bottom curve.
Exclusion method: 1. Reduce the temperature at the bottom of the heating zone or use a damp cloth to lower the temperature at the bottom of the embryo tube; 2. Increase the number of exhaust holes and make them evenly distributed; 3. Adjust the stretching rod to the bottom of the bottle; 4. Replace the stretching rod head; 5. Increase the blowing pressure; 6. Clean the blow valve with gasoline; 7. Add streamlined design to the bottle bottom curve.
PET bottle bottom water outlet position offset
Reason: 1. Start blowing too early; 2. The stretching rod did not descend to the bottom; 3. The stretching rod is offset from the centerline of the bottle shaft; 4. Uneven thickness of embryo tube wall or uneven injection density; 5. Uneven heating.
Exclusion methods: 1. Delay the blowing time or increase the descent speed of the stretching rod; 2. Adjust the position of the magnetic pole switch; 3. Adjust the position of the stretching rod; 4. Improve the quality of embryo tubes; 5. Improve heating conditions or check for any issues with embryo tube rotation.
Reason: 1. Heating temperature is too high; 2. Heating time is too long; 3. Compressed air contains moisture; 4. The injection molded tube itself is opaque; 5. Inappropriate embryo tube design; 6. The inflation ratio is too small.
Exclusion method: 1. Cooling down; 2. Shorten heating time; 3. Use a dryer to remove water; 4. Improve the quality of embryo tubes, select materials, and increase the dryness of raw materials; 5. Improve embryo tube size design; 6. Reduce the diameter of the embryo tube.
PET bottle shows pearl luster and whitening
Reason: 1. The heating temperature is too low; 2. Uneven wall thickness of embryonic tube; 3. The thickness of the embryo tube is too thick, and the heating penetration is insufficient.
Exclusion methods: 1. Heat up or slow down the revolution speed; 2. Improve the quality of embryo tubes; 3. Reduce the thickness of the embryo tube, or try raising the outer cover of the heating device to increase the surface temperature dissipation of the embryo tube.
PET bottle bottom water outlet position offset
Reason: 1. Start blowing too early; 2. The stretching rod did not descend to the bottom; 3. The stretching rod is offset from the centerline of the bottle shaft; 4. Uneven thickness of embryo tube wall or uneven injection density; 5. Uneven heating.
Exclusion methods: 1. Delay the blowing time or increase the descent speed of the stretching rod; 2. Adjust the position of the magnetic pole switch; 3. Adjust the position of the stretching rod; 4. Improve the quality of embryo tubes; 5. Improve heating conditions or check for any issues with embryo tube rotation.
Uneven wall thickness of PET bottles
Reason: 1. The stretching rod is not located at the center of the embryo tube; 2. Asymmetric blowing holes with varying pore sizes; 3. The stretching ratio is too low or the inflation ratio is too small; 4. The embryo tube does not rotate in the heating furnace; 5. Uneven wall thickness of the embryo tube or uneven injection density.
Exclusion method: 1. Adjust the position of the stretching rod; 2. Adjust the position and aperture of the blowing hole; 3. Increase the stretching ratio or inflation ratio; 4. Check the rotation device; 5. Improve the quality of embryo tubes.
The upper part of the bottle is too thick
Reason: 1. The upper temperature is too low; 2. The position of the mold exhaust hole is too far from the upper part; 3. The stretching ratio is too low; 4. The inflation ratio at the top of the bottle is too low; 5. The speed of the stretching rod is too slow.
Exclusion method: 1. Upper heating; 2. Adjust the position of the exhaust vent; 3. Increase the stretching ratio; 4. Change the shape of the bottle; 5. Adjust the speed of the stretching rod.
The bottom of the bottle is too thin
Reason: 1. Start blowing too early; 2. The bottom temperature is too high; 3. The bottom of the embryo tube is too thin.
Exclusion method: 1. Delay the start time of blowing air; 2. Reduce the bottom temperature; 3. Increase the thickness of the bottom of the embryo tube.
The bottle mold line is obvious
Reason: 1. Insufficient clamping pressure; 2. The sealing time is too early; 3. Mold issues; 4. The size of the embryo tube mouth does not match the mold fit.
Exclusion method: 1. Increase the clamping pressure and adjust the clamping strut angle (<5 degrees); 2. Position of the switch for the rear moving mold closing stroke; 3. Repair the mold or check the assembly position of the mold, such as whether the guide column is loose or whether the mold is not tightly pressed; 4. Repair the fitting position of the mold teeth.
Roll up or accumulate material at the bottom or bottleneck of the bottle
Reason: 1. The delayed blowing time is too long; 2. One roll, one good; 3. The temperature at the material storage area is too low; 4. The unstable air pressure during the action affects the descent speed of the stretching rod.
Exclusion methods: 1. Shorten the delayed blowing time or reduce the descent speed of the stretching rod; 2. Reduce the gas volume on one side of the bottle; 3. Increase the heating temperature at the location of the embryo tube; 4. Add a gas storage tank to the operating gas source, or shorten the gas supply pipeline.
Stretch perforation at the bottom of the bottle
Reason: 1. Insufficient temperature, no penetration; 2. The delay stretching time is too long; 3. The stretching ratio is too large; 4. The bottom of the embryo tube is too thin; 5. The stretching rod head is too sharp.
Exclusion method: 1. Heating; 2. Shorten the delay stretching time; 3. Reduce stretch ratio; 4. Improve the design of the bottom of the embryo tube; 5. Round and stretch the rod head.
Bottom explosion of bottle
Reason: 1. The delayed blowing time is too short; 2. The delay in mold opening time is too short; 3. The temperature is too high; 4. The exhaust valve is not functioning.
Exclusion methods: 1. Extend the delay blowing time or increase the descent speed of the stretching rod; 2. Extend the delay in mold opening time; 3. Cooling down; 4. Clean the exhaust valve with gasoline.
The bottom of the bottle is not full
Reason: 1. The temperature at the bottom of the bottle is too high; 2. Insufficient or uneven exhaust holes at the bottom of the mold bottle; 3. The stretching rod has not reached the bottom; 4. The design of the stretching rod head does not conform to the shape of the bottom of the embryo tube; 5. Insufficient blowing pressure; 6. Insufficient flow of blowing valve; 7. Poor design of bottle bottom curve.
Exclusion method: 1. Reduce the temperature at the bottom of the heating zone or use a damp cloth to lower the temperature at the bottom of the embryo tube; 2. Increase the number of exhaust holes and make them evenly distributed; 3. Adjust the stretching rod to the bottom of the bottle; 4. Replace the stretching rod head; 5. Increase the blowing pressure; 6. Clean the blow valve with gasoline; 7. Add streamlined design to the bottle bottom curve.
PET bottle bottom water outlet position offset
Reason: 1. Start blowing too early; 2. The stretching rod did not descend to the bottom; 3. The stretching rod is offset from the centerline of the bottle shaft; 4. Uneven thickness of embryo tube wall or uneven injection density; 5. Uneven heating.
Exclusion methods: 1. Delay the blowing time or increase the descent speed of the stretching rod; 2. Adjust the position of the magnetic pole switch; 3. Adjust the position of the stretching rod; 4. Improve the quality of embryo tubes; 5. Improve heating conditions or check for any issues with embryo tube rotation.
