Classify by fault occurrence characteristics
sudden failure
This type of malfunction often occurs suddenly without any prior warning. It often occurs during the use stage of fully automatic hollow blow molding machines, and is often caused by defects in design, manufacturing, assembly, and materials, or operational errors or illegal operations.
Intermittent fault
The fully automatic hollow blow molding machine loses some of its functions in a short period of time, which can be restored with a little repair and debugging, without the need to replace parts.
Damage fault
Some parts of the fully automatic blow molding machine are damaged and need to be replaced or repaired to restore use.
Classified by the degree of impact of the malfunction
Overall malfunction
Resulting in the loss of function of the fully automatic hollow blow molding machine.
Localized malfunction
Resulting in the loss of certain functions of the fully automatic blow molding machine.
Specific faults in daily use
Blow bottle deformation
There are wrinkles under the bottleneck: usually due to poor cooling of the preform at the bottleneck, or too late pre blowing, or too low pre blowing pressure.
Whitening at the bottom of the bottle: usually due to excessive stretching, too cold preform, too high pre blowing pressure, or too early pre blowing.
Thick at the top and thin at the bottom: This is usually due to premature pre blowing, which can reduce the pre blowing pressure, decrease the air flow rate, or delay the pre blowing time.
Common faults during blow molding
No discharge or unstable discharge during startup
Mold surface overcooling: If the cold air is turned on for too long in advance and the mold surface is overcooled, it is necessary to check whether the temperature of the extrusion cylinder, relay, and various parts of the mold head meets the standard; Although the temperature outside the above-mentioned parts has reached the standard, it is necessary to confirm whether the heating time is sufficient to make the internal and external temperatures consistent; Check for damaged heaters or thermocouples. If damaged, repair or replace them immediately.
Startup temperature issue: Check if the adhesive material at the mold surface outlet has melted.
Film adhesion
Raw material issue: Raw materials containing an appropriate amount of anti adhesive agent can be used; Anti adhesive agents can also be added to the raw materials themselves or other materials with better lubricity can be added, but attention should be paid to the physical properties of the product, such as the appearance of the film, which may be affected by uneven dispersion of additives.
Cooling issue: Increase the height of the clamp roller; Add multiple sets of cooling air rings; The temperature of the film tube passing through the forming film and the clamping roller when it reaches the clamping roller; Reduce the temperature of the mold head and the height of the cooling line; Increase the airflow entering the cooling air ring; Use cold air to increase the cooling effect of the cooling air ring; Reduce the discharge speed.
Clamp problem: Check the clamp to see if the pressure of the spring, piston, and air pressure is uniform; Check if the clamp axis is parallel; Check if the clamp is eccentric; Check if the rubber of the clamp is worn out.
Guide wheel or forming film problem: Adjust the guide wheel or forming film so that it is parallel to the clamp and symmetrical at an angle of 3.
Uneven pressure between the clamps
Check the clamping rod to see if the pressure of the spring, piston, and air pressure is uniform; Check if the clamp axis is parallel; Check if the clamp is eccentric; Check if the rubber of the clamp is worn out.
Cooling line too low
Reduce cooling air volume or increase melt temperature; Adjust the extrusion conditions, such as increasing the melting temperature, back pressure, or mixing effect, to obtain a smooth film surface; If possible, slightly lower the extrusion temperature.
The inflation ratio is too high
Increase the diameter of the mold head to reduce the inflation ratio.
Excessive pressure between the clamping rollers
Reduce the pressure on the springs or pistons on both sides of the pinch roller.
Excessive winding tension (pulling force)
Reduce winding tension; Fully cool the film; Adjust the film thickness evenly.
Uneven film thickness
Mold head issue: Adjust the gap between the mold heads to ensure that the discharge is the same at any relative position of the mold heads; If the adjustment of the gap between the mold heads is still ineffective, it indicates that there is a significant difference in the discharge of the lower half of the mold head. Therefore, it is necessary to clean the mold and readjust the gap between the lower half of the mold wall and the mold core; If it is still ineffective, the mold head needs to be repaired or redesigned; Check if there are any errors or defects in the design of the mold head that are sufficient to produce uneven material flow, such as a general bottom feed gyroscope or mold head with smaller discharge at the material receiving point and thinner film thickness; Regularly cleaning the mold head, if there are oxides or residues on the inner wall of the mold head, it will affect the uneven discharge.
Squeezing condition issue: Adjust the squeezing conditions, such as increasing the melting temperature, back pressure, or mixing effect, to obtain a smooth film surface.
