Blow Molding
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Parison flash
Problem Phenomenon
During the injection '2079851475616104457 production process, the product exhibits the quality defect of "Parison flash".
Specifically manifested as flash appearing on the parison parting line.
This defect is relatively common when processing materials such as PET, PP, HDPE, and PS, and its occurrence conditions are usually related to unreasonable settings of injection pressure, parison temperature, blowing air pressure, and mold temperature.
When the Parison flash situation is severe, it will cause a series of chain-reaction quality defects in the product in terms of appearance, dimensional accuracy, mechanical properties, etc., which not only reduces the usability and safety of the product, but also directly increases the scrap rate and production cost.
Therefore, this problem requires systematic diagnosis and optimization from multiple dimensions, including material selection, the condition of the injection '2079851475616104457 machine, core rod, parison mold, blow mold, and transfer mechanism, as well as injection pressure, parison temperature, blowing air pressure, and mold temperature.
Cause Analysis
1.
Insufficient mold clamping force.
This factor leading to the problem reflects that certain process conditions or material properties in injection blow '2079851475616104453ing have not met the optimal molding requirements.
Such problems often have cumulative and hidden characteristics, and should be investigated and verified as key focus items during process debugging and finalization to ensure that hidden dangers are eliminated from the source.
2.
Injection pressure too high.
Pressure directly determines the filling ability of the melt and the mold-contacting effect during the '2079851475616104453.
Insufficient pressure results in incomplete filling and poor replication accuracy; excessive pressure may cause secondary defects such as flash and excessive internal stress.
The setting of pressure should comprehensively consider factors such as material viscosity, product dimensions, and mold structure.
3.
Wear of the mold parting line.
The mold is the core tool that imparts shape and surface quality to the product.
Unreasonable mold design, such as improper runner/gate dimensions, insufficient venting, inadequate draft angle, etc., will directly cause molding defects.
The machining accuracy, surface treatment quality, and daily maintenance condition of the mold also directly affect product quality.
In terms of equipment maintenance, inadequate regular overhaul and accuracy confirmation of the injection '2079851475616104457 machine, core rod, parison mold, blow mold, and transfer mechanism cause the actual operating parameters of the equipment to deviate from the process requirements, which can also become a potential inducement of the Parison flash problem.
Solution
1.
Increase the mold clamping force.
When implementing adjustments, it is recommended to adopt the single-factor variable method, adjusting only one parameter at a time and fully evaluating the effect, to avoid multiple parameters changing simultaneously making the cause of the problem untraceable.
The adjustment magnitude should be small rather than large; each adjustment is recommended to be controlled within 5%~10% of the original value, and after adjustment, run stably for at least 3~5 mold cycles to observe the effect.
2.
Reduce the injection pressure.
Adjustments should follow the principle of gradual progress; the magnitude of each adjustment should not be too large, and it is recommended to decrease in steps of 5%~15% of the current value.
After each adjustment, observe the product quality changes stably for at least 5~10 mold cycles, and continue adjusting only after confirming that the improvement direction is correct; one-step excessive adjustment must be avoided.
3.
Repair and finish the parting line.
The polishing operation should proceed step by step from coarse to fine; each time a finer abrasive is used, the polishing direction should be changed to eliminate the texture marks of the previous step.
The final surface roughness should be tested with a roughness meter to confirm that it meets the standard.
After polishing is completed, it should be thoroughly cleaned to remove residues of abrasives and grinding agents to prevent them from entering the melt and contaminating the product.
In terms of material management, incoming inspection of raw materials and in-process inspection of work-in-progress should be strengthened, and the key performance indicators of PET, PP, HDPE, and PS should be strictly controlled to ensure the stability of molding quality from the source.
Key Takeaway
In summary, the causes of the "Parison flash" problem can be attributed to the combined action of multiple factors such as insufficient mold clamping force and injection pressure too high.
Solving this problem requires starting from aspects such as increase the mold clamping force and reduce the injection pressure, and adopting systematic governance measures.
In actual production, it is recommended to establish a prevention and rapid response mechanism for this problem, achieving stable production and continuous improvement through parison wall thickness uniformity and transfer temperature control.
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