Blow Molding
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Insufficient filling of bottle body reinforcing ribs
Problem Phenomenon
During the extrusion '2079851475616104457 production process, the product exhibits the quality defect of "Insufficient filling of bottle body reinforcing ribs".
Specifically manifested as incomplete filling at the reinforcing ribs or grooves.
This defect is relatively common when processing materials such as HDPE, PP, PVC, and PC, and its occurrence conditions are usually related to unreasonable settings of melt temperature, extrusion speed, blowing air pressure, and mold temperature.
When the Insufficient filling of bottle body reinforcing ribs 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 extruder, die head, die, mold clamping mechanism, and blowing system, as well as melt temperature, extrusion speed, blowing air pressure, and mold temperature.
Cause Analysis
1.
Insufficient blowing air pressure.
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.
2.
Reinforcing rib depth too large.
This factor leading to the problem reflects that certain process conditions or material properties in extrusion 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.
3.
Poor venting at that area.
Mold venting is a basic condition to ensure smooth filling of the melt.
When venting is poor, the air in the mold cavity is compressed to form a high-pressure air cushion, which hinders melt flow and causes problems such as insufficient filling, burnt, and weld lines.
A reasonable venting design should consider the venting position and venting gap to ensure that air is discharged in time.
In terms of equipment maintenance, inadequate regular overhaul and accuracy confirmation of the extruder, die head, die, mold clamping mechanism, and blowing system cause the actual operating parameters of the equipment to deviate from the process requirements, which can also become a potential inducement of the Insufficient filling of bottle body reinforcing ribs problem.
Solution
1.
Increase the blowing air pressure.
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 reinforcing rib depth.
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.
Add venting structures.
The installation of equipment or accessories should strictly follow the installation manual; the key mating surfaces must be cleaned and checked for damage before installation.
Fastening bolts should be tightened evenly according to the specified torque values and diagonal sequence; after installation, use precision measuring tools to verify whether the installation accuracy meets the technical requirements.
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 HDPE, PP, PVC, and PC should be strictly controlled to ensure the stability of molding quality from the source.
Key Takeaway
In summary, the causes of the "Insufficient filling of bottle body reinforcing ribs" problem can be attributed to the combined action of multiple factors such as insufficient blowing air pressure and reinforcing rib depth too large.
Solving this problem requires starting from aspects such as increase the blowing air pressure and reduce the reinforcing rib depth, 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 control and parison temperature uniformity.
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