Common problems of extrusion blow molding process in blow molding products processing plant

Author: MULAN - Plastic Molding Manufacturer

The extrusion blow molding process mainly involves two issues of material selection and processing conditions. Blow molding product processing plants should take into account the influence of polymer structure on melt strength and parison drape when selecting materials. The difference in material structure will make the product performance different. When using intermittent extrusion blow molding, it is necessary to consider whether the molecular weight distribution of the material used is suitable for this kind of processing, because the production rate of the parison at the mouth of the storage cylinder is very high, and it is easy to cause melt fracture, which will affect the appearance of the product. Blow molding products processing plant When considering the processing conditions, under the premise of ensuring uniform melting of the melt, the melting temperature should be slightly lower, which can increase the strength of the melt and reduce the phenomenon of drooping 

Blow molding products processing plant The common problems in the extrusion blow molding process mainly include the formation of the parison, the inflation of the parison, the design of the cutting port, and the cooling and solidification time of the parison 

 1. From the perspective of product design and economy, the shape and thickness of the parison must be controlled before the blow mold is closed over the entire length of the parison. The factors affecting the parison include the structure of the die, the molecular parameters of the polymer and the operating conditions 

 2. The shape of the blow mold cavity has a significant effect on the wall thickness distribution of blow molded products. When designing the cavity of the blow molding model, it is necessary to refer to the empirical formula of the parison wall thickness variation ratio 

 3. Large-scale hollow products require high strength and rigidity, and good sealing. The seam formed by the cutting mouth is the key part that affects the sealing. The cutting opening should be designed according to the characteristics of the polymer, the size of the product and the conditions of the processing equipment 

 4. The cooling stage is the longest part of the entire blow molding cycle. In order to improve production efficiency, cooling efficiency needs to be improved. However, high cooling rates can cause freezing stress and defects in the article. Therefore, optimization of the cooling device should be considered. Blow molding product processing plants should strengthen cooling for the thick-walled part and the cut-off area when designing the mold.