Handern Seiko extrusion blow molding process
DATE：2021/1/7 8:59:23 / READ： / SOURCE：This station
Handern Seiko extrusion blow molding process
The main factors that affect the quality of hollow Ouli processing and product quality are raw materials, temperature, twist ratio, eurskin ratio, die size, blow molding pressure, mold cooling and molding shrinkage.The choice of raw materials for the manufacture of solar mechanical film www.handern.com
Take polyethylene fiber products as an example, we must choose the brand of raw materials according to the use of the products. The main parameters were the density and the sleeve index. Softening temperature and rigidity are functions of density. The higher the density, the higher the softening temperature and rigidity. In order to maintain the structure and shape of products and develop thin-walled products, it is necessary to use resins with high density and low melt index.
Secondly, containers containing detergents and other chemical reagents and containers containing inserts of other materials have higher requirements on the resistance to stress cracking of products. The stress cracking is related to density, molecular weight and molecular weight distribution. The melt index is the characterization of molecular weight, so the environmental stress cracking resistance of polyethylene is related to the melt index. When the melt index decreases, the environmental stress cracking increases.
In addition, by observing the self sag phenomenon, it can be found that when the billet reaches a certain length, the descending speed of the billet increases, and the length of the billet is called the critical length. The critical length can be used as a rough criterion for the sag of the blank. There is a close relationship between sag and melt index. The higher the melt index is, the faster the billet sagging speed is, that is, the shorter the critical length is. Mechanical manufacturing of solar back panel film www.handern.com
In order to improve the rigidity, impact strength, environmental stress cracking resistance and processing stability of hollow products, it is appropriate to select the resin with low melting index and high density. Ethylene / butene or ethylene / ethylene copolymer is often used in HDPE. The melt index is 0.2 ~ 0.4. The melt index of LDPE Blends is generally in the range of 0.3 ~ 1. When the blending ratio of LDPE is small, the melt index should not exceed 2.
2. Molding temperature
Each brand of resin has a certain melting temperature, which should be strictly controlled during processing. When the temperature is low or high, the surface roughness will appear. In order to improve the appearance quality, the temperature at the die lip should be slightly higher than the material temperature (about 5C higher). The extrusion temperature also directly affects the sag degree, expansion ratio and cooling setting time of the blank. Therefore, melting temperature is an important parameter to control product quality and determine production efficiency.
3. Expansion ratio
The expansion ratio refers to the phenomenon that the size of the extruded molten billet is larger than that of the die. The energy transfer ratio of the plastic products produced the elasticity of the second end of the polymer. It is of great significance to know the limiting expansion ratio, control the shape or wall process, improve the product quality, determine the die design size and select the die. Mechanical manufacturing of solar back panel film www.handern.com
Author：admin