Key points of mold design for blow molding processing in Shanghai

There are various types of blow molding molds in Shanghai, with different structural compositions and design requirements.

The main requirements for extrusion blowing molds are:

① The inflation ratio should be appropriate, and the distribution of various parts of the product should be as uniform as possible;

② Can effectively clamp the billet, and the strength of the joint at the clamp is sufficient;

③ Reliable exhaust ensures rapid expansion of the billet and adherence to the mold wall;

④ Cooling is fast and uniform.

Mold cavity design:

A parting surface: usually the plane that passes through the largest part of the product's cross-sectional profile. Products with complex shapes can have curved surfaces or be composed of multiple flat surfaces. The container handle is usually located on the parting surface.  

B-type cavity surface: Low inflation pressure, low molding temperature, plastic will not enter micro uneven (rough) valleys. A relatively rough surface not only does not affect the surface state of the product, but also facilitates exhaust. For products with special requirements such as high gloss and high transparency, the cavity should be polished.

C-side parting: In order to achieve uniform wall thickness for blow molded products in Shanghai, even if there are side indentations, a large slope is gradually transitioned. In addition, the demolding temperature is high and the elasticity is good, so it can be forcibly demolded without the need for side parting. For deep grooves with smaller slopes, a side parting mechanism should be installed

Clamp mouth and residual material groove

A、clamp mouth

The clamping edge is also known as the cutting edge. At the same time as the extrusion blow molding mold is closed, the remaining material needs to be cut off, so a clamping mouth should be set at the corresponding part of the mold.

B、surplus material tank

The leftover material cut by the cutting edge of the billet just falls onto the parting surface, affecting the closure of the mold. Therefore, a leftover material groove is opened at the corresponding position to accommodate the leftover material

The structural dimensions of the clamping mouth and residual material groove are the key to the design of the extrusion blow mold. In addition to cutting off excess materials, the clamping mouth also has the function of clamping and sealing the billet. If the width and angle of the clamping mouth are improper, the joint surface is not tightly fitted, and the capacity of the remaining material groove is insufficient, it may result in insufficient clamping, continuous cutting of the billet, or insufficient strength of the joint after the billet is cut.

The residual material trough is usually located on the upper and lower sides of the incision, and its size should be determined according to the width and thickness of the residual material after the billet is clamped, based on whether the mold can be tightly closed. The width of the clamping mouth is generally selected as 1-2mm, and the angle is taken as 13 ° -15 °.