What are the Plastic Blow Molding Process

Plastic blow molding process is a processing technique that heats thermoplastics until softened to form a tubular parison. Compressed air is then blown into a mold to expand it and adhere to the mold walls. After cooling, the parison is demolded to produce a hollow product. The process varies depending on the specific method. The following is a breakdown:

1. Raw Material Preparation

Select appropriate plastic particles (such as PE, PP, PVC, PET, etc.) based on product requirements. Mix the raw materials and masterbatch according to the recipe and stir evenly.

Hygroscopic plastics (such as PA and PC) are dried to remove internal moisture and ensure product quality.

2. Mold Preparation

Select an appropriate mold based on the product shape and preheat it to ensure uniform mold temperature.

Inspect the mold cavity for a smooth surface, scratches, or dents, and for smooth opening and closing.

3. Parison Forming

After the plastic raw materials are heated to a molten state, they are formed into a tubular plastic parison using an extruder or injection molding machine. In extrusion blow molding, the preform is continuously extruded through the extruder head; in injection blow molding, the preform is formed in a single step in the injection mold.

4. Inflation Molding

The hot preform is quickly placed in the blow mold, and compressed air (usually at a pressure of 0.2-1.0 MPa) is introduced into the preform.

The air pressure causes the preform to expand and adhere to the mold walls, forming it into the shape of the mold cavity.

5. Cooling and Shaping

The inflation pressure is maintained until the part cools and sets. Cooling methods include water cooling, air cooling, or natural cooling.

After cooling, the mold is opened, the hollow part is removed, and any excess material (such as flash and excess material) is trimmed.

6. Post-Processing and Inspection

The part is trimmed, waste edges are removed, and preliminary inspections (such as for branding, weight, and airtightness) are performed.

The product is inspected for damage using a leak detector. After comprehensive inspection, it is packaged and stored.

Qingdao Xueyu Molding Products Co., Ltd. is mainly engaged in the design and manufacturing of injection molds, injection molding and secondary processing (spraying, pad printing, ultrasonic welding, stamping), etc. For more information about plastic blow molding process, please contact us.

Website: www.xyzmould.com

Address: No.18 Henan Head Road, Henan Head Community, Jihongtan Street, Qingdao Industrial Park, Shandong Province, China

Email: wangmiaotian8@163.com