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Extrusion Blow Molding

Blow molding has become ubiquitous in modern society, even if it is unclear to most people what it is. This manufacturing process is essential for producing various hollow plastic products used in our day to day lives. Goods such as bottles, watering cans, and various types of containers can all be made with blow molding.

This article will outline the extrusion blow molding processes and highlight key factors to consider in this particular manufacturing industry.

Extrusion Blow Molding (EBM) Process

There are several blow molding methods and technologies. Extrusion blow molding is one of the most common. EBM begins with the extrusion of a continuous parison in the form of a tube. Afterwards, a mold is clamped into place around the parison, any excess material from the parison is clipped off by the mold. Next, compressed air is forced into the cavity via a blow pin, expanding the plastic against the mold into the desired shape. The thickness of the parison can be adjusted to produce the desired wall thickness of the finished product. Though it is not as exact as other forming methods, this method is useful for high volume output. It is particularly suitable for producing bottles, containers, and larger hollow items.

Key Considerations for Quality Blow Molded Products

Creating high-quality blow molded products involves careful consideration of the following key factors:

Material Selection

Here are the aspects encompassing material selection:

  • Material characteristics: The choice of plastic material impacts the product’s properties. Thus, factors such as strength, flexibility, transparency, and resistance to external factors must be considered. In many cases, the end use will determine the most suitable material. For instance, if a blow molded product is to be used for storing water or other beverages, a food-grade plastic should be selected.
  • Compatibility with the process: The selected material should suit the chosen molding process to ensure optimal results. Fortunately, extrusion blow molding is compatible with a variety of plastic materials, including but not limited to: Acetal, Acrylonitrile Butadiene Styrene (ABS), High Density Polyethylene (HDPE), Polypropylene (PP), Polyester (PET/PETG), and many more.
  • Recyclability: In line with sustainable manufacturing practices, choosing recyclable materials supports environmentally friendly production. Recyclability may be subject to regional availability.

Design Considerations

The following are crucial design considerations to look into:

  • Mold design: The mold design is critical to achieving the desired shape. In conjunction with control of the extruder output, it can help minimize defects like warping and uneven distribution of material. Uniformity will be easier to manage with more simple designs.
  • Wall thickness: Maintaining consistent thickness throughout the product is not as precise as other molding techniques such as thermoforming or rotational molding. The thickness can be controlled to some extent by managing the thickness of the parison.
  • Complexity and detail: Extrusion blow molding is ideal for large volume, low cost, and quick production speeds, but the drawbacks include a limitation to forming hollow parts and the need for trimming excess material.

Quality Control Measures

Listed below are the quality control measures to consider in the molding process:

  • Process monitoring: Monitoring parameters such as temperature, pressure, and cycle times ensures product consistency.
  • Dimensional accuracy: Regular inspections for dimensional accuracy are crucial. Deviations from the intended specifications can lead to functional and aesthetic defects.
  • Defect detection: Employing advanced visual inspection systems and quality checks at various stages helps detect and rectify air pockets, uneven thickness, or surface imperfections.

Choose Lerner Molded Plastics for High-Quality Blow Molded Components

Lerner Molded Plastics has over 35 years of expertise in providing top-tier custom molding services throughout the United States! At the core of our operations is a commitment to delivering high-quality custom components, all while maintaining competitive pricing. Whether it is a prototype or a full-scale production run, we are well-equipped to handle projects of varying scales.

Contact us today to learn more about our capabilities, or request a quote now.