Molding Techniques – How to Choose the Best Process for your Project

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Plastic Molding Comparison

In manufacturing, molding refers to the process of shaping material into a rigid form. Pexco is the North American Leader in plastic molding, offering our customers a variety of techniques and materials to best meet their needs.

Choosing the appropriate molding process for manufacturing plastic parts depends on several factors, including the design, size, complexity, production volume, and material properties required. Here’s an overview of when to use each type of molding:

Plastic Injection Molding

Plastic Injection Molding is a process that involves heating a polymer above its melting point and then injecting the molten resin into a mold.

  • High-Volume Production: Ideal for producing large quantities of identical parts.
  • Complex Geometries: Suitable for intricate designs with detailed features and tight tolerances.
  • Material Variety: Can be used with a wide range of thermoplastic and thermosetting polymers, such as FEP, PFA, PAI (Torlon®), Peek, and PEI (Ultem®).

Blow Molding

Blow molding is the forming of a hollow object by inflating or blowing a molten polymer into the outside shape of the mold.

  • Hollow Parts: Best for making hollow objects, such as bottles and containers.
  • Medium to High Production Volumes: Economical for large production runs in materials such as HDPE, PP, PETG and PC.
  • Lightweight Products: Ideal for products where weight reduction is important.

Compression Molding

Compression Molding is a process that uses heat, pressure, and time to shape pre-measured materials into parts with various lengths, thicknesses, and complexities.

  • Large, Flat, or Curved Parts: Suitable for producing large and relatively simple parts.
  • Thermosetting Materials: Commonly used for thermosetting plastics and composites such as silicone, polyurethane and phenolic.
  • Low to Medium Production Volumes: Effective for lower production volumes than injection molding.

Extrusion Molding

Extrusion molding is used to form plastic materials into pre-defined shapes.

  • Suited for long, hollow formed applications.
  • Continuous Profiles: Best for creating long continuous shapes with a consistent cross-section in materials such as acrylic, polycarbonate, PVC and polyethylene.
  • High Production Volumes: Economical for high-volume production of parts.

Rotational Molding

Rotational molding is a technique that creates hollow plastic parts of any size. A hollow mold is filled with powdered resin, and the mold rotates bi-axially and then is transferred to an over.  The mold continues to rotate as the resin melts and coats the wall of the mold.

  • Relatively low-cost tooling.
  • High durability, stability, and strength using materials such as LDPE, HDPE, PP and PO (nylon).
  • Fine-detail surface textures, symbols and/or lettering


Thermoforming is the process a heating a thermoplastic sheet or block to its softening point.  The items are then stretched across a single-sided mold and manipulated into the desired shape.

  • Flexibility and low cost of entry
  • Durability, color and texture options using materials such as ABS, HDPE, PVC, and PC.
  • Sustainability

Choosing the right molding process depends on the project’s specific requirements, including its design, material, production volume, and cost considerations. Each method offers distinct advantages that make it suitable for different applications.

Pexco offers expertise in material engineering, materials and processing and can assist you in choosing the best process for your project.  Pexco processes over 500 different materials including FEP, PFA, PAI, PEEL, PPS, PEI, acrylic, polycarbonate, PVC and polyethylene, and can help you find the best fit for your next project.

For more information on these processes, materials, or how Pexco can help you with your project, please contact Rich Reed, Vice President of Sales – Custom, at [email protected] or visit our website at