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Methods of Plastic Fabrication

fabricated plastic bottlesPlastic fabrication is the design, manufacture, or assembly of plastic products through one of a number of methods. Some manufacturers prefer plastic fabrication over working with other materials (such as metal or glass) due to the process’s advantages in certain applications. Plastic's malleability and cost-effectiveness can make it a versatile and durable material for a range of different products.

Plastic Welding

Like metal welding, plastic welding involves the use of heat to melt two or more work pieces together. This process is effective when handling thermoplastics that are unsuitable for adhesive binding. Individual pieces are often fused with a filler material between them, especially if the plastics have dramatically different melting points. Welding can be accomplished through several different methods, including hot gas emissions, high-frequency vibration, spinning, or contact welding. The equipment used in welding depends on the selected process and type of plastic involved.

Compounding (or Blending)

Compounding is a type of fabrication that combines two or more plastics into an amalgam, before forming them into a single part. It involves mixing molten plastics to exact specifications and then forming them with a mold, die, or other shaping tool.

Compounding is often used to improve the ease of processing a given material or to enhance product performance. By combining the advantages and disadvantages of several types of plastic, the process can result in a unique material complementary to a specific application. Some common types of plastic compounds include:

• Polymer fillers
• Base resins
• Pigment master batches
• Blowing agents
• Flame-retardants
• Purge compounds

Plastic Lamination

Plastic lamination creates a barrier along the surface of another material. This process is most often used to improve the durability, styling, or aesthetic quality of a product. It can also be a cost-effective measure by shielding a sensitive or deterioration-prone material and reducing its potential need for maintenance.

Film and resin are the two most common types of lamination. In both processes, heat and pressure are applied to a fabricated film to enable its adhesion to a moving substrate. Film lamination is more effective for forming a plastic barrier on the exterior of a product, while resin lamination is more frequently used to create an adhesive layer between two substrates. Paper, fabrics, metal sheeting, and flexible foam are common lamination base materials.

Molding Processes

In molding, plastic is formed into a specified shape by allowing the heated, pliable work piece to cool and harden around or within a mold. There are numerous plastic molding methods, including injection molding, blow molding and rotational molding. Blow molding is often used to create containers, such as bottles or fuel tanks, while injection molding is helpful in applications requiring a higher melt index, like dishware production. Rotational molding results in hollow plastic products, such as canoes, toys, buoys, and automotive parts.

Plastic Extrusion


Plastic extrusion can be used to create tubing, piping, or sheeting components. It is also applied to enhance the effectiveness of further forming or processing stages. For example, plastic extrusion is often a precursor to adhesion or lamination procedures.

Profile extrusion and sheet extrusion are the most common forms of the process. Profile extrusion uses a single screw extruder to melt plastic pellets, move the molten plastic through a pressurized screw mechanism, and force it into an annular die. The plastic then solidifies around a calibration sleeve to create a pipe or tube component of a specific diameter. Sheet extrusion, unsurprisingly, uses a similar technique to create thin plastic sheeting.

Plastic Foaming

Foam products can be formed into a variety of different shapes. Common foaming configurations include round, sheet, film, solid plank, rod and bun stock. To achieve the desired characteristics, polymer composites are typically shaped through a process of physical or chemical blowing. As in compounding, additives such as pigments,
antioxidants and fire-retardants can be included in the base material to optimize product performance for the user.

Choosing a Plastic Fabrication Process

Product functionality and ease of manufacturing are important things to consider when choosing a plastic fabrication process. Some methods are inefficient for fabricating certain types of plastic, and therefore may not be helpful for your particular project. Some other issues to keep in mind include:

• The need for single plastics versus plastic compounds
• The intended proportion of plastic to non-plastic material in the product
• The role of plastic in your fabrication process (as adhesion, lamination or base product)
• The dimensions and use of the final product

 

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