Plastic rods are solid plastic shapes, made either through the process of plastic extrusion or the process of plastic coextrusion. They contrast plastic profiles and plastic tubing, which are hollow. They are used in a variety of industries, such as aerospace, electronics, marine, petrochemicals and transportation. In these industries, plastic rods often serve as raw materials to be machined into parts for gaskets, seals, bearings, corrosion-resistant pieces, sleeving, static control, insulation and more. They also have use in industrial, construction and commercial industries, serving, for example, applications related to structural support of industrial equipment and point of purchase displays.
No matter the exact material or materials used to extrude or co-extrude plastic rods, all plastic rods share some of the unique properties of plastic materials. These properties include: non-conduction, low density, low porosity, structural integrity, corrosion resistance, heat resistance and ease of shaping. However, manufacturers have the opportunity to produce rods with different materials and chemical combinations, and, in doing so, they are able to create products with the particular properties that they want.
The plastic formulas used to extrude plastic rods are diverse and many, but despite this, most formulas still fall into one of two groupings: thermoplastics and thermosets. Of the two, thermoplastics hold the majority of plastics. Thermoplastics consist of all plastics that can both soften and melt when heated or reheated, and harden when cooled. They may be heated and remolded over and over again. This category includes plastics such as PVC, ABS, polyethylene, polycarbonate, polypropylene and polystyrene. Thermosets will also become molten when heated and will also harden when cooled, but, unlike thermoplastics, they cannot be successfully reheated, reshaped or rehardened. Examples of thermosets include polyesters, phenolics, silicones and epoxies. Each plastic grouping presents pros and cons. For instance, in general, thermoplastics are easier to mold and faster produce than thermosets. Thermosets, on the other hand, tend to have superior strength components and, unlike thermoplastics, they retain their strength when heated. Furthermore, each individual plastic material offers manufacturers different attributes that they may want their product to have as well. For example, because PVC has high fire, heat and chemical resistance, it is popular for use with building exteriors, metal anodizing, chemical processing and sewage treatment. Acetal plastic rods have very low water absorption and they are chemically resistant, but they are relatively weak and susceptible to the effects of high heat. Therefore, they work well for food processing applications that do not require especially high heat resistance or strength. Manufacturers that produce flexible and/or scratch resistant products are likely to use plastics like HDPE or acrylic. Both of these plastics are also valued for the ease with which they can be manipulated.
In addition, despite having the word "plastic" in their name, plastic rods are not actually always completely made of plastic. Instead, they can sometimes be coextruded with materials other than plastic, like metals. What, exactly, is coextrusion? Coextrusion is an altered extrusion process by which single products are made from two or more different materials. To make this happen, multiple extruders that are pointed at a single die melt the polymers intended to be make up the product. After they become molten, the materials are forced into the die at an even pace and volume. They enter the die at the same time, where they fill it out in layers. In general, the goal of coextrusion is to endow a product with properties or qualities that it cannot get from just one polymer. The choice to co-extrude a plastic rod with a different type of plastic or with another material altogether is usually made either to lower material costs or to strengthen the core of the rod. Low-cost co-extrusion materials are usually only used with applications that require little structural strength. In the case of applications requiring structural support, metal is usually the material that fills the rod. Other qualities frequently sought after by co-extruders include increased stiffness, increased wear resistance and oxygen permeability.
While it is not needed every time, some manufacturers may choose to further fashion their plastic rods with secondary processes, such as drilling, deburring, powder coating, painting, labeling, notching and industrial finishing. Generally, plastic rods may be clear or come in any color, including custom-matched colors. This versatility and plastic extrusion's wealth of material choices are two of the many reasons that manufacturers love working with extruded plastic rods so much. Plastic rods are an excellent choice for people looking for quick, inexpensive, durable parts and products.
Image Provided by Polytec Plastics Inc.