Measuring in the laboratory is a good first step in quality control. Many producers or buyers of plastic films will want to know the thickness and variability of the thickness of their films for reasons of performance and quality. Online quality control is based on sensor technologies and on the technicians who operate the equipment that produces polymeric components. These technicians generally perform visual inspections and remove any markedly defective finished parts.
In addition, technicians can have simple equipment to check product quality, such as meters. When a meter is used, a technician places the processed polymer product in a pre-constructed guide to ensure that the product meets the shape and dimension specifications. Technicians can perform this test on every tenth component, as recommended by the quality assurance department. Technicians may also be asked to analyze the resins in the raw materials to determine the content of moisture or other contaminants before introducing them into the process.
Blow-cut, multilayer, biaxially oriented film extrusion lines move quickly and only have to stop to change jobs. To ensure quality, many plastic manufacturers extract a film sample to be measured in the laboratory, but when a problem of color, turbidity or transparency is identified, most of the print run has already been wasted. An early warning system can help plastic manufacturers keep color, brightness, transparency and haze in harmony so that the line can keep moving. A variety of plastic manufacturing processes have been developed to cover a wide range of applications, part geometries and types of plastics.
For any designer and engineer working in product development, it is essential to be familiar with the manufacturing options available today and with new developments that indicate how parts will be manufactured in the future. Blow molding is a manufacturing technique used to create hollow plastic parts by inflating a heated plastic tube inside a mold until it takes on the desired shape. ESwin closed-loop color control software when combined with an X-Rite online color measurement instrument manages color quality on continuous process manufacturing lines, displays the results and executes automatic closed-circuit in-line color control on plastic machinery. An online solution from X-Rite can help manufacturers of plastic films and sheets to ensure color harmony, from raw material inspection and color matching in the laboratory to production quality control and final inspection.
In short, there are several methods available for measuring the thickness of plastic film, and which one you select depends on your needs and process. Plastic manufacturing processes are constantly evolving and the tipping points at which it makes sense to move from one technique to another are changing due to improvements in equipment, materials and economies of scale. Opaque films will be measured in reflectance, while transparent films will be measured in transmission to quantify color, turbidity and light transmission. A similar method known as reaction injection molding (RIM) is used to manufacture thermosetting plastic parts.
While most plastic manufacturing processes require expensive industrial machinery, dedicated facilities, and trained operators, 3D printing allows companies to easily create plastic parts and rapid prototypes in their own facilities. The X-Rite online plastic color measurement and control system includes a non-contact spectrophotometer, a customized transverse beam to reach predefined positions on the plastic band, and quality control software to monitor color throughout the print run. The ASTM D6988 standard describes the use of a deadweight calibrator to measure the thickness of plastic film. Softer thermosetting plastics require specialized tools to support the parts during machining, and filled plastics can be abrasive and reduce the life of the cutting tool.
Vacuum forming or thermoforming is a manufacturing method in which a plastic is heated and formed usually using a mold.
