Injection molding is a simple and reliable process that allows for production of large quantities of intricate parts with high precision. Quality control is an essential part of this process, ensuring high-quality finished products and minimizing the risk of faults.

Top-rated mold injection companies have in place reliable quality protocols that include different checkpoints and parameters for optimized production. Keep reading to find out more about the quality assurance process they employ to give you premium-quality parts that match your specific requirements.

What is quality control in injection molding?

It’s a carefully planned process that helps secure a reliable production that yields maximum capacity with minimal errors. Let’s explore the essential parameters and methods used from beginning to end:

Quality parameters

The basic parameters that are crucial for successful manufacturing of quality parts are carefully set and monitored throughout the process and include:

  • Tolerance levels. These refer to the limits within which the final product’s dimensions can vary from the original design. They typically range between +/- 0.1mm when it comes to general parts and +/- 0.025 for parts that require high precision.
  • Cavity pressure is measured by sensors at various stages of the process. It helps prevent different faults like burn marks or other aesthetic defects that can result from the pressure that’s either too high or too low.
  • Rate, time, and speed of injection. Comparing the rate, time, and speed of injection with industry standards for a specific type of injection molding project helps spot any potential anomalies that could result in faults.
  • Cooling time typically takes up most of the production time. Factoring this period into the project planning and timetables helps improve the quality of the final part.
  • Adherence to customer specifications. Referring to the original specifications provided by the client is crucial for efficient quality monitoring.

Quality methods

Even with the careful monitoring of the mentioned parameters, there always exists a possibility of certain defects being created along the way. This is why manufacturers implement additional processes to support the parameters and further reduce the risk of defects. The methods include:

  • Total Quality Management (TQM) refers to the continuous process of detecting and minimizing or eliminating errors throughout the process.
  • Computer Aided Quality (CAQ) helps examine and monitor dimensions, warpage and shrinkage, material thickness, and tolerance levels. It checks selected aspects or areas of the final product and compares them to the pre-programmed parameters.
  • Advanced Quality Planning (AQP) examines the design and overall feasibility of the product.
  • Statistical Process Control (SPC) refers to different tools that are essential for identifying unwanted variations, understanding process capabilities, and refining the overall process. These tools allow manufacturers to make reliable decisions based on data generated during in-process production and initial qualification.
  • Totally Integrated Automation (TIA) aims to streamline all automation components into a single cohesive system. It offers several benefits, including centralized control of the entire process, improved efficiency, detailed monitoring and diagnostics, flexibility and scalability, advanced data analytics and production optimization.

Potential faults

While the stringent quality checks reduce the risk of faulty parts to a minimum, they’re never fully eliminated and some products can be rejected during the process of monitoring. Some common faults include:

  • Sink marks. This is a common defect that occurs when dents or craters appear in the thicker areas of part and can cause issues with performance and aesthetics.
  • Gas or burn marks refer to the rusty color on the surface of a product and can be caused by injection speeds that are too high or excessive heating.
  • Flow lines appear on the surface as a result of varying speeds at which the material flows through the injection machine.

In conclusion, while the tools and strategies of quality control in injection molding may be complex, their goal is simple: to ensure that every product not only meets but exceeds the expectations set forth by clients and industry standards. Through meticulous attention to detail, continuous process improvement, and a steadfast commitment to quality, the field of injection molding continues to set a high bar for manufacturing excellence, ensuring that quality is never compromised.