05.25.23 | 6 min read

The Role of Quality Assurance and Quality Control in Plastics Manufacturing

There is an emphasis placed on quality in injection molding that is driven by the competitiveness of the industries relying on these products and the desire to reduce costs. The efforts companies put forth towards creating processes that support manufacturing quality products vary from injection molder to injection molder. Evaluating the quality management system, comprised of quality assurance and quality control in plastic manufacturing operations, will reveal the company’s steadfast commitment to providing excellent quality. 

What Does Quality Mean?

Many people think that a quality part is a perfect part. But quality is a word typically used with an adjective, such as poor, good, or excellent, because quality is defined as the degree to which a product’s characteristics fulfill requirements. The requirements can come from the customer, a standard, a regulation, or another source. So, if the requirements differ, one person’s excellent quality part can be another’s inferior quality part. 

Many companies implement a quality management system (QMS) to ensure work meets specified requirements. QMS is composed of interacting or interrelated policies, processes, and objectives used to document and implement practices that will result in good-quality work. ISO 9001 is a globally recognized international standard that sets the framework for a company’s QMS. Its seven quality management principles (QMP) include customer focus, leadership, engagement of people, process approach, improvement, evidence-based decision making, and relationship management. Two aspects of a QMS are quality assurance and quality control in plastics manufacturing and across all industries.

Quality Assurance in Plastic Manufacturing

Sometimes quality assurance (QA) and quality control (QC) are used interchangeably, but they have different but interrelated roles in a robust quality system. Quality assurance is just as it sounds. Assurance that aspects of the system are appropriately implemented. How will the plastic injection molder provide confidence that the products they manufacture will meet requirements consistently? QA focuses on preventing errors and communicating confidence to stakeholders – customers or certifiers, for example. Injection molding processes, internal and external audits, employee training, monitoring change controls, and investigative procedures are examples of quality assurance. 

Quality Control in Plastics Manufacturing

Quality control in plastics manufacturing is focused on finding errors before they reach the customer. QC centers around inspection and process monitoring. It may involve raw material inspection, acceptance sampling (e.g., visual inspection, product measurements, testing), and process controls. Quality control is typically a reactive process. Once QC uncovers the error, the QA framework sets the guidance on what to do to prevent future out-of-spec products, such as implementing corrective actions.

QMS for Automotive and Other Industries 

The automotive industry has additional requirements for manufacturers. The IATF 16949, the automotive quality management standard, is intended to sit on top of the ISO 9001 framework and cannot be used as a stand-alone QMS standard. In addition to quality requirements, it also emphasizes product safety. Many automotive manufacturers have specific requirements related to IATF 16949.

Core tools are used for the implementation and maintenance of an automotive QMS. While not explicitly given in the standard, they are provided in supplemental publications by AIAG (Automotive Industry Action Group). These tools have worked so well for the automotive industry that they have been adopted by the aerospace, defense, medical, and pharmaceutical industries. Most automotive manufacturers require the use of one or more of these tools. 

  • Advanced Product Quality Planning (APQP) is a five-phase approach to reduce the complexity of product quality planning by providing a structure for planning, defining, and completing necessary activities to produce products that meet customer needs. 
  • Failure Mode and Effects Analysis (FMEA) is a tool to identify and address failure modes in products and processes.
  • Statistical Process Control (SPC) is the use of statistical methods to monitor and control the quality of a production process.
  • Measurement Systems Analysis (MSA) is a tool for assessing measurement systems and addresses what percentage of tolerance is taken up by measurement error. 
  • Production Part Approval Process (PPAP) ensures that engineering design and product specification requirements are met.  

Benefits of Quality Assurance and Quality Control In Plastic Manufacturing

Implementing processes for quality assurance and quality control in plastic manufacturing should be a priority for injection molders. Customers expect defect-free products that consistently meet requirements. When molders implement a robust quality management system, customers reap many benefits.

Becoming ISO 9001 and IATF 16949 certified represent big commitments – commitments in time, money, and resources. It involves creating processes, procedures, and work instructions; employee training; maintaining documentation; passing audits; and implementing continuous process improvements. This is all done for the benefit of the customer.

The benefits of a QA process include process optimization, consistency, cost savings, and customer satisfaction. QC provides defect detection, process control, and risk mitigation and ensures compliance.

QA practices optimize the injection molding process by identifying potential issues in the design phase and throughout production. With techniques like FMEA, risks are identified before a product gets into production. QA also helps to maintain consistency in product quality by ensuring all products are produced within the set parameters. When quality is built in from the start and maintained throughout the delivery of the injection molded product, unnecessary costs related to scrap and reworks are removed, and efficiency is increased, allowing the injection molder to offer more competitive pricing. In addition, the customer may see reduced returns or warranty claims. One of the most significant benefits of QA is customer satisfaction – for the injection molder’s customers and downstream to their customers.

The greatest benefit of QC is that it detects defects before they reach the customer. Process controls and regular QC checks provide feedback for process optimization that leads to increased efficiency. The risk of receiving a defective part is significantly mitigated, as well as the costs associated with it. Finally, in industries that rely on compliance with standards or regulations, QC checks ensure that all parts are in compliance. 

Both QA and QC are essential for injection molding companies that desire to produce high-quality parts consistently and efficiently. Together they form a comprehensive approach to quality management that offers tangible benefits to customers. 

Striving For Excellence in Plastic Injection Molding

As an ISO 9001:2015 and IATF 16949:2016 certified manufacturer, we are committed to delivering excellence in every project – whether it is injection molding or metal fabrication. Our robust quality management system ensures we meet your requirements and consistently provide superior products. 

When you work with LMC Industries, you can be confident that every piece we deliver has been meticulously manufactured to meet your specifications and expectations. 

Take the first step toward unrivaled quality, and contact us today to get started creating excellent products together. 


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