Edition #25 - Process Risk Assessments: Building Quality Into Your Assembly Line

Many aspects of a product’s quality are determined on the assembly line. In the previous newsletter, we looked at the importance of good assembly line design. Here, we will explore a tool that can help you further improve that design.

Whether you are setting up an entirely new assembly line or addressing a problematic one, a process risk assessment provides a structured way to evaluate risk. You work through each station or process, identify, assess, and rate potential risks. You can then target improvements to ensure that faults are caught early or, ideally, prevented altogether.

Faults should be caught before they move to the next station, or at the very next step before additional value is added. If a missed fastener, uninstalled part, or assembly error is not detected immediately, it can move down the line, causing bigger problems and higher costs. The later a fault is discovered, the more expensive it is to fix. If errors are not found until the product reaches the customer, the impact can be severe. This is where a process risk assessment adds significant value.

The most effective way to carry out a process risk assessment is to walk the line (cue Johnny Cash), taking photos or videos to capture each process. This allows you to thoroughly analyse the process later with your risk assessment team and determine what actions are needed.
Process Failure Modes and Effects Analysis (PFMEA) is a great framework for this assessment because it considers both the likelihood of a fault occurring and the likelihood it will be detected. Insights from this process also allow the development of a robust control plan with the necessary checks and processes at critical stages of production. This proactive approach helps prevent quality issues, ensuring consistency and minimising defects in the final product.

The second key to making sure the risk assessment truly adds value is keeping it up to date. Minor product changes can impact the assembly process and unintentionally create new risks that were not captured in the original assessment. When product changes occur, such as post-market improvements, it is important to consider their impact on assembly and revisit the risk assessment if needed. Think of the process as a safety net that catches issues that get through your first line of defence - good assembly line design.

By identifying risks early and taking steps to eliminate or control them, businesses can save time, reduce costs, and consistently deliver high-quality outcomes.