By Cesar Lucero, M.S.c (AI Technology) VTI Life Sciences Lead Automation Engineer
Introduction
In production environments, time is of the essence and quality is non-negotiable. Companies still using manual processes and human inspections face significant challenges such as fatigue, decreasing attention spans, and variability between operators. These issues are further compounded by shifts, staff rotation, and the need for specialized training or certification for critical inspections.
Process automation is not a simple ‘yes’ or ‘no’ decision, but rather a spectrum that offers varying degrees of automation.
For manual assembly lines, individual workstations typically handle changes to the work’s fit, form, and function, with subassemblies and materials passed along through conveyors or hand-to-hand. Test stations may be located at the end of the process or in a quality control lab near the production floor.
The manual assembly allows for flexibility and customization, especially in low-volume production and high-model changeover scenarios. These processes may suffice for small batches or made-to-order products but depend heavily on personnel dexterity. As demand increases due to company growth, the limitations of manual processes will become evident, making them unsustainable.
Semi-automatic assembly lines offer a flexible solution, involving varying degrees of equipment-human interaction. These solutions strike a balance between human oversight and the speed that robotic processes provide. If automating a task is prohibitively expensive, an operator can work alongside the conveyor or index system to complete tasks manually, passing the product back to the machine for testing. This flexibility ensures quality while controlling costs, making it a potentially cost-effective solution for many companies.
Fully automated assembly systems, while offering high speed, repeatability, and reliability, come with their own set of challenges. These systems only require raw material feeding and occasional product jam clearance, but they typically require a team of specialized technicians and automation engineers. The complexity of the equipment and its interactions underscores the importance of skilled personnel in these systems.
Automation drastically reduces defects and increases efficiency by eliminating human variability and fatigue, particularly in high-speed production across various industries. However, more complex equipment necessitates an in-depth analysis of process parameters, test validation, and material variability.
Process validation for automated assembly systems ensures the sustainability of production by testing different scenarios to establish the optimal configuration through Design of Experiments (DOE). DOE is a statistical method used to test machine settings and optimize the process systematically. When raw material dimensions or consistency vary, the equipment must absorb these changes and continue producing acceptable parts, provided the material passes incoming inspection. It falls within an acceptable range, even near specification limits. Similarly, functional tests and machine vision inspections must adapt to slight product variations, such as color or surface finish changes (e.g., gloss vs. matte). These scenarios must be challenged through Test Method Validation to ensure the equipment behaves as expected, which improves the detectability score in the Process Failure Mode and Effect Analysis (PFMEA). This brings added benefits, such as lower AQL (Acceptable Quality Level) requirements and a smoother regulatory approval process and audits.
A case study:
In a recent project with a client using an automated assembly system for a medical device intended for diabetes care, VTI’s automation team conducted a Test Method Validation on several vision systems. This uncovered that two of the cameras were inaccurately measuring length and angle readings, causing not only acceptable parts to be marked as rejects—impacting the production yield rate—but also allowing some reject parts to pass. After our automation engineers conducted a root cause analysis, adjustments to the vision systems improved the detection accuracy by nearly 30%. Additionally, a new range of process parameters for a prior assembly process reduced scrap production by 7% across two different defect types.
There is no doubt that Validation is the pathway to automation robustness.
Process validation ensures that each configuration can handle high throughput and raw material variability regardless of the automation level. Validation ensures consistency and quality from manual setups, where operator variability is a risk, to fully automated systems requiring complex parameter tuning.
Ready to optimize your automation process further? Contact us today to learn how our validation services can ensure your system operates with maximum efficiency and quality.
Reference:
Assembly Magazine. Automated Assembly: Manual, Semiautomatic, or Fully Automatic? Sprovieri, John. June 25, 2023. Retrieved from: https://www.assemblymag.com/articles/97869-manual-semiautomatic-or-fully-automatic
