Case Study

Elimination of Porosities in Aerospace Production

The Company

This company is a Tier 1 supplier of aerostructures. They also provide a wide range of complex and high-tech engine components to leading aerospace manufacturers.

The Challenge

The main challenge faced by the company was related to high costs of non-quality centered on a specific part and defect, precisely the occurrence of porosities (small bubbles) during production. These quality issues were intermittent and primarily detected during the high-pressure autoclave phase. Despite analyzing the causes, the company could not significantly reduce scrap costs. Prioritizing analysis and actions at specific points in the process did not yield the expected results, mainly because the root causes were not correctly identified. Additionally, the company lacked essential process control variables for a thorough analysis.

This internal project failed to effectively impact quality errors, resulting in significant scrap costs, with 22 parts being dismantled, each costing 6,800 euros, totaling 149,500 euros.

The Approach

The Six Sigma methodology was implemented to address the quality control issues using the DMAIC process (Define, Measure, Analyze, Improve, Control). The steps included:

• Define: Conduct SIPOC analysis, identify critical-to-quality (CTQ) factors, study process phases, and define objectives using 5W+1H.
• Measure: Focus on process study, R&R tests, input stability analysis, data collection, and evaluate process stability and capability.
• Analyze: Use the 6M diagram, 5 Whys, relationship diagrams, and multivariate analyses to identify root causes.
• Improve: Apply Failure Mode and Effects Analysis (FMEA), Design of Experiments (DOE), and standardize processes.
• Control: Establish statistical process control and conduct audits to ensure consistent quality.

Given the manual environment and lack of data, the measurement phase was particularly critical, requiring extensive data collection to validate and quantify the problem. The implementation roadmap highlighted the definition of the control system as the first action, which was crucial for the project’s success.

Results

The implementation of the Six Sigma methodology resulted in significant improvements:

• The number of high non-quality costs (HNC) and scrap parts were drastically reduced by 98% and 100%, respectively;
• The total cost savings achieved amounted to 149,500 euros;
• A defect analysis model was developed based on measuring and controlling process variables, ensuring the identification of critical process points;
• Creation of a quality control system that does not rely on individual operators, thus reinforcing the overall process.