Manufacturing Quality Control Using Capability Zones
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Solution Overview
Problem
Current quality control methods, such as statistical process control, are inadequate for ensuring compatibility between parts manufactured by different suppliers in complex industries like aerospace, where numerous variables and suppliers lead to incompatibilities due to features gravitating towards tolerance limits, causing increased costs and time in production.
Innovation Solution
A system and method using digital computers to visualize and assess how close part features are to nominal values by assigning measurements into capability zones, allowing for easy identification and correction of manufacturing issues, and calculating capability scores to compare manufacturers' performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If statistical process control is used to monitor manufacturing variation, then process capability can be maintained within control limits, but features may gravitate towards specification limits causing incompatibility between mating parts
Solution Approach 1:
The patent changes the parameter focus from control limits (±3σ) to capability zones measured from the nominal value. By establishing capability zones at 50%, 75%, and 100% of tolerance from nominal, the system shifts monitoring parameters to ensure features gravitate toward nominal rather than merely staying within control limits, thereby improving mating part compatibility
Solution Approach 2:
The system implements feedback by calculating capability scores based on the distribution of measurements within capability zones and providing this information to manufacturers. This feedback loop enables manufacturers to adjust their processes to improve their capability scores, directly addressing the compatibility issue between mating parts
2Productivity
If multiple suppliers are used to increase productivity and reduce costs, then manufacturing efficiency improves, but the number of potential incompatibility areas increases exponentially
Solution Approach 1:
The patent creates a universal capability scoring system that can be applied across multiple suppliers and manufacturing processes. This standardized methodology allows different suppliers to be evaluated using the same criteria (capability zones and scores), simplifying the management of multi-supplier complexity while maintaining productivity benefits
Solution Approach 2:
By introducing the capability score parameter that quantifies how close features are to nominal values, the system provides a common language for evaluating all suppliers. This parameter transformation converts complex quality assessment into comparable numerical scores, reducing supply chain management complexity
3Adaptability or versatility
If features are allowed to vary within tolerance to maintain process capability, then manufacturing flexibility is maintained, but mating parts may become incompatible requiring modification or replacement
Solution Approach 1:
The patent introduces capability zones (50%, 75%, 100% of tolerance from nominal) as intermediate parameters between nominal and specification limits. This parameter refinement allows manufacturing flexibility within tolerance while providing guidance to keep features closer to nominal, thereby improving compatibility without sacrificing adaptability
Solution Approach 2:
The system performs preliminary assessment of feature distribution within capability zones before final assembly. By evaluating capability scores in advance, potential incompatibility issues can be identified and addressed before parts are assembled, preventing the need for costly modifications or replacements
Data Source
AI summary
A system and method for performing manufacturing quality control with the aid of a digital computer are provided. A specification for manufacturing a part feature is maintained in a storage, the specification including a target value. Measurements for the feature on a plurality of parts manufactured in accordance with the specification using a manufacturing process are maintained in the storage. A score associated with the manufacturing process is calculated based on how close at least some of the measurements associated with the manufacturing process are to the target value. The score is displayed. A recommendation of at least one corrective action to the manufacturing process to remedy one or more causes of non-conformance that are associated with the score is provided, wherein the manufacturing process is changed based on the recommendation to remedy one or more of the causes for non-conformance.