Smaller-the-better-type six sigma product index.

Area of Science:

• Industrial Engineering
• Quality Management
• Manufacturing Systems

Background:

• Machine tools possess critical quality characteristics that are often of the "smaller-the-better" type.
• Existing six sigma quality indices effectively measure process yield and quality levels for single characteristics.

Purpose of the Study:

• To propose an integrated six sigma product index for products with multiple "smaller-the-better" quality characteristics.
• To develop a robust evaluation and improvement model for product quality in the machine tool industry.

Main Methods:

• Integration of multiple "smaller-the-better" quality indicators into a single six sigma product index.
• Derivation of confidence intervals for the proposed index to establish an evaluation model.
• Development of a product improvement testing model to identify and ensure process enhancements.

Main Results:

• A novel six sigma product index capable of evaluating products with diverse "smaller-the-better" quality traits.
• An evaluation model guaranteeing both required quality levels and high product yield.
• An improvement model to systematically enhance manufacturing processes and reduce waste.

Conclusions:

• The proposed comprehensive model enhances product value and reduces environmental pollution in the machine tool industry.
• The confidence interval-based approach minimizes misjudgments caused by sampling errors.
• The model supports corporate social responsibility by decreasing rework and scrap.