Optimization of Metal Injection Molding Processing Conditions for Reducing Black Lines and Meld Lines in Bone Plates

Area of Science:

• Materials Science
• Manufacturing Engineering
• Biomedical Engineering

Background:

• Bone plates for fracture healing are manufactured using metal injection molding (MIM).
• MIM processes can produce defects like black lines and meld lines due to low or uneven powder concentration and inadequate melding temperature.
• These defects negatively impact product appearance and mechanical properties.

Purpose of the Study:

• To determine optimal MIM processing conditions for bone plates, focusing on powder concentration and melding temperature.
• To enhance product quality and mechanical performance by minimizing defects.
• To develop an integrated framework for multi-objective optimization in MIM.

Main Methods:

• Utilized mold flow analysis simulations combined with the Taguchi robust design method.
• Employed Grey Relational Analysis (GRA) for simultaneous optimization of multiple MIM objectives.
• Implemented a Robust Multi-Criteria Optimization (RMCO) technique to address factor interactions and refine optimization.

Main Results:

• Initial GRA provided improvements but was surpassed by single-objective Taguchi experiments due to melt temperature dominance.
• The RMCO technique effectively identified dominant factors and redesigned experiments to optimize non-primary factors.
• RMCO eliminated interference between multiple factors, leading to superior multi-objective optimization outcomes.

Conclusions:

• The proposed integrated framework, particularly the RMCO technique, significantly advances MIM process optimization for bone plates.
• This approach leads to demonstrably improved product quality and performance in surgical implants.
• The study provides a robust methodology for optimizing complex manufacturing processes with multiple objectives.