The Study on Resolution Factors of LPBF Technology for Manufacturing Superelastic NiTi Endodontic Files

Area of Science:

• Materials Science and Engineering
• Additive Manufacturing
• Biomedical Engineering

Background:

• Laser Powder Bed Fusion (LPBF) is crucial for creating complex metal structures in aerospace and medical fields.
• Current LPBF applications typically involve feature sizes >300-400 microns.
• There is a growing need for higher resolution LPBF to produce micro-scale devices like stents and microfluidics.

Purpose of the Study:

• To investigate the resolution limitations of LPBF for manufacturing superelastic Nickel-Titanium (NiTi) Self-Adjusting Files (SAF).
• To identify key factors affecting LPBF resolution for micro-scale applications.
• To optimize LPBF parameters for producing high-resolution NiTi endodontic instruments.

Main Methods:

• Manufacturing of thin walls and SAF samples using NiTi powder (15-45 μm fraction) via LPBF.
• Utilizing an LPBF system with a 55-micron laser spot diameter.
• Conducting X-ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC) tests to analyze phase composition and transformations.
• Evaluating physical, apparatus, and software factors influencing resolution.

Main Results:

• Identified physical, apparatus, and software factors limiting LPBF resolution.
• Determined optimal process parameters: 100 W laser power, 850 mm/s scanning speed, and 20 μm layer thickness.
• Successfully manufactured SAF files meeting required resolution standards.
• Analyzed the impact of single track scanning on NiTi phase composition and transformation temperatures.

Conclusions:

• Optimized LPBF parameters enable the high-resolution manufacturing of NiTi Self-Adjusting Files.
• The findings are applicable to producing NiTi micro-objects using LPBF and micro-LPBF (μLPBF).
• This research contributes to advancing additive manufacturing for precision medical instruments.