Surface Topography and Tolerance Quality Evaluation of Polymer Gears Using Non-Contact 3D Scanning Method

Area of Science:

• Materials Science and Engineering
• Manufacturing Technology
• Metrology

Background:

• Lightweight powertrain designs demand rigorous characterization of polymer gears for performance and longevity.
• Non-contact metrology is crucial for evaluating complex geometries like polymer gears.

Purpose of the Study:

• To assess the effectiveness of structured-light 3D scanning for characterizing polymer gears.
• To compare the dimensional accuracy and surface topography of polymer gears produced by conventional hobbing, Material Extrusion (MEX), and Selective Laser Sintering (SLS).

Main Methods:

• Utilized a structured-light 3D scanner to capture high-density point clouds of polymer gears.
• Compared scanned data against nominal Computer Aided Design (CAD) models.
• Evaluated geometrical deviations using DIN 3961 standards and surface roughness using ISO 25178 parameters.

Main Results:

• Conventionally hobbed POM-C gears achieved the highest precision (DIN quality grades Q9-Q10) and smoothest surface finish (Sa = 5.0 µm).
• SLS-printed PA 12 gears presented intermediate quality (Q11, Sa = 12 µm).
• MEX-printed PPS-CF gears showed significant deviations (exceeding Q12) and the roughest surfaces (Sa = 25 µm) due to stair-stepping.

Conclusions:

• Conventional hobbing offers superior dimensional precision for polymer gears compared to current additive manufacturing techniques.
• Structured-light 3D scanning provides an efficient metrological framework for polymer gear quality control.
• The scanning methodology is applicable to quality assurance for additively manufactured tooling and fixtures in automotive assembly.