A Measurement Solution of Face Gears with 3D Optical Scanning.

Gears are usually measured by the contact metrology method in gear measuring centers or coordinate measuring machines. Recently, three-dimensional (3D) optical scanning, a non-contact metrology method, has been applied in the industry as an advanced measurement technology mainly due to its high efficiency. However, its applications to gears with complicated geometry, such as face gears, are still limited due to its relatively low accuracy and the void of related measurement solutions. In this work, an accurate measurement solution with 3D optical scanning is proposed for the tooth surface deviations of orthogonal face gears. First, point cloud collection is carried out by the 3D scanner. Furthermore, the measurement solution is implemented with a three-stage algorithm by aligning point clouds with the design model. Subsequently, 3D modeling is studied by numbering the points and reconstructing the real tooth surfaces. An example with a measurement experiment and loaded tooth contact analysis is given to show the validity of the proposed method.

Comparative Study of the Influence of Bio-Resin Color on the Dimension, Flatness and Straightness of the Part in the 3D Printing Process.

This paper aims to determine whether the color of based-plant resin called, by the manufacturer, eco-resin has an influence on the dimensions and geometric accuracy of the 3D-printed part. The analysis of flatness, straightness and dimensions deviations was carried out with high-precision measurement systems, and according to current standards regarding linear dimensions and geometrical tolerances. A coordinate measuring machine with contact probes was used to measure the printed part's physical characteristics, and analysis of variance and response surface design methods were used for the data analysis. The printing experiment was carried out for each color. After that, the measurement of the printed parts and the study of the data were performed. The first finding is that for black and clear eco-resin, there are problems with the printing of the supports. Based on standard data for the range of nominal lengths of the part for linear dimensions, flatness and straightness, the measurement results can be included in different tolerance classes within standard value limits. The best value of the printed structure was obtained for clear eco-resin. The paper demonstrates that the impact of the color of the eco-resin is more important than the supports density for all the studied features. Based on 3D measurements, the optimal values for each of the eco-resin colors regarding the flatness, straightness and linear dimensions deviations of the 3D printed part were also determined.

Accuracy of 3D surface scanners for clinical torso and spinal deformity assessment.

Externally visible deformities are cosmetic features of great concern for Adolescent Idiopathic Scoliosis (AIS) patients. Current assessment techniques for AIS do not fully encompass the external deformity. A non-invasive method capable of capturing superficial anatomy, such as 3D scanning, would enable better qualitative and quantitative evaluation of cosmesis. This study aimed to quantify the accuracy of commonly available scanners, in assessing posterior asymmetry in AIS. The technique of 3D surface deviation analysis was proposed as a suitable method for comparing the models created by each scanner. Eight plaster cast moulds manufactured to create braces for AIS patients were used as test samples. Four 3D scanners were selected: Solutionix RexScan CS+; Artec Eva; Microsoft Kinect V1; iPhone with 123D Catch App. These scanners were selected from those available as representative of a range of scanning technologies. Each cast was scanned and 3D models created. A simulated rib hump measurement was obtained and the surface-to-surface deviations between the Solutionix scan and all other scans were determined. The Solutionix scanner is a metrology scanner of very high quality and so it was selected as the reference. Surface-to-surface deviations were calculated in the positive and negative directions separately to specifically identify size and volume inaccuracies created by the scans. Surface deviations showed excellent agreement between the Solutionix and the Eva with deviations of +0.17 ±â€¯0.17 mm (Eva regions larger) and -0.20 ±â€¯0.32 mm (Eva regions smaller) (mean±SD). The Kinect showed lower agreement (+1.58 ±â€¯1.50 mm and -0.58 ±â€¯0.58 mm). The iPhone scans were not able to be scaled to the correct size, so were excluded. Rib hump measurements with all scanners were within clinical measurement variability (±4.9 deg) of the known values. These commercially available 3D scanners are capable of imaging torso shape in 3D and deriving clinically relevant external deformity measures. The non-invasive 3D topographic information provided can be used to improve assessment of torso shape in spinal deformity patients.