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Machined Parts Inspection
MACHINED PARTS
inspection from CAD model using 3D profilometry
Author:
Duanjie Li, PhD
Revised by
Jocelyn Esparza
INTRODUCTION
The demand for precision machining able to create complex geometries has been on the rise across a spectrum of industries. From aerospace, medical and automobile, to tech gears, machinery and musical instruments, the continuous innovation and evolution push expectations and accuracy standards to new heights. Consequently, we see the rise of the demand for rigorous inspection techniques and instruments to ensure the highest quality of the products.
Importance of 3D Non-Contact Profilometry for Parts Inspection
Comparing properties of machined parts to their CAD models is essential to verify tolerances and adherence to production standards. Inspection during the service time is also crucial as wear and tear of the parts may call for their replacement. Identification of any deviations from the required specifications in a timely manner will help avoid costly repairs, production halts and tarnished reputation.
Unlike a touch probe technique, the NANOVEA Optical Profilers perform 3D surface scans with zero contact, allowing for quick, precise and non-destructive measurements of complex shapes with the highest accuracy.
MEASUREMENT OBJECTIVE
In this application, we showcase NANOVEA HS2000, a 3D Non-Contact Profiler with a high-speed sensor, performing a comprehensive surface inspection of dimension, radius, and roughness.
All in under 40 seconds.
NANOVEA
HS2000
CAD MODEL
A precise measurement of the dimension and surface roughness of the machined part is critical to make sure it meets the desired specifications, tolerances and surface finishes. The 3D model and the engineering drawing of the part to be inspected are presented below.
FALSE COLOR VIEW
The false color view of the CAD model and the scanned machined part surface are compared in FIGURE 3. The height variation on the sample surface can be observed by the change in color.
Three 2D profiles are extracted from the 3D surface scan as indicated in FIGURE 2 to further verify the dimensional tolerance of the machined part.
PROFILES COMPARISON & RESULTS
Profile 1 through 3 are shown in FIGURE 3 through 5. Quantitative tolerance inspection is carried out by comparing the measured profile with the CAD model to uphold rigorous manufacturing standards. Profile 1 and Profile 2 measure the radius of different areas on the curved machined part. The height variation of Profile 2 is 30 µm over a length of 156 mm which meets the desired ±125 µm tolerance requirement.
By setting up a tolerance limit value, the analysis software can automatically determine pass or fail of the machined part.
The roughness and uniformity of the machined part’s surface play an important role in ensuring its quality and functionality. FIGURE 6 is an extracted surface area from the parent scan of the machined part which was used to quantify the surface finish. The average surface roughness (Sa) was calculated to be 2.31 µm.
CONCLUSION
In this study, we have showcased how the NANOVEA HS2000 Non-Contact Profiler equipped with a high speed sensor performs comprehensive surface inspection of dimensions and roughness.
High-resolution scans enable users to measure detailed morphology and surface features of machined parts and to quantitatively compare them with their CAD models. The instrument is also capable of detecting any defects including scratches and cracks.
The advanced contour analysis serves as an unparalleled tool not only to determine whether the machined parts satisfy the set specifications, but also to evaluate the failure mechanisms of the worn components.
The data shown here represents only a portion of the calculations possible with the advanced analysis software that comes equipped with every NANOVEA Optical Profiler.
