With the wide application of 3D printing technology, its application in industrial manufacturing, medical care, education, architecture and other fields is getting deeper and deeper. However, the dimensional accuracy of 3D printed products is always one of the important indicators to measure its quality. In order to ensure that the printed parts meet the design requirements and use requirements, it is particularly important to detect their dimensional accuracy. This paper will discuss the measurement method and matters needing attention of dimensional accuracy of 3D printed parts.

1. Factors affecting the dimensional accuracy of 3D printing

Before measurement, it is necessary to know the main factors that affect the dimensional accuracy. It mainly includes the accuracy of printing equipment, the shrinkage of printing materials, the setting of layer thickness, the filling rate, temperature control and post-processing technology. For example, FDM (fused deposition modeling) technology is easy to lead to dimensional deviation due to material cooling shrinkage and interlayer superposition error; However, SLA (light curing) technology may also affect the final size due to the deformation during light curing.

Second, the commonly used dimensional accuracy measurement tools

1. Vernier caliper: It is suitable for measuring large-sized structures, such as length, width and height, but the accuracy is generally about 0.02mm, so it is suitable for preliminary detection.
　　2. Micrometer (spiral micrometer): used to measure finer dimensional changes with an accuracy of 0.001 mm..

3. Coordinate measuring machine (CMM): High-precision measuring equipment, suitable for precise detection of complex curved surfaces and three-dimensional structures, and often used in industrial-grade detection.
　　4. Optical measuring instrument (such as laser scanner): non-contact measurement, suitable for 3D printed parts with complex or fragile surfaces, and can quickly obtain 3D data.
　　5. Software comparison and analysis: 3D scanning technology is used to compare the object with the original CAD model, and the error distribution is visually displayed through the color deviation diagram.

Third, the measurement methods and steps

1. Preparation stage: Make sure that the printed parts have been cooled and post-processed, such as polishing and de-supporting, so as to reduce errors.

2. Select datum plane: determine the datum plane or datum axis of measurement to ensure the uniformity and repeatability of measurement.

3. Measurement of key dimensions: Focus on measuring the key dimensions marked in the design drawings and record the data.

4. Error analysis: compare the measured value with the theoretical value, and calculate the error percentage or absolute deviation.

5. Data processing and feedback: Optimize the printing parameters or process flow according to the measurement results, and improve the accuracy level of subsequent prints.

Fourth, suggestions to improve the dimensional accuracy

-Calibrate the printer to ensure the nozzle height, platform levelness and other settings are accurate;

-Select high-quality printing materials with good thermal stability;

-appropriately reduce the layer thickness and improve the printing resolution;

-Control printing temperature and ambient temperature to avoid material shrinkage;

-Reducing the deformation risk of the suspended part by using the supporting structure.

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　　To sum up, the dimensional accuracy measurement of 3D printed parts is not only related to product quality, but also directly affects its functionality and adaptability. Through scientific measurement means and systematic error analysis, the accuracy of printed parts can be effectively improved, which provides a strong guarantee for practical application. In the future, with the continuous integration of measurement technology and 3D printing technology, we have reason to believe that personalized manufacturing will be more accurate and efficient.