TOLERANCE & ACCURACY
The dimensional accuracy of 3D printed parts manufactured by 3D People
Tolerance is the permissible variation in dimensional accuracy. At 3D People, we use two types of 3D printing technologies, each one meeting a standard of accuracy. The parts we produce through our online service will measure within our 3D printing tolerances. The parts we produce through our online service will measure within our 3D printing tolerances.
Three factors contribute to the precision and accuracy of 3D printed parts.
All 3D printers have variations in accuracy determined by their engineering and construction. The many moving components must remain calibrated to one another for accurate results. Tolerances provided by the machine manufacturers give us guidelines on what to expect. However, these only apply to designs optimised for 3D printing with their technology.
3D printed polymers shrink as they are cooled during the printing process. Elements of a part that shrink at a different rate cause internal stresses that can affect the dimensional accuracy. Several variables cause uneven shrinkage such as part geometry, heat distribution, printer settings, orientation and cooling rates.
3D printed parts undergo additional processes after removal from the machines. Cleaning of the surfaces, removal of support material and other finishing techniques can alter the external dimensions. An optimised design considers the post-processing requirements for the printing technology and minimises its impact on the accuracy of its surfaces and features.
The value of tolerance for each of our 3D printing technologies are a result of 3D printing and measuring many thousands of custom components. The vast majority of parts we produce are considerably more accurate than our guaranteed tolerances. The reason we cannot guarantee more accurate tolerances as some dimensionally challenging geometries are prone to warping.
3D Printing Technology | 95% of printed parts | Guaranteed Tolerance* | Guaranteed Lower Limit | Layer Height |
---|---|---|---|---|
Selective Laser Sintering (SLS) | ± 0.15% | ± 0.3% | ± 0.15 mm | 100 microns |
Multi Jet Fusion (MJF) | ± 0.2% | ± 0.3% | ± 0.25 mm | 80 microns |
*We use a percentage to calculate the tolerance for a given dimension. For example, an SLS 3D print with a measurement of 100 mm has a permissible range of 99.7 mm to 100.3 mm
We use highly accurate measuring equipment to record the dimensions of the 3D printed parts and check them against their corresponding 3D file. Any measurement that lies outside of the acceptable range out of tolerance.
Measure a dimension from the 3D file in a 3D CAD program. It is best to use the exported mesh file as opposed to the original CAD model.
Calculate the permissible range for this dimension using the tolerance percentage for the corresponding 3D printing technology.
Measure the same dimension off of your 3D print. We recommend recording several measurements and using the average values.
Check to see if the measurement of the 3D printed part lies within the permissible range calculated in step 2.