What is precision engineering? Can 3D printing support the prototyping and production of highly precise parts? According to the American Society of Precision Engineering (ASPE), an authority on the subject, precision engineering is “a discipline that encompasses the design, development, and manufacturing of and for high-accuracy components, instruments, and machines.” Accuracy isn’t the same as precision, however, and engineering and manufacturing aren’t the same either. There are also significant differences in size between 3D parts produced at the microscale and the macroscale.
That’s why examining a few definitions is a good place to start.
Accuracy vs. Precision
Accuracy is defined as the closeness of a measured amount to its true value. If a part needs to be 100 mm but is 125 mm, then the 3D printer that tried to produce the 100-mm part isn’t very accurate. Precision is different. In fact, it’s possible to be both inaccurate and precise or accurate and imprecise. That’s because precision refers to the repeatability or reproducibility of the measurement. In our example, a 3D printer that produces 50 125-mm units that are supposed to be 100-mm is a precise machine. All production units have the same measurement (125 mm), but this measurement is not accurate.
Part Tolerances
Tolerance, another term that’s familiar to engineers, is probably more useful here. Tolerance refers to the amount of acceptable variation between the target dimension and the actual dimension. In our example, a difference of 25-mm is significant. That’s almost an inch’s worth of difference, an amount that is large enough to interfere with part assembly. But what if all of the units produced were 101 mm instead of 100 mm? In many industrial applications, a 1-mm difference would be within tolerance. However in other applications, such as optics or microelectronics, a 1-mm difference could be a problem.
Macroscale vs. Microscale 3D Printing
Another way to think about precision engineering is in relative terms. The website Practical Precision suggests “a level of accuracy that is many orders of magnitude smaller” than the size of what’s produced. So, which part is a better example of precision engineering? A 101 mm part that is supposed to be 100 mm or a 101 µm part that is supposed to be 100 µm? Millimeters (mm), the first unit of measure, are 1000 times larger than microns (µm). For some perspective, consider that a human hair is 70 µm while 70 mm refers to a frame size for movie film.
Precision Engineering vs. Precision Manufacturing
Precision engineering isn’t limited to specific applications – and neither is 3D printing. Here, it helps to consider two manufacturing technologies: precision machining and precision injection molding. As the name suggests, precision machining uses machine tools to achieve very close tolerances, including complex geometric shapes. Precision injection molding can also achieve very tight tolerances. In other words, you might say that all of the injected molded parts (and typically there are thousands) are manufactured close enough to the desired measurement, regardless of any part-to-part variations.
Print Resolution at the Microscale
Most 3D printers can’t produce very small parts, and not all the printers that can have enough accuracy and precision for applications such as medical devices, optics, and microelectronics. These 3D printers may also lack the required print resolution, which refers to the printed part’s level of detail. If a 3D printer has low print resolution, then it’s parts won’t look like a precision machined or precision injection molded part. If a 3D printer has a high print resolution, however, it can support the precision engineering (and precision manufacturing) of parts for high precision applications like tiny MEMS devices and microfluidic devices.
Precision Engineering and PµSL Technology
Let’s say you want to 3D print a microstructure with a printing tolerance of +/- 10µm ~ +/- 25µm and that has a resolution of 2µm ~ 50µm. That’s not an uncommon example at many leading companies, universities, and government laboratories. Projection Micro Stereolithography (PµSL), a form of 3D printing developed by Boston Micro Fabrication (BMF), provides a combination of accuracy, and precision for more exact, intricate, and replicable parts. With its ultra-high resolution, it also supports the part-level precision engineering that’s needed not just by engineers, but by scientists and researchers as well.
Precision Engineered 3D Printers
To learn more about microscale 3D printing with ultra-high resolution, accuracy, and precision, download our Introduction to 3D Printing with PuSL Technology white paper. The microARCH™ series of products include 2 µm, 10 µm, and 25 µm printers, and these machines are precision engineered for positioning and stability to very small dimensions. BMF’s microARCH™ S230, our most advanced and highest-resolution 3D printer, was recently recognized as a TCT Awards 2022 winner for the TCT Hardware Award – Polymer Systems category.
For precision engineered 3D printed parts, it only makes sense to use precision engineered 3D printers. Contact BMF for more information.
