How to Define Precision in 3D Printing, Factors that Affect Precision, and Possible Trade-offs.

Precision, accuracy, and resolution are terms that are often used interchangeably to describe the exactness of a standard. However, in the context of engineering, such as 3D printing, precision can refer to either the accuracy of parts or the resolution of a machine.

In addition, precision can also measure the repeatability in producing consistent results. In the manufacturing industry, precision can refer to the ability to produce parts within tolerances. However, the precision of a machine cannot be measured in the same way as the precision of the parts it produces.

When it comes to 3D printing, there are three ways to define precision. These definitions are influenced by various factors that affect the precision of 3D printing. Choosing a 3D printer involves considering the tradeoffs that come with each definition of precision.

Defining precision in 3D printing

Precision in 3D printing can be defined in several different ways. One way is the repeatability of 3D-printed parts. In this case, precision measures the consistency of a precision 3D printer to produce the same result. Precision is measured by how close the measurements of the same part printed on the same machine are to each other.

Another way to define precision in 3D printing is through dimensional accuracy and tolerance. This refers to the level of accuracy and detail that can be achieved in the printed object, and how closely it matches the intended design or dimensions of the digital file. Tolerance is used to measure dimensional accuracy and represents the allowable margin of error or the range within which the printed object can deviate from the intended design while still being considered acceptable.

Precision can also refer to the precision of the 3D printer machine itself. When discussing the precision of the machine, is a combination of the machine's ability to print with accuracy, repeatability, and with high resolution. Essentially, it measures how exacting the machine can be in its ability to print parts.

To understand this better, consider painting as an analogy - while using a wide brush with fast, indiscriminate strokes is more efficient for covering an area, a fine-tipped paintbrush wielded by a trained artist can add a much higher level of detail.

The precision of a 3D printer depends on two variables: the tooltip and the motion control system. The tooltip can be a nozzle, laser, or cutter. The motion control system moves the tooltip across the X, Y, and Z axes. If you compare two 3D printers, one with a 0.4mm wide nozzle and the other with a 0.25mm wide nozzle, the machine with a 0.25mm nozzle would be considered more precise. Similarly, a machine with a motion control system that can operate in smaller increments of movement is also considered more precise.

Factors that can impact the precision of 3D printing are:

• Resolution:
  The precision of the 3D printer relies on its resolution, which determines the level of detail that can be achieved. The smaller the layer heights or minimum feature sizes, the greater the precision.
• Calibration:
  Proper calibration of the 3D printer is critical to achieving precise prints. It involves fine-tuning various parameters such as nozzle height, bed leveling, and extrusion rate to ensure accurate deposition of material.
• Observational tools:
  EOAT can include cameras and sensors to observe other work processes for tasks like quality inspection, part recognition, and material handling.
• Mechanical stability:
  The stability and rigidity of the printer's frame and components are crucial to achieving precision. A well-built and sturdy printer is less likely to experience vibrations or wobbling during printing, resulting in more precise prints.
• Material properties:
  The material properties, such as shrinkage rates, thermal properties, and flow characteristics can affect the precision of a printed part. Understanding and accounting for these properties can help achieve better part precision.
• Design considerations:
  The design of the object being printed can impact precision. Features such as overhangs, bridges, and intricate details may require additional support structures or specific printing techniques to maintain accuracy during the printing process, which may affect the accuracy of the printed part.
• Post-processing:
  Many 3D printed parts require post-processing, such as the removal of support structures or sanding, which can affect the accuracy of the final part.

Tradeoffs for precision in 3D printing

It is worth noting that achieving high precision in 3D printing often involves making tradeoffs. For instance, if the machine's capabilities are constant, printing with higher precision usually requires a compromise in print speed. Using a smaller tool tip can result in higher-resolution prints, but this means that material needs to be deposited at a slower rate.

However, metal binder jetting, such as on the Markforged PX100, is an exception to this rule. This process can produce accurate parts very quickly by using multiple heads to simultaneously jet binding material in several different places at the same time. Therefore, a single build can yield tens or hundreds of accurate parts.

Precision 3D printing can also require new design considerations that were not previously taken into account, especially for complex designs. Fine or intricate features may need to be modified to ensure stability during the printing process.

Precision and considerations for choosing a 3D printer

Precision is a crucial factor in 3D printing as it determines the accuracy of printed parts. Therefore, users should opt for a reliable 3D printing platform that has a proven track record of producing successful prints within acceptable margins.

The level of precision required for a 3D printer depends on the specific applications of the organization. For instance, resin 3D printing is ideal for producing parts with fine features but may not be as strong as high-performance industrial thermoplastics. The latter is a better choice for quickly producing sturdy tooling or fixtures.

When it comes to metal 3D printing, binder jetting is an excellent option for precision without compromising speed. It can create accurate parts quickly with consistency while using less energy, which lowers operating costs per part. Thus, platforms like the Markforged PX100 are a suitable option for producing precise metal parts at scale.