The tolerance of 3D printing for prototype manufacturing depends on several factors, including the type of 3D printing technology, the state and the settings of the printing parameters of the 3D printer, the materials chosen, the model design, etc.

1. What is tolerance?

Tolerance is the amount by which a measurement or calculation might change and still be acceptable. In other words, it is a measure of how closely the actual part produced matches the size of the original design. The tolerance is generally expressed in percentages or millimeters, such as ±1% or ±0.5 mm.

Because 3D printers rely on multiple moving parts, the process will never produce a 100% accurate part (no manufacturing process can do that). 

2. Tolerances of different 3D printing technologies

3D Printing Technologies General Introduction Tolerance

FDM

(Fused Deposition Modeling)

As it is the most affordable 3D printing technology, it is currently being used by the majority of desktop-grade printers.

± 0.5 mm for desktop-level FDM printer

± 0.2 mm for industrial-level printer

SLA

(Stereolithography)

DLP

(Digital Light Processing)

 Both are light polymerization printing technology that uses a light source such as a laser or projector to cure the photosensitive resin.

Generally ± 0.1 mm

± 0.01 mm for professional resin 3D printers

SLS

(Selective Laser Sintering)

 It uses a laser to sinter powder particles, usually with nylon powder. ± 0.3 mm

SLM

(Selective Laser Melting)

 It is a metal powder fusion process that uses a laser to fuse or sinter metal powder particles. ± 0.1 mm

MJ

(PolyJet)

 It is not as common as other 3D printing technologies. MJ is highly precise because it does not require heating, which may lead to distortion, such as warpage. ± 0.05 mm

3. Other factors that affect tolerances of 3D printing

The type of 3D printing is not the only factor affecting the tolerance. Materials, part design, and printing parameters have an impact too.

Printer quality

There is a significant difference in quality between high-end and entry-level printers. Desktop-level 3D printers typically cost only a few thousand, while industrial-level 3D printers start at tens of thousands. It is common to use different electronic components at different prices, such as stepping motors, depending on the price.

Part design

Poorly designed parts are difficult to print accurately even with the best 3D printers. There would be problems, such as too much area, too much length, no support, etc.

Materials

Some materials are less difficult to be printed than others, thus more conducive to making accurate parts. Non-standard materials (e.g. flexible PLA, alloys containing precious metals) tend to sacrifice printability for their unique advantages.

Print parameters

Based on the range of printer settings, users can customize print parameters such as layer height, print speed, filler, etc. These parameters all have an impact on accuracy. For example, the faster the printing speed, the lower the accuracy.

4. How to improve the tolerances of 3D printing?

  • Remove or simplify complex features when designing parts.

  • Export STL files at the highest possible resolution.

  • Calibrate the 3D printer regularly or before important print work.

  • Use supports to stabilize the object while printing. Be careful when removing supports to avoid damaging the part or changing its final dimensions.

  • Use a heated print bed (FDM) or heated chamber (SLS/metal) to keep the temperature of the part consistent to prevent distortion.

  • If there is no time requirement, turn down the print speed if possible.