Get instant quote

Dimensional accuracy of 3D printed parts

This article presents the expected dimensional accuracy of parts produced via 3D printing and discusses why part inaccuracies occur.

Dimensional accuracy of 3D printed parts

Introduction

The aim of this article is to provide engineers and designers with a method for comparing the expected dimensional accuracy that can be obtained from 3D Printing technologies. While all technologies have strengths and weaknesses, the 2 most governing factors on whether a part will print to specifications are:

Design - The accuracy of printed a part depends heavily on the design. Variations in cooling and curing result in internal stresses that can lead to warping or shrinkage. 3D printing is not suited for flat surfaces or long thin unsupported features. Accuracy will also decrease as part sizes become larger. Specific design recommendations for each of the technologies discussed in this article can be found in Chapter 5 of the Knowledge Base.

Materials - Like design, accuracy also depends upon material. Often the accuracy of a part is sacrificed for the enhancement of a specific material property. For example, a standard SLA resin will produce more dimensionally accurate parts than flexible resin. For parts where high accuracy is critical, standard printing materials are recommended.

How to Make Perfect 3D Printed Parts

Accuracy variables

In order to help quantify the accuracy of a 3D printed part the following parameters will be used.

  • Dimensional accuracy - quantitative values from machine manufacturers and material suppliers that state the expected accuracy of parts. All tolerances stated are with respect to well designed parts on a well calibrated machines.
  • Warping or shrinkage - the likelihood a part will warp or shrink during the printing stage. This depends heavily on design however some processes produce parts that are inherently more at risk of warping or shrinking.
  • Support requirements - for many 3D printing technologies, the amount of support used will govern how accurately a surface or feature is printed. The downside to this is that support affects the surface finish of a part as it must be removed.

For information on the minimum feature size and details that each 3D printing technology is able to achieve refer here. The impact layer height has on a 3D printed part is discussed in this article.

FDM

Fused deposition modeling (FDM) is best suited for low-cost prototyping, where form and fit are more important than function.FDM produces parts one layer at a time by extruding a thermoplastic onto a build plate.

For large parts, this can lead to big variations in temperature across the build platform. As different areas of the part cool at different rates internal stress cause the print to deform, leading to warping or shrinkage. Solutions like printing rafts, heated beds, and radii at sharp edges and corners can help to reduce this.

Differnet materials are more prone to warping than others. For example, ABS is known to be more susceptible to warping than PLA.

Dimensional tolerance ± 0.5% (lower limit: ± 0.5 mm) - desktop± 0.15% (lower limit: ± 0.2 mm) - industrial
Shrinkage/warping Thermoplastics that require a higher print temperature are more at risk. Adding a radius on the bottom edge in contact with the build plate or a brim is recommended. Shrinkage usually occurs in the 0.2 - 1% range depending on material.
Support requirements Essential to achieve an accurate part. Required for overhangs greater than 45o degrees.

Curious about the cost and material options for FDM?

Get instant quote See all FDM materials

SLA

SLA (stereolithography) printers use a laser to UV cure specific areas of a resin tank to form a solid part one cross-section at a time. These cured areas, however, are not at full strength until post-processing with UV. Because of this and the angle and orientations that SLA parts are typically printed at, sagging of unsupported spans can occur.

As one layer is built up at a time, this effect becomes cumulative leading to the dimensional discrepancies sometimes seen in tall SLA parts. Dimensional discrepancies can also occur because of the peeling process used by some SLA printers. The pulling force during the peeling process can cause the soft print to bend which again can accumulate as each layer is built up.

Resins that have higher flexural properties (less stiff) are at a greater risk of warping and may not be suitable for high accuracy applications.

Dimensional tolerance ± 0.5% (lower limit: ± 0.10 mm) - desktop± 0.15% (lower limit: ± 0.01 mm) - industrial
Shrinkage/warping Likely for unsupported spans.
Support requirements Essential to achieve an accurate part.

Curious about the cost and the available material options of SLA 3D printing?

Get instant quote See all SLA materials

SLS

Selective laser sintering (SLS) produces parts with high accuracy and can print designs with complex geometry. A laser selectively sinters powder one layer at a time to form a solid part.

To restrict the likelihood of parts warping or shrinking during printing, SLS printers use heated build chambers that heat up the powder to just below the sintering temperature. This does still, however, result in temperature gradients in large SLS parts where the bottom of the part has cooled while the recently printed top layers remain at an elevated temperature. To further mitigate the likelihood of warping occurring parts are left in the powder to cool slowly (often for 50% of the total build time).

Dimensional tolerance ± 0.3% (lower limit: ± 0.3 mm)
Shrinkage/warping Shrinkage usually occurs in the 2 - 3% range however most SLS print providers allow for this in the design.
Support requirements Not required.

Curious about the cost and available material options for SLS 3D printing?

Get instant quote See all SLS materials

Material Jetting

Material jetting is considered the most accurate form of 3D printing. Because there is no heat involved in the printing process warping and shrinkage rarely occur.

Most dimensional accuracy issues related to features and thin walls that are printed below printer specifications. Material jetting prints support as a solid structure from a soft secondary material that is removed after printing. The solid nature of the support results in surfaces in contact with the support being printed to a high level of accuracy. Care must be taken when handling parts produced via material jetting as they can warp and dimensionally change as a result of exposure to ambient heat, humidity, or sunlight.
















Dimensional tolerance ± 0.1% (lower limit: ± 0.05 mm)
Shrinkage/warping Not an issue for material jetting.
Support requirements Essential to achieve an accurate part.

Metal 3D printing

Metal printing (specifically DMLS and SLM) use a laser to selectively sinter or melt metal powder to produce metal parts. Much like SLS, metal printing produces parts one layer at a time in a controlled, heated environment on industrial-sized machines. This layer-by-layer construction coupled with the very high temperatures involved in the process creates extreme thermal gradients, and the net effect is that stresses are built into the part.

As a result, metal printed parts are at a high risk of distorting or warping, meaning good design practices and part orientation are critical to achieving an accurate part. Unlike SLS, support structures are vital to minimize distortion of the part during production. Parts are also generally built upon a solid metal plate and need to be removed once the print process is complete. A sound understanding of the process is required along with solid and lattice support structures to keep the part securely attached to the print bed and stop it from detaching. Most parts are also stress relieved (via a heat treatment process) after they’re built and before removal from the build plate (doing so allows the crystalline structure to relax, preventing failure later).

Since the cost of metal 3D printed parts is high, simulations are often used to validate the accuracy of a design, before starting the print job.

Dimensional tolerance ± 0.1 mm
Shrinkage/warping Parts at a high risk of shrinkage or warping. Bracing and support are used to help reduce the likelihood of this occurring.
Support requirements Essential to achieve an accurate part.

Curious about the cost and available material options for Metal 3D printing?

Get instant quote See all Metal 3D printing materials

Rules of thumb

  • For the highest accuracy (and when budget is not a constraint), Material Jetting is the optimal solution.
  • For high accuracy, SLA is recommended for parts smaller than 1000 cm3 (10 x 10 x 10 cm), and SLS for parts with dimensions greater than 1000 cm3 (10 x 10 x 10 cm).
  • Quick, cost-effective prototyping FDM is the best solution.

More resources for engineers

A custom designed part printed on MJF printer.

What is Multi Jet Fusion (MJF)? Explained by Hubs

Multi Jet Fusion (MJF) is a 3D printing process for building prototyping and end-use parts fast. This article explains how MJF works and its main advantages.

Read article
FDM Rapid Prototyping Service

What is rapid prototyping?

Rapid prototyping uses 3D computer-aided design (CAD) and manufacturing processes to quickly develop 3D parts or assemblies for research and development and/or product testing.

Read article
SLA 3D Printing materials compared

SLA 3D printing materials compared

Compare the main SLA 3D printing resins - standard, tough, durable, heat resistant, rubber-like, dental and castable - by material properties and find the best option for your application.

Read article
Introduction to Binder Jetting 3D printing

What is Binder Jetting 3D printing?

In this introduction to Binder Jetting 3D printing, we cover the basic principles of the technology. After reading this article you will understand the fundamental mechanics of the Binder Jetting process and how these relate to its benefits and limitations.

Read article
Selecting the right 3D printing process

Selecting the right 3D printing process

Decision making tools and generalized guidelines to aid you select the right 3D printing process for your application.

Read article
Introduction to Metal 3D printing

What is metal 3D printing and how does it work?

What is metal 3D printing? How does this additive technology work? In this comprehensive introduction, we cover the basic principles of SLM (selective laser melting) and DMLS (direct metal laser sintering). Learn the fundamental mechanics of SLM and DMLS and how these relate to the key benefits and limitations of 3D printing.

Read article
HP MJF vs. SLS: A 3D Printing Technology Comparison

What is the difference between Selective Laser Sintering (SLS) and Multi Jet Fusion (MJF) 3D printing?

What is the difference between MJF and SLS 3D printing technology in terms of accuracy, materials, cost and lead times? Here’s how to choose the right additive manufacturing technology for your custom part needs.

Read article
Introduction to Material Jetting 3D Printing

Introduction to material jetting 3D printing

In this introduction to Material Jetting 3D printing, we cover the basic principles of the technology. After reading this article you will understand the fundamental mechanics of the Material Jetting process and how these relate to its benefits and limitations.

Read article
3D printed Injection Molds: Materials Compared

3D printed injection molds: Materials compared

We compare critically two industrial 3D printing materials used for low-run injection mold manufacturing.

Read article
Introduction to SLS 3D Printing

What is SLS 3D printing?

Learn about the basic principles of selective laser sintering, also known as SLS 3D printing. Discover how SLS 3D printing works, the advantages of SLS techniques for rapid prototyping and low-production runs, and the various materials and options available that will suit your part or project.

Read article
Introduction to SLA 3D Printing

What is SLA 3D printing?

Get to know the basics of stereolithography, also known as SLA 3D printing. Find out why the original 3D printing technique is still so popular and cost-effective, learn about how SLA printing works and its parameters and discover which materials and options will best suit your custom part needs.

Read article
Online rapid prototyping service

What is FDM (Fused Deposition Modeling) 3D printing? Explained by Hubs

Interested in learning the basics of FDM 3D printing? In this article, we explain why this technology is an efficient and cost-effective choice for rapid prototyping and other applications.

Read article
A custom designed part printed on MJF printer.

What is Multi Jet Fusion (MJF)? Explained by Hubs

Multi Jet Fusion (MJF) is a 3D printing process for building prototyping and end-use parts fast. This article explains how MJF works and its main advantages.

Read article
FDM Rapid Prototyping Service

What is rapid prototyping?

Rapid prototyping uses 3D computer-aided design (CAD) and manufacturing processes to quickly develop 3D parts or assemblies for research and development and/or product testing.

Read article
SLA 3D Printing materials compared

SLA 3D printing materials compared

Compare the main SLA 3D printing resins - standard, tough, durable, heat resistant, rubber-like, dental and castable - by material properties and find the best option for your application.

Read article
Introduction to Binder Jetting 3D printing

What is Binder Jetting 3D printing?

In this introduction to Binder Jetting 3D printing, we cover the basic principles of the technology. After reading this article you will understand the fundamental mechanics of the Binder Jetting process and how these relate to its benefits and limitations.

Read article
Selecting the right 3D printing process

Selecting the right 3D printing process

Decision making tools and generalized guidelines to aid you select the right 3D printing process for your application.

Read article
Introduction to Metal 3D printing

What is metal 3D printing and how does it work?

What is metal 3D printing? How does this additive technology work? In this comprehensive introduction, we cover the basic principles of SLM (selective laser melting) and DMLS (direct metal laser sintering). Learn the fundamental mechanics of SLM and DMLS and how these relate to the key benefits and limitations of 3D printing.

Read article
HP MJF vs. SLS: A 3D Printing Technology Comparison

What is the difference between Selective Laser Sintering (SLS) and Multi Jet Fusion (MJF) 3D printing?

What is the difference between MJF and SLS 3D printing technology in terms of accuracy, materials, cost and lead times? Here’s how to choose the right additive manufacturing technology for your custom part needs.

Read article
Introduction to Material Jetting 3D Printing

Introduction to material jetting 3D printing

In this introduction to Material Jetting 3D printing, we cover the basic principles of the technology. After reading this article you will understand the fundamental mechanics of the Material Jetting process and how these relate to its benefits and limitations.

Read article
3D printed Injection Molds: Materials Compared

3D printed injection molds: Materials compared

We compare critically two industrial 3D printing materials used for low-run injection mold manufacturing.

Read article
Introduction to SLS 3D Printing

What is SLS 3D printing?

Learn about the basic principles of selective laser sintering, also known as SLS 3D printing. Discover how SLS 3D printing works, the advantages of SLS techniques for rapid prototyping and low-production runs, and the various materials and options available that will suit your part or project.

Read article
Introduction to SLA 3D Printing

What is SLA 3D printing?

Get to know the basics of stereolithography, also known as SLA 3D printing. Find out why the original 3D printing technique is still so popular and cost-effective, learn about how SLA printing works and its parameters and discover which materials and options will best suit your custom part needs.

Read article
Online rapid prototyping service

What is FDM (Fused Deposition Modeling) 3D printing? Explained by Hubs

Interested in learning the basics of FDM 3D printing? In this article, we explain why this technology is an efficient and cost-effective choice for rapid prototyping and other applications.

Read article

Show more

Show less

Design ready? Upload your parts for a free, instant quote

Get an instant quote