Dimensional precision and robustness of Fused Deposition Modelling (FDM) additive manufacturing processes

Lead Research Organisation: UNIVERSITY OF CAMBRIDGE
Department Name: Engineering

Abstract

Additive Manufacturing (AM) presents designers with a unique set of new possibilities, to design new components with new shapes. Fused Deposition Modelling has become one of the most ubiquitous of AM processes, due to the comparatively low cost of these machines. However, the utility of FDM to designers is limited by the performance capabilities of these machines, especially with complex or small structures. As a result, much of the use is by 'hobbyists' and many parts require several iterations of production due to inaccuracies in manufacture. Whilst most machine brochures cite 'resolution' and axis speed as an indicator of performance, dimensional precision is extremely often not indicated.
This project aims to explore the dimensional capability of 3D printing technologies, more specifically that of FDM machines. The first output will be a greater understanding of the current capability of different machines, which is essential data if these technologies are to be used be designers. This data will be used to deliver the second output, the re-design of an FDM machine using the principles of robust machine tool design.
Experiments will be conducted on as wide a set of FDM machines as is possible. This will include a baseline study of machine repeatability as well as the characterisation of dimensional accuracy over the full build volume. These experiments will also establish the interdependencies and impact of different process settings on print quality.
It is expected that analysis of the outputs from the experimental phase in relation to the underlying machine design principles adopted, will determine how the machine design might influence the variations seen. Outputs from this phase will be used to design a new FDM machine, with the objective of producing parts with a high level of dimensional accuracy and repeatability.
The project covers the EPSRC research areas of Engineering Design and Manufacturing Technologies.

Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509620/1 30/09/2016 29/09/2022
1971221 Studentship EP/N509620/1 05/01/2018 29/09/2021 Samuel Massey
NE/W503204/1 31/03/2021 30/03/2022
1971221 Studentship NE/W503204/1 05/01/2018 29/09/2021 Samuel Massey
 
Description The first thing that has been undertaken has been a thorough test of current desktop FDM (a type of 3D printing) machine capability. This covered accuracy and precision in all 3 axes (X,Y,Z) across machines of varying price points, different prints, different areas of the print bed and for different nominal dimensions. This showed some deviation from the intended dimensions (i.e. a lack of accuracy), some shape inaccuracies and some precision error. From this, it was shown that by error correction either in the software or machine, significant improvements were possible. Further, it was demonstrated that the user/designer could make specific design choices which best utilise the technology, minimising the errors demonstrated in the experimentation above.
Additional testing on individual strand deposition has also been conducted, and shapes analysed. This has shown the root character of some of these inaccuracies. Modified extrusion geometry has been fabricated, which shows the potential to improve component properties in a variety of ways.
Finally the current best available software has been analysed to understand the difference between what the machine code is expecting (i.e. nominal shape) and what actually is produced. This has included a detail review of the most popular software packages to understand their component creation algorithms.
Exploitation Route The most obvious way this would be taken forwards is by producers FDM machines and of so-called 'slicing' software. With the work that has been carried out, superior machines should be able to be produced which give more accurate and precise printed components. However, with further work this may also be beneficial to certain specific user groups, especially those operating as smaller length scales or with traditionally difficult-to-print materials such as in biofabrication or the food industry.
Sectors Agriculture

Food and Drink

Creative Economy

Education

Healthcare

Manufacturing

including Industrial Biotechology
 
Title Complete literature database 
Description A full database of relevant literature has been created, with categorisations, macros to query certain aspects, and the ability to produce the desired citation format. This has been used by other members in the department to find specific literature for their work on a number of occasions. 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
Impact I have been able to give more targeted literature to a number of other students by searching my own database for certain items. It has also enabled higher-level findings, such as the frequency of publications in specific fields or geographical areas of high research activity. 
 
Description Engagement with Formula One team r.e. Additive Manufacturing 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Industry/Business
Results and Impact Dialogue with the Operations Director of a Formula One team to discuss how they can use Additive Manufacturing in their operations. Now in discussions to run student projects with the team which I will help to supervise.
Year(s) Of Engagement Activity 2020
 
Description Presentation to colleagues regarding FDM accuracy and precision 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Postgraduate students
Results and Impact Presentation within the Institute for Manufacturing regarding project work undertaken
Year(s) Of Engagement Activity 2018