Search results

1 – 3 of 3
Per page
102050
Citations:
Loading...
Access Restricted. View access options
Article
Publication date: 13 October 2020

Mattia Mele, Giampaolo Campana, Gregorio Pisaneschi and Gian Luca Monti

Multi jet fusion is an industrial additive manufacturing technology characterised by high building speed and considerable properties of the parts. The cooling phase represents a…

300

Abstract

Purpose

Multi jet fusion is an industrial additive manufacturing technology characterised by high building speed and considerable properties of the parts. The cooling phase represents a crucial step to determine productivity, since it can take up to 4.5 times the building time. The purpose of this paper is to investigate into effects of cooling rate on parts manufactured by multi jet fusion. Crystallinity, density, distortions and mechanical properties of specimens produced through an HP multi jet fusion 4200 are examined.

Design/methodology/approach

An experimental activity is carried out on specimens cooled down at three different rates. Properties of the parts are analysed by means of differential scanning calorimetry, optical microscopy, three-dimensional scanning and tensile testing.

Originality/value

The present work makes a contribution to the body of knowledge providing correlations between the cooling phase of multi jet fusion and part properties. These results can be used to choose the right balance between production time and product quality.

Details

Rapid Prototyping Journal, vol. 26 no. 10
Type: Research Article
ISSN: 1355-2546

Keywords

Access Restricted. View access options
Article
Publication date: 26 April 2023

Mattia Mele, Giampaolo Campana, Gregorio Pisaneschi, Luciano De Martino and Michele Ricciarelli

The purpose of this paper is to give an insight into relevant aspects of 3D printing of clay paste enhanced with scrap polymer powder which have not been investigated by previous…

150

Abstract

Purpose

The purpose of this paper is to give an insight into relevant aspects of 3D printing of clay paste enhanced with scrap polymer powder which have not been investigated by previous studies. Specifically, the geometrical features of the deposited lines, dimensional accuracy of benchmarks and mechanical properties of printed parts are investigated.

Design/methodology/approach

Firstly, the 3D printer is used to deposit lines of the paste under various combinations of material composition and process parameters. 3D scanning is used to measure their dimensional and geometrical errors. The results are elaborated through statistics to highlight the role of material and processing conditions. Then, four benchmark parts are printed using materials with different percentages of polymer powder. The parts are scanned after each step of the post-processing to quantify the effects of printing, drying and melting on dimensional accuracy. Finally, drop weight tests are carried out to investigate the impact resistance of specimens with different powder contents.

Findings

It is found that the quality of deposition varies with the printing speed, nozzle acceleration and material composition. Also, significant differences are observed at the ends of the lines. Materials with 10 Wt.% and 40 Wt.% of powder exhibit relevant shape variations due to the separation of phases. Accuracy analyses show significant deformations of parts at the green state due to material weight. This effect is more pronounced for higher powder contents. On the other hand, the polymer reduces shrinkage during drying. Furthermore, the impact test results showed that the polymer caused a large increase in impact resistance as compared to pure clay. Nonetheless, a decrease is observed for 40 Wt.% due to the higher amount of porosities.

Research limitations/implications

The results of this study advance the knowledge on the 3D printing of clay paste reinforced with a scrap polymer powder. This offers a new opportunity to reuse leftover powders from powder bed fusion processes. The findings presented here are expected to foster the adoption of this technique reducing the amount of waste powder disposed of by additive manufacturing companies.

Originality/value

This study offers some important insights into the relations between process conditions and the geometry of the deposited lines. This is of practical relevance to toolpath planning. The dimensional analyses allow for understanding the role of each post-processing step on the dimensional error. Also, the comparison with previous findings highlights the role of part dimensions. The present research explores, for the first time, the impact resistance of parts produced by this technology. The observed enhancement of this property with respect to pure clay may open new opportunities for the application of this manufacturing process.

Details

Rapid Prototyping Journal, vol. 29 no. 7
Type: Research Article
ISSN: 1355-2546

Keywords

Access Restricted. View access options
Article
Publication date: 20 April 2022

Mattia Mele, Gregorio Pisaneschi, Giampaolo Campana, Andrea Zucchelli and Michele Ciotti

The body of the literature on the Arburg Plastic Freeforming process is still very limited despite the increasing industrial importance of this technology. This paper aims to…

225

Abstract

Purpose

The body of the literature on the Arburg Plastic Freeforming process is still very limited despite the increasing industrial importance of this technology. This paper aims to contribute to a better understanding of this technology by investigating relations between characteristic process parameters and part features. Particularly, the effects of nominal dimension, drop aspect ratio, build chamber temperature and part position on accuracy are investigated. The density of manufactured parts is also measured to understand its relation with dimensional error.

Design/methodology/approach

A benchmark part was designed and manufactured in Polycarbonate on an Arburg Plastic Freeformer 2K-3A. The process was repeated with two levels of drop aspect ratio (1.2125 and 1.2150) and two build chamber temperatures (90°C and 120°C). Each build job included five parts in different positions of the chamber. The dimensional accuracy of benchmarks was measured by using a digital caliper, while Archimede’s principle was used for density measurements. All the acquired results were processed through an analysis of variance to investigate the role of experimental factors.

Findings

Results demonstrate that the linear shrinkage occurring at the end of the 3D printing process is the main source of inaccuracy. The higher the building chamber temperature, the most the part accuracy is influenced by the nominal dimension. The drop aspect ratio affects the dimensional error in the XY plane by increasing the overlap of adjacent droplets. On the other hand, this parameter does not influence the accuracy along the Z direction. The position of the parts inside the building chamber exhibited an influence on results, arguably due to the hot airflows.

Research limitations/implications

This research did not allow for a complete understanding of the role of part positioning on part accuracy. Further study is needed to understand the detail of this phenomenon.

Practical implications

The results of this study can aid the users of Arburg Plastic Freeforming technology by uncovering the role of the main process parameters.

Originality/value

This paper expands the body of knowledge on the Arburg Plastic Freeforming process by providing new information on the role of the main process parameters on dimensional accuracy and density. Particularly, the results answer a research question on the role of the drop aspect ratio, demonstrating that its main effect is to vary the droplets overlap, which, in turn, affects the thermal shrinkage.

Details

Rapid Prototyping Journal, vol. 28 no. 9
Type: Research Article
ISSN: 1355-2546

Keywords

1 – 3 of 3
Per page
102050