A Study on Binder Jetting of High Dimensional Stability Alloy<strong> </strong>

Abstract

This work opens a new pathway to fabricate high dimensional stability Invar36 aerospace devices with Binder Jetting technology, for applications where temperature fluctuations directly interfere in the correct performance of high sensibility systems. Since full density part fabrication is one of the main ongoing challenges for Binder Jetting, the leading objective of this work is to study and optimise the main process parameters to increase the final density of Invar36 printed parts. Microstructural analysis and obtained density and CTE values, confirmed the feasibility to fabricate Invar36 parts.

Powder condition and spreading parameter impact on green and sintered density in metal binder jetting

“…The lower influence of the circumferential roller speed on the sintered density is related to the lower impact of the roller diameter on the sintered density compared to the green density. According to previous studies, the rotational roller speed has no considerable influence in general [11] unless it drops below a critical speed and acts as a doctor blade [46,50]. These investigations confirm the literature regarding the negligible impact of the roller rotation speed.…”

“…In other studies, an increase in the supply to spread ratio has not yet shown consistent results. While Azurmendi et al [11] reported an increase in sintered density below the statistical error in a small varied range, Shrestha et al [16] observed a significant improvement in powder-binder interaction and densification. What makes the specific investigation of the supply to spread ratio so difficult is the fact that its precise setting is complex.…”

“…Due to the low resolution, only predictions regarding the main effects can be made. This method has already been used for MBJ investigations before [11,16,41–43].…”

“…Instead of selectively melting the particles of the powder bed, in MBJ a liquid binder deposited by a print head is bonding the powder particles to create green parts, which are then consolidated by a subsequent sintering step [3]. This enables a high build-rate as well as the processing of a wide range of materials [4,5] such as hard weldable materials like high-carbon tool steels [6], ceramics [7–9] and hard metals [10] or functional materials [11–14] in addition to the most common user metals, like stainless steels [15–19], titanium alloys [20,21], nickel-based alloys [22–24] and cobalt-based alloys [25,26]. Materials that tend to show high residual stresses and cracks in LBM [6,25–27] can be processed without distortion due to the homogeneous temperature distribution during sintering.…”

Correlation of Different Cemented Carbide Starting Powders with the Resulting Properties of Components Manufactured via Binder Jetting

“…Furthermore, the powder-based system is distinguished by its low green density compared to conventional pressing or extrusion while also ensuring high productivity. Previously, hardmetals with medium and coarse WC grain size, often exhibiting abnormal WC grain growth, and with a cobalt content of 12 wt.% or above have been studied [20][21][22][23][24][25][26][27][28][29][30]. Investigations on starting materials with smaller WC grain sizes were also carried out with older binder jetting printers [31].…”