Suitability of a South African Silica Sand for Three-Dimensional Printing of Foundry Moulds and Cores

Nyembwe, Kasongo; Oyombo, D.; Beer, Deon de; Tonder, PJM van

doi:10.7166/27-3-1662

Cited by 4 publications

(6 citation statements)

References 4 publications

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“…Acharya et al [13] and Nyembwe et al [14] mentioned that it is important to characterize the sand before testing for foundry properties. Although there are several tests available for sand characterization, the most important tests to determine the performance and properties of furan no-bake, sand are: sieve analysis, LOI, pH tests, strength tests, acid demand value, chemical composition, bulk density, and grain shape.…”

Section: Characterisationmentioning

confidence: 99%

“…Nevertheless, all results are within the minimum required bend strength specified by Voxeljet, which is 220 N/cm 2 . The reduced strength of used sand can be explained by the fact that, as shown by the high pH value of the used sand in figure 10, the pH increases during storage, which tends to delay the polycondensation process, resulting in less strength [19]. If there is a high amount of water present in the sand sample, the curing takes long, the bonds between sand particles become weaker and the strength of the moulds and cores reduces.…”

Section: Bend Strengthmentioning

confidence: 99%

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Effects of used sand recycling on the foundry properties of three-dimensional printed sand moulds and cores

Matjila,

Nyembwe

2023

MATEC Web Conf.

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Sand casting is one of the important metal casting processes that involves hard labour and patternmaking to produce sand moulds. However, it has evolved considerably since the adoption of rapid sand casting, a type of additive manufacturing. This advancement has reduced costs and improved lead time by eliminating tooling. Nevertheless, there are still some challenges that are being experienced, such as the recyclability of the waste sand produced by the foundry. With high costs of virgin sand and sand disposal, reusing the used sand is important. The objective of this paper is to evaluate the feasibility of adding new sand to the used sand during rapid sand casting. The results indicate that the semi-activated sand collected from the hopper can be reused to produce sand moulds and cores if new sand is added to it.

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Section: Characterisationmentioning

confidence: 99%

Section: Bend Strengthmentioning

confidence: 99%

Effects of used sand recycling on the foundry properties of three-dimensional printed sand moulds and cores

Matjila,

Nyembwe

2023

MATEC Web Conf.

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“…Process mainly is divided into the following three phases, respectively, pre-processing phase, regeneration phase and post-processing, as shown in Figure 16 (Cai, 2010). Combined with Chinese national standards GB/T 9442-2010-Foundry silica sand, key quality control indexes of reclaimed sand mainly include loss content on ignition, size distribution, acid demand value, angularity, pH, clay content and refractoriness (Nyembwe et al , 2016; Huang, 2012). Key quality control indexes listed above have a particular importance when determining properties of sand moulds, such as strength, permeability, flow ability, plasticity, toughness, gas evolution, deformability and collapsibility (Cai, 2010; Huang, 2012).…”

Section: A New Approach Of 3d Sand Mould Printingmentioning

confidence: 99%

3D sand mould printing: a review and a new approach

Zhao

Guo²,

Zhang³

et al. 2018

RPJ

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Purpose The purpose of this paper is to review available technologies, analyse their features, propose a new approach of 3D sand mould printing based on line forming, introduce the manufacturing principle and show advantages of this approach, especially for larger parts with large Z steps in the build, such as 2 mm stepwise. Design/methodology/approach This paper introduces 3D sand mould printing, compares and analyses technological process and existing fabrication approaches among available technologies first. Then, a new approach of 3D sand mould printing is proposed to improve build speed. In addition, the proposed system will be analysed or benchmarked against existing systems. Findings A new approach based on line forming of sand mould printing is put forward by reviewing and analysing available technologies, to improve build speed from the aspect of basic moulding movement instead of optimization of moulding methods and process parameters. The theoretical calculation and analysis shows that build speed can be improved greatly, and it is more suitable for the manufacture of large-scale casting’s sand mould when considering dimensional accuracy and printing error, as well as uniformity of each layer. Research limitations/implications The specific implement scheme of line forming and nozzle’s specific structure of this new approach need further study. Practical implications Much higher build speed of 3D sand mould printing with new approach brings evident implication for moulds companies and manufacturing industry, having a far-reaching influence on the development of national economy. Originality/value This paper reviews available technologies and presents a new approach of 3D sand mould printing for the first time. Analysis of the new approach shows that this new method of sand mould printing can boost build speed greatly. So, its application prospect is great.

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“…Chromite sand has good metal chilling properties, high thermal resistance, resistance to liquid metal penetration and uniform thermal expansion thus minimizing finning problems [6]. Chromite sand is usable with all types of steels and is particularly suitable for parts made of chrome, chrome nickel and manganese steel [7]. Although chromite sand has superior properties, silica sand is still in use for many castings in South Africa.…”

Section: Introductionmentioning

confidence: 99%

“…As the recommended moulding sands for 3D printing are very expensive, to overcome this challenge and find a cheaper and lasting solution, in 2019 Hodder and Chalaturnyk asked the following question: "Can traditional foundry or non-standard sand be used in 3D printing?" The answer to the question might be essentially "yes", however it has to be established that the sand can flow easily, otherwise it might lead to casts with below-standard mechanical properties resulting in poor dimensional accuracy due to the absence of compaction as the sand is deposited [7].…”

Section: Introductionmentioning

confidence: 99%

Assessment of South African Chromite Sand for Binder Jetting Application

Chauke

Nyembwe²,

Mojisola³

2022

MATEC Web Conf.

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Binder Jetting is an Additive manufacturing (AM) technique in which binding liquid is jetted on layers of powdered materials, selectively according to the Computer Aided Design (CAD) model to form a 3D part. One of the applications of binder jetting technology is the manufacturing of sand moulds for sand casting known as Rapid Sand Casting. Silica sand is often used in both Rapid Sand Casting and traditional moulding due to its good refractory properties coupled with its low cost. However, the use of silica sand is associated with some technical limitations, including its high thermal linear expansion and low conductivity, hence it is not appropriate to all casting applications. Chromite sand is used as an alternative refractory material to address the shortcomings of silica sand. This study assessed the suitability of South African Chromite sand for rapid sand casting. Tensile bending and compression test specimens were manufactured from different South African chromite sand samples using a Voxeljet VX 3D printer. The mechanical properties of the specimen produced using binder jetting were compared to those produced by traditional moulding. It was observed that all five printed specimens met the minimum tensile strength of 220 N/cm2 for casting. Hence locally sourced South African Chromite sand can be utilised for rapid sand casting, reducing environmental impact and operational cost.

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Suitability of a South African Silica Sand for Three-Dimensional Printing of Foundry Moulds and Cores

Cited by 4 publications

References 4 publications

Effects of used sand recycling on the foundry properties of three-dimensional printed sand moulds and cores

Effects of used sand recycling on the foundry properties of three-dimensional printed sand moulds and cores

3D sand mould printing: a review and a new approach

Assessment of South African Chromite Sand for Binder Jetting Application

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