Binder Saturation as a Controlling Factor for Porosity Variation in 3D-Printed Sandstone

Binder jet additive manufacturing (BJ-AM) is a rapidly evolving 3D printing technique where the access to an array of powder materials is expanding. The use of silica sand has grown in popularity within the BJ-AM sector and has been shown to have a high potential of replicating physiochemical properties of natural materials for geoengineering applications. Consistent porosity is critical for 3D-printed samples used in rock testing since homogeneity between samples would provide unlimited capabilities in a laboratory setting. Binder saturation is one of the key user-set parameters that controls the ratio between the dimensional tolerance and porosity. Nonetheless, the binder saturation is an internal calculation by the printer’s software that relies on several assumptions, where the most important physical aspect is droplet spacing. This study establishes relationships between the droplet spacing, dimensional tolerance, binder saturation, and porosity. By holding the droplet volume constant and changing its spacing, better control of saturation was observed. Higher saturation reduced porosity and increased circularity of cylindrical samples, but overall dimensional tolerance of fine features was reduced. This study provides improvements of 3D-printed rock for the representation of porosity and geomechanical properties observed in natural sandstones.

Classification of Dimensional Deviation in Additive Manufacturing LPBF Process for AlSi10Mg Alloy According to ISO 286 and ANSI B4.2

Additive manufacturing (AM) processes are gaining popularity and are currently used in many research activities including the biomedical applications, the automotive industries and the aerospace. Laser powder bed fusion (LPBF) is an important AM process. Metallic LPBF process is experiencing significant growth, but one of the difficulties facing this growth is limited knowledge of its dimensional and geometrical performances, in addition to the inability to predict it. In this paper, we present the dimensional deviations of some LPBF-manufactured parts selected for this investigation. a uniform method was developed regarding relevant test specimens to examine dimensional deviations in order to derive dimensional tolerance values. The manufactured test specimens were measured to examine the process dimensional deviations behavior. These parts were manufactured from AlSi10Mg powder using an EOSINT M280 printer. The results show possible dimensional tolerance values that were classified from IT1 to IT11 according to the international standard ISO 286.

Three-dimensional tolerance analysis of discrete surface structures based on the torsor cluster model

Purpose The purpose of this paper is to propose a novel mathematical model to present the three-dimensional tolerance of a discrete surface and to carry out an approach to analyze the tolerance of an assembly with a discrete surface structure. A discrete surface is a special structure of a large surface base with several discrete elements mounted on it, one, which is widely used in complex electromechanical products. Design/methodology/approach The geometric features of discrete surfaces are separated and characterized by small displacement torsors according to the spatial relationship of discrete elements. The torsor cluster model is established to characterize the integral feature variation of a discrete surface by integrating the torsor model. The influence and accumulation of the assembly tolerance of a discrete surface are determined by statistical tolerance analysis based on the unified Jacobian-Torsor method. Findings The effectiveness and superiority of the proposed model in comprehensive tolerance characterization of discrete surfaces are successfully demonstrated by a case study of a phased array antenna. The tolerance is evidently and intuitively computed and expressed based on the torsor cluster model. Research limitations/implications The tolerance analysis method proposed requires much time and high computing performance for the calculation of the statistical simulation. Practical implications The torsor cluster model achieves the three-dimensional tolerance representation of the discrete surface. The tolerance analysis method based on this model predicts the accumulation of the tolerance of components before their physical assembly. Originality/value This paper proposes the torsor cluster as a novel mathematical model to interpret the tolerance of a discrete surface.

A quasi-Monte Carlo statistical three-dimensional tolerance analysis method of products based on edge sampling

Purpose The conventional statistical method of three-dimensional tolerance analysis requires numerous pseudo-random numbers and consumes enormous computations to increase the calculation accuracy, such as the Monte Carlo simulation. The purpose of this paper is to propose a novel method to overcome the problems. Design/methodology/approach With the combination of the quasi-Monte Carlo method and the unified Jacobian-torsor model, this paper proposes a three-dimensional tolerance analysis method based on edge sampling. By setting reasonable evaluation criteria, the sequence numbers representing relatively smaller deviations are excluded and the remaining numbers are selected and kept which represent deviations approximate to and still comply with the tolerance requirements. Findings The case study illustrates the effectiveness and superiority of the proposed method in that it can reduce the sample size, diminish the computations, predict wider tolerance ranges and improve the accuracy of three-dimensional tolerance of precision assembly simultaneously. Research limitations/implications The proposed method may be applied only when the dimensional and geometric tolerances are interpreted in the three-dimensional tolerance representation model. Practical implications The proposed tolerance analysis method can evaluate the impact of manufacturing errors on the product structure quantitatively and provide a theoretical basis for structural design, process planning and manufacture inspection. Originality/value The paper is original in proposing edge sampling as a sampling strategy to generating deviation numbers in tolerance analysis.

Binder Saturation, Layer Thickness, Drying Time and Their Effects on Dimensional Tolerance and Density of Cobalt Chrome- Tricalcium Phosphate Biocomposite

Traditional metals such as stainless steel, titanium and cobalt chrome are used in biomedical applications (implants, scaffolds etc.) but suffer from issues such as osseointegration and compatibility with existing bone. One way to improve traditional biomaterials is to incorporate ceramics with these metals so that their mechanical properties can be similar to cortical bones. Tricalcium phosphate is such a ceramic with properties so that it can be used in human body. This research explores the use of binder jetting based additive manufacturing process to create a novel biocomposite made of cobalt chrome and tricalcium phosphate. Experiments were conducted and processing parameters were varied to study their effect on the printing of this biocomposite. Layer thickness, binder saturation and drying time affected the dimensional tolerance and the density of the green samples. This effect is important to understand so that the material can be optimized for use in specific applications.

Analysis of Dimensional Tolerances on Hydraulic and Acoustic Properties of a New Type of Prototypal Gear Pumps

This study focuses on the construction of a prototype series of pumps. The technological capabilities of the entire series of gear pumps with a three-poly-involute outline were determined. We developed neural networks to analyze the dimensional tolerance and composition of the pump components and impact on the distribution for the constructed units. The most crucial dimensions to control were then determined—namely, dimensional and form tolerance were necessary—with a reduction in accuracy classification where it is less important. Measurements of acoustic quantities and of vibrations were also carried out. In conclusion, after positive verification, printed polyethylene wheels can be manufactured in greater, mass-produced quantities. Optimization techniques can then be applied, leading to reduced manufacturing costs and increased efficiency.