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21 – 30 of 148
Article
Publication date: 1 April 2006

Jaroslav Mackerle

To provide a selective bibliography for researchers working with bulk material forming (specifically the forging, rolling, extrusion and drawing processes) with sources which can…

4715

Abstract

Purpose

To provide a selective bibliography for researchers working with bulk material forming (specifically the forging, rolling, extrusion and drawing processes) with sources which can help them to be up‐to‐date.

Design/methodology/approach

A range of published (1996‐2005) works, which aims to provide theoretical as well as practical information on the material processing namely bulk material forming. Bulk deformation processes used in practice change the shape of the workpiece by plastic deformations under forces applied by tools and dies.

Findings

Provides information about each source, indicating what can be found there. Listed references contain journal papers, conference proceedings and theses/dissertations on the subject.

Research limitations/implications

It is an exhaustive list of papers (1,693 references are listed) but some papers may be omitted. The emphasis is to present papers written in English language. Sheet material forming processes are not included.

Practical implications

A very useful source of information for theoretical and practical researchers in computational material forming as well as in academia or for those who have recently obtained a position in this field.

Originality/value

There are not many bibliographies published in this field of engineering. This paper offers help to experts and individuals interested in computational analyses and simulations of material forming processes.

Details

Engineering Computations, vol. 23 no. 3
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 9 April 2018

Piotr Wolszczak, Krystian Lygas, Mateusz Paszko and Radoslaw A. Wach

The paper aims to investigate the problem of heat distribution in FDM 3D printing. The temperature distribution of the material is important because of the occurrence of shrinkage…

Abstract

Purpose

The paper aims to investigate the problem of heat distribution in FDM 3D printing. The temperature distribution of the material is important because of the occurrence of shrinkage and crystallization phenomena that affect the dimensional accuracy and strength of the material.

Design/methodology/approach

The study uses a thermoplastic material (polylactide) and a test stand equipped with a 3D printer adapted to perform thermographic observations. The main source of heat in the study was a molten laminate material and a hot-end head.

Findings

When the material is molten at the temperature of 190°C, the temperature of a previous layer increases above the glass transition point (Tg = 64.8°C) and reaches to about 80°C. In addition, at the boundary of the layers, there occurs a permanent bonding of the consecutive layers because of their partial melting. The paper also reports the results of porosity of PLA samples printed at the temperature ranging between 205 and 255°C. The degree of porosity depends on the temperature of the extruded material.

Practical implications

The results may be helpful for designers of various printed parts and construction engineers of printing heads and 3D printer chambers.

Originality/value

Thermograms of material layers with a height of 0.3 mm are obtained using a thermal imaging camera with a lens for macro magnification (43 pixels/mm).

Details

Rapid Prototyping Journal, vol. 24 no. 3
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 1 August 1999

Jaroslav Mackerle

This paper gives a bibliographical review of the finite element methods (FEMs) applied to the analysis of ceramics and glass materials. The bibliography at the end of the paper…

2607

Abstract

This paper gives a bibliographical review of the finite element methods (FEMs) applied to the analysis of ceramics and glass materials. The bibliography at the end of the paper contains references to papers, conference proceedings and theses/dissertations on the subject that were published between 1977‐1998. The following topics are included: ceramics – material and mechanical properties in general, ceramic coatings and joining problems, ceramic composites, ferrites, piezoceramics, ceramic tools and machining, material processing simulations, fracture mechanics and damage, applications of ceramic/composites in engineering; glass – material and mechanical properties in general, glass fiber composites, material processing simulations, fracture mechanics and damage, and applications of glasses in engineering.

Details

Engineering Computations, vol. 16 no. 5
Type: Research Article
ISSN: 0264-4401

Keywords

Open Access
Article
Publication date: 9 February 2024

Martin Novák, Berenika Hausnerova, Vladimir Pata and Daniel Sanetrnik

This study aims to enhance merging of additive manufacturing (AM) techniques with powder injection molding (PIM). In this way, the prototypes could be 3D-printed and mass…

Abstract

Purpose

This study aims to enhance merging of additive manufacturing (AM) techniques with powder injection molding (PIM). In this way, the prototypes could be 3D-printed and mass production implemented using PIM. Thus, the surface properties and mechanical performance of parts produced using powder/polymer binder feedstocks [material extrusion (MEX) and PIM] were investigated and compared with powder manufacturing based on direct metal laser sintering (DMLS).

Design/methodology/approach

PIM parts were manufactured from 17-4PH stainless steel PIM-quality powder and powder intended for powder bed fusion compounded with a recently developed environmentally benign binder. Rheological data obtained at the relevant temperatures were used to set up the process parameters of injection molding. The tensile and yield strengths as well as the strain at break were determined for PIM sintered parts and compared to those produced using MEX and DMLS. Surface properties were evaluated through a 3D scanner and analyzed with advanced statistical tools.

Findings

Advanced statistical analyses of the surface properties showed the proximity between the surfaces created via PIM and MEX. The tensile and yield strengths, as well as the strain at break, suggested that DMLS provides sintered samples with the highest strength and ductility; however, PIM parts made from environmentally benign feedstock may successfully compete with this manufacturing route.

Originality/value

This study addresses the issues connected to the merging of two environmentally efficient processing routes. The literature survey included has shown that there is so far no study comparing AM and PIM techniques systematically on the fixed part shape and dimensions using advanced statistical tools to derive the proximity of the investigated processing routes.

Article
Publication date: 31 March 2022

Jorne Driezen and Axel S. Herrmann

This study aims to design a novel strategy to avoid thermal defects in three-dimensional (3D) printing processes. A combination of subroutines and utility routines allows for in

Abstract

Purpose

This study aims to design a novel strategy to avoid thermal defects in three-dimensional (3D) printing processes. A combination of subroutines and utility routines allows for in situ variations of the key process parameters (KPP) in the thermal simulation and produces by post-processing the output an updated machine code for enhanced quality of the printed part in a single iteration.

Design/methodology/approach

The input data for the thermal simulation were obtained by characterising an acrylonitrile butadiene styrene filament and calibrating an Ultimaker S5 printer. Abaqus subroutines were used to accurately simulate the continuous deposition of molten material. A utility routine extracted the nodal temperatures during simulation and detected regions that were prone to overheating. We developed a method, enabling the introduction of variable process parameters in the thermal simulation and validated it by printing several test geometries.

Findings

The results of the thermal simulation indicate that decreasing the print speed enhances the amount of heat dissipated to the environment. Therefore, it is an efficient way to avoid overheating of the printed geometry. The validation geometries showed improvements when adapting the print speed.

Originality/value

This approach is the first to demonstrate the potential of variable process parameters using implemented routines in the thermal process simulation. Here, the focus is on predicting and avoiding thermal hotspots. However, more potential can be obtained by enabling the prediction and adaptation of KPP to ensure mechanical performance. This would be an alternative way to tackle the cost- and time-inefficient post-processing of 3D-printed parts.

Details

Rapid Prototyping Journal, vol. 28 no. 8
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 26 November 2019

Mushtaq Beigh, Syed Zameer Hussain, Tahiya Qadri, Bazila Naseer, Tariq Raja and Haroon Naik

Keeping in view the diabetes status that has affected about 415 million people globally and is the leading cause of death in many countries along with therising demand for low…

Abstract

Purpose

Keeping in view the diabetes status that has affected about 415 million people globally and is the leading cause of death in many countries along with therising demand for low Glycemic Index (GI) foods, the purpose of this paper is to optimize the extrusion process for the development of low GI snacks from underutilized crops like water chestnut and barley.

Design/methodology/approach

The extrusion parameters (screw speed and barrel temperature), feed moisture and water chestnut flour, barley flour proportion, were varied and their effects on system and product responses (specific mechanical energy, water absorption index, water solubility index, bulk density, expansion ratio and breaking strength) were studied.

Findings

All the system and product responses were significantly affected by independent variables. Response surface and regression models were established to determine the responses as function of process variables. Models obtained were highly significant with high coefficient of determination (R2=0.88). The optimum processing conditions obtained by numerical optimization for the development of snacks were 90°C barrel temperature, 300 rpm screw speed, 14 per cent feed moisture and WCF-to-BF ratio as 90:10. Shelf life studies confirmed that the developed snacks can be safely stored in HDPE bags for a period of six months under ambient conditions.

Originality/value

Water chestnut and barley flour did not blend till date for extrusion cooking. Such snacks shall be a viable food option for diabetic people and can act as laxative due to high fibre and β-glucan content from barley.

Details

British Food Journal, vol. 122 no. 1
Type: Research Article
ISSN: 0007-070X

Keywords

Article
Publication date: 1 April 1985

Americus

The coating of plastics has occupied the attention of polymer chemists for the past 30 years. Several problems are immediately obvious. If the coating is a hard resistant…

Abstract

The coating of plastics has occupied the attention of polymer chemists for the past 30 years. Several problems are immediately obvious. If the coating is a hard resistant thermoset like a baked phenolic, it provides a surface to which every few substances will adhere: Two generations ago all telephones were black for this reason. If on the other hand the polymer is thermoplastic, adhesion is not necessarily a problem but solvents are, since the solvent in the coating can erode the polymer's surface. Plastic surfaces require coating for a number of reasons and this has caused imaginative chemists to devise new coatings and new coating techniques to meet the challenges. Some plastics require coatings simply for decoration. Some require coatings in order to protect the surfaces. This is particularly true in the electronics area. The need for coatings for plastics has been accelerated by the desire of the automotive industry to replace metal with polymers. If the plastic is part of the automobile body it must be coated to match perfectly the coated metal part. Reaction injection moulding (RIM) is providing a means for supplying the automotive industry with large parts such as bumpers, fascias, and in the not too far future doors and hoods. Naturally the coatings on these must duplicate precisely the coating on the metal portions of the car.

Details

Pigment & Resin Technology, vol. 14 no. 4
Type: Research Article
ISSN: 0369-9420

Article
Publication date: 1 May 1991

Edgar S. Lower

A number of derivatives of vegetable and animal oils and fats are useable in the processing of rubbers, including fatty acids, fatty acid amides, amines, metallic soaps, and…

Abstract

A number of derivatives of vegetable and animal oils and fats are useable in the processing of rubbers, including fatty acids, fatty acid amides, amines, metallic soaps, and sulphur containing materials, etc.

Details

Pigment & Resin Technology, vol. 20 no. 5
Type: Research Article
ISSN: 0369-9420

Article
Publication date: 2 September 2021

Mattia Mele, Michele Ricciarelli and Giampaolo Campana

Powder bed additive manufacturing processes are widespread due to their many technical and economic advantages. Nevertheless, the disposal of leftover powder poses a problem in…

Abstract

Purpose

Powder bed additive manufacturing processes are widespread due to their many technical and economic advantages. Nevertheless, the disposal of leftover powder poses a problem in terms of process sustainability. The purpose of this paper is to provide an alternative solution to recycle waste PA12 powder from HP multi jet fusion. In particular, the opportunity to use this material as a dispersion in three-dimensional (3D) printed clay is investigated.

Design/methodology/approach

A commercial fused deposition modelling printer was re-adapted to extrude a viscous paste composed of clay, PA12 and water. Once printed, parts were dried and then put in an oven to melt the polymer fraction. Four compositions with different PA12 concentration were studied. First, the extrudability of the paste was observed by testing different extrusion lengths. Then, the surface porosities were evaluated through microscopical observations of the manufactured parts. Finally, benchmarks with different geometries were digitalised via 3D scanning to analyse the dimensional alterations arising at each stage of the process.

Findings

Overall, the feasibility of the process is demonstrated. Extrusion tests revealed that the composition of the paste has a minor influence on the volumetric flow rate, exhibiting a better consistency in the case of long extrusions. The percentage of surface cavities was proportional to the polymer fraction contained in the mix. From dimensional analyses, it was possible to conclude that PA12 reduced the degree of shrinkage during the drying phase, while it increased dimensional alterations occurring in the melting phase. The results showed that the dimensional error measured on the z-axis was always higher than that of the XY plane.

Practical implications

The method proposed in this paper provides an alternative approach to reuse leftover powders from powder bed fusion processes via another additive manufacturing process. This offers an affordable and open-source solution to companies dealing with polymer powder bed fusion, allowing them to reduce their environmental impacts while expanding their production.

Originality/value

The paper presents an innovative additive manufacturing solution for powder reuse. Unlike the recycling methods in the body of literature, this solution does not require any intermediate transformation process, such as filament fabrication. Also, the cold material deposition enables the adoption of very inexpensive extrusion equipment. This preliminary study demonstrates the feasibility and the benefits of this process, paving the way for numerous future studies.

Details

Rapid Prototyping Journal, vol. 28 no. 2
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 17 September 2019

Daniel A. Porter, Nicholas Davis, Paul S. Krueger, Adam L. Cohen and David Son

Techniques of extrude and cure additive manufacturing for thermally cured, high viscosity and medical-grade silicone are investigated by using a small ram extruder and a…

Abstract

Purpose

Techniques of extrude and cure additive manufacturing for thermally cured, high viscosity and medical-grade silicone are investigated by using a small ram extruder and a near-infrared (IR) laser. The purpose of this study is to evaluate the process parameter effects on the stiffness of the final products.

Design/methodology/approach

Process parameter effects on axial stiffness values and durometer are explored. Parameters such as extrusion layer height, laser speed, laser current, laser raster spacing and multiple laser passes were investigated and compared to traditional cast and cure methods. Dimensional changes were also recorded and compared.

Findings

Tensile and durometer tests show that certain curing parameters give tensile stress and durometers within 10 per cent of bulk material specifications at 200 per cent strain. Parameters that had the highest impact on tensile stress at 200 per cent strain were layer height (0.73 per cent) followed by laser power (0.69 per cent), and then laser raster spacing (0.45 per cent). Parameters that had the highest impact on durometer were laser power (1.00 per cent), followed by layer height, (0.34 per cent) and then laser raster speed (0.32 per cent). Three-dimensional printed samples had about 11.2 per cent more shrinkage than the bulk cast samples in the longest dimension.

Originality/value

This paper is one of the first that demonstrates near IR laser curing parameter effects on three-dimensional printed, commercial off-the-shelf, medical-grade and viscous silicone. The ability to cure very viscous thermosets locally enables interesting technologies such as wire encapsulation, high voltage actuators and drug delivery devices.

Details

Rapid Prototyping Journal, vol. 26 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

21 – 30 of 148