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1 – 10 of over 3000
Article
Publication date: 1 September 1999

Hiroyuki Narahara, Fumiki Tanaka, Takeshi Kishinami, Satoru Igarashi and Katsumasa Saito

In the industrial use of stereolithography, precision is always a problem. The basic phenomenon of solidification shrinkage has not been sufficiently investigated. This…

1012

Abstract

In the industrial use of stereolithography, precision is always a problem. The basic phenomenon of solidification shrinkage has not been sufficiently investigated. This study aims at clarifying the initial linear shrinkage of cured resin in a minute volume. Experimental equipment has been developed which measures the time history of the single strand in situ in a stereolithography machine. An analysis model of the time history of a minute volume linear shrinkage was shown using the measured shrinkage of a cured line segment. The relation between the time history of the linear shrinkage and temperature was measured and the shrinkage in the minute volume after irradiation was found to result due to temperature variation. Deformation and linear shrinkage were measured with two scanning orders to control the thermal distribution in layer forming. The effects of thermal distribution were also observed in one layer forming.

Details

Rapid Prototyping Journal, vol. 5 no. 3
Type: Research Article
ISSN: 1355-2546

Keywords

Open Access
Article
Publication date: 31 October 2022

Solomon O. Obadimu and Kyriakos I. Kourousis

The wide application of metal material extrusion (MEX) has been hampered by the practicalities associated with the resulting shrinkage of the final parts when commercial…

Abstract

Purpose

The wide application of metal material extrusion (MEX) has been hampered by the practicalities associated with the resulting shrinkage of the final parts when commercial three-dimensional (3D) printing equipment is used. The shrinkage behaviour of MEX metal parts is a very important aspect of the MEX metal production process, as the parts must be accurately oversized to compensate for shrinkage. This paper aims to investigate the influence of primary 3D printing parameters, namely, print speed, layer height and print angle, on the shrinkage behaviour of MEX Steel 316L parts.

Design/methodology/approach

Two groups of dog-bone and rectangular-shape specimens were produced with the BASF Ultrafuse Steel 316L metal filament. The length, width and thickness of the specimens were measured pre- and post-debinding and sintering to calculate the percentile shrinkage rates. Analysis of variance (ANOVA) was used to evaluate and rank the significance of each manufacturing parameter on shrinkage. Typical main print quality issues experienced in this analysis are also reported.

Findings

The shrinkage rates of the tested specimens ranged from 15.5 to 20.4% along the length and width axis and 18.5% to 23.1% along the thickness axis of the specimens. Layer height and raster angle were the most statistically significant parameters influencing shrinkage, while print speed had very little influence. Three types of defects were observed, including surface roughness, surface deformation (warping and distortion) and balling defects.

Originality/value

This paper bridges an existing gap in MEX Steel 316L literature, with a focus on the relationship between MEX manufacturing parameters and subsequent shrinkage behaviour. This study provides an in-depth analysis of the relationship between manufacturing parameters – layer height, raster angle and print speed and subsequent shrinkage behaviour, thereby providing further information on the relationship between the former and the latter.

Details

Rapid Prototyping Journal, vol. 28 no. 11
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 1 September 1999

Xiangwei Wang

Selective laser sintering (SLS) is one of the most successful rapid tooling processes. Shrinkage and beam offset are the two most important control parameters in this…

1466

Abstract

Selective laser sintering (SLS) is one of the most successful rapid tooling processes. Shrinkage and beam offset are the two most important control parameters in this process. First, the SLS process and procedure of calibration are described. Second, based on the property of shrinkage and beam offset, a basic formula of shrinkage and beam offset is derived. Finally, the procedure of applying shrinkage (scaling factor) and beam offset is described.

Details

Rapid Prototyping Journal, vol. 5 no. 3
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 30 January 2007

C.N. Herath and Bok Choon Kang

This paper aims to study the dimensional characteristics such as fabric density variations, dimensional constant parameters, linear and area dimensional changes and…

Abstract

Purpose

This paper aims to study the dimensional characteristics such as fabric density variations, dimensional constant parameters, linear and area dimensional changes and spirality angle variations of 1 × 1 rib knitted structures made from cotton‐spandex core spun yarns, under laundering regimes till 10th washing cycle.

Design/methodology/approach

Samples of the above fabrics underwent dry, wet and full relaxation treatments and were subjected to standard atmospheric conditions prior to take the measurements. Washing was done in a front loading machine under normal agitation with machine 56 RPM. Each washing regime includes wash, rinse, spin, tumble dry steps. Washing temperature was set at 40°C and water intake for washing was 30 l and rinsed with cold water. 0.1 g/l standard wetting agent was used. The mass of the load was maintained constant to 3 kg to keep the material ratio as 1:10. Washing regimes were continued till 10th cycle.

Findings

Cotton‐spandex rib structures came to a more stable state (minimum energy state) after 10th laundering cycle under the experimental conditions. Cotton did not come to such a state, even after 10th cycle proceeded. ANOVA analysis done under 95 percent confidential level has shown that fabric tightness and relaxation procedures give significant effect on dimensional characteristics of cotton‐spandex and cotton rib structures. However, area shrinkage variations of cotton rib fabrics have shown an exception to this.

Research limitations/implications

According to the dimensional constant values, evenafter 10th washing cycle, cotton rib structures did not come to a stable position. This should be further investigated to achieve a better stable rib knitted structure.

Practical implications

The number of washing cycles can be increased or tumble dry duration can be increased to 120 min. to get a more stable state of cotton rib structures.

Originality/value

The results are important for the knitting industry to predict the dimensional behavior of designed knitted fabric under relaxation. These data can be used to set the circular machine parameters to achieve a more stable fabric after laundering.

Details

International Journal of Clothing Science and Technology, vol. 19 no. 1
Type: Research Article
ISSN: 0955-6222

Keywords

Article
Publication date: 14 December 2018

Tomaz Brajlih, Urska Kostevsek and Igor Drstvensek

One of the main problems of selective laser sintering (SLS) manufacturing process is the dimensional accuracy of products. Main causes of dimensional deviations are…

Abstract

Purpose

One of the main problems of selective laser sintering (SLS) manufacturing process is the dimensional accuracy of products. Main causes of dimensional deviations are material shrinkage and size of laser heat affected zone (LHAZ). This paper aims to present a new method of adapting SLS manufacturing shrinkage and LHAZ compensation parameters to the geometrical characteristics of processed parts to improve their accuracy.

Design/methodology/approach

The first part of this work presents a hypothesis asserting that the shrinkage and the LHAZ size depend on geometrical properties of products. A method that defines geometrical properties by numerical influence factors is described in the continuation. A multi-factorial experiment with adaptable test part is set up. Then, test builds are manufactured on an SLS machine and measured with a three-dimensional optical scanner. Afterwards, the results are analysed in relation to the presumed hypothesis.

Findings

The analysis of variance of multi-factorial experiment proves the hypothesis and the influence of the geometrical properties on the accuracy of the SLS manufacturing process. Afterwards, a part is manufactured with adapted values of compensation parameters and the archived accuracy is discussed.

Research limitations/implications

Presented research is limited on a single SLS material. Also, some numerical factors are directly linked to the build volume dimensions of the SLS machine that was used in the experiment. However, results can be generalised and some guidelines for shrinkage and LHAZ compensation method are presented. Also, some guidelines for future research are proposed.

Practical implications

Based on the presented results, it can be determined that using constant shrinkage and LHAZ values on an SLS machine will not yield the same results in terms of accuracy if the geometrical properties of parts change significantly.

Social implications

By correctly adapting compensation values, the overall achievable accuracy of the SLS process can be achieved, enabling a more reliable production of mass-customised end-user parts such as customised medical accessories and devices for example.

Originality/value

A similar method of numerically describing geometrical properties of part in regard to SLS and directly adapting shrinkage and LHAZ compensation values to them for every individual build has not yet been proposed.

Details

Rapid Prototyping Journal, vol. 25 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 1 November 2006

Paul Chapman and Simon Templar

Measures and measurement systems must reflect the context to which they are applied, requiring that the contextual issues relating to retail shrinkage must be identified…

1357

Abstract

Purpose

Measures and measurement systems must reflect the context to which they are applied, requiring that the contextual issues relating to retail shrinkage must be identified as a necessary precursor when measuring shrinkage. Without considering these issues any decision on which method of shrinkage measurement to employ will be uninformed, arbitrary and at best intuitive. The objective of this paper is to scope out and summarise the contextual issues surrounding retail shrinkage in Europe's grocery sector and to offer a view on the implications of these issues to shrinkage measurement.

Design/methodology/approach

The methodology adopted was a scoping study of the key issues that influence shrinkage measurement, drawing these from prior research and exposing these findings to the informed opinion of a review panel for critique and to highlight areas for further investigation.

Findings

The findings from the study were to identify a range of contextual issues relating to shrinkage and to summarise these issues into four categories, namely: stewardship and performance improvement; cost reduction and sales improvement; local effects of systemic issues; and the detailed nature of retailing.

Practical implications

The implications of these key issues are significant to the measurement of shrinkage in terms of the scope across the business from which shrinkage needs to be considered. This finding highlights the need to consider shrinkage as a systemic issue that extends across a business from design, through planning to operational execution. It also identifies the impact of shrinkage on increasing cost and depressing sales and considers the responsibility of management teams in addressing these matters.

Originality/value

This paper is theoretically original and thus of value to the academic community. It is also of value to the practitioner community in grocery retailing where shrinkage and its measurement is of worldwide strategic importance.

Details

International Journal of Retail & Distribution Management, vol. 34 no. 11
Type: Research Article
ISSN: 0959-0552

Keywords

Article
Publication date: 8 January 2020

Ante Džolan, Mladen Kožul, Alen Harapin and Dragan Ćubela

This paper aims to present an approach for the numerical simulation of concrete shrinkage. First, some physical mechanisms of shrinkage are described and then the…

Abstract

Purpose

This paper aims to present an approach for the numerical simulation of concrete shrinkage. First, some physical mechanisms of shrinkage are described and then the developed numerical model for the analysis of shrinkage of spatial three-dimensional structures using thermal analogy is presented. Results of the real behavior of structures because of concrete shrinkage using the developed numerical model are compared with the experimental and it is clearly shown that the developed numerical model is an efficient tool in predicting the time-dependent behavior of all concrete structures.

Design/methodology/approach

In this paper, Fib Model Code 2010 to predict shrinkage deformation of concrete is used, and it was incorporated in the three-dimensional numerical model using the thermal analogy. Mentioned three-dimensional numerical model uses the modified Rankine material law to describe concrete behavior in tension and modified Mohr-Coulomb material law to describe concrete behavior in compression. The developed three-dimensional numerical model successfully analyzes the behavior of reinforced and/or prestressed concrete structures including time-dependent deformations of concrete as well.

Findings

Results are shown in this paper clearly demonstrate the reliability of the developed numerical model in predicting the shrinkage strain, as well as its impact on concrete and reinforced concrete structures. The results obtained using the developed numerical model are in better agreement with the experimental results, than the results obtained using the numerical models from literature that also use the Fib Model Code 2010 to predict the shrinkage strain. So, it can be concluded that for a real simulation of concrete structures, alongside the model for predicting the shrinkage strain, the models for concrete behavior in tension and compression have a very important role.

Originality/value

Results of the developed three-dimensional numerical model were compared with experimental results from literature and with theoretical foundations, and it can be talked that this numerical model presents a good tool for analysis of reinforced and prestressed concrete structures including shrinkage deformation of concrete. Results obtained using the developed three-dimensional numerical model are better agreed with experimental than results of other numerical model from literature.

Details

Engineering Computations, vol. 37 no. 4
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 7 April 2015

Attila Geczy, Márta Fejos and László Tersztyánszky

This paper aims to reveal the causes and find an efficient method to compensate the shrinkage to reduce failure costs. Reflow-induced printed circuit board (PCB) shrinkage

Abstract

Purpose

This paper aims to reveal the causes and find an efficient method to compensate the shrinkage to reduce failure costs. Reflow-induced printed circuit board (PCB) shrinkage is inspected in automotive electronics production environment. The shrinkage of two-sided, large PCBs results in printing offset errors and consequently soldering failures on smaller components during the reflow soldering of the second PCB side.

Design/methodology/approach

During the research, the investigations had to adapt to actual production in an electronics manufacturing plant. A measurement method was developed to approximate the overall shrinkage of the given product. With the shrinkage data, it is possible to perform an efficient compensation on the given stencil design in computer-aided manufacturing environment.

Findings

It was found that even with the investigated lower-quality PCB materials, the compensation on the stencil significantly reduces the quantity of failures, offering an efficient method to improve the yield of the production.

Research limitations/implications

Research was oriented by the confines of production (fixed PCB sources, given PCB materials, reflow process and production line), where an immediate solution is needed. Future investigations should be focussed on the PCB parameters (different epoxy types, glass-fibre reinforcements, etc.).

Practical implications

The optimised production reduces overall failure costs. The stencil re-design and application is a fast and efficient way to immediately act against the shrinkage-induced failures. The method was successfully applied in automotive electronics production.

Originality/value

The paper presents a novel approach on solving an emerging problem during reflow.

Details

Soldering & Surface Mount Technology, vol. 27 no. 2
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 14 April 2020

Xuzhong Su and Xinjin Liu

Tensile property is one basic mechanics performance of the fabric. In general, not only the tensile values of the fabric are needed, but also the dynamic changing process…

97

Abstract

Purpose

Tensile property is one basic mechanics performance of the fabric. In general, not only the tensile values of the fabric are needed, but also the dynamic changing process under the tension is also needed. However, the dynamic tensile process cannot be included in the common testing methods by using the instruments after fabric weaving.

Design/methodology/approach

By choosing the weft yarn and warp yarn in the fabric as the minimum modeling unit, 1:1 finite element model of the whole woven fabrics was built by using AutoCAD software according to the measured geometric parameters of the fabrics and mechanical parameters of yarns. Then, the fabric dynamic tensile process was simulated by using the ANSYS software. The stress–strain curve along the warp direction and shrinkage rate curve along the weft direction of the fabrics were simulated. Meanwhile, simulation results were verified by comparing to the testing results.

Findings

It is shown that there are four stages during the fabric tensile fracture process along the warp direction under the tension. The first stage is fabric elastic deformation. The second stage is fabric yield deformation, and the change rate of stress begins to slow down. The third stage is fiber breaking, and the change of stress fluctuates since the breaking time of the fibers is different. The fourth stage is fabric breaking.

Originality/value

In this paper, the dynamic tensile process of blended woven fabrics was studied by using finite element method. Although there are differences between the simulation results and experimental testing results, the overall tendency of simulation results is the same as the experimental testing results.

Details

International Journal of Clothing Science and Technology, vol. 32 no. 5
Type: Research Article
ISSN: 0955-6222

Keywords

Article
Publication date: 1 March 2000

M. Gutauskas, V. Masteikaite and L. Kolomejec

Presents the results of investigation of fabrics’ and fused systems shrinkage force and its influence on the shape instability of fused textile systems after various…

Abstract

Presents the results of investigation of fabrics’ and fused systems shrinkage force and its influence on the shape instability of fused textile systems after various treatments such as wetting and drying. Also the method for determination and prediction of the twisting phenomenon of fused composites is presented. From the analysis of the data the twisting phenomenon was characterised by several parameters. They are system’s twisting sign, the shape of twisted system, the twisting coefficient and fused system’s twisting direction.

Details

International Journal of Clothing Science and Technology, vol. 12 no. 1
Type: Research Article
ISSN: 0955-6222

Keywords

1 – 10 of over 3000