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Article
Publication date: 27 May 2014

Werner Timans, Kees Ahaus and Jiju Antony

The purpose of this paper is to provide a demonstration of the application of techniques for robust optimization for improvement of the injection moulding processes in an…

Abstract

Purpose

The purpose of this paper is to provide a demonstration of the application of techniques for robust optimization for improvement of the injection moulding processes in an injection moulding small and medium sized enterprise (SME).

Design/methodology/approach

A critical to quality characteristic (CtQ) which is connected to assembly problems is the subject of investigation. The CtQ is not directly measurable. The variation in a dimension of a product, which is correlated to the CtQ, is studied using design of experiments (DoE) and Taguchi methods. A two-cavity mould is used in the injection moulding process. To evaluate the robustness of the process using signal-to-noise analysis, the data were transformed to compensate for the systematic differences between the mould cavities.

Findings

The initial results showed that finding optimal process parameter settings commonly valid for both cavities was impossible. After a modification of the mould, the experiments were rerun and optimal settings could be found.

Practical implications

Applying DoE techniques in small and medium-sized injection moulding companies is far from common practice. This case study demonstrates a method to apply DoE with five process parameters which can serve as a standard method to prepare production when a new mould is used for the first time.

Originality/value

The originality is connected to the combination of the applied methods and, in the context of the case study, carried out in an SME unfamiliar with the power of the applied methods. The value of the paper is to demonstrate the power of the most powerful technique in quality engineering to improve an injection moulding process within the context of SMEs. The authors would accentuate the point that the true power becomes visible when this powerful technique is introduced into an organization with very little understanding of the technique. In addition, the case study is valuable to practitioners because it proposes a new scientific and systematic approach to understand and optimize the start-up of the moulding process.

Details

International Journal of Lean Six Sigma, vol. 5 no. 2
Type: Research Article
ISSN: 2040-4166

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Article
Publication date: 16 January 2009

Pedro Gonçalves Martinho, Paulo Jorge Bártolo and António Sérgio Pouzada

This paper aims to explore the influence of the materials used in moulding blocks of hybrid moulds on the injection moulding setup and the properties of the mouldings.

Abstract

Purpose

This paper aims to explore the influence of the materials used in moulding blocks of hybrid moulds on the injection moulding setup and the properties of the mouldings.

Design/methodology/approach

An instrumented (pressure and temperature) hybrid mould with exchangeable moulding blocks, produced by rapid prototyping and tooling techniques (RPT), was used to produce polypropylene tubular mouldings. The configuration of the mould was varied with combinations of moulding block materials, namely, an epoxy resin composite processed by vacuum casting and steel. The processing conditions were adjusted to obtained steady processing conditions. The mouldings were assessed in terms of the microstructure and the shrinkage.

Findings

Due to the properties of the moulding block obtained by RPT being different from tool steel, the injection moulding processing conditions and the plastics parts properties are different when hybrid moulds are used. The cycle time depends on the moulding block properties and must be adjusted to the desired running temperature. The morphology of the mouldings is strongly affected by the thermal properties of the moulding block materials. When different materials are used in the core and the cavity asymmetric structures develop in the part. The shrinkage of the mouldings, when resin cores are used is also affected by the deformation of the core caused by the injection pressure.

Originality/value

This paper makes a contribution to understanding the morphology of semi‐crystalline mouldings obtained using hybrid moulds and enhances the importance of the core deformation on the shrinkage of the mouldings.

Details

Rapid Prototyping Journal, vol. 15 no. 1
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 December 2000

Neil Hopkinson and Phill Dickens

Advances in rapid prototyping and machining have resulted in reduced lead times for injection moulding tooling. Comparisons between aluminium and stereolithography (SL…

Abstract

Advances in rapid prototyping and machining have resulted in reduced lead times for injection moulding tooling. Comparisons between aluminium and stereolithography (SL) tools are made with regard to the ejection forces required to push mouldings from the tools, heat transfer through the tools and the surface roughness of the tools. The results show that ejection forces for both types of tools are increased when a longer cooling time prior to ejection is used. The ejection forces required from a rough aluminium tool are considerably higher than those from a smooth aluminium tool. SL tools do not appear to be subjected to any smoothing as a result of moulding polypropylene parts. The rubber like nature of the tool’s surface is as a direct consequence of the low glass transition temperature and low thermal conductivity of the tool material. Further potential benefits of the low thermal properties of the tool are discussed.

Details

Rapid Prototyping Journal, vol. 6 no. 4
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 July 2004

Armando Sá Ribeiro, Neil Hopkinson and Carlos Henrique Ahrens

In this work, the changes to stereolithography (SL) resin mechanical properties during the injection moulding process were evaluated. A multi‐impression SL mould was built…

Abstract

In this work, the changes to stereolithography (SL) resin mechanical properties during the injection moulding process were evaluated. A multi‐impression SL mould was built and used to inject a series of small flat mouldings. The fixed half SL tool insert included recesses to accommodate tensile test specimens. Tensile test specimens made from SL resin were positioned in these recesses and plastic parts were injected. After injecting a predetermined number of mouldings, tensile tests were performed using the tensile test specimens. The results from the tensile tests show that the thermal cycling encountered during the injection moulding process did not significantly affect the mechanical properties of the resin. Observations indicate that decrease in the temperatures encountered in the tool may lead to longer tool life.

Details

Rapid Prototyping Journal, vol. 10 no. 3
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 April 2001

Ian Hyland

Robots have been used on plastic injection moulding machines for many years. Linear robots account for the vast majority of applications but there is a small increase in…

Abstract

Robots have been used on plastic injection moulding machines for many years. Linear robots account for the vast majority of applications but there is a small increase in use of six‐axis articulated arm types for certain applications. This paper discusses the pros and cons for the various types being used and describes the downstream processes that can be incorporated within the automated cell.

Details

Industrial Robot: An International Journal, vol. 28 no. 2
Type: Research Article
ISSN: 0143-991X

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Article
Publication date: 15 August 2019

Joel Vasco, F.M. Barreiros, Andreia Nabais and Nilza Reis

The purpose of this study is to compare the overall performance of the injection moulding process by using metallic inserts produced by both conventional technologies and…

Abstract

Purpose

The purpose of this study is to compare the overall performance of the injection moulding process by using metallic inserts produced by both conventional technologies and selective laser melting (SLM).

Design/methodology/approach

A systematic methodology is proposed for prior evaluation of the effectiveness of conformal cooling channels to reduce cycle time and/or to reduce the scrap rate.

Findings

The mould was reengineered considering the SLM process and manufactured. Injection trials were carried out to validate expectations provided by injection simulations, which resulted on good quality parts and a significant decrease on cooling time, and, consequently, on the overall cycle time. The minimisation of scrap provided energy savings and time-to-market reduction.

Research limitations/implications

The initial costs for AM tools still pose some doubts on decision-makers. The challenge of this study is to implement the methodology on a small-scale production and still ensure that benefits are achieved.

Practical implications

The case study selected for this research work is based on a parking sensor housing, which is a plastic part assembled on the vehicle’s front and rear bumpers, therefore, with aesthetics concerns. The part produced with the conventional mould exhibits surface defects that, to be minimised (not eliminated), require a longer packing time to diminish the sink marks.

Social implications

The economic impact of the use of SLM is relevant despite the low batch size for the case study presented. Energy savings are achieved due to scrap reduction and shorter cycle time.

Originality/value

The systematic methodology proposed for prior evaluation of the advantages of conformal cooling is possible to be applied both on small scale and high production series.

Details

Rapid Prototyping Journal, vol. 25 no. 7
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 August 1998

Jaroslav Mackerle

This paper gives a review of the finite element techniques (FE) applied in the area of material processing. The latest trends in metal forming, non‐metal forming, powder…

Abstract

This paper gives a review of the finite element techniques (FE) applied in the area of material processing. The latest trends in metal forming, non‐metal forming, powder metallurgy and composite material processing are briefly discussed. The range of applications of finite elements on these subjects is extremely wide and cannot be presented in a single paper; therefore the aim of the paper is to give FE researchers/users only an encyclopaedic view of the different possibilities that exist today in the various fields mentioned above. An appendix included at the end of the paper presents a bibliography on finite element applications in material processing for 1994‐1996, where 1,370 references are listed. This bibliography is an updating of the paper written by Brannberg and Mackerle which has been published in Engineering Computations, Vol. 11 No. 5, 1994, pp. 413‐55.

Details

Engineering Computations, vol. 15 no. 5
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 20 June 2016

Tomaz Brajlih, Matej Paulic, Tomaz Irgolic, Ziga Kadivnik, Joze Balic and Igor Drstvensek

This paper aims to present a comparison between selective laser sintering and injection moulding technology for the production of small batches of plastic products.

Abstract

Purpose

This paper aims to present a comparison between selective laser sintering and injection moulding technology for the production of small batches of plastic products.

Design/methodology/approach

The comparison is based on analysing the time–cost efficiencies of each manufacturing process regarding the size of the series for the selected product sample. Both technologies are described and the times and costs of those individual processes needed to create a final product are assessed when using each of the manufacturing processes.

Findings

The study shows that the time-cost efficiency of the selected laser sintering technology increases according to the complexity of the product and decreases with increasing series size and product volume.

Research limitations/implications

The study and absolute values of the presented results are limited to a selected plastic product, but the series size-focused efficiency analysis could be expanded to general cases.

Originality/value

The presented analysis could be used as a general guideline for a decision-making process regarding the more efficient manufacturing method. In addition, the results show the viability of using selective laser sintering during the early stages of production when fast product availability is required, regardless of the series size. Also, some complementary effects of using both technologies in the serial production of the same part are discussed.

Details

Rapid Prototyping Journal, vol. 22 no. 4
Type: Research Article
ISSN: 1355-2546

Keywords

Content available
Article
Publication date: 10 May 2021

Akinloluwa Samuel Babalola

Values of parameters such as temperature, humidity, number of plastic products and the location of plastic injection moulds are required to determine the efficiency of…

Abstract

Purpose

Values of parameters such as temperature, humidity, number of plastic products and the location of plastic injection moulds are required to determine the efficiency of plastic injection moulds with a view to improving the quality of the outputs. This article determined the appropriate sensors for the measurement of these essential parameters in the most suitable form of representation of the data to aid a proficient analysis of the data.

Design/methodology/approach

The outputs of these sensors were obtained by connecting the sensors to the general-purpose input/output (GPIO) pins of a Raspberry Pi and writing a Python programme for the connected GPIO pins. The values of the outputs of these sensors were represented in a graphical form. The connection of the Raspberry Pi and the sensors were done with a full-sized breadboard and jumper wires. A computer-aided design (CAD) of the connections was produced using Fritzing software.

Findings

The appropriate sensors determined are MLX90614 infrared thermometer sensor, DHT11 humidity sensor, pixy2 vision sensor and Neo-6m GPS sensor. This study proposed that the sensors analytic system be applied on an industrial plastic injection mould to measure and display the various parameters of the injection moulds for the purpose of understanding and improving the performance of the injection mould

Originality/value

An electronic system that provides the continuous values of essential parameters of a plastic injection mould in operation.

Details

Frontiers in Engineering and Built Environment, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 2634-2499

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Article
Publication date: 15 January 2019

Anurag Bagalkot, Dirk Pons, Don Clucas and Digby Symons

Polymer rapid tooling (PRT) inserts can be used as injection moulding (IM) cavities for prototyping and low volume production but lack the robustness of metal inserts…

Abstract

Purpose

Polymer rapid tooling (PRT) inserts can be used as injection moulding (IM) cavities for prototyping and low volume production but lack the robustness of metal inserts. Metal inserts can withstand high injection pressure and temperature required, whereas PRT inserts may fail under similar parameters. The current method of parameter setting starts with using the highest pressure setting on the machine and then fine-tuning to optimize the process parameters. This method needs modification, as high injection pressures and temperatures can damage the PRT inserts. There is a need for a methodical process to determine the upper limits of moulding parameters that can be used without damaging the PRT inserts.

Design/methodology/approach

A case study analysis was performed to investigate the causes of failure in a PRT insert. From this, a candidate set-up process was developed to avoid start-up failure and possibly prolong tool life. This was then tested on a second mould, which successfully avoided start-up failure and moulded 54 parts before becoming unusable due to safety issues.

Findings

Process parameters that are critical for tool life are identified as mould temperature, injection pressure, injection speed, hold pressure and cooling time.

Originality/value

This paper presents a novel method for setting IM process parameters for PRT inserts. This has the potential to prevent failure at start up when using PRT inserts and possibly extend the operating life of the PRT inserts.

Details

Rapid Prototyping Journal, vol. 25 no. 9
Type: Research Article
ISSN: 1355-2546

Keywords

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