Layer thickness and draft angle selection for stereolithography injection mould tooling

“…It has also been demonstrated that appropriate choices in mould design and process variables can reduce the risk of failure in SL tooling [2][3][4].…”

Section: Stereolithography Tooling For Injection Mouldingmentioning

confidence: 99%

Crystallinity control in parts produced from stereolithography injection mould tooling

Harris¹,

Hague²,

Dickens³

2003

Proc. Instn Mech. Engrs, Part L: J. Mat

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• This is an article from the journal, Proceedings of the Institu- This item was submitted to Loughborough's Institutional Repository (https://dspace.lboro.ac.uk/) by the author and is made available under the following Creative Commons Licence conditions.For the full text of this licence, please go to: http://creativecommons.org/licenses/by-nc-nd/2.5/ Crystallinity control in parts produced from stereolithography injection mould tooling R A Harris*, R J M Hague and P M Dickens Rapid Manufacturing Research Group, Loughborough University, Loughborough, UK Abstract: The use of moulds produced by stereolithography (SL) for injection moulding provides a quick route to manufacturing a low volume of parts without expensive hard tooling. However, these parts have been shown to exhibit different material property characteristics than those produced from metal tooling. The aim of the present work is to research methods that would allow SL moulds to produce parts of similar material property characteristics to those from conventional metal tools. This work has identi ed that the different part characteristics are due to differing levels of crystallinity developed in the parts from the comparative mould varieties (SL and metal). These crystallinity differences have been associated with the cooling rates imparted owing to the thermal properties of the mould material. The latter part of this work concerns controlling and manipulating this degree of crystallinity. After a discussion of possible methods, two approaches are taken to modifying the crystalline content of parts produced by SL moulds. One of the approaches is material based, the other concerns the injection moulding process. Differential scanning calorimetry (DSC) is used to quantify the resulting levels of crystallinity in the parts. The results show that by process modi cation it is possible to produce parts by SL moulding that possess a similar crystalline content to those moulded from metal tooling. The use of modi ed materials allows parts created in SL and metal tools to be of a consistent crystalline content. The work concludes that not only are SL moulds capable of producing parts that are more like those from metal moulds but also present some unique opportunities that have been demonstrated to be unachievable in metal moulds.

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“…Design variables for stereolithography tools have previously been examined [8], and this work attempts to perform a similar analysis for tools made by the DMLS process.…”

Section: Dmls For Injection Mouldingmentioning

confidence: 99%

Reducing ejection forces for parts moulded into direct metal laser sintered tools

Majewski

Hopkinson

2003

The International Journal of Advanced Manufacturing Technology

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With the development and refinement of Rapid Prototyping technologies, a gradual move into tooling applications has occurred. However, the design principles that are traditionally applied to mould tools are not always suitable for use with layer-manufactured tools. As these technologies develop, so must the ways in which they are used.Tools produced using Direct Metal Laser Sintering (DMLS) have previously been shown to be suitable for several applications, in particular for plastic injection moulding. However, there has been little work undertaken on the best procedures to follow when designing tools made using the DMLS process. This work has been performed to determine the effect of layer thickness, level of finishing and draft angle on the forces required to eject parts from DMLS injection mould tools.Results show that, although the choice of layer thickness and the level of tool finishing have a substantial effect on the ejection forces required, the level of draft included does not show an obvious trend towards increasing or decreasing the force.

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Layer thickness and draft angle selection for stereolithography injection mould tooling

Cited by 26 publications

References 3 publications

Part shrinkage anomilies from stereolithography injection mould tooling

Part shrinkage anomilies from stereolithography injection mould tooling

Crystallinity control in parts produced from stereolithography injection mould tooling

Reducing ejection forces for parts moulded into direct metal laser sintered tools

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