Molding (process) | EPFL Graph Search

Molding (American English) or moulding (British and Commonwealth English; see spelling differences) is the process of manufacturing by shaping liquid or pliable raw material using a rigid frame called a mold or matrix. This itself may have been made using a pattern or model of the final object. A mold or mould is a hollowed-out block that is filled with a liquid or pliable material such as plastic, glass, metal, or ceramic raw material. The liquid hardens or sets inside the mold, adopting its shape. A mold is a counterpart to a cast. The very common bi-valve molding process uses two molds, one for each half of the object. Articulated molds have multiple pieces that come together to form the complete mold, and then disassemble to release the finished casting; they are expensive, but necessary when the casting shape has complex overhangs. Piece-molding uses a number of different molds, each creating a section of a complicated object. This is generally only used for larger and mor

Water Injection in isothermal co-rotating scroll compressor and turbine

Roberto Passini

This project deals with the study of a quasi-isothermal scroll compression/expansion obtained by spray injection of water. The spray injection process is first described from the theoretical point of view as it concerns the droplets formation and breakup processes, both directly related to the evaporation. A simulation of spray injection is also performed using Ansys CFX. The last part deals with an experimental application in the laboratory of the system studied. Results are presented and discussed both for CFD simulation and experimental part.

2012

Hybrid Processing of Thermoplastic Based Multimaterials

Rajasundar Chandran

There is a growing interest in exploring novel material combinations and processing technology to manufacture complex 3D shaped polymer and composite structures. In the field of prosthetics and orthotics, this need is significant with additional challenges of providing patient specific customization to these devices in a cost-effective manner. Thermoplastic based materials(TP) including thermoplastic elastomers (TPE) and their composite counterparts have the potential to address these applications. The objectives of the research are to develop composite preforms that can conform to complex 3D structures, understand the processing phenomena in particular the fusion bonding mechanisms of different thermoplastic materials forming hard and soft interfaces and finally develop processing strategies that are suitable for the manufacture of complex 3D structures with these multimaterials. A novel TPE based composite preform consisting of continuous glass fibres was first manufactured by a continuous melt impregnation technique, extremely well suited for the studied TPE material. This process resulted in superior fibre wetting and impregnation characteristics for the composite preform. Furthermore, TPE reinforced by glass fibres provided preforms which can conform easily to 3D shapes owing to the flexible nature of the matrix. Then isothermal integration of polypropylene based glass fibre (iPPGF) composites with the TPE materials was studied and the bond strengths of bilayer specimens under different processing conditions were determined. The bonding temperature and pressure were tuned to promote the best fusion bonding conditions which was verified from peel tests and microscopic characterization of the interfaces. Further improvements in bond strength and fusion bonding time was achieved by non-isothermal fusion bonding techniques namely overmolding and 3D printing. The processing windows were then obtained for these two processes under a wide range of fusion bonding conditions and for various TPE and TP based materials. The presence of a continuous plasticized iPP phase in the TPE was determined to play an important role in the bonding through the establishment of intimate contact and interdiffusion mechanisms during the molding process. The influence of the interface temperature and bonding pressure was shown to govern the wetting and intimate contact of the interfaces and to compensate shrinkage respectively. The established processing conditions permitted tailoring of the bond strengths for TPE-iPP and TPE-iPPGF interfaces. These results can be directly applied for high volume manufacture of complex 3D shaped composite parts. The effects of the TPE composition (fillers, reinforcements, TP content, surface roughnessâŠ) and of bonding temperature, pressure and time, were thus better understood under the non-isothermal bonding conditions encountered in the additive processes. The results of the FDM printing can be combined with other low pressure processing techniques such as thermoforming to manufacture hybrid multimaterials 3D structures. The research is applied in developing a hybrid processing technology which proposes the combination of thermoplastic-based multimaterials and different processing techniques that are suitable for the manufacture of the next generation of composite applications in particular for customized affordable prosthetic limbs.

EPFL2017

Rapid processing of net-shape thermoplastic planar random composite preforms

Patrick Blanchard, Simon Jespersen, Jan-Anders Månson, Véronique Michaud, Daniel Schmäh

A novel thermoplastic composite preforming and moulding process is investigated to target cost issues in textile composite processing associated with trim waste, and the limited mechanical properties of current bulk flow- moulding composites. The thermoplastic programmable powdered preforming process (TP-P4) uses commingled glass and polypropylene yarns, which are cut to length before air assisted deposition onto a vacuum screen, enabling local preform areal weight tailoring. The as-placed fibres are heat- set for improved handling before an optional preconsolidation stage. The preforms are then preheated and press formed to obtain the final part. The process stages are examined to optimize part quality and throughput versus processing parameters. A viable processing route is proposed with typical cycle times below 40 s (for a plate 0.5 × 0.5 m2, weighing 2 kg), enabling high production capacity from one line. The mechanical performance is shown to surpass that of 40 wt.% GMT and has properties equivalent to those of 40 wt.% GMTex at both 20°C and 80°C.

Springer Netherlands2009

Hybrid Processing of Thermoplastic Based Multimaterials

Rajasundar Chandran

EPFL2017