Gas assisted injection moulding: adding two components and moveable inserts

Neerincx, PE Peter; Meijer, Heh Han

doi:10.1179/146580109x12540995045408

Cited by 3 publications

(1 citation statement)

References 20 publications

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“…During injection moulding, significant attention has been paid to shortening the total cycle time per part. Since the cooling times are responsible for the largest share of the total cycle time [2–25], the open and closed cooling times are gradually decreased while keeping a stable cycle and producing good parts. For example, a closed cooling time of 10 s is sufficient to eject non-deformed parts at a slightly higher temperature of 100°C.…”

Section: Resultsmentioning

confidence: 99%

Optimising open and closed cooling time for hybrid injection moulding of polypropylene with polyamide inserts from multi jet fusion

Fernandez

Ryse

Cavicchiolo

et al. 2020

Plastics, Rubber and Composites

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To reduce the lead time and costs for developing short run production injection moulding tools the potential of additive manufactured mould inserts is investigated. These hybrid moulds are compared to conventional steel-based moulds, considering mechanical and thermal differences. For part production and insert material, respectively polypropylene and polyamide12 manufactured by Multi Jet Fusion (MJF) are chosen. Moldex3D simulation results show that lower clamping forces and injection pressures are sufficient upon using MJF inserts due to a 20 times lower thermal diffusivity compared to conventional steel, resulting in thinner skin layers and increased solidification times. Practical injection moulding parameters have been optimized by reducing the cooling time with 75 seconds (60%) using forced convectional cooling at 15 °C. Core and cavity inserts show a deviating cooling behaviour linked to the higher amount of insert material and presence of steel. The wear of the mould inserts is minor after producing 360 parts. .

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Section: Resultsmentioning

confidence: 99%

Optimising open and closed cooling time for hybrid injection moulding of polypropylene with polyamide inserts from multi jet fusion

Fernandez

Ryse

Cavicchiolo

et al. 2020

Plastics, Rubber and Composites

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A Disposable Bioreactor for Culturing and Testing of Tissue-engineered Heart Valves

Neerincx

Meijer

2010

International Polymer Processing

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A disposable bioreactor is designed consisting out two identical shells that are fabricated via a two component, hard and soft, injection molding technique. In the bioreactor an autologous-cell-seeded scaffold can be placed for culturing (growing and conditioning) and testing tissue-engineered heart valves. The soft polymer is used for membranes, that drive the fluid flow, and for the steering valves and the sealings. The hard polymer comprises the casing parts that hold the soft parts in place. The steering valves are used for directing the fluid flow and controlling the closing pressure exerted on the growing heart valve. Air pressure actuation is used because of its flexibility, simplicity and reliability. Different spherical membrane geometries are evaluated in their performance to realize a reproducible deformation. Relaxation of flow-induced orientation inside the membrane results in buckling and tilting, which makes ultrasonic position measuring troublesome. The problem is solved by developing a membrane geometry that allows high volume displacements combined with relaxation to a neutral geometry as it is initially molded. The bioreactor is successfully tested, imitating the cardiac pressures and cardiac flows needed during the culturing and testing of tissue-engineered heart valves.

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Appendices

Kennedy¹,

Zheng²

2013

Flow Analysis of Injection Molds

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For personal use only. A.3 Simulation in the Eighties 209or wireframe based. This meant that geometry was represented as surfaces with no thickness displayed. However, when meshed the local thickness information was assigned to elements. It was thus a time ripe for the introduction of finite element methods using 2.5D or Hele-Shaw approximation. Indeed the 2.5D approximation enabled the advancement of both academic and commercial software. Such is its importance that we provide a detailed derivation of the equations in Chapter 5. This decade saw a rapid evolution of computer hardware. In the early eighties, large mainframe systems and time-share distribution of software were common. In the mid-eighties the hardware moved to the super mini, while at the end of the decade the UNIX workstation was introduced. The latter provided vastly improved graphics and higher computational speed. A.3.1 Academic Work in the EightiesIn the eighties, academic and commercial interest extended to other aspects of the process. Certainly there were further advances in simulating the filling phase, but interest shifted to other phases of the process. Consequently we find a broadening of simulation to the packing and cooling phases. Another feature of this period is the formation of several centers focusing on the injection-molding process. Each center was based around a university department, and each produced its own computer code to further research on simulation of molding. A.3.1.1 Mold FillingMcGill University had a team led by Musa Kamal. As well as academic work on foundations, the McGill group developed the McKam software for molding simulation [187]. McKam used the finite difference method for numerical calculations and utilized the most advanced algorithms available. Analysis of both filling and packing phases was possible, and the program focused on the long-term goal of determining product properties such as birefringence and tensile modulus. In 1986 Lafleur and Kamal [215] presented an analysis of injection molding that included the filling, packing, and cooling phases with a viscoelastic material model.

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Gas assisted injection moulding: adding two components and moveable inserts

Cited by 3 publications

References 20 publications

Optimising open and closed cooling time for hybrid injection moulding of polypropylene with polyamide inserts from multi jet fusion

Optimising open and closed cooling time for hybrid injection moulding of polypropylene with polyamide inserts from multi jet fusion

A Disposable Bioreactor for Culturing and Testing of Tissue-engineered Heart Valves

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