The Thermal Effect of Variate Cross-Sectional Profile on Conformal Cooling Channels in Plastic Injection Moulding

Cooling system is an important role in designing a productive plastic injection moulding (PIM). The selection of geometry and layout for plastic injection moulding cooling channels strongly influences the cooling performance such as cooling time and thermal distribution that leads to shrinkage and warpage. This paper presents the study to determine the best cooling channel layout and cross-sectional profile which include circular straight drilled cooling channels, circular conformal cooling channels, square shape conformal cooling channels, elliptical conformal cooling channels and diamond conformal cooling channels. The cooling time and thermal distribution were simulated by Moldflow Insight (MFI) software. Results are presented based on ejection time and temperature variation by using transient analysis in MFI. The results found the best cross-sectional of cooling channels indicated by square shape conformal cooling channels, compare to others due to the shortest cooling time that recorded from simulation. The conformal cooling channel layout also resulted greater thermal distribution compared to straight drilled cooling channel design. Â

Thermo-mechanical analysis of additively manufactured hybrid extrusion dies with conformal cooling channels

Profile overheating and surface defects during hot aluminum extrusion can occur when seeking higher productivity rates at increased ram speed velocities. The incorporation of cooling channels in the die-design allows overcoming this process limitation by keeping the profile temperature below the melting point of the alloy used [1]. Selective laser melting (SLM) of conformal cooling channels provides, in contrast to conventional manufacturing techniques, the opportunity to place the cooling circuit inside the mandrel of a porthole-die in a well-defined position to the critical bearing region [2]. In the framework of this study, a preliminary numerical investigation on the extrusion process under the assumption of liquid nitrogen cooling is analysed. The results show, that by combining conformal cooling channels with liquid nitrogen as a cooling media high cooling rates, which are well beyond the state of the art of conventional dies, can be achieved. In a hybrid extrusion die set-up, a part of the mandrel, that is additively manufactured, is either joined [3] or directly selective leaser melted onto the conventionally manufactured parts [4]. For a proper implementation in the extrusion process, material testing of the welded joint are needed. Thus, in the current study, tensile tests performed at room temperature for hybrid specimens, partially consisting of conventionally processed tool steel 1.2343 and partially additively manufactured 1.2709, will be presented. Moreover, four different heat treatment sequences of the hybrid specimens will be discussed. In addition, for each configuration, micro-structural images are taken to investigate failure at the bonding region. Finally, an optimal manufacturing sequence for a hybrid die with the described material combination is proposed

New method used to fabricate light-weight heat exchanger for rocket motor

A grooved capstrip, to straddle the metal edges of regenerative cooling channels, increases the strength and heat transfer characteristics of lightweight motor cases. This capstrip is so designed as to form a firm joint between the channels that form the rocket casing wall

Numerical Investigation of Conformal Cooling Channels in Injection Molds

To accommodate the increasing demand for consumer plastic products with higher quality and the industry’s desire for injection molding processes with higher production rate, metal 3D printing technologies have been introduced into the injection molding industry to fabricate cooling channels which can be placed more conformal to the working surface of the injection mold. These channels are referred to as conformal cooling channels. Since the manufacturing cost of mold-inserts with conformal cooling channels are higher than those with conventional cooling channels, it is necessary to confirm the advantage of using conformal cooling channels rather than conventional cooling channels. In this thesis, CFD simulations are used to compare the performances of a conventional cooling system and a conformal cooling system. The conformal cooling system is shown to have better cooling performance while not consuming more pumping power. Since the injection mold cooling system design is highly dependent on the geometry of the molded plastic part, it is difficult to construct general design guidelines for all conformal cooling channels. Therefore, commonly used conformal cooling systems that consist of U-shape bends are studied in this thesis. The influences of three geometrical design parameters, namely configuration of the U-shape bends, cooling channel depth from the heating surface and number of cooling channels, on the cooling performance are examined in a parametric study

Nozzle fabrication technique

This invention relates to techniques for fabricating hour glass throat or convergent divergent nozzle shapes, and more particularly to new and improved techniques for forming rocket nozzles from electrically conductive material and forming cooling channels in the wall thereof. The concept of positioning a block of electrically conductive material so that its axis is set at a predetermined skew angle with relation to a travelling electron discharge machine electrode and thereafter revolving the body about its own axis to generate a hyperbolic surface of revolution, either internal or external is novel. The method will generate a rocket nozzle which may be provided with cooling channels using the same control and positioning system. The configuration of the cooling channels so produced are unique and novel. Also the method is adaptable to nonmetallic material using analogous cutting tools, such as, water jet, laser, abrasive wire and hot wire

MANX: A 6D Ionization-Cooling Experiment

Six-dimensional ionization cooling of muons is essential for muon colliders and possibly beneficial for neutrino factories. An experiment to demonstrate six-dimensional ionization cooling using practical apparatus is presented. It exploits recent innovative ideas that may lead to six-dimensional muon-cooling channels with emittance reduction approaching that needed for high-luminosity muon colliders.Comment: 3 pages, 4 figures, to appear in Proceedings of the 9th International Workshop on Neutrino Factories, Superbeams, and Betabeams (NuFact07), August 6-11, 2007, Okayama University, Japa

Theory of cooling by flow through narrow pores

We consider the possibility of adding a stage to a dilution refrigerator to provide additional cooling by ``filtering out'' hot atoms. Three methods are considered: 1) Effusion, where holes having diameters larger than a mean-free path allow atoms to pass through easily; 2) Particle waveguide-like motion using very narrow channels that greatly restrict the quantum states of the atoms in a channel. 3) Wall-limited diffusion through channels, in which the wall scattering is disordered so that local density equilibrium is established in a channel. We assume that channel dimension are smaller than the mean-free path for atom-atom interactions. The particle waveguide and the wall-limited diffusion methods using channels on order of the de Broglie wavelength give cooling. Recent advances in nano-filters give this method some hope of being practical.Comment: 10 pages, 3 figures. Corrected typos and made some minor wording change