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When designing injection molds, many decisions are made while quoting. Parts are examined for entrapment or details that cause them. Solving entrapment issues requires creative undercut solutions. There are many undercut solutions offered today. The designer needs to know how to quickly select the correct option for the most efficient molding and tool building.
This paper addresses methods of releasing threads, snaps, hooks, holes and anything that has a mechanical action that must take place before a part can be ejected and the mold opened. Often a certain method is used for a mold that is traditional, but with a fresh look at the part and current solutions, the design can be simplified. This can result in lowering molding time, manufacturing time and ultimately cost.
This informative guide addresses the most common undercut conditions with simple and long-lasting solutions. It compares traditional methods to non-traditional methods and explains the advantages and disadvantages.
Lun Howe Mark, Guilong Wang, Chul. B. Park, Ungyeong Peter Jung, May 2015
Using gas-assist in conjunction with foam injection molding has the potential of creating a highly synergistic production technique. By combining two supplementary processing strategies, weight savings with higher quality cell morphologies can be achieved. In this study, the effects of gas-assist processing parameters were systematically examined on the cell morphology of TPU. These gas-assist parameters include the holding time, holding pressure and start delay. The cavity pressure for different gas-assist pressure profiles was also examined.
Cellulose nanofiber (CeNF) is generally provided by micronizing a plant fiber to a nanometer-size in diameter. A CeNF reinforced thermoplastic composite is recently expected to indicate integrated high performance concerning light weight, thermal resistance and mechanical strength. It is important to disperse and defibrate CeNF uniformly in a resin in the extrusion process. In this study, various compounds of microcrystalline cellulose (MCC), CeNF, PLA, and PP were made using additives by the extrusion process. The mechanical properties were also evaluated.
Modern inorganic pigments are no longer just colorants for visual appeal; rather, they are functional colored materials exhibiting a wide range of properties. This distinction is important as pigments now provide specific physical and chemical advantages in addition to bright colors. It is therefor important to understand the fundamental correlations between crystal structure and physical properties when designing new pigments. New research pushes the boundaries of traditional metal oxide pigments by utilizing unusual host lattices, new elemental combinations, and unique synthetic methods. This paper will establish the basic considerations of modern pigment design and discuss the recent advancements in blue pigments, namely in the YIn1-xMnxO3 family.
In Japan, eggs are widely used in many food products on the market, and 200,000 tons of eggshells are annually discharged and most of them get discarded. Re-use of discarded eggshells into food trays is one of the efficient ways to realize a recycling-oriented society. Many food trays consist of polypropylene or polystyrene, and sometimes recycled products. Thus, it is possible to use biomass materials such as eggshells as a bulking agent. Eggshells need to be compounded into resin when used in food trays, but the egg?s unique sulfur smell is emitted when applying heat in the manufacturing process. In order to solve this odor problem, we compounded under different conditions with polypropylene and eggshell to research ways to reduce odor. The results suggested that molding temperatures exert significant influence on odor generation. By molding at the lowest temperature that enables resin to mold, a possible countermeasure for odor reduction is created.
Fiber-reinforced composites assume a key function in lightweight design. Due to high material and manufacturing costs, the objective is the near net shape manufacture of composite components via the forming processes. Subsequent cutting processes such as deburring are, however, still necessary. This post-processing leads to a reduction in the mechanical properties, not only through the cutting of the continuous fibres but also through potential production-related damage. The excellent durability properties of fiber-reinforced composites are thus lost. In this paper it is assumed that the production-related reduction in the mechanical properties of composites with thermoplastic matrix is not only caused and influenced by the design of the machining process but also through the method of clamping the parts which is necessary during the process. The qualitative evaluation is done through microscopical determination of the surface damage and the inter-laminar damage through ultrasonic inspection. Following an accelerated ageing process under the influence of bending loads, the determination of the flexural strength is carried out.
Current lightweight composite solutions demonstrate their technological feasibility by using lightweight material. The whole lightweight potential of composite parts, however, can only be used in combination with lightweight design principles. There is a limitation in creating lightweight optimized applications. The manufacturing technology must achieve both, economic process with low cycle times and high process integration.
The article gives an overview of material lightweight and structural lightweight design of continuous fibre reinforced thermoplastic composite applications. Furthermore new process technologies for present automotive applications are shown (bumper systems, seat structures) which integrate structural and material design in a One-Shot-Process. The key benefit of the Technologies, beside the lightweight potential of the used materials and design, is a short cycle time (less a minute) that can only be realized due to using thermoplastic composites and a process integration/combination. Therefore these processes are ready for implementation in mass production.
Selective laser sintering (SLS) of polymer powder is readily used for the additive manufacturing of plastic parts. During SLS processing a laser is used to fuse powders together to form whole parts. The build direction, which corresponds to the axis on which the longest dimension of the part is oriented, can greatly influence the morphology and material performance of the final product. In this study we evaluate the microstructure and mechanical behavior of SLS processed polyamide 12 (PA-12) as a function of build direction.
LORD offers adhesive solutions that effectively bond plastics to substrates directly in an injection molding process. A specially designed injection mold was created to evaluate adhesive technologies and their effectiveness in bonding various thermoplastics, such as nylon, polycarbonate, PC/ABS, and TPU?s, to substrates such as aluminum and glass. This paper focuses on in-mold bonding of PC, PC/ABS, and nylon 66 to aluminum. Molded assemblies were tested for adhesion directly after molding and after environmental exposures (thermal cycling, heat and humidity, and anodizing). This process and product technology offers a number of design and cost benefits, such as light weighting, design freedoms, and manufacturing efficiencies.
Injection molding, a typical batch process with two-dimensional (2D) dynamics along the time direction as well as batch direction, is a widely used polymer processing technology transforming plastics into products of various shapes and types. Despite of fast development of hardware, computational load has to be considered in injection molding control system. Meanwhile parameters of control algorithm should be easy to tune and separately relative with control performance like set-point tracking and disturbance rejection. In this paper, a fast and effective 2-dimensional (2D) control algorithm combining model predictive control (MPC) and 2D error prediction is proposed based on the characteristics of injection molding processes, all parameters are normalized within 0 and 1, and separately related to control performance. The proposed control scheme is tested experimentally through the closed-loop control of a key process variable, packing pressure. The result shows the good performance and verifies the previous designs.
During the extrusion of polymers, it is generally necessary to provide heating and cooling capabilities at the extruder barrel for start-up and temperature control during operation. The most common solutions used, are electric resistance heaters in combination with air-cooling by radial blower fans. These heaters are usually grouped in zones to allow the setting of temperature profiles along the barrel. Although this well-established solution benefits from several of its properties, there is one major disadvantage. At certain operating points, it is unavoidable that cooling is applied to keep the processing temperature within the given limits. By the use of air-cooling, the extracted heat is wasted and the energy efficiency of the extrusion process decreases.
The main goal of the presented approach is to preserve this extracted energy inside the system and make it utilizable at another location in the process. This is achieved by a fluid heating system using thermal oil as heat transfer medium. The system provides two global temperature levels of thermal oil and uses bypasses for each zone along the barrel of the extruder. These bypasses allow the setting of a specific desired feed temperature for every single zone without the requirement to provide an independent fluid heating system respectively. The return flow is distributed back to the global fluid streams based on the fluid temperature after the zone. Depending on the specific operating conditions, this distribution leads to a decreasing power demand of the complete temperature control system by utilizing extracted process heat to minimize the additional global heat requirement.
Qi Li, John P. Beaumont, Alicyn Rhoades, John P. Coulter, May 2015
Runner based shear imbalance has been existed since the beginning of the related polymer injection molding development. The major phenomenon of the shear imbalance is the non-unique filling results in the molding cavities, even if the cavities are balanced in space and position. Researchers have been studying the shear imbalance problems, such as shrinkage or warpage, and the associated solutions for years. However, there is not such a solution that could be universally accepted by all industries or research academies. In some previous studies, a novel technology, Melt Rotation Technology, has been studied and developed theoretically and experimentally, providing persuasive evidence that the melt flow shear gradients developed in the runner system during traditional injection molding process is mainly responsible for the imbalance filling results, and Melt Rotation Technology was able to overcome the shear induced problem and modify the thermal, physical or mechanical properties of the molded specimens. In the current study, polymer samples molded with and without Melt Rotation Technology were tested and compared logically. Specimens from higher shear melt flow regions exhibited higher crystallinity as well as higher melting temperatures due to the localized shear rate variation. New molding trials were implemented and more experimental results have been found to support the effectiveness of Melt Rotation Technology.
In this research, direct fiber feeding injection molding (DFFIM) technique was used to produce PC/ABS/PC oligomer blends composites reinforced Glass Fiber. The continuous roving of glass fibers were fed into the vented barrel directly and mixed with matrix. The number average fiber length of 10 wt% oligomer composite is longer than that of 0 wt% oligomer composite. Oligomers reduce viscosity of matrix, fiber attrition is reduced. The tensile strength of specimen containing oligomer is limited by about 115 MPa in case that fiber volume content is over 12 %, because increasing amount of fibers is facilitated attrition of fibers. From observation of scanning electron microscope, interfacial adhesion is poor, because of gap between matrix and fiber. The effect of oligomers is nothing to tensile properties.
Patrick M. Mabry, Steffen Ropers, Tim A. Osswald, Annegret Mallach, May 2015
Draping simulation tools improve virtual prototyping for Fiber Reinforced Plastics (FRP) by eliminating a costly trial and error development process. While the mechanical in-plane properties, i.e. tensional and shearing behavior, of FRP are widely studied, the out-of-plane bending is not well understood. The bending stiffness of a thermoplastic pre-preg was determined in dependency of temperature, fabric orientation and bending length, using a modified cantilever test. Simulation tools were used to validate the results. As the thermoplastic matrix and textile matrix interactions were expected to have a significant influence on the bending behavior, DMA was performed to account for viscoelastic effects during deformation.
Jin Wang, Ba Nghiep Nguyen, Raj N. Mathur, Bhisham Sharma, Michael D. Sangid, Franco Costa, Xiaoshi Jin, Charles L. Tucker, Leonard S. Fifield, May 2015
A set of edge-gated and center-gated plaques were injection molded with long carbon fiber-reinforced thermoplastic composites, and the fiber orientation was measured at different locations of the plaques. Autodesk Simulation Moldflow Insight (ASMI) software was used to simulate the injection molding of these plaques and to predict the fiber orientation, using the Anisotropic Rotary Diffusion and the Reduced Strain Closure models. The phenomenological parameters of the orientation models were carefully identified by fitting to the measured orientation data. The fiber orientation predictions show very good agreement with the experimental data.
Nathan Warner, Andres Garcia, Mickey Richarson, Hugo Diaz, Nandika D?Souza, Luu Nguyen, May 2015
Hexagonal boron nitride (h-BN) nano-particle composites were prepared with Bismaleimide (BMI) resin and low concentrations of filler to compare their thermal and mechanical properties. Silver was used as a filler to increase the thermal conductivity and to see the effect in the dielectric strength. Thermal conductivity values in the axial and radial direction were measured. The dielectric strength, dielectric constant, and the Tg were compared and analyzed among the different concentrations and particles sizes of the BN in the BMI resin. The thermal conductivity values increase as the concentration of the h-BN particles increase, and the axial and radial thermal conductivity gradient increases as the concentration increases due to the orientation of the particles as they become more closely packed. The Tg has remained constant among the different h-BN particle sizes. The dielectric strength shows improvement with the boron nitride particles as filler. Silver decreases the dielectric strength considerably. A Nova NanoSEM was used to precisely analyze the orientation and dispersion of the h-BN particles.
Syed Hussain R. Rizvi, Yoni Mercier, Thunyatorn Pukkrueapun, Nandika D?Souza, May 2015
Physical morphology, mechanical and thermal properties of potential drug delivery devices and scaffold structures were examined. PCL and PBAT were selected because of their biodegradable and biocompatible nature. Properties of electrospun single component PCL and PBAT meshes were compared with coaxial fibers of PCL as a sheath material and PBAT as core. DMA test results indicate that the stiffness of the coaxial fiber sample has increased significantly diminishing the flexibility of the mesh. DMA results also reinforced that the strength of the coaxial fibers increases many fold as compared to individual fibers spun.
Neil P. Doll, Anthony J. Verdesca, Eduardo Bastos, Tim A. Osswald, Rod Kleiss, May 2015
Beginning in June 2014, a small group of students at the Polymer Engineering Center at the University of Wisconsin-Madison collaborated with Kleiss Gears, Inc. in an effort to provide a fundamental understanding of the viscoelastic behavior of high-speed polymer gearing in heavy-duty applications. The project has the following ongoing objectives: material characterization, injection molding simulation, thermal-mechanical simulation, and experimental validation. The goal of this paper is to present the first look at a methodology for creating a robust viscoelastic material model that can be utilized by ANSYS? for precise simulation of thermal and mechanical behavior in polymer gears made from polyetheretherketone (PEEK).
Raymond K. Chu, Lun Howe Mark, Chul. B. Park, May 2015
The manufacture of polymeric foams with high cell densities with injection molding is of great interest to industry, primarily because of the flexibility and cost-effectiveness of the technology. Nonetheless, achieving high cell density foams with foam injection molding is inherently challenging due to process constraints. In our earlier work [1], we showed that by controlling the cooling and crystallization time within the mold cavity, foams with cell densities as high as 1010 cells/cm3 were attainable. In this work, we investigated the use of a crystal-nucleating agent in controlling the crystallization behaviors of the polypropylene and studied its influence on the foaming behavior during foam injection molding.
Novel three-dimensional (3D) open-celled carbon scaffolds (CS and CS-GR) anodes were prepared by carbonizing the microcellular polyacrylonitrile (PAN) and PAN/graphite composites (PAN-GR), which were obtained by means of foaming via using supercritical carbon dioxide as physical foaming agent. Both anodes were assembled in microbial fuel cells (MFCs) based on Escherichia coli (E. coli). The improved performance for the CS anode is ascribed to remained ?C=N group resulting in considerably improved hydrophilicity and biocompatibility after carbonization and the 3D open-celled scaffold structure contributing to the substrate transfer and internal colonization of E. coli bacteria. Meanwhile, the superior performance for the CS-GR anode is mainly attributed to increased specific surface area and active reaction area resulting from the addition of graphite. This work provides an effective method to develop a 3D open-celled biocompatible CS-GR anode, which facilitates the extracellular electron transfer for high-performance MFCs that are promising for practical applications on a large scale.
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Any article that is cited in another manuscript or other work is required to use the correct reference style. Below is an example of the reference style for SPE articles:
Brown, H. L. and Jones, D. H. 2016, May.
"Insert title of paper here in quotes,"
ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
Available: www.4spe.org.
Note: if there are more than three authors you may use the first author's name and et al. EG Brown, H. L. et al.
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