CAE applications in a thermoforming mould design (original) (raw)
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Prediction of Wall Thickness Distribution in Simple Thermoforming Moulds
Strojniški vestnik – Journal of Mechanical Engineering, 2014
Thermoforming is widely used in manufacturing industries to produce large and labour-intensive products. Compared to other manufacturing techniques, thermoforming is an extremely efficient process that is suitable for high-efficiency mass production. In this paper, experimental thermoforming operations were carried out using a lab-scale, sheet-fed thermoformer. Carbon fibre-reinforced PP and unreinforced PS thermoplastic sheets were used in experimental thermoforming operations. The processing parameters were determined for each thermoformed material. Furthermore, a simulation of the thermoforming process was performed using LS-Dyna TM software. The thickness distributions obtained from the experiments were compared with the simulation results. The results show that the parameter that most affects the wall thickness distribution is the geometry of the clamping ring. To produce thermoformed products that have a more uniform thickness distribution, the clamping tool geometry must be selected according to the geometry of the product being thermoformed.
Progress in Canadian Mechanical Engineering, 2018
The mold costs for low volume production molds can be expensive due to the mold material, the process planning time, and the fabrication costs. The focus of this research is to develop a methodology to fabricate molds for low volume production, where the production quantities vary between 1-200 components. For this application, the cycle time is not an issue. Employing an additive manufacturing solution could reduce the required amount of materials and the processing planning costs, but there are cost, or technology feasibility issues related to constructing a mold directly from a CAD file. Consequently, a hybrid manufacturing approach is taken where an AM process (material extrusion based) is used to create a sacrificial pattern for specialty, low cost, interchangeable inserts manufactured using an epoxy (Aremco 805). An over molding case study is carried out using a high temperature molding material-Technomelt-PA 7846 black. The pattern, insert, coating, and mold fabrication is discussed, as well as the initial results. The initial material cost estimates to fabricate this over molding solution is approximately $140 US. The durability of the RTV coating and the inserts needs to be determined to yield the final solution costs.
Numerical Investigation of the Gas Flow Temperature on the Thermoforming and Blow-Molding Processes
Journal of Reinforced Plastics and Composites, 2009
In this article, we consider a finite element approach for analysis of the effect of the air flow temperature on the forming of a thin, isotropic, and incompressible thermoplastic membrane. Also, to take into account the enclosed gas volume, responsible for inflation of the thermoplastic membrane, we considered a thermodynamic approach to express external work in terms of a closed volume. The dynamic pressure load is thus deduced from the van der Waals equation of state. The viscoelastic behavior of the K-BKZ model is considered. Numerical validation is performed by comparing the obtained results with the theoretical results for the HDPE grade. Moreover, the effect of the temperature of the gas on the thickness and stress distribution is presented.
Laminated Injection Mould with Conformal Cooling Channels: Optimization, Fabrication and Testing
2013
Conformal cooling channels follow the cavity shape and can provide a better cooling performance in injection moulds. Laminated tooling is one of the techniques for manufacturing injection moulds with conformal cooling systems. A laminated tool is made by stacking metal sheets of varying thicknesses from which pre-calculated profiles have been cut. The stacked sheets result in a jagged die surface that has to be finished before use. Although larger number of small thickness sheets result in small irregularities that can be finished easily, it increases the cost of profile cutting process. Therefore, one of the issues in laminated tooling is determination of sheet thicknesses so that the laminated die can be made optimally. In this paper, an optimization method is presented to find the best size of the various laminas based on CAD model surface geometry such that the surface jaggedness and the number of slice is reduced at the same time. The final mould is fabricated based on suggeste...
The International Journal of Advanced Manufacturing Technology, 2019
The paper presents the geometric design of a new lattice element of conformal type integrated into the cooling system of an injection mold. The geometric variables of this element are parameterized and are included in the design of the mold cooling system so that it can be valid for any type of geometry of plastic parts. Similarly, a physical model is presented to analyze the energetic behavior of the cooling lattice. Through the application of expert-type optimization algorithms to the presented physical model, the geometrical variables of the cooling lattice are dimensioned as well as the technological variables that govern the cooling phase of the plastic part. This methodology has been applied to four plastic parts with different geometrical characteristics. The results obtained have been compared with numerical simulations carried out by means of CFD-type software for plastic parts analysis, concluding that the new cooling lattices are adapted to the design criteria of an optimal cooling system. The new cooling lattices improve, in turn, the efficiency of thermal exchange in the cooling phase for plastic parts with large concavities, fine details, internal turrets, and housings. A simplified model focused on the energy analysis of a single cooling cell has been defined, which allows us to evaluate the thermal exchange between the cooling lattice and the plastic part, avoiding the computational complexity in the generation of the discrete mesh of the mold inserts. Similarly, in order to guarantee the structural safety of the cooling grids, a numerical mechanical analysis of the structural behavior of the injection mold insert under the most unfavorable contour conditions during the injection process has been carried out. The new conformal system presented in the paper does not require expert designers for its dimensioning, considering it as an adequate tool for reducing the overall design time of the mold while allowing the manufacturing process to be more efficient, reducing cycle time, and increasing the quality of the parts produced.
Materials, 2022
The study aims to compare mechanical properties of polymer and metal honeycomb lattice structures between a computational model and an experiment. Specimens with regular honeycomb lattice structures made of Stratasys Vero PureWhite polymer were produced using PolyJet technology while identical specimens from stainless steel 316L and titanium alloy Ti6Al4V were produced by laser powder bed fusion. These structures were tested in tension at quasi-static rates of strain, and their effective Young’s modulus was determined. Analytical models and finite element models were used to predict effective Young’s modulus of the honeycomb structure from the properties of bulk materials. It was shown, that the stiffness of metal honeycomb lattice structure produced by laser powder bed fusion could be predicted with high accuracy by the finite element model. Analytical models slightly overestimate global stiffness but may be used as the first approximation. However, in the case of polymer material,...
Optimal design and manufacture of thin-walled polystyrene structures
Polymer Engineering & Science, 2005
In this study, we investigated the implementation of an automatic procedure for optimizing thermoformed thinwalled structures. Such objects are created in great numbers, especially in the food packaging industry. The methodology for the optimal design of such structures is based on the use of a parameterized geometry model created within an interactive design environment. By varying the parameters associated with the computeraided design (CAD) model, one can create a rich variety of possible designs. One can then subject these designs to physical analysis to calculate their physical properties, and thus select an optimal design. The two distinct stages of this process-the prediction of the shape of the thermoformed structure, and the physical behavior of the structure-were validated by experiments. This article reports the experimental investigation of the deformation behavior of polystyrene, the mechanical behavior of specially prepared deformed polystyrene sheets, and the response to loading of a hemispherical structure (used in the validation). POLYM. ENG. SCI., 45: 694 -703, 2005.
Finite element simulation of thermoforming processes for polymer sheets
Mathematics and Computers in Simulation, 2003
The problem of modelling and the finite element simulation of thermoforming processes for polymeric sheets at various temperatures and for different loading regimes is addressed. In particular, the vacuum forming process for sheets at temperatures of approximately 200 • C and the Niebling process for sheets at temperature of 100 • C with high pressure loading are both described. Discussion is given to the assumptions made concerning the behaviour of the polymers and the physical happenings in the process in order that realistic models of the inflation part of each process may be produced. Stress-strain curves produced from experimental testing of BAYFOL ® at various strain rates and temperatures are presented. A model for the elastic-plastic deformation of BAYFOL ® is described and is used within the finite element framework to simulate the inflation part of the Niebling process. Numerical results for the deformation of sheets into a mould in the Niebling context are presented.