David Juarez

Validation of the Use of SEBS Blends as a Substitute for Liquid Silicone Rubber in Injection Processes

Liquid silicone rubber is an interesting material at an industrial level, but there are great difficulties in the design and machining of molds, and in addition, it cannot be processed using conventional equipment. Therefore, new lines of research have focused on the search for new materials capable of providing final properties similar to liquid silicone rubber, that can also be engineered using simple, conventional processes and machinery. In this investigation, a range of compatible blends, based on two commercial grades of styrene-b-ethylene-co-butylene-b-styrene (SEBS) thermoplastic elastomer, was studied in order to obtain a range of different Shore A hardness blends for industrial applications where liquid silicone rubber (different hardness) is currently used. The two blended elastomers used had widely differing Shore A hardness values (5 and 90). Once the blended materials had been characterized, the Cross and Williams et al. [20] (Cross-WLF) mathematical model was applied in order to obtain theoretical performance curves for the viscosity of each of the blends. After this, a model was developed using the Computer Aided Engineering (CAE) software package Autodesk Moldflow 2012™. This computer modeling validated the results obtained from the mathematical models, thus making available to process engineers the full range of hardnesses necessary for industrial products (where liquid silicone rubber is used), while still providing the advantages of thermoplastic injection molding.

A review of concurrent engineering

94 Abstract— This paper attempts to explain and disaggregate different focuses of concurrent engineering, analyzing their application to product development and highlighting the improvements involved in their enforcement. Improvements can be observed in projects (quality), in scheduling (reducing the duration) and the cost of implementation (savings), basic achievements of concurrent engineering. Companies that already apply concurrent engineering are often multinationals, being the majority group in use. Its implementation in medium and small businesses is a very useful and achievable goal, in a field that has not developed the methodology. The entire organization (human group) is involved in the implementation of concurrent engineering, with an effort aimed at multifunctional integration and development of both product and process concurrently.

Application of concurrent engineering in product and process design

77 Abstract— Traditional methods applied to the development of new products are becoming obsolete, being necessary advanced methods based on a new approach that allows work cooperatively. This is called Concurrent Engineering and this paper intends to carry out a review of the integration of this discipline in the new ways of working. The main objective of the new forms of work is to systematize the design by interdisciplinary teams simultaneously working the products, the processes, getting the right design, with a corresponding reduction in costs and time. The introduction of CAPP systems (Computer Aided Process Planning) facilitates process design tools. Therefore, some previous work incorporating such systems are included.

Study, mechanical characterization and mathematical modeling of compatible SEBS blends for industrial applications in orthopedics and childcare

In this work, a system of compatible blends based on two commercial grades of a thermoplastic elastomer, styrene-ethylene/butylene-styrene (SEBS), with extreme Shore A hardness values (5 and 90), was studied in order to obtain a range of different performance blends for orthopedic and childcare applications, where usually liquid silicone rubber is used. Mechanical properties of different blends were obtained, and Equivalent Box Model (EBM) was used for the prediction of the mechanical behavior. The results show good agreement between the theoretical model and experimental data of new blends of SEBS.

Rheological Characterization and Mathematical Modeling of a SEBS Blend for Industrial Applications where Nowadays Liquid Silicone Rubber is Used

SEBS (styrene-ethylene/butylene-styrene) is a hydrogenated SBS used as a compatibilizer of other thermoplastic or as a blend to improve the properties (mainly impact). There is very little information about SEBSs research, independent of other materials. This study focuses on a blend from the providers SEBS extreme hardness (50% Shore-A 5 and 50% Shore-A 90) in order to analyze the miscibility of mixed materials from the storage of 2 references only. It has been used the thermoplastic elastomer Megol TA® SEBS, whose characteristics make it special due to the wide range of hardness and transparency, and can be obtained blend for industrial applications where nowadays liquid silicone rubber is used. Next step is rheological characterization of the blend, analyzing the viscosity for subsequent mathematical modeling. Finally, in order to reproduce the rheological behavior of materials during the injection process, Autodesk Moldflow Inside 2010 CAE (Computer Aided Engineering) tool has been used with Cross-WLF model parameters, and compared with tests injected.

Modelization of ironing process. Application to a three-layered polymer coated steel.

This document shows a modelization for the ironing process (the most crucial step in can manufacturing) done by using a Neural Network. A design of experiments has been done, in which a number of process variables have been taken in consideration, controlled directly by the operator: die angle, punch speed, temperature and reduction in thickness. These will be the process inputs, whereas the exits are formed by two variables result: Surface quality factor and average roughness. Once the results have been obtained, data have been introduced in a neural network software, so that after being trained the network and used the BP algorithm (BackPropagation), generates a configuration that provides the smaller permissible error. Later, by means of the sensitivity analysis, the neural network generated has been simplified with a new configuration of a minimum error.

COMPUTER AIDED ENGINEERING IN THE INJECTION MOLDING PROCESS: DETERMINATION OF SPECIFIC HEAT CAPACITY OF A THERMOPLASTIC

One important property of thermoplastics is specific heat capacity. This property, along with others, determines the solidification time of the material inside the mold. In this work the most precise process was used. Finally, Computer simulation was used to determine optimum process conditions and ie, the injection pressure and cycle time.