CONVENTIONAL AND NONCONVENTIONAL RESEARCH ABOUT THE WORKING OF ACTIVE PARTS FOR THE THERMOPLASTIC MATERIALS INJECTION DIES Traian BUIDOŞ, Mircea-Petru URSU, Dan CRĂCIUN University of Oradea, tbuidos@uoradea.ro , mpursu@uoradea.ro , dancraciun28@yahoo.com Abstract: the paper presents a case study regarding the design and realization of the active parts for a specified thermoplastic materials injection die (plastic lid made of polyamide PA66), which was made as a part of a research contract with SC. MECORD S.A. Oradea; it starts from the execution drawing for the part to be injected, it continues with the classical working of the active parts on numerical commanded milling machines, the design and realization of the finishing electrodes on electric discharge machines with massive electrode, and it ends with the superfinishing of the die active parts with abrasive materials, stones and bands of various granulations, as well as diamond pastes, obtaining final roughness values of 0.2µm. Keywords: thermoplastic materials, injection, dies, active parts, superfinishing 1. INTRODUCTION Until now, the injections of thermoplastic materials was more of craft than of science, implying heuristic methods such as test and eliminate the error, even in developed industries. The major problem of designers and fabrication technology engineers is the fact that the phases of the realization for an injected part (the design of process and the technological process itself) are inter-correlated, maybe even more than in other industrial fields. In the field of the machines construction technology, massive transformations have occurred after 1990. The last century brought unprecedented development, and many technological advances were made by production automation. One could mention here the transfer lines, the occurrence of the numerical control, industrial robots and flexible fabrication systems, improvement and use of new ceramic and polymer materials, and the occurrence and development of the computing techniques and informatics and their applications in industrial activities. The importance of the polymer materials in the industry of the last decades surely increases in this millennium. The more and more intricate geometrical shape of the parts and their quality have established the plastic materials in many branches of industry and consumer goods production. Nowadays, one of the most adequate ways to optimize the fabrication of injection dies consists of the typification of the dies component parts. The efficiency of the typification in the design and realization of the injection dies has been confirmed by many examples in countries with developed industry, as well as by the experience gathered in many companies in our country. Even if the dies are quite different, according to the geometrical shape, the mass and the material of the part to be made, the frontal injection surface etc., all injection dies feature a large number of typified elements. The electronic libraries which come along with the CAD/CAM/CAE systems offer components and assemblies of the most used firms, of which one can say that they became international standards: DME, HASCO and FUTABA. For all constructive possibilities of the injection dies, which can be very diverse, the electronic libraries offer many different standard components: throwing rods, guiding bushings, screws, clamping plates, throwing plates, spacer plates etc. Of course, the active parts and the pistons which mold the injected material will have the constructive shape of the part to be injected. Nowadays, the realization of a die consists of the working of the active parts, which differ according to the product to be made, and the assembling is done by means of standardized elements. Next there is a case study which refers to the realization of a certain plastic product – lid made of polyamide PA66. Nonconventional Technologies Review – no. 2/2011 19