Diseño y construcción de moldes para la obtención de probetas en verde a compresión bajo normas ASTM

Abstract

This document deals with the design and construction of molds for obtaining green test specimens under ASTM standards, so the design of the molds was carried out respecting the measures detailed in the standards, later a work material was selected that This project was a steel AISI D3 commercially known steel K100, which due to its chemical composition in the analysis carried out in a design software (von misses and safety factor) fulfilled what was required. In the case of the punches, being the part that suffers the most during the compaction process, a mathematical analysis was carried out. Then proceeded to the machining of each of the parts that make up the molds, where for the preparation of the plate-female was used a wire EDM cutter, to have a better accuracy in the measurements of the molds manufactured. As regards the process of compaction of the metallic powder, a hydraulic press with a plunger diameter of 20.5 cm was used, which allowed us to give a compaction pressure of 1000 PSI, obtaining test pieces for tension tests with thicknesses of 3.56 and 6.35 mm within the tolerance of ± 0.13 and specimens for impact tests with thicknesses of 10 mm with a tolerance of ± 0.10. The mold that presented the least difficulty was that of the test pieces for stress testing since its geometry has several radii, which improve the process. Vaseline was used as a lubricant, as it is considered a natural lubricant and would not affect the chemical composition of the compacted powder. The quantities of powder initially calculated to be placed in each mold can vary when obtaining the specimens, because some material is lost when placing the powder in the cavity of the molds as in the case of tension test tubes. an amount of 17.5 gr was weighed for 3.56 mm and 31.5 mm thickness specimens for 6.35 mm specimens where, after being compacted, they had a variation of 0.3 g with respect to the initial amount, and for the specimens for impact tests the The amount of the powder was 54 gr, so after the compaction it obtained a weight of 53.5 gr.