Banca de DEFESA: BRUNO NONEMACHER

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : BRUNO NONEMACHER
DATE: 12/04/2024
TIME: 14:00
LOCAL: Campus Farroupilha (https://meet.google.com/yai-ksib-czz)
TITLE:

ANALYSIS OF THE EVOLUTION OF THE FRAGMENTATION OF MACHINING CHIPS SUBJECTED TO GRINDING IN BALL MILLS

KEY WORDS:

Machining, Chips, Grinding, Metal Powder, Powder Metallurgy.

PAGES: 115
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Metalurgia de Transformação
SPECIALTY: Metalurgia de Pó
SUMMARY:

One of the most commonly used processes in industrial manufacturing is machining. This process is responsible for high waste generation, with chips being the most significant portion. Due to the impossibility of completely eliminating industrial waste production and with the aim of adding value to them, promoting more sustainable productions with lower environmental impacts, the reprocessing of waste becomes interesting, applying them in new manufacturing processes other than just casting. One advantage of machining chips is the possibility of being reprocessed and transformed into metallic powders, allowing their reuse in the production of new parts, mechanical components, among other goods of interest, through processes like powder metallurgy. It is through this technique that excellent economic results can be obtained by producing metallic powder from machining chips, adding value to them. Based on these points, this research aimed to analyze the evolution of the fragmentation of machining chips subjected to the milling process in a ball mill. For this purpose, portions of machining chips from materials such as SAE 1045 steel and AISI H13 were subjected to the milling process in a ball mill for periods of 20, 40, and 80 hours. After the completion of each milling period, the residual chips were separated and characterized regarding morphology, size distribution, microhardness, and microstructure. In addition to characterizations, the grinding efficiency calculation was applied to the residual chips. As for the obtained metallic powders, techniques such as scanning electron microscopy (SEM), laser diffraction granulometry, flowability, and compressibility were applied. Regarding the residual chips, it was noticed that, for both materials, the milling process used was able to fragment them into smaller particles than the original ones, and there is an influence of the milling time on the particle size. It was observed that, for SAE 1045 steel, there was a significant alteration in the shape of the microstructural grains and an increase in microhardness. However, for H13, there were no changes in these aspects. Regarding the produced powders, fine and superfine powders were obtained for both materials, with a predominant particle size range of 1 to 25 µm. Through scanning electron microscopy, it was identified that SAE 1045 steel produced some flakes-shaped particles for the 20-hour period, and for the other milling times, the predominant shape was polygonal. As for AISI H13 steel, the particles varied between spherical and polygonal shapes. It was not possible to confirm if these shapes would be the standard because, being very fine, these powders ended up generating many agglomerates. Flowability analysis characterized the powders of both materials with free-flowing behavior, and finally, compressibility testing showed that the powders exhibit similar behaviors during sample compression. After verifying the amount of residual chips present at the end of each milling period, it was found that the grinding efficiency was low for both materials, however, it was higher for SAE 1045 steel. The presence of metallic powders within the same particle size range was also verified, even for shorter milling periods. It is concluded from this research that, despite representing low efficiency, the milling process using a ball mill is capable of processing machining chips and turning them into smaller particles to obtain metallic powders with superfine dimensions, and these particles can serve as raw material for the powder metallurgy process, especially for metal injection molding, given the characteristics of the obtained material.

COMMITTEE MEMBERS:
Presidente - 1446153 - DANIELA LUPINACCI VILLANOVA
Interno - 1332290 - EDSON LUIZ FRANCISQUETTI
Externa ao Programa - 1768385 - LISIANE TREVISAN
Externo à Instituição - VINICIUS KARLINSKI DE BARCELLOS - UFRGS