Banca de QUALIFICAÇÃO: CLEDERSON BARRO

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : CLEDERSON BARRO
DATE: 01/12/2022
TIME: 15:30
LOCAL: Banca online
TITLE:

PERFORMANCE OF POLYTETRAFLUORETHYLENE AND MOLYBDENUM DISULFIDE COATINGS IN WOODEN DRILLING DRILLS

KEY WORDS:

Wood drill, polytetrafluoroethylene, molybdenum disulfide, thin films

PAGES: 23
BIG AREA: Engenharias
AREA: Engenharia Mecânica
SUBÁREA: Processos de Fabricação
SPECIALTY: Matrizes e Ferramentas
SUMMARY:

The present study presents a surface coating with polytetrafluoroethylene (PTFE) and molybdenum disulfide (MoS2) on the cutting edges and on surfaces of the channel of Auger Bits twist drills used for drilling in wood, mainly Pinus elliottii, widely used in civil construction. The chemical characterization of the functional groups of the coating layer was carried out by Fourier transform infrared spectroscopy (FTIR), the tool life evaluation through bench tests, and the latter torque variation during the drilling process. The films and substrates' hardness were verified by Vickers durometer, and the metallography was performed to identify the drill microstructure and the film thicknesses. All analyzes were performed comparatively between the variations of samples with PTFE, MoS2, and uncoated standard samples. The tests were carried out in the laboratory with controlled parameters after the characterization of the samples concerning dimensional, heat treatment, and coating applied. In the analyses compared to the uncoated samples, the drills with PTFE obtained reductions of up to 38% in roughness, reduced drilling torque in the tip and channel region, required less power and energy from the screwdriver obtained low levels of layer peeling. On the other hand, the MoS2 samples showed a roughness reduction of up to 30% in some regions. Still, an increase of 66% in the channel region, presented an increase in drilling torque of more than 22%, an increase in consumed power of 16% in the channel region, and an 18% increase in energy consumption, in addition, to completely peeling off the coating layer in the cutting edges. The torque in samples with PTFE was lower than MoS2 in all cut regions of the drill. The core drills microstructures were martensitic, and due to the coating process, the core hardness on the HRC scale decreased. In general, PTFE-coated samples showed the best results when compared to MoS2 but, actually, had been observed a changing in the drills performances, which still needs to be further evaluated to improve tool life

COMMITTEE MEMBERS:
Interna - 1934288 - CINTHIA GABRIELY ZIMMER
Interna - 2383615 - DAIANE ROMANZINI