A common goal for industrial manufacturers is to create a safer working environment and reduce production costs. One common method to achieve this goal is to drastically reduce cutting fluid use in machining. Recent advances in machining technologies have made it possible to perform machining with minimum-quantity lubrication (MQL). Drilling takes a key position in the realization of MQL machining. In this study the effects of using MQL in drilling AISI 1018 steel with HSS tools using a vegetable based lubricant were investigated. A full factorial experiment was conducted and regression models were generated for both surface finish and hole size. Lower surface roughness and higher tool life were observed in the lowest speed and feed rate combination.

Comachara cadburyi Franclemont has benn classified as a sarrothripine (Noctuidae), lithosiine (Arctiidae), and afridine (Nolidae). Larval morphology and behavior indicate a close phylogenetic relationship with Polygrammate hebraeicum Hübner, an acronictine noctuid. The egg and larva of Comachara are described and illustrated with line drawings and scanning electron micrographs. Photographs of last instars of both Comachara and Polygrammate are provided. Larval feeding and pupation habits of C. cadburyi are briefly described and compared with those of Polygrammate. Larvae of both Polygrammate and Comachara exhibit a dramatic coloration change in the last instar, transitioning from a green phase to a mottled, steely gray form. As the color change progresses, the larva ceases feeding and enters a wandering phase, during which it seeks out wood in which to pupate. Interpretation of L group setal homologies on the ninth abdominal segment is briefly addressed. Comachara provides a poignant example of the importance of immatures in elucidating phylogeny - adult features of Comachara misled a number of the twentieth century century's finest lepidopterists.

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Today, drilling can be considered the most common of all metal cutting operations. Drilling can be accomplished on nearly all machines that can produce a relative rotation of the spindle, and/or the workpiece. These machines can include drill presses, lathes, milling machines and machining centers. Of the more than 1.70 million machine tools in the United States, that are located in plants employing more than twenty workers, more than half of these machines can, and probably are performing drilling functions. Drilling has been studied in numerous investigations with the objective of increasing drill performance. Severely lacking in this research has been the use of statistically designed experiments. Traditional experimental techniques in tooling have been conducted under a one variable at a time methodology. The twist drill, however, is one of the most complex metal cutting tools in existence today. Changing one variable at a time can lead to unwanted changes in other variables. With today's statistical techniques and computers, variables and variable interactions should be able to be adjusted and controlled. Because drilling is one of the leading metal cutting operations, an ever so slight increase in the level of drill performance could yield important benefits to manufacturing. Investigation into drill geometry and variable interaction may also lead to significant increases in drill performance. A quantitative analysis was performed to determine the effect of different independent variables on tool life for Titanium Nitride Coated tools. This was accomplished in two stages. In Stage 1, the variables lip height, helix angle, and margin width were tested one at a time for their effect on tool life. In Stage 2, the variable lip height from Stage 1 and the independent variables, speed and feed, were tested for their effect on tool life in a three variable, two level factorial treatment design. Secondary measurements were also taken in Stage 2 on acceleration, torque and face wear. Stage 1 showed that tighter tolerances on lip height could improve tool life. The 39 degree helix angle was more of a detriment than an aid, to increase tool life. The lowest level of margin width had lower tool life than either of the other two levels. In stage 2 feed and lip height had a significant effect on tool life at the 90% confidence level. Speed did not have an effect on tool life. No variable in Stage 2 had an significant effect on acceleration at either the 95% or 90% confidence level. At the low level of the feed, acceleration readings seemed applicable in determining pending tool failure. The largest values of crater width on the face were associated with the low values of feed. No true distinction can be made with torque, between any of the combinations of levels tested. This research has attempted to further quantify some of the variables and variable interactions associated with drilling for Titanium Nitride Coated tools. / M.S.

This thesis presents a detailed analysis of the plane rake faced drill design, its grinding method and grinding wheel geometry. A fundamental geometrical analysis has then been carried out on the major cutting edges of the modified drills according to the national and international standards. It has been shown that this new drill design results in a significant increase in the normal rake angle at lips as well as point relieving at the chisel edge region. Geometrical models for the various drill point features have been established which uniquely define the drill point features of the modified drill design. A comprehensive experimental investigation has been carried out to study the drilling performance of the modified drills, when drilling a high tensile steel, ASSAB 4340, with TiN coated high speed steel drills over a wide range of drilling conditions. Comparing to the drilling performance with conventional twist drills under the corresponding conditions, it has been found that the modified drills can reduce the thrust force by as much as 46.9% with the average of 23.8%; the reduction of drilling torque is also significant at an average of 13.2% and the maximum of 24.9%. Similarly, the new drill design shows great superiorities over the conventional drills in terms of drill-life. In the drill-life tests, a few conventional drills were broken, but all plane rake faced drills performed very well. In order to estimate the cutting performance in process planning on a mathematical and quantitative basis when drilling with the modified drills, predictive cutting force models have been developed based on the unified-generalized mechanics of cutting approach. The models have been assessed qualitatively and quantitatively and showed good agreements with the experimental thrust, torque and power. Empirical-type force equations have also been developed to provide simple alternatives for practical applications.

This thesis presents a detailed analysis of the plane rake faced drill design, its grinding method and grinding wheel geometry. A fundamental geometrical analysis has then been carried out on the major cutting edges of the modified drills according to the national and international standards. It has been shown that this new drill design results in a significant increase in the normal rake angle at lips as well as point relieving at the chisel edge region. Geometrical models for the various drill point features have been established which uniquely define the drill point features of the modified drill design. A comprehensive experimental investigation has been carried out to study the drilling performance of the modified drills, when drilling a high tensile steel, ASSAB 4340, with TiN coated high speed steel drills over a wide range of drilling conditions. Comparing to the drilling performance with conventional twist drills under the corresponding conditions, it has been found that the modified drills can reduce the thrust force by as much as 46.9% with the average of 23.8%; the reduction of drilling torque is also significant at an average of 13.2% and the maximum of 24.9%. Similarly, the new drill design shows great superiorities over the conventional drills in terms of drill-life. In the drill-life tests, a few conventional drills were broken, but all plane rake faced drills performed very well. In order to estimate the cutting performance in process planning on a mathematical and quantitative basis when drilling with the modified drills, predictive cutting force models have been developed based on the unified-generalized mechanics of cutting approach. The models have been assessed qualitatively and quantitatively and showed good agreements with the experimental thrust, torque and power. Empirical-type force equations have also been developed to provide simple alternatives for practical applications.

A preparação das arestas de corte é um processo que tem chamado a atenção na indústria de fabricação e recondicionamento de ferramentas em função dos benefícios que tem trazido especialmente na vida útil da ferramenta. Este processo dá um grande diferencial competitivo àqueles que detém o conhecimento de como aplicá-lo e por isso é mantido como um segredo industrial. No que se refere a brocas helicoidais a escassez de informações é ainda maior, em função da alta complexidade da ferramenta e do processo. O presente trabalho traz os resultados da influência da preparação das arestas de corte (alteração da microgeometria) de brocas helicoidais no processo de furação do aço SAE 4144M temperado e revenido com 38 HRC. O processo manual de escovamento foi utilizado para preparar as ferramentas com arestas arredondadas e o processo manual de limagem para as ferramentas com arestas chanfradas. Foram medidas várias características das peças usinadas tais como: diâmetro, circularidade, desvio de posição, rugosidade dos furos obtidos, dureza, microdureza dos corpos-de-prova, força de avanço e torque do processo de furação, avaliação do tipo e forma dos cavacos gerados no processo. Os resultados mostraram que o processo de preparação de arestas aumenta a resistência da ferramenta ao desgaste e consequentemente aumenta sensivelmente sua vida, especialmente as de arestas arredondadas. Além disso, exerce influência na integridade superficial do furo obtido (circularidade e rugosidade) e na microdureza da região próxima à parede do furo obtido. Não houve diferença significativa no torque entre as geometrias analisadas, porém a força de avanço foi menor para a ferramenta apenas afiada sem preparação de aresta. / The cutting edge preparation is a process which has drawn attention from the tool’s manufacturing and refurbishing industry due to specialization to its benefits specially to tool useful life. This process results in a major competitive advantage to those who have the knowledge of its application and, for this reason, it is kept as a trade secret. As far as the twist drills are concerned, the scarcity of information is even greater, due to the high complexity of the tool and process itself. This dissertation presents the results of the influence of the preparation of the twist drills cutting edges microgeometry alteration in steel drilling process SAE 4144M quenched and tempered steel with 38 HRC. The manual brushing process was used to prepare tools with rounded edges and manual filing process was used to prepare tools with chamfered edges. Several features from the machined parts were measured, such as diameter, roundness, position deviation, roughness of the obtained holes, hardness and microhardness of specimens, feed force and torque of the drilling process, assessment of type and shape of the chips from the process. The results showed that the edges preparation process increases the wear resistance of the tool and thereby increases its useful life significantly, especially for tools with rounded edges. In addition, it influences the surface integrity of the obtained hole (circularity and roughness) and the hardness of the region near the wall of the obtained hole. There was no significant difference in torque between the analyzed geometries, however the thrust force was lower for the sharpened tool without any edge preparation.

This master's thesis describes a design of horizontal boring mills. The first part is dedicated to description of the various types of these machines and their accessories. There are also described drives and linear guideways. There is a list of plate horizontal boring mills of Czech and foreign producers. The second part of this thesis deals with designing of comlete machine's bed and its slides (X-axis). Casting of the bed and its slides are designed for universal machining to the use of rolling or hydrostatic guideways. The drive of X-axis is also designed and it works in master/slave mode. The final result of this master's thesis is a 3D model of the machine in two variants, with hydrostatic and rolling quideways. Machining drawings of the bed for both variants are attached to this thesis.

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