Burrs severely inhibit the performance and aesthetics in machined parts besides posing a safety risk to the user and manufacturer. Abrasive assisted brushing presents a fast and effective method for deburring these parts but is difficult to control. The dependence of deburring rate on the workpiece material, abrasive grit size, type and rotational speed of the brush is studied. It is found that deburring rate is proportional to initial burr height indicating fracture of the burr at the root. Deburring rate increases with spindle speed and is higher for diamond than SiC. The formation of burrs in micromilling of a thin nickel-titanium alloy (nitinol or NiTi) foil used in implantable biomedical device applications is analyzed as a function of micromilling process parameters such as spindle speed, feed, tool wear, backing material and adhesive used to attach the foil to the backing material. All factors except spindle speed are found to affect burr size. If initial penetration is sufficient to cause the foil to fail in tension, the foil tears with the crack starting closer to the upmilling side and thereby resulting in larger downmilling burrs. If penetration is insufficient, the foil plastically deforms until it tears typically in the middle of the cutter tooth path. A kinematic model that captures this behavior is used to predict burr widths and is verified through experiments. The thesis also presents an investigation of the abrasive impregnated brush deburring process for thin NiTi foils. Models based on Hertzian indentation and fracture mechanics are proposed to predict the rates of indentation and deburring during brushing and are validated using experiments. The predictions of the models are within the experimental variation. Burrs can be removed with this process within 12 minutes for a 6 mm long groove with no more than a micron change in foil thickness. Knowledge of burr formation and deburring is applied to a novel micromilled thin shape memory based NiTi foil device used for the surgical correction of Age-related Macular Degeneration (AMD), a leading cause of blindness in the western world in those over age 50. Burrs on the surface of the structure are used successfully to mechanically constrain and translocate an autograft to replace the diseased RPE-Bruch's membrane under the macula. The shape memory device is analyzed using experiments and simulations.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009. / Committee Member: Rhett Mayor; Committee Member: Shreyes Melkote; Committee Member: Steven Danyluk. Part of the SMARTech Electronic Thesis and Dissertation Collection.

This thesis is solving issues concerning deburring of hydraulic valve blocks with industrial robot. Thesis is focused on deburring of inside space of hydraulic valve blocks, although deburring of outer edges is marginally mentioned due to determining of approximate deburring time of all edges on the valve block. Search of deburring methods and tools suitable for deburring of inside and outside edges is made on the basis of valve blocks´ analysis. Paths of tools chosen for deburring of valve block B1 are programmed in CAM program. CAD program ProEngineer is used to create simplified model of robotic workplace and its layout. According to customer´s requirements, deburring method, which allows creating universal robotic workplace for deburring of hydraulic valve blocks, was chosen. Approximate deburring time of all edges on B1 block was set on the basis of tools´ paths and these were checked in the simplified model of robotic workplace in PowerMill Robot Interface. Deburring procedure, estimating of approximate deburring time of B1 block and layout of robotic workplace are main results of this thesis.

This thesis was submitted to the School of Graduate Studies in partial fulfillment of the requirements for the Degree Master of Applied Science. / <p>Accuracy and surface finishes play an important role in modem industry. However, the deformability of ductile materials induces challenges in achieving high accuracy and surface finish. Undesired projections of material produced during metal cutting, known as burrs, significantly reduces the accuracy of the parts and affect both the assembly process and product quality. Around 30% of total production costs are used for deburring processes. This thesis presents one modem and promising method in reducing burr size through the use of ultrasonic assistance. With ultrasonic assistance, high frequency vibrations are added in the feed direction during cutting. In particular, ultrasonic assisted drilling of 1100-0 aluminum using high speed steel standard twist drills was investigated.</p> <p>Two simulation studies were conducted. Firstly, a finite element model of orthogonal cutting with and without ultrasonic assistance was developed. The results predicted that ultrasonic assistance should produce smaller burrs for the simulated operating conditions. Secondly, a drilling exit burr model was created based on a circular plate deflection model. Unfortunately this simulation failed to predict the experimentally observed burr sizes and thus the model requires further development.</p><p>To provide the ultrasonic vibration a preloaded workpiece holder and a drive circuit were designed and implemented for use with a commercial piezoelectric actuator. This equipment was cost effective (costing about 400 CAN$) and functional.</p><p>The effects of ultrasonic assistance under different vibration and cutting conditions were investigated experimentally. The experimental results demonstrated that, for certain combinations of vibration frequency and amplitude, burr size reduction can be achieved. Under these conditions the ultrasonic impact actions become significant, causing chip segmentation and smaller burrs. The results also show that ultrasonic assisted drilling allows a higher spindle speed and feed to be used without increasing burr size. However, ultrasonic assistance has a negative impact on tool life. Compared with conventional drilling, chipping of the chisel edge and greater wear of the cutting lips was observed after drilling 10 holes. This situation may be improved in the future if drills with suitable coating are used in place of the standard high speed steel drills.</p> / Thesis / Master of Engineering (ME)

In the aerospace industry, burr removal is a very important part of the manufacturing process. Stacks of material on sections of an aircraft are assembled and drilled by hand. Due to extensive burr formation the sheets must be destacked so that burrs can be removed and then the stacks are reassembled and fastened together. If burrs are minimized in the drilling process, this would reduce the necessity for the sheets to be destacked and deburred. One approach to minimizing burrs is to lower the thrust force in drilling through suitable modification of the drill geometry such as the use of a step drill. Although prior researchers have analyzed different drill geometries such as step drills and their effect on hole exit burr formation in the drilling process through experimentation, no work has been reported on modeling and analysis of step drilling forces and their relationship to burr formation as a function of the step drill geometry parameters. Consequently, this thesis focuses on the modeling of the thrust force and torque for step drills and analyzes their relationship with burr size as a function of the step drill geometry parameters. In the first step, a mechanistic model for thrust and torque in drilling is implemented for a standard twist drill. This mechanistic model is then adapted to predict the thrust and torque for a step drill. Subsequently, experiments are performed to validate the mechanistic model and to evaluate burr formation with standard and step drills. The influence of thrust and torque on hole exit burr formation is analyzed for different step drill geometries and experimental feeds and speeds. The results show that the predicted thrust and torque values for both drill geometries are in good agreement with measured values, although the torque model consistently underpredicts. For standard drill geometry in the calibration tests, the average error in the thrust prediction is 7.09% and the average error in the torque prediction is -18.05%. In validation tests, the average error for predicted thrust is 2.29% and the average error for predicted torque is -18.46%. For the step drill model the average error in thrust is 0.72% while the average error in torque is -8.72%. In addition, a reduction in the predicted thrust force for a step drill relative to the standard twist drill is found to correlate well with a reduction in the measured burr size. However, further reduction in the thrust force by varying the step angle and diameter ratio do not correlate well with the measured burr size. Likely reasons for these results are presented in this thesis.

Detta examensarbete genomfördes för att undersöka hur   materialhanteringen runt avgradningssystemet Fladder kan utvecklas och   automatiseras. Behovet uppkom av dagens manuella hantering som är ineffektiv   och tidskrävande och behöver därmed optimeras. Arbetet genomfördes med metodik från   produktutvecklingsprocessen för att erbjuda layout-förslag på hur   materialhantering kan förbättras. Först gjordes en förstudie där en   datainsamling, litteraturstudie och nulägesanalys att identifiera behovet.   Koncept genererades baserat på kraven på systemet och genom olika   beslutsmatriser valdes två lösningar för vidareutveckling. Lösningarna   granskades och analyserades mer i detalj och beräkningar på deras   effektivitet och lönsamhet genomfördes. Lösningarna förfinades och mynnade ut i två layouter på   hur materialhanteringen kan förbättras. Där slutkoncept 1 är ett enkelt   system för situationen idag och slutkoncept 2 är en mer avancerad lösning för   framtida investeringar. / The bachelor   thesis was performed to investigate how material handling around the   deburring system Fladder can be developed and automated. The reason is due to   today's manual handling which is inefficient and time consuming and therefore   needs to be optimized. The work was   carried out with methodology from the product development process to offer   layout suggestions on how material handling can be improved. First, a   feasibility study was conducted in which a data collection, literature study   and current situation analysis were done to identify the needs. Concepts were   generated based on the requirements of the system and through various   decision matrices, two solutions were chosen for further development. The   solutions were reviewed and analyzed in more detail and calculations of their   efficiency and profitability were made. The solutions   were refined and resulted in two layouts on how the material handling can be   improved. The first concept is a simple system for the situation today and   the second concept is a more advanced solution for future investments. / <p>Betyg 2019-07-24</p>

No passado, o processo de rebarbação era tratado como uma etapa secundária dentro do processo de manufatura de uma peça. Entretanto, a indústria vem cada vez mais reconhecendo sua importância, fato que veio a motivar este estudo. Várias soluções podem ser encontradas na literatura visando eliminar o problema de formação de rebarba, bem como para a remoção automática das mesmas. Contudo, ainda existem pontos a serem explorados dentro do desenvolvimento destas soluções. Desta forma, é proposta principal deste trabalho identificar lacunas não exploradas na literatura e propor ações para cada uma destas. Neste contexto, será inicialmente proposto um novo algoritmo para minimização de rebarba em furação, baseado em um novo movimento de avanço da ferramenta. Adicionalmente, propõe-se identificar os requisitos reais da operação de rebarbação e classificar os problemas de rebarbação em cenários que apresentem características similares, considerando: morfologia da rebarba, geometria da peça e precisão do sistema de fixação. Subseqüentemente, para cada cenário, uma solução de rebarbação robótica é indicada. No caso de controle ativo do robô, um novo parâmetro de controle será criado (Fast Abrasive Power - FAP), baseado na fusão dos sinais de emissão acústica e potência. / In the past, deburring used to be treated as a secondary operation within the manufacturing sequence of a part. However, the industry came to realize its importance, which becomes the motivation for this study. In the literature, several solutions for burr minimization and automatically burr removal can be found. However, some topics need more investigation in order to establish a final solution. Thus, the main objective of this research is to identify these topics and to propose solutions for each of them. Therefore, a new algorithm for drilling burr minimization will be defined, based on a vibratory movement of the tool in feed direction. Additionally, it is proposed to identify the real requirements of the deburring operation and to classify the deburring problem into classes with similar characteristics, taking into account: burr morphology, workpiece geometry and precision of the fixture system. Subsequently, for each class, a robotic deburring solution is proposed. In the case of active robotic control, a new control parameter will be defined (Fast Abrasive Power, FAP) based on the fusion of acoustic emission and power signals.

During the drilling process, sharp edges of material called burrs are produced and protrude from the original surface. When a through-hole is drilled, burrs form on both the entry and exit surfaces around the hole, requiring expensive deburring operations to be performed in order to meet part specifications. A common hole producing operation in aircraft assembly is drilling holes through multiple sheet metal layers in order to fasten them together. However, at the interface between two layers, burrs form on both the exit of the first layer (termed "skin") and entry of the second layer (termed "frame"). Consequently, the layers frequently need to be taken apart, deburred, and put back together again before being fastened, resulting in additional costs and increased assembly time. The goal of this thesis was to understand the role of key factors such as drill geometry, drill wear and clamping conditions on burr formation at the interface of two thin sheets of 2024-T3 aluminum so that interlayer burr formation could be minimized. This problem was approached from three different angles. First, an experimental study was performed to find the drill geometry parameters for minimization of interlayer burrs and to ascertain the relationship between the average burr size and drill wear. Next, a new kind of clamping system for holding sheet metal layers together during drilling was designed, prototyped, and tested for its effectiveness. Finally, a preliminary analytical model of interlayer burr formation was created in order to better understand the burr formation process in stacked layers of sheet metal and to better understand the effect that each drilling parameter has on the resulting burr size.

No passado, o processo de rebarbação era tratado como uma etapa secundária dentro do processo de manufatura de uma peça. Entretanto, a indústria vem cada vez mais reconhecendo sua importância, fato que veio a motivar este estudo. Várias soluções podem ser encontradas na literatura visando eliminar o problema de formação de rebarba, bem como para a remoção automática das mesmas. Contudo, ainda existem pontos a serem explorados dentro do desenvolvimento destas soluções. Desta forma, é proposta principal deste trabalho identificar lacunas não exploradas na literatura e propor ações para cada uma destas. Neste contexto, será inicialmente proposto um novo algoritmo para minimização de rebarba em furação, baseado em um novo movimento de avanço da ferramenta. Adicionalmente, propõe-se identificar os requisitos reais da operação de rebarbação e classificar os problemas de rebarbação em cenários que apresentem características similares, considerando: morfologia da rebarba, geometria da peça e precisão do sistema de fixação. Subseqüentemente, para cada cenário, uma solução de rebarbação robótica é indicada. No caso de controle ativo do robô, um novo parâmetro de controle será criado (Fast Abrasive Power - FAP), baseado na fusão dos sinais de emissão acústica e potência. / In the past, deburring used to be treated as a secondary operation within the manufacturing sequence of a part. However, the industry came to realize its importance, which becomes the motivation for this study. In the literature, several solutions for burr minimization and automatically burr removal can be found. However, some topics need more investigation in order to establish a final solution. Thus, the main objective of this research is to identify these topics and to propose solutions for each of them. Therefore, a new algorithm for drilling burr minimization will be defined, based on a vibratory movement of the tool in feed direction. Additionally, it is proposed to identify the real requirements of the deburring operation and to classify the deburring problem into classes with similar characteristics, taking into account: burr morphology, workpiece geometry and precision of the fixture system. Subsequently, for each class, a robotic deburring solution is proposed. In the case of active robotic control, a new control parameter will be defined (Fast Abrasive Power, FAP) based on the fusion of acoustic emission and power signals.

This diploma thesis was created in cooperation with Mubea company. It deals with proposal of alternative technology of groove deburring. A special tool was designed for this technology and was experimentally tested. There are also tests for finding suitable cutting conditions, tests for appropriate tool’s positioning against a workpiece and tests for comparison the alternative technology of groove deburring to grinding technology included in this diploma thesis