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Robot Applications
Published in David D. Ardayfio, Fundamentals of Robotics, 2020
Burrs are often generated when metal parts are machined. Manual removal of burrs is a monotonous and expensive operation. In special applications, sandblasting and explosive shocks may be employed in deburring. Using industrial robots is an economical method for automation of the deburring process. There are many different types of burrs, depending on how they are generated. Machining burrs are generated by drilling, milling, grinding, punching, and cutting operations. Burrs from die-cast metal parts and some molded plastic parts are similar to machining burrs. Excess materials from sand casting are often considerably heavier than machining burrs. There are considerable variations in burr size, shape, and brittleness. Robot deburring installation puts a high requirement on the robot capabilities in contouring, repeatability, speed, servo stability, and programming. The contouring capability is necessary to follow an arbitrary contour with high accuracy to obtain satisfactory deburred quality. Very high repeatability is important in guaranteeing that the robot can move without noticeable variations. During a deburring operation different speeds are normally required for different parts of the contour. Servo stability ensures that the servo system will quickly compensate for varying loads as a result of the different sizes of the burrs.
Materials Used in Switched Reluctance Machines
Published in Berker Bilgin, James Weisheng Jiang, Ali Emadi, Switched Reluctance Motor Drives, 2019
Elizabeth Rowan, James Weisheng Jiang
Figure 6.28 shows some common types of cutting techniques for rotor and stator laminations. Each method introduces different levels of stress and will affect the permeability and losses in the final core differently. Punching is an efficient high-volume cutting technique. A press uses a punch and die to cut the entire lamination at once, allowing for high-speed operation as well as the ability to cut multiple pieces simultaneously, such as the rotor and stator together. However, punching can introduce burrs to the edges of the cut piece, which can form electrical paths between laminations after assembly. Burr formation can be controlled by keeping dies sharp, either through the use of long-lasting die materials like carbide or through frequent sharpening. Tool design is another important aspect to consider, ensuring that the tool was designed to work with the mechanical properties of the steel being used. Any burrs that are introduced during the punching process must be removed prior to assembly. Burrs can be removed through grinding or chemical means. Mechanical cutting techniques like punching and rotational cutting cause plastic deformation along the edge of the piece, distorting the grain structure of the metal.
Machinability of Materials
Published in David A. Stephenson, John S. Agapiou, Metal Cutting Theory and Practice, 2018
David A. Stephenson, John S. Agapiou
The best known early studies of burr formation were carried out by Gillespie et al. [69–71], who identified three principle types of burrs. The first is the Poisson or compression burr (Figure 11.12), which results from the workpiece material’s tendency to bulge in the direction parallel to the cutting edge when compressed by flank forces on the tool. For large flank forces, such as those typical of worn tools, burrs of considerable size can be produced by this mechanism. The second and most common type of burr is the rollover burr (Figures 11.13 and 11.14), produced when a partially formed chip bends in the direction of the cutting velocity at the end of the cut. The third is the tear or breakout burr (Figure 11.15), formed when work material ruptures rather than deforms at the end of the cut. Gillespie and Blotter [69] analyzed the formation of Poisson and rollover burrs and derived equations for their approximate size under given cutting conditions. The quantitative accuracy of these equations is difficult to assess due to the difficulty of specifying some inputs, but they are useful in identifying measures that can minimize burr size.
Drilling of titanium alloy (Ti6Al4V) – a review
Published in Machining Science and Technology, 2021
Chua Guang Yuan, A. Pramanik, A. K. Basak, C. Prakash, S. Shankar
Burrs formation is a type of common issues existing on almost every conventional process including drilling, milling and cutting. Compared with other softer material with high thermal conductivity, excessive burrs formation is observed when CD is performed on titanium alloys. Regardless of workpiece materials, burrs are impossible to be eliminated. However, size of burrs formed can be effectively controlled and minimized with several processing parameters. Furthermore, post-processing burrs removal is key to prolong workpiece life cycle. It is reported that deburring process effectively increased average life cycle of titanium alloy workpiece by 69% and 283% for aluminum workpiece (Abdelhafeez et al., 2018). Deburring process can be classified into four main categories such as mechanical, thermal, chemical and electrical deburring (Gillespie, 1999). Due to chemical reactivity and poor thermal conductivity, mechanical deburring is the most common deburring technique used for titanium alloys. Mechanical deburring process can be done either manually or by machining center. However, effectiveness of mechanical deburring is greatly affected by geometries of holes formed (intersecting holes and inclined exit surface). Ton et al. (2011) developed new deburring tool, which is proven to be effective in removing inclined burrs.
Micro-end milling of biomedical Tz54 magnesium alloy produced through powder metallurgy
Published in Machining Science and Technology, 2020
Ali Erçetin, Kubilay Aslantas, Özgür Özgün
Another important issue in the micro-milling process is surface roughness and it is as important as micro burr formation. After micro milling process, mechanical deburring is difficult to remove by a second process (such as grinding). Therefore, suitable cutting parameters must be determined for minimum burr formation. Some optimization methods have been used to determine suitable cutting parameters for minimum burr formation and good surface quality (Thepsonthi and Özel, 2012; Ucun et al., 2014). In micro-milling, the burr formation is influenced by the mechanical properties of the workpiece material, tool geometry and tool coating material. It was determined that the burr sizes in Ti6Al4V and NiTi alloys which are used as biomedical materials are quite large. The burr width for the Ti6Al4V alloy is about 180 μm (Thepsonthi and Özel, 2012), while the value for the NiTi alloy is about 250 μm (Aslantas and Kaynak, 2019). In particular, the burr widths occurring at feed values close to the minimum chip thickness are too large to be cleaned by a second process. The production method and grain size of the workpiece are other factors to be considered. The burr sizes in the cutting of materials produced by the continuous casting method are larger (Lee et al., 2012), than those of the materials produced by the powder metallurgy (Erçetin et al., 2018).
Experimental investigation of top burr formation in high-speed micro-end milling of titanium alloy
Published in Machining Science and Technology, 2018
Chakradhar Bandapalli, Kundan Kumar Singh, Bharatkumar Mohanbhai Sutaria, Dhananjay Vishnuprasad Bhatt
Commercially, pure titanium and its alloys are commonly utilized for aerospace, marine, automotive, railways and biomedical applications because of its better material properties than other materials. Surface roughness and burr formation are the key parameters which define the effectiveness and robustness of machining process. In order to be a key player in current and future market, less lead time and cost saving processes are considered by firms in their product portfolio. High-speed micro-end milling (HSMEM) stands as a strategic machining process to generate micro-shapes or features with burr-free and mirror-like surface finish on different materials. The effective utilization of HSMEM of titanium and its alloys is challenging due to the influence of its micro-structure, the increase in the hardness of alpha phase to beta phases of material, low thermal conductivity and generation of high temperatures at tool-workpiece interaction, vibration and deflection of the tool. Burr is an unnecessary projection formed on the machined surface due to plastic flow of a material from cutting and shearing operations. Burrs formed are of different sizes and shapes based on the machining conditions, formation mechanism, desired shape on work material and variation in properties of work and tool materials. Burrs formed on the work material limits the quality of a surface by altering the dimensional accuracy of the desired part (Aurich et al., 2009; Dornfeld et al., 2009; Schueler et al., 2009).