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Focused Ion Beams
Published in Orloff Jon, Handbook of Charged Particle Optics, 2017
A serious negative complication to milling is redeposition. As material is sputtered away, some of it becomes redeposited in the volume that is being sputtered. In normal mechanical machining, buildup of machined material is avoided by the use of liquid or air streams, which carry the swarf away. Redeposition is critically dependent on how the milling is done. It has been shown that for the same total dose, scans that are repeated many times to mill a rectangular area cause less redeposition to occur than a single slow pass to mill the rectangle. For the slow scan, redeposited material is not removed, whereas for the fast repeated scans, some fraction of the primary beam is used to sputter away redeposited material, so that the sputter yield is less for the fast scans, but the total number of atoms sputtered is nearly the same. In an experiment that showed good agreement with results of Yamaguchi et al. (1985), Crow (1990) showed that the sputter yield as a function of scan speed in the range 0.05–1.0 cm/s remains constant. In addition, the sputter yield as a function of line pitch also remained constant.
Introduction to Polyurethanes
Published in I.R. Clemitson, Castable Polyurethane Elastomers, 2015
Polyurethane has a memory and when a force is removed, the material will return to its previous shape. A cutting tool will distort the polyurethane. After the tool has moved on, the material that has not been removed will return to its original shape. The swarf can foul the tool and generate more heat. The clearances on the tool must allow for the swarf to clear easily.
The Cast Zinc Alloy Product
Published in Frank Porter, Zinc Handbook, 1991
In the machining of zinc alloys there is sometimes a tendency for the metal to pile up on the cutting edge. This can be minimised by correct setting of the tool, provision of proper rake and clearance angles, lapping tool surfaces or clearance spaces, avoiding drag by reduction of the tool surface in contact with the work, and using the proper lubricant. In designing and grinding tools, one of the objectives should be to cause swarf to feed away from the cutting edges and to provide plenty of swarf clearance.
A radius compensation method of barrel tool based on macro variables in five-axis flank machining of sculptured surfaces
Published in International Journal of Production Research, 2019
Rufeng Xu, Xun Li, Guangming Zheng, Xiang Cheng, Yebing Tian
Suppose that the tool moves along the u parameter direction, and the machining range are v∈[0.0, 0.8] and u∈[0.0, 1.0], respectively. Also, assume that the tolerance of step size is 0.005 mm, and the tolerance of the scallop height is 0.01 mm. Tool axis was determined by ‘Swarf Drive’ of multi-axis machining strategies, and the tilt angle was set to be 5°. A barrel tool R12r20, that is, R = 12 mm, r = 20 mm, h = 4 mm, H = 8 mm, d = 10 mm and L = 83 mm, was used to machine the blade surface, and tool paths were generated on the UG/CAM® software as shown in Figure 6(b). Through checking ‘Output Contact Data’ in the dialog of ‘Non Cutting Moves’, one could then obtain the CLSF containing CC points of the above tool paths, as shown in Figure 7. If Siemens controller (such as SINUMERIC 840D) was applied on the five-axis machine tool, then macro variables were denoted by R parameters. Finally, the NC programme with macro variables of delta value for the barrel tool was produced by the developed post-processor, as shown in Figure 8, where R1 denotes the macro variable of delta value of the tool radius, and R2 denotes the macro variable of delta value of the barrel radius. If R1 or R2 is less than 0, then the actual tool radius or barrel radius is smaller than that in NC programming. If R1 or R2 is greater than 0, then the actual tool radius or barrel radius is larger than that in NC programming. If both R1 and R2 are equal to 0, the actual tool radius and barrel radius are the same as that in NC programming.
Necessity and suitability of in-line inspection for corrosion resistant alloy (CRA) clad pipelines
Published in Ships and Offshore Structures, 2023
Ahmed Reda, Mohamed A. Shahin, Ibrahim A. Sultan, Chiemela Victor Amaechi, Kristoffer K. McKee
Table 2 lists the materials of the intelligent pigging tool that could have come into contact with the pipe cladding. Thermal spraying was used to apply tungsten carbide wear protection to the skids with a thickness of 0.3–0.4 mm. The tungsten carbide is known for its high brittleness and excellent wear resistance. When the front edge of the protection layer is chipped, it peeled off, whereas when the layer is removed (for whatever reason), the skids drive on the base material. To produce a swarf like the one shown above in Figures 1 and 2, a geometrically defined and hardened cutting edge is required, as well as constant cutting forces throughout the process (e.g. machining metal in a turning machine).
Electrocinder deposition with 110G13L steel chips at a current-supplying crystallizer
Published in Welding International, 2021
Yu. M. Kuskov, I. L. Bogaychuk, N. P. Shevchenko, M. A. Fesenko
Dry swarf obtained in the machining of rail frogs was chosen as the 110G13L steel surfacing material. Blanks of steel St3 with a diameter of 170 mm and thickness of 20 mm served as the base metal. The surfacing operations were carried out using a hard start with a graphitized electrode Ø50 mm in a two-section CSM Ø180 mm. The surfacing flux used was ANF-29. The electrical power of the surfacing process was varied from 70 to 120 kW. Swarf feed was effected with a vibrating feeder designed at the E.O. Paton Electric Welding Institute with a productivity from about 5 to 45 kg/h. In all the experiments, the thickness of the deposited layer was not greater than 10–15 mm.