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Machining engineering materials by turning
Published in David Salmon, Penny Powdrill, Mechanical Engineering Level 2 NVQ, 2012
The applications and uses for these work-holding devices are described below: Three-jaw self-centring chuck – The most widely used chuck on a centre lathe. It can be used only to hold bright round barstock, bright hexagonal barstock or previously turned components. Insert the chuck key in the square and turn it clockwise; all three jaws move in together to grip the workpiece. Female jaws can be used to hold large diameter workpieces.The drawback with this type of chuck is that if a workpiece is removed and replaced back into the chuck, the workpiece no longer runs exactly true (concentric). There is no means to correct this run-out.When changing the jaws, ensure that the set of jaws you are going to fit are an actual set (they are usually numbered with a code). The slots on the front face of the chuck and each jaw are numbered 1, 2 and 3. Make sure that jaw No. 1 goes into slot No. 1 and is ‘picked up’ by the scroll first, then insert jaw No. 2 in slot No. 2 and so on.Never leave a chuck key in a chuck when not in use. If the machine is started with the chuck key in, the chuck key will fly out causing injury or damage.Four-jaw independent chuck – The jaws of this type of chuck are each adjusted independently to grip the workpiece. Workpieces of any constant cross-sectional shape (e.g. square, octagon or black round bar) can be accurately gripped if it is set up with the aid of a dial test indicator.Four-jaw chucks are used for holding part finished work that must run absolutely true; however, they are slow to set up. Face plate – The face plate is used for holding large irregular-shaped workpieces. The workpiece is bolted to the face plate through its slots. Sometimes, counter balance weights are necessary to ensure the smooth running of the machine. They must be securely fixed to the face plate for safety. Face plates are only used for short workpieces and are very slow to set up. Catch plate – The catch plate has a peg or slot that transmits the rotary drive to the workpiece via a carrier when it is held between centres as shown.Work is normally held in this way when all the diameters must be concentric and it is to be machined all over. Spring collets – Spring collets can be used for holding workpieces when a higher degree of concentricity is required than that provided by a three-jaw chuck. They also cause little damage to the workpiece's surface.
Advanced Autonomous Welding for Refabrication and Follow-On Testing of Previously Irradiated Nuclear Fuel
Published in Nuclear Technology, 2023
Justin D. Yarrington, Jason L. Schulthess, Spencer H. Parker, Jordan M. Argyle, Clayton G. Turner, John D. Stanek, Cad L. Christensen
Fuel was then removed from both ends of each rodlet in preparation for press fitting new endcaps. The fuel pins contained fuel with low to medium burnup [approximately 9 GWd/tonne heavy metal (HM) (Ref. 22)] that had bonded to the cladding intermittently and had the potential to shift if a force was applied. The fuel was mechanically removed using a modified precision mill (Wabeco F1210) with an additional fourth axis, as shown in Fig. 3. The fourth axis used a lathe chuck and collet combination that securely held the rodlet. The mill spindle was rotated 90 deg to align coaxially with the fourth axis. The alignment of these were checked using height gauges and high-accuracy indicators and were set to be within 0.0254 mm. An in-cell vacuum system was used to collect fuel and cladding particulates during milling operations.
Electrochemical nucleic acid hybridization biosensor based on poly(L-Aspartic acid)-modified electrode for the detection of short oligonucleotide sequences related to hepatitis C virus 1a
Published in Preparative Biochemistry & Biotechnology, 2019
Soner Donmez, Leman Çağdaş, Halit Arslan, Fatma Arslan
A CHI-1020 potentiostat with a three-electrode cell was used for voltammetric measurements. PGE (as a working electrode), Pt wire (as an auxiliary electrode), and Ag/AgCl (as a reference electrode) were connected through a potentiostat to construct a DNA biosensor. The brand of pencil graphite lead used was Tombow (type HB), obtained from a local bookstore. The diameter of the lead was 0.3 mm, and the length of the lead was 50 mm. During each measurement, a total of 5 mm of the pencil was dipped in the solution. A copper drill chuck was used as the working electrode holder. A fresh PGE surface was used for each measurement. The pH values of the prepared buffer solutions were measured using a pH meter (Orion Model 720 A). Temperature control of the solution was carried out using a Grant W14 thermostat.
Fabrication of the Metal Particle in Plastic Bead Target for the LLE Ultra-Strong-Spherical Shock Campaign
Published in Fusion Science and Technology, 2018
E. M. Giraldez, M. Vu, M. L. Hoppe, E. Losbanos, N. Ravelo, A. Greenwood, M. Schoff, M. P. Mauldin, P. Fitzsimmons, M. P. Farrell, W. Theobald
The precision single-point diamond-turning was done on a Moore Nanotech 350 FG (Moore Nanotechnology Systems, Swanzey, New Hampshire) configured as a four-axes machine (x, y, z, and c axes). This lathe has a water cool air–bearing spindle and the spindle has a vacuum chuck for work holding. The lathe has a CNC motion controller with a 0.01-nm programming resolution and a thermally insensitive linear scale feedback system with 0.034-nm resolution. The single-point diamond-machining tools were supplied by Chardon Tool (Chardon, Ohio) and consisted of vacuum-brazed synthetic single–crystal diamond, with 25- and 5-µm tip radiuses, a 0.25-µm maximum waviness over a 130-deg window, a neutral top rake angle, an 18-deg included angle, a 12-deg conical clearance angle, and a 20-deg secondary clearance angle.