China
Africa
Explore chapters and articles related to this topic
Engineering materials, processes and techniques
Published in Mike Tooley, Engineering A Level, 2006
Figure 1.95(a) shows a hole being reamed in a lathe. A machine reamer is being used and it is held in the barrel of the tailstock. Note that reamers are sizing tools and they actually remove very little metal. Because a drilled hole invariably runs out slightly, the pilot hole should be single-point bored in order to correct the position and geometry of the hole. It is finally sized using the reamer. Only the minimum amount of metal for the surface of the hole to clean up should be left in for the reamer to remove.
Make engineered products
Published in Mike Tooley, Engineering GNVQ: Intermediate, 2012
Figure 3.85(a) shows a hole being reamed in a lathe. A machine reamer is being used and it is held in the barrel of the tailstock. Because a drilled hole invariably runs out slightly, the pilot hole should be single-point bored in order to correct the position and geometry of the hole. It is finally sized using the reamer. Only the minimum amount of metal for the surface of the hole to clean up should be left in for the reamer to remove.
Drilling techniques and drilling machines
Published in Roger Timings, Engineering Fundamentals, 2007
The poor cutting conditions at the chisel point of the drill resist its penetration into the metal being cut. This is why, when drilling a large diameter hole, it is often preferable to drill a pilot hole first using a smaller diameter drill. This will have a smaller chisel point and will penetrate the metal more easily, reducing the feed force required and putting less of a load on the drilling machine.
Technical considerations for the management of segmental osseous defects with an internal bone transport nail
Published in Expert Review of Medical Devices, 2022
Lee M Zuckerman, John A Scolaro, Matthew P Gardner, Thomas Kern, Philipp Lanz, Stephen M. Quinnan, J. Tracy Watson, Jan Duedal Rölfing
As many proximal and distal interlocking screws as possible should be placed in order to obtain maximal stability, particularly if a short segment is present. A step drill is used to place the partially threaded screws and the tactile feedback after penetrating the far cortex can be lacking. In order to prevent poor purchase of the screws, fluoroscopy can be used to determine when the drill bit has been advanced through the second cortex. Additional stabilization screws can also be added, abutting the nail to provide further stability and to prevent migration post-operatively. Drilling for the 3.5 mm intercalary screw can sometimes prove difficult in thick, cortical bone. Drilling a pilot hole with a K-wire or smaller diameter drill bit can be used if necessary. The location of the magnet in the BTN should be marked on the patient and it is helpful to place a nonabsorbable stitch in this location for the patient to reference. The fast distractor or ERC should be used to confirm that the intercalary segment moves by advancing the segment 1 mm (Figure 5). Alternatively, the nail can be predistracted a few millimeters prior to placement to allow the nail to be tested by compressing the osteotomy site and thereby minimize bone gapping during the latency period. The final defect should be measured.
Drilling and structural property study of multi-layered fiber and fabric reinforced polymer composite - a review
Published in Materials and Manufacturing Processes, 2019
Yermal Shriraj Rao, Nanjangud Subbarao Mohan, Nagaraja Shetty, Basavannadevaru Shivamurthy
Cryogenic assisted drilling reduces delamination and hole-wall surface roughness. It permits to drill at an elevated speed and maintains better dimensional accuracy as compared to the dry drilling. It also reduces the tool wear and maintains smooth cutting action.[33,34]Minimum quantity lubrication assisted drilling reduces zone temperature, tool wear, burr-height and hole-wall surface roughness. It increases the tool life and dimensional accuracy of the drilled hole compared to the dry drilling.[158,161] However, if it aimed only at reducing delamination, the MQL drilling is not an essential process.[161]The thrust force also reduces by drilling a small pilot hole followed further drilling[44] and appropriate machining parameters such as low feed and high speed,[45,95] low feed rate with a small size drill bit.[96]Micro-holes can be produced with better quality in aircraft structures at a feed value nearer to tool edge radius.[163,165]
Wanapum Dam repaired using post-tensioning anchors
Published in DFI Journal - The Journal of the Deep Foundations Institute, 2018
Abigail Stein, Aled R. Hughes, Rick Deschamps, Brian D. Barkauskas
Drilling the 16-inch boreholes for the 61-strand tendons proved to be one of the more gruelling challenges on the project. The design trajectory of the anchors was such that it allowed for only a small window to advance the boreholes without intersecting the gallery or drilling out the upstream face of the piers. In addition to the tight alignment tolerances, drilling challenges also entailed advancing boreholes through highly variable and fractured basalt rock. To achieve an on-target borehole, Nicholson elected to first establish a ‘pilot hole’ by advancing a stabilised HQ coring system through the concrete structure into bedrock (Fig. 10). Using specialised azimuth alignment and gyro equipment, pilot-hole alignment was verified at 10-foot intervals during the entire drilling operation.