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Representation of Machine Elements
Published in Ken Morling, Stéphane Danjou, Geometric and Engineering Drawing, 2022
The screw thread is probably the most important single component in engineering. The application of the screw thread to nuts, bolts, studs, screws, etc., provides us with the ability to join two or more pieces of material together securely, easily and, most importantly of all, not permanently. There are other methods of joining materials together, but the most widely used ones – riveting, welding and (very common these days) using adhesives – are all permanent. It is true that these methods are cheaper, but when we know that we might have to take the thing apart again, we use the screw thread. Since the screw thread is so important it is well worthwhile looking at the whole subject more closely.
Joining Technologies
Published in Raghu Echempati, Primer on Automotive Lightweighting Technologies, 2021
Threaded fasteners are widely used and manufactured in a wide variety of shapes and sizes. Application methods range from manual use to fully automated (robotic) systems. For aluminum structures, screws and bolts are usually made of steel, but also other materials (including high-strength aluminum alloys) can be used.
Rotary Pumps
Published in J. T. McGuire, Pumps for Chemical Processing, 2020
Two-screw pumps are furnished in both lined and unlined construction. Casing materials include those for three-screw pumps plus more corrosion-resistant alloys such as bronze, aluminum bronze, 316 stainless steel, and higher alloys. Liners, when used, are furnished in a similar range of materials. Screws materials are determined by strength and corrosion resistance, the usual choices being carbon steel, chrome steel, 316 stainless steel, and higher alloys. When the liquid dictates a bore/screw material combination prone to adhesive wear, bore surface treatments (e.g., hard chrome), and screw tip coatings (e.g., Stellite), are employed to realize acceptable service life. Javia [7.13] presented a tabulation of various bore/screw material combinations and their relative performance.
Design approaches and challenges for biodegradable bone implants: a review
Published in Expert Review of Medical Devices, 2021
The journey of Internal fixation medical devices as a fractured bone healing aid began more than 100 years ago with metal plating being used in 1895 for orthopedic surgery [1]. Many different types of plates emerged later, corresponding to types and position of fractures, for example, clover leaf plate, spoon plate, L-plate, T-plate, cobra head plate, reconstruction plate, straight plate, tubular plate, etc. An adjustable locking plate was designed and received good response because of offering many advantages, such as allowable movement to segmental fractured bone for structural stability and precise positioning of disconnected segments [36]. These plates were usually fixed with screws made up of NB materials. In fact, screws were used in 1850 to fixate an olecranon fracture where two wooden screws and a leather strap were used. In 1920, stainless steel made its entry as bone screw material. It had reasonable and allowable biocompatibility. Its modified design with some additional features incorporated for human bone was developed in 1940 [16]. Three types of screws have been mainly used for joints or oblique fractures: V-shape threaded, square-threaded and buttress-threaded. Out of them, the buttress-threaded screws have been one of the most preferred options for surgeons as they provide comparatively high axial thrust and pull-out resistance [14]. The NB implants have been used in biomedical engineering for long but design investigations have been relatively few. For bone fracture fixation applications, Mg-alloys have been frequently used for manufacturing biodegradable bone implants.A brief history depicting some examples of biodegradable implants made by Mg or its alloys is enumerated in Figure 2[37–43].