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Gear Cutting/Manufacturing
Published in Zainul Huda, Machining Processes and Machines, 2020
Hobbing is a machining process involves the rotation of both the cutting tool (hob) and the workpiece in a continual timed relationship. Its productivity and versatility render hobbing as one of the most fundamental machining processes for gear manufacturing. Gear hobbing is a generating machining operation i.e. the shape of the gear tooth is generated by the combined motions of workpiece (gear blank) and hob. The hob is a cutting tool that is used to cut the teeth into the workpiece. In order to manufacture a spur gear, the hob is angled equal to the helix angle of the hob. It is important for precise machining that the gear blank and the hob be synchronized in the rotation. While the hob and gear blank are rotating, the hob normally feeds axially across the gear-blank’s face at the tooth depth to produce a gear cut (see Figure 10.8). The hob makes successive cuts on the gear blank to generate the gear teeth. For single-start hob, the gear blank will advance one tooth for each revolution of the hob. For a double-start hob, the gear blank is rotated over 2 teeth for each revolution of the hob; for a triple-start hob, the gear blank is rotated over 3 teeth for each revolution of the hob, and so on. Gear hobbing with multi-start hobs results in saving cycle time thereby improving productivity (see Example 10.16).
Advances and Applications of Nontraditional Machining Practices for Metals and Composite Materials
Published in T. S. Srivatsan, T. S. Sudarshan, K. Manigandan, Manufacturing Techniques for Materials, 2018
Ramanathan Arunachalam, Rajasekaran Thanigaivelan, Sivasrinivasu Devadula
Production of gears for the automotive industry during 2008 is estimated to have been between 2000 and 2500 trillion, from which 1000 to 1400 trillion pieces were high-quality gears (Karpuschewski et al. 2008). Increasing standards on environmental impacts associated with products force the modern manufacturing industry to take a critical approach on making processes environmental friendly. Gear form cutting (broaching and milling) and gear generating (shaping and hobbing) are two of the main gear manufacturing methods. Usually, production involves three stages: (i) soft machining, (ii) heat treatment, and (iii) hard machining. Limitations of the conventional machining methods (difficult to cut materials, high cost of specialized cutting tools, high cutting tool failures, high cost of machine tools, stresses generated, and cutting force) affect the component life and cost and require alternative ways of material removal that do not affect the mechanical properties while delivering high-quality products in a cost-effective way, which is the goal of the industry. A large volume of material is removed during conventional gear production, resulting in higher lead time, greater use of cutting fluids (and its disposal), chip handling (and its disposal), and dust. In this context, abrasive waterjet cutting is considered to be a good addition to the current production system due to the low amount of applied force, negligible heat generated during machining, minimal change in material properties, versatility, lower initial investment, and environmental friendliness (no chip generation and no need for cutting fluids). To demonstrate the capability of the proposed approach in manufacturing spur gears and helical gears, forged gear blanks typically used in the automobile industry were used for initial tests and gears were produced and individual teeth have been separated from each gear and tested from different perspectives—metrological, surface integrity, productivity, and production cost comparisons (Babashov and Mammadova 2015). While improvements were achieved from environment and surface integrity perspectives, abrasive waterjet cutting cannot replace the soft machining stage because of increased lead time and production cost. A novel hybrid gear manufacturing method was proposed from this research and compared with the conventional method employed in the automotive industry. The proposed hybrid approach is composed of an abrasive waterjet cutting process as the major material removal method and a conventional five-axis machining method for final finishing or maintenance of tight tolerances and, at the same time, for decreasing initial investment and adding further flexibility to the production system.
Improving spur gear microgeometry and surface finish by AFF process
Published in Materials and Manufacturing Processes, 2018
Anand C. Petare, Neelesh Kumar Jain
There are various international standards to assess quality of a gear by comparing deviations in its microgeometry with the tolerance values specified for each quality level. American Gear Manufacturing Association (AGMA), Deutsches Institut fur Normung (DIN), and Japanese Industrial Standards are the most commonly used standards for defining gear quality. The DIN 3962 standard used for cylindrical gears has 12 categories from 1 to 12, whereas AGMA (2015-1-A01 and A06) standard for cylindrical gears has 10 categories from A2 to A11 corresponding to the best quality and the worst quality gears, respectively.[5]
Investigations on tip relieving of spur gears by non-contact process
Published in Materials and Manufacturing Processes, 2023
Vivek Rana, Neelesh Kumar Jain, Sunil Pathak
Normalized case-hardened Alloy steel 20MnCr5 was chosen as the material to manufacture workpiece gears due to its commercial use in spur gear manufacturing. The gear hobbing process was manufactured with specifications such as a 3 mm module; 16 teeth; 20 mm face width; and 20° pressure angle. The samples have hardness in the range 170–190 HB, which follows the guidelines as per EN10084:2008 standard.[20]