Cylindrical gear design can be divided into three steps. In the first step, rough gear pair dimensions such as center distance and face width are being estimated. Center distance and face width are directly linked to the available space (housing dimensions) and influence the overall size, weight and cost of the gears. In addition, the torque capacity strongly depends on the chosen gear materials, heat treatment and gear quality. Although case-hardened gears tend to give a higher torque capacity than nitrided gears, a final machining process like for example grinding is required to compensate the hardening distortion. Considering all these factors in a gear rough sizing and finding the best solution becomes a tough challenge. In the next step, gear macro geometry is defined. In a conventional gear manufacturing process, the choice of normal module, pressure angle and reference profile are directly linked to the cutter geometry. The consideration of available tools in the early design stage can save a lot of effort in the later manufacturing steps. In addition, the resulting gear geometry must satisfy the required safety factors in accordance with the selected gear strength calculation method. Although a higher gear root radius tends to give higher root safeties, it may produce contact interference and require a special cutter. Evaluating different geometric solutions and eliminating non-feasible ones in the early design phase becomes an important task.

In the last phase, gear micro-geometry is defined. The aim of this step is to specify flank line and profile modifications for optimal contact pattern, lower noise emissions and various other parameters. Here, the choice of modification parameters is directly linked to the final machining process. Often a grinding worm with associated dressing wheel is used. If a specific list of grinders/dressers is available, it makes sense to consider them in the layout process to avoid extra costs in the manufacturing process. In this paper we will present an efficient gear layout procedure based on international standards for gear geometry and strength calculation with the consideration of manufacturing constraints such as lists of hobs, grinders and dressers. The aim is to reduce costs in the later manufacturing steps or alternatively, to be able to predict the need for additional tools in the early design process.

In the Gear Rough Dimensioning section, an approach for gear rough dimensioning is presented. The resulting center distance and face width are used for the next step, i.e.—gear fine-sizing. In Gear Macrogeometry and Optimization, the focus is on gear macro geometry. Parameters such as normal module, pressure angle, helix angle and reference profile are found to meet certain optimization criteria. Two macro-geometric solution examples are used for further analysis; this is followed by Gear MicroGeometry andOptimization. Lead modifications are used to optimize the load distribution along the flank line. Profile modifications and contact analysis are used to optimize the load distribution in profile direction and reduce gear noise. Each chapter also focuses on selected manufacturing constraints that influence the overall design process of cylindrical gears.