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Views: 50 Author: Site Editor Publish Time: 2024-06-06 Origin: Site
By paying attention to six often-overlooked considerations in CNC part design, you can unlock numerous possibilities and enhance your designs' potential. We won't be covering the usual CNC design basics like fillets, thin walls, or deep cavities, as you are likely already familiar with these principles. As seasoned mechanical parts engineers, we frequently encounter design practices that can be optimized for more efficient manufacturing, higher quality, and greater precision. By addressing these six subtle aspects of CNC part design, you can significantly improve your design outcomes.
When designing machined parts, it is essential to account for the quality of subsequent processes like heat treatment. Sharp edges and corners can cause stress concentrations during quenching, leading to cracking. Thus, before quenching, the root of the shoulder on a heavy-duty stepped shaft should have fillets, and chamfers should be added to the shaft end and shoulder.
Moreover, uneven wall thickness in a part can lead to deformation during heat treatment. To ensure uniform wall thickness and avoid deformation, it is recommended to add a process hole as needed.
Clamping in CNC machining involves firmly holding a workpiece in place to ensure stability and precision during machining operations. Designing parts for easy clamping allows for accurate positioning and secure holding, which enhances machining efficiency and ensures high-quality results.
In the original design shown in Figure-2, the part has point contact with the jaws when clamped in a three-jaw chuck, leading to insufficient holding. The optimized design includes a cylindrical section that increases the contact area between the workpiece and the jaws, facilitating easier and more reliable clamping.
The large flat workpiece was initially difficult to clamp securely during machining. By adding flanges, the clamping process becomes more convenient and reliable. These flanges allow screws and pressure plates to securely hold the workpiece. Furthermore, the addition of flanges aids in lifting and handling, making transportation and manipulation of the workpiece easier.
By minimizing the number of tool passes required, machining time can be reduced, leading to lower costs. In the original design shown in Figure-4, machining features at varying heights required adjusting the worktable for each height, increasing the time needed. In the optimized design, features of different heights are adjusted to the same level, enabling them to be machined in a single tool pass. This approach enhances production efficiency and makes it easier to maintain relative positional accuracy.
Reducing the machining area can lead to shorter machining times and lower costs. As illustrated in Figure-5, the original design of the bearing component features a large area that requires extensive machining. By optimizing the design, the machining area is significantly reduced, decreasing both the machining volume and tool wear. This improvement enhances machining efficiency and lowers costs. Additionally, incorporating convex features or grooves in the component design can further minimize the machining area.
To ensure the positional accuracy of surfaces that must align precisely with one another, it is best to machine them in a single clamping operation. This approach maintains the relative accuracy of the surfaces and minimizes the need for multiple clamping operations. As depicted in Figure-6, achieving coaxial accuracy between the inner and outer cylindrical surfaces is essential. In the original design, the part required two separate clamping operations to machine the outer cylindrical surface and the inner hole, complicating the achievement of coaxial accuracy. The improved design introduces a raised platform structure, allowing both the inner and outer cylindrical surfaces to be machined in a single clamping. This not only simplifies meeting the coaxiality requirements but also lowers machining costs.
