In the field of CNC machining, there exists a diversity of machine configurations, imaginative design solutions, choices of cutting speeds, dimensional specifications, and types of materials that can be machined.
A number of standards have been developed to guide the implementation of machining processes. Some of these standards are the result of long periods of trial and error and practical experience, while others are the result of carefully planned scientific experiments. In addition, some standards have been officially recognized by the International Organization for Standardization (ISO) and enjoy international authority. Others, although unofficial, are also well known and adopted in the industry, with slightly different standards.
1. Design standards: Design standards are unofficial guidelines specifically designed to guide the computer-aided design aspect of the CNC machining design process.
1-1: Tube Wall Thickness: During the machining process, the resulting vibration may cause fracture or deformation of parts with insufficient wall thickness, a phenomenon that is particularly significant in the case of low material stiffness. In general, the standard minimum wall thickness is set at 0.794 mm for metal walls and 1.5 mm for plastic walls.
1-2: Hole/Cavity Depth: Deep cavities make it difficult to mill effectively, either because the tool overhang is too long or because the tool is deflected. In some cases, the tool may not even reach the surface to be machined. To ensure effective machining, the minimum depth of a cavity should be at least four times its width, i.e. if a cavity is 10 mm wide, its depth should not exceed 40 mm.
1-3: Holes: It is recommended to plan the design of holes with reference to the existing standard drill sizes. As far as the depth of the hole is concerned, it is generally recommended to follow the standard depth of 4 times the diameter for design. Although in some cases the maximum depth of the hole may extend to 10 times the nominal diameter.
1-4: Feature Size: For tall structures such as walls, a critical design criterion is the ratio between height and thickness (H:L). Specifically, this means that if a feature is 15 mm wide, its height should not exceed 60 mm. Conversely, for small features (e.g., holes), the dimensions can be as small as 0.1 mm. However, for practical application reasons, 2.5 mm is recommended as the minimum design standard for these small features.
1.5 Part size: Currently, normal CNC milling machines are widely used and are typically capable of machining workpieces with dimensions of 400 mm x 250 mm x 150 mm. CNC lathes, on the other hand, are usually capable of machining parts with a diameter of Φ500 mm and a length of 1000 mm. When faced with large parts with dimensions of 2000 mm x 800 mm x 1000 mm, it is necessary to use ultra-large CNC machines for machining.
1.6 Tolerance: Tolerance is a critical consideration in the design process. Although precision tolerances of ±0.025 mm are technically achievable, in practice, 0.125 mm is usually considered the standard tolerance range.
2. ISO Standards
2-1: ISO 230: This is a 10-part series of standards.
2-2: ISO 229:1973: This standard is specifically designed to specify speed settings and feed rates for CNC machine tools.
2-3: ISO 369:2009: On the body of a CNC machine tool, some specific symbols and descriptions are usually marked. This standard specifies the specific meaning of these symbols and their corresponding explanations.
Guan Sheng has strong manufacturing capabilities covering a wide range of processing techniques: CNC machining, 3D printing, sheet metal processing, injection molding, and so on. Trusted by our customers, we have been chosen by excellent brands from various industries.
If you are still worried about how to solve your CNC problem, please contact us:
Post time: Feb-20-2025