Basics of dimensional tolerancing (General Tolerances | ISO Tolerances | Deviations | Fits) скачать в хорошем качестве

Basics of dimensional tolerancing (General Tolerances | ISO Tolerances | Deviations | Fits)

In manufacturing, there are always deviations between the nominal dimensions, meaning the theoretical values, and the actual dimensions of a component. These deviations arise from various factors such as play in the tool guidance, thermal influences, or tool wear. That is why it is necessary to define tolerances, which are permissible deviations from the nominal dimension. It is important that these tolerances are chosen so that the function of the component is not impaired, while also avoiding unnecessarily tight tolerances in order to keep manufacturing costs low. There are three main types of tolerance specifications: Direct specification of deviations: In this case, the permissible deviations are given directly next to the nominal dimension. These deviations are referred to as upper and lower deviations. A positive deviation means that the actual dimension may be larger than the nominal dimension, while a negative deviation allows for a smaller size. General tolerances: These are used when no specific tolerances are indicated. They are based on standardized tolerance classes, such as those defined in DIN 2769 or DIN EN ISO 22081, and vary depending on the nominal size range and the required level of precision, for example, a for very fine, b for medium, c for coarse, and d for very coarse.. SO tolerances: These consist of a combination of letters and numbers and define how dimensional tolerances are specified. The letters, with uppercase letters for internal dimensions such as holes and lowercase letters for external dimensions such as shafts, define the fundamental deviation. The numbers indicate the fundamental tolerance grade. The tolerance grade, expressed as the IT number, defines the size of the tolerance zone, while the fundamental deviation, indicated by the letter, defines the position of the tolerance zone. Depending on the combination of tolerance classes between shaft and hole, different types of fits result. In a clearance fit, the tolerance zone of the shaft is always below that of the hole. In an interference fit, the tolerance zone of the shaft is always above that of the hole. In a transition fit, the tolerance zones overlap. 00:00 Principle of tolerancing 02:24 Direct Tolerance Specification 03:21 Upper Deviation es (écart supérieur) und Lower Deviation ei (écart inférieure) 04:23 Calculation of Maximum and Minimum Size 05:20 Calculation of Dimensional Tolerance 06:11 Symmetrical specification of deviations using the plus-minus sign 06:53 Deviation of zero 07:49 Both deviations positive or negative 08:46 Tolerancing of Joining Geometries 09:33 General Tolerances: Tolerance Classes 10:56 General Tolerances: Example 12:46 ISO Tolerances 13:43 Fundamental Tolerance Grades 14:43 Manufacturing Examples for Fundamental Tolerance Grades 15:47 Determination of the Fundamental Tolerance for ISO Tolerances 18:56 Determination of Limit Dimensions for ISO Tolerances 19:52 Fits (clearance, press, interference, transition) 22:06 Summary