What is the national standard for thickness tolerance of aluminum profiles?

Legal analysis: The minimum wall thickness of the profile is only 0.4 mm, and its tolerance requirement is ±0.04mm. The extrusion production process has very strict requirements on equipment, tools, molds, and processes. This extrusion technology is usually called precision extrusion. 1. Examples of precision aluminum extruded profiles. The tolerances of some small precision aluminum profiles are more than half smaller than the special grade tolerances in the JIS standard. Generally, the required dimensional tolerance of precision aluminum profiles is between ±0.04~±0.07mm. The cross-section of the precision aluminum profile used for potentiometers is "︼", the profile weight is 30 g/m, and the cross-sectional dimensional tolerance range is ±0.07 mm. The cross-section of the precision aluminum profile used for looms is "", and the cross-sectional dimensional tolerance is ±0.04mm. The angle deviation is less than 0.5° and the curvature is 0.83×L. The minimum wall thickness of A1050, A1100, A3003, A6061, A6063 (low and medium strength aluminum alloy) small precision extrusion profiles is 0.5mm, and the minimum cross-sectional area is 20mm2. A5083, A2024, A7075, (medium and high strength aluminum alloy) small precision extrusion profiles The minimum wall thickness of pressed profiles is 0.9mm, and the minimum cross-sectional area is 110mm2. Examples of dimensional tolerances of precision aluminum profiles Dimensions/mm Allowable dimensional tolerances/mmJIS Special Grade Small, Precision A 2.54 ±0.15 ±0.07B 1.78 ±0.15 ±0.07C 3.23 ±0.19 ±0.072, Precision extrusion technology requirements Generally speaking, aluminum alloy hot extrusion The degree of compression deformation is large, changes in extrusion temperature and speed, alignment of extrusion equipment, deformation of tooling and molds, etc. can easily affect the accuracy of profile dimensions, and their mutual influence factors are difficult to overcome. Figure 3 lists the influencing factors of precision extrusion. 3. Requirements for Tools and Molds Molds are the most direct factor affecting the dimensional accuracy of extruded products. To ensure that the cross-sectional dimensions of extruded products remain unchanged or change very little during production, the rigidity, heat resistance, and wear resistance of the mold must be improved. meet certain requirements. First of all, it is necessary to ensure that the mold is not easy to deform under high temperature and high pressure and has high heat resistance. It is more stringent for precision extrusion. It is required that the yield strength of the mold material is not less than 1200N/mm2 at the working temperature (around 500°C). .Secondly, high wear resistance is required, which is mainly determined by the hardness and thickness of the nitride layer. Generally, the hardness of the nitride layer is required to be above 1150HV, and the depth of the nitride layer is between 0.25 mm and 0.45mm. After nitriding, the mold Changes in size should be within 0.02mm. For solid profiles and hollow profiles with cantilevered sections, the elastic deformation of the mold must also be considered. In order to ensure a certain stiffness of the mold, you can consider appropriately increasing the thickness of the mold or equipping it with a special pad of similar shape. In order to control changes in the profile opening size, diversion grooves can be opened on the mold to control the flow of metal.

Legal basis: "Standardization Law of the People's Republic of China"

Article 11 serves as a guide for all relevant industries in meeting basic requirements, supporting mandatory national standards, and Recommended national standards can be formulated based on the technical requirements required for functions and functions.

Recommended national standards are formulated by the standardization administrative department of the State Council.

Article 12 For technical requirements that do not have recommended national standards and need to be unified within a certain industry across the country, industry standards can be formulated.

Article 13 In order to meet special technical requirements such as local natural conditions, customs and habits, local standards may be formulated.

Local standards are formulated by the standardization administrative departments of the people's governments of provinces, autonomous regions and municipalities directly under the Central Government; the standardization administrative departments of the people's governments of districted municipalities shall, in accordance with the special needs of their own administrative regions, consult with the people of the provinces, autonomous regions and municipalities where they are located. With the approval of the government's standardization administrative department, local standards for this administrative region may be formulated. Local standards shall be reported to the standardization administrative department of the State Council by the standardization administrative department of the people's government of the province, autonomous region, or municipality directly under the Central Government for filing, and the standardization administrative department of the State Council shall notify the relevant administrative departments of the State Council.