GB 4436-84 Aluminum and Aluminum Alloy Tube Out-Of-Round Tolerances
GB 4436-84 is a China national standard concerning tolerances for out-of-roundness of aluminum and aluminum alloy tubes. This national standard applies to the design, manufacture, and acceptance of aluminum and aluminum alloy tubes of out-of-roundness with an outside diameter greater than or equal to 28mm and less than or equal to 300mm.
This national standard stipulates the allowable tolerances for out-of-roundness of aluminum and aluminum alloy tubes (outside diameter). The maximum allowable out-of-roundness shall not exceed 0.5% of the outside diameter of the tube. This national standard places an emphasis on a uniform allowance for out-of-roundness relative to the outside diameter of the tube and may be used in specifying the maximum allowable out-of-roundness of aluminum and aluminum alloy tubes.
Requirements for out-of-roundness of aluminum and aluminum alloy tubes (outside diameter) detailed in GB 4436-84 shall be based on measuring the out-of-roundness at eight ordinal points (i.e., 90° intervals) along the circumference of the tube. The maximum accumulative point difference must not be greater than the allowable out-of-roundness value specified by this national standard. If additional points are utilized for measuring the out-of-roundness of the tube, the measured point difference shall not exceed the applicable maximum value for out-of-roundness of aluminum and aluminum alloy tubes.
The degree of out-of-roundness for aluminum and aluminum alloy tubes shall be expressed as the difference between the two measured points (in millimeters) divided by the circumference of the tube. This national standard also provides allowable tolerance requirements for measuring the out-of-roundness of aluminum and aluminum alloy tubes using a side-shift method. The side-shift method shall be used when the maximum out-of-roundness value specified by this national standard exceeds 0.7% of the outside diameter of the tube.
In conclusion, GB 4436-84 aluminum and aluminum alloy tubes out-of-roundness tolerances is an important technical basis, which is purpose to ensure the manufacturing accuracy of aluminum and aluminum alloy tubes and guarantee the quality, appearance and performance of products. This national standard not only determines the allowable tolerance for out-of-roundness but also stipulates the requirements for measuring the out-of-roundness of aluminum and aluminum alloy tubes.
