China Automotive Industry StandardLimit Deviations without Tolerance Indication of Automobile Molded Plastic PartsQCn 29017-911 Subject and Scope of ApplicationThis standard specifies the limit deviations of dimensions without tolerance indication for automobile molded plastic parts.This standard is applicable to dimensions without tolerance indication of plastic parts that are made of thermosets and thermoplastics by stamping, injection and casting.This standard is not applicable to dimensions without tolerance indication of plastic parts that are made by squeezing, blow molding, cold drawing, sintering and foaming processes.2. Quoted StandardsZB T04 006.2Limit Deviations of Dimensions without Tolerance Indication for Machined Automobile Parts3. TermsMolding contraction volume (V): the difference between the mold dimension (LW) in standard environment and the corresponding dimension (LF) of the molded part measured after it has been kept in the temperature 232 and the relative humidity (502)% for 24 hours.Molding contraction coefficient, VS: to be calculated according to Equation (2).Radial molding contraction coefficient, VSR: the molding contraction coefficient in the direction of injection.Tangential molding contraction coefficient, VSR: the molding contraction coefficient in the direction perpendicular to that of injection.Differential molding contraction coefficient, VS: the difference between the radial and the tangential molding contraction coefficients.Contraction property value: the value corresponding to the sum (absolute value) of the radial molding contraction coefficient and the differential molding contraction coefficient of the molded part, as shown in Table 1. Table 1The sum (absolute value) of the radial and the differential molding contraction coefficients %Contraction property value and its grading011223340-11-22-33-44 Dimensions without tolerance indication of molded plastic parts can be divided into two classes:a. Class a refers to the dimension limited by a single mold, while class b refers to the dimension not limited by a single mold, as shown in Figure 1:Approved by China National Automotive Industry Corp. on May 16, 1991Effective date: June 01, 1991 1QCn 29017-91Mold closing directiona-the dimension limited by a single moldb-the dimension not limited by a single moldFigure 15 Limit Deviations of Dimensions without tolerance indication for molded plastic parts are specified in Table 2.Table 2mmContraction property valueDimension classificationBasic dimension0-11-22-33-4abababab 3 36 610 1015 15222230 304040535370709090120120160 160 200200250250315315400400500500630630800800 0.090.10 0.11 0.13 0.150.17 0.20 0.24 0.280.340.410.500.600.80 1.00 1.20 1.501.90 2.402.900.190.200.210.230.250.270.300.340.380.440.510.60 0.700.901.101.301.602.002.503.000.11 0.120.140.170.20 0.240.28 0.330.40 0.500.600.75 0.951.151.45 1.80 2.202.803.504.500.210.220.240.270.30 0.340.380.430.500.600.70 0.851.051.251.551.902.302.903.604.600.150.170.20 0.240.280.330.390.470.580.710.871.11.41.702.102.703.304.20 5.206.500.250.270.300.34 0.380.43 0.490.570.680.81 0.971.201.501.802.202.803.404.30 5.306.600.200.230.270.320.39 0.47 0.560.680.841.051.301.70 2.102.603.204.005.006.207.809.900.30 0.33 0.370.42 0.490.570.66 0.78 0.94 1.151.40 1.802.202.70 3.304.105.106.307.9010.00Note: The values in the table are acquired after the molded parts have been kept in the standard environment of the temperature 232 and the relative humidity (502) for 24 hours. In the non-standard environment, the measured values must be modified by the corresponding linear expansion coefficient. 6 Limit deviations of thread length, dip angle and radius without tolerance indication for molded plastic partsAs specified in ZB T04 006.2.Annex AThe Corresponding Relationship between Molded Plastic Materials and their Contraction Property Values(Supplementary)Table AlBasic Material CodeMaterial nNameContraction Property ValueEPEpoxy resin0-1PFPhenolric resinWith inorganic filler0-1With organic filler1-2UFMFUrea formaldehyde resin and melamine polyformaldehyde resinWith organic filler1-2With inorganic filler0-1With organic and inorganic fillers1-2UPUnsaturated polyester resin0-1ABSAcry