QCN29017-91标准（英文版）

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 resin0-1ABSAcrylonitrile-butadiene-styrene copolymer (with and without filler)0-1CACellulose acetate plastics1-2PAPolyamide plastics (Amorphous, without filler, with filler)0-1PA6Nylon 6 plastics (without filler)1-2PA9Nylon 9 plastics (without filler)1-2PA66Nylon 66 plastics (without filler)1-2PA610Nylon 610 plastics (without filler)1-2PA11Nylon 11 plastics (without filler)1-2PA12Nylon 12 plastics (without filler)1-2Glass fiber reinforced Nylon 6/66/610/11/12 plastics0-1PA1010Nylon 1010 plastics0-1PCPolycarbonate plastics (Not filled, filled)0-1PEPolyethylene plastics (not filled)2-3PMMAPoly (methyl-methacrylate)0-1POMPolyformaldehyde* (not filled)Part length150mm1-2Polyformaldehyde* (not filled)Part length150mm2-3Polyformaldehyde* glass fiber reinforced0-1PPPolypropylene plastics (not filled)2-3Polypropylene plastics* glass fiber reinforcedFilled with talc powder or asbestos fiber1-2PP/EPDMPolypropylene/ethylene propylene diene monomer blend (no filled)1-2Table A1 (Continued)Basic Material CodeMaterial NameContraction Property ValuePPOPolyphenylene (Polyphenylene oxide) plastics0-1PSPolystyrene plastics0-1PSUPolysulfone plastics (filled, not filled)0-1PVCVinylene chloride plastics without plasticizer0-1Vinylene chloride plastics with plasticizerThe contraction property value depends on the compositions of the plasticizerSANStyrene-acrylonitrile copolym (filled, not filled)0-1SBStyrene-butadiene0-lNote: Materials marked with “*” refer to thermoplastics crystallized in unfilled parts. When the wall thickness is over 4 mm, choose the tolerance one grade higher according to the contraction property value.Additional Explanatory Notes:This standard is proposed by China National Automotive Industry Corp.This standard is under the management of China Automotive Technology and Research Center. This standard is drafted by Joint Action Group of China Automotive Technology and Research Center. Main standard drafter: Liu Li and Zhu Xiquan7Limit Deviations without Tolerance Indication of Automobile Molded Plastic PartsKey Points of Compilatory Explanation1 Scope of ApplicationThis standard is applicable to both thermosets and thermoplastics. Though their characteristics and process technologies are apparently different, we have taken into consideration the contraction property values of different materials and whether the dimension are influenced by mold actions when deciding the dimension deviations. The plastic parts specified in the standard refer to those that have gone through forming or necessary final process, and they shall be inspected in the environment specified in this standard.This standard is not applicable to the parts that are made by squeezing, blow molding, cold drawing, sintering and foaming processes. This is because their material contraction properties and laws of tolerance are different and they are not applicable to plastic cut parts.2 TermsFor most designers, the contraction property value is still a new term, but it is a parameter capable of showing main properties of the plastics, so we provide not only its definition but also the calculating method. The contraction property value is the property parameter of plastics measured in a certain standard environment, and it is applicable to both thermosets and thermoplastics, so it is reasonable to give different tolerance grades to plastics of different properties.3 Limit Deviations of DimensionsIn terms of molding process alone, the dimension tolerances of plastic parts are caused by two aspects: manufacturing process alteration and tool shapes, which is also the case for metal part processing. However, due to the material properties of plastics, DIN 16901-1982 drafters of West Germany performed practical testing and summed up empirical data, and they found out that the corresponding relationship between dimension tolerances and nominal dimensions of plastic parts is different from that of metal parts and has its own regularity for change. Therefore, their tolerances can not be determined by quoting ISO basic tolerances.According to large quantities of data both at home and abroad, several aspects must be considered when we try to determine the dimension tolerances:a. Material classification: West Germanys standard classifies the materials according to their contraction property values and gets the corresponding tolerance grades, while Japanese Standard adopts three material classes depending on three degrees of accuracy. b. Dimension direction: Dimensions are divided into two classes according to their relative activity relationship with molds: dimensions limited and not limited by molds.c. Maximum part dimensions.Different data show different focuses, among which West German and Japanese standards are the most considerate. The three classes of materials listed in Japanese standard, however, are too rough and the dimension stability for materials modified by filling, not filling and reinforcing is not taken into account, so this standard, based on DIN 16901-1982 and common domestic materials, gives four grades of tolerances according to different contraction property values, and two grades of limit deviations are given for each tolerance grade depending on whether it is influenced by the mold.