1、GM DAEWOO Auto & Technology EDS Engineering, GM DAEWOO Auto & Technology Standards METHOD OF DEFECT TEST FOR BOLT AND NUT EDS-T-7146 ISSUED DATE: 1994. 04. 01 REVISED DATE: 2006. 06. 19 VERSION: 2 EDS-T-7146METHOD OF DEFECT TEST FOR BOLT AND NUT PAGE: 1/3 ISSUED DATE: 1994. 04. 01 REVISED DATE: 2006
2、. 06. 19 VERSION: 2 GM DAEWOO Auto & Technology 1. PURPOSE This standard aims at helping test personnel perform the test in an appropriate method by describing the method to examine the defects which may occur on the surface and inside during the manufacture and processing of hardwareNote 1). Note 1
3、) The hardware refers to bolts, nuts, pins, washers, rivets, etc. But it refers to only bolts and nuts in this standard. 2. SCOPE This standard specifies the method to examine the occurrence of surface defects of hardware used for automobiles. 3. DEFINITIONS 3.1. Surface defects: Surface defects are
4、 the surface discontinuities on parts, caused by cracks, seams, folds, and laps. etc. 3.2. Cracks: A crack is a crystalline fracture passing through or across the grain boundaries without inclusion of foreign elements. Note 2)The cracks are divided into quench cracks, forging cracks, grinding cracks
5、, etc. 3.3. Seams: A seam is a continuous line discontinuties running parallel to the product axis, caused by dents, tensile flaws, blowholes, etc. 3.4. Folds: A fold is a doubling over of metal at a intersection of diameter configuration changes which may occur during a faulty forging operation. 3.
6、5. Lap: A lap is a fold-over of metal parallel to the surface of the threads, caused by an inappropriate thread rolling. 4. TEST 4.1. Testing equipment 4.1.1. Stereoscope: The adjustment of magnification shall be practicable, and the observation by magnifications of 3 to 30 shall be possible. 4.1.2.
7、 Microscope: The adjustment of magnification shall be practicable, and the observation by magnifications of 50 to 200 shall be possible. 4.2. Test piece 4.2.1. For the test piece, the product as it is(bolt, nut) shall be used. EDS-T-7146METHOD OF DEFECT TEST FOR BOLT AND NUT PAGE: 2/3 ISSUED DATE: 1
8、994. 04. 01 REVISED DATE: 2006. 06. 19 VERSION: 2 GM DAEWOO Auto & Technology 4.2.2. Impurities on the product surface and grease remaining on the thread surface shall be removed clearly by an ultrasonic cleaner prior to the test. 4.2.3. The number of test pieces shall be 3 or more for initial appro
9、val, and 1 or more for routine quality control. 5. TEST METHOD The test of surface defect examination shall be divided into 2 methods, macro and micro test method. The surface defect shall be observed by macro method, and then micro method. 5.1. Macro test method This method shall be used mainly for
10、 observing defects such as bursts, seams, folds. 5.1.1. Observe the product surface visually or using a magnifier or stereoscope. 5.1.2. In case of using the stereoscope, observe from the low to high magnification. 5.1.3. When observing the surface defect, mark its portion using a marking pen or oth
11、er markable pens. 5.2. Micro test method This method shall be used mainly for observing defect observed by macro method and laps in screw. 5.2.1. Cut off the observed defect part and screw part parallel to the axis using a cut-off machine. Here, pay attention to the cut surface not to discolor due t
12、o heat. 5.2.2. Grind the cut surface with a grinding machine smoothly. For the sand paper of the grinding machine, use #80. 5.2.3. Mold the ground product using mounting press equipment or epoxy resin. 5.2.4. Grind the molded product using a grinding machine. Here, grind it from grinding of #220 #40
13、0 #800 to polishing of 1 0.3 0.05 in sequence. 5.2.5. The ground surface shall be mirror-like surface without scratch, etc. 5.2.6. Decide the defect type by observing the observed defect part or threads of screw by the macro method under a microscope. 5.2.7. In this case, observe from the low magnif
14、ication of 50 to the high magnification. 5.2.8. Observe the general defect under a magnification of 100, and measure the defect size using a ruler with scale of a ocular. 6. EVALUATION Evaluation of the surface defects shall conform to the relevant standard and specifications on the drawing. EDS-T-7
15、146METHOD OF DEFECT TEST FOR BOLT AND NUT PAGE: 3/3 ISSUED DATE: 1994. 04. 01 REVISED DATE: 2006. 06. 19 VERSION: 2 GM DAEWOO Auto & Technology 7. REFERENCE KS B 0101 Screw threads and fasteners-Vocabulary DIN 267 Part 19 Surface discontinuities on bolt and screw DIN 267 Part 20 Surface discontinuities on nut GM 6102-M Surface discontinuities on bolt and screw GM 6103-M Surface discontinuities on nut
