JB/T 6729-2007 English PDF (JBT6729-2007)

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JB/T 6729-2007: Internal combustion engines. Magnetic particle inspection for Crankshafts and camshafts
JB/T 6729-2007
JB
MACHINERY INDUSTRY STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
ICS 27.020
J 92
Record No..
Replacing JB/T 6729-1993
Internal combustion engines - Magnetic particle
inspection for crankshafts and camshafts
ISSUED ON. AUGUST 28, 2007
IMPLEMENTED ON. FEBRUARY 1, 2008
Issued by. National Development and Reform Commission, People's
Republic of China
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Inspection method ... 4 
4 Personnel qualification ... 4 
5 Division of crankshaft, camshaft magnetic particle detection surface area ... 5 
6 Classification and level of defects ... 6 
7 Allowable limit value of defect magnetic trace ... 8 
8 Determination of magnetic trace ... 9 
9 Demagnetization ... 10 
Foreword
This Standard replaces JB/T 6729-1993 “Internal combustion engines -
Magnetic particle inspection for crankshafts and camshafts”.
Compared with JB/T 6729-1993, the main changes in this Standard are as
follows.
- added the requirements for personnel qualification (Clause 4 of this Edition);
- made partial adjustment on the division of magnetic particle inspection
surface area (5.1 of this Edition);
- the expression of the limit value of the defect magnetic trace is given in the
form of a table (Clause 7 of this Edition).
This Standard was proposed by China Machinery Industry Federation.
This Standard shall be under the jurisdiction of National Technical Committee
on Internal Combustion Engines of Standardization Administration of China
(SAC/TC 177).
Main drafting organization of this Standard. Shanghai Diesel Engine Research
Institute.
The drafting organization of this Standard. Anhui Jinguang Auto Parts Co., Ltd.
Main drafters of this Standard. Shen Hongjie, Zhang Jiyu.
Versions of standard substituted by this Standard are.
- NJ 317-1984, JB/T 6729-1993;
- NJ 318-1984.
Internal combustion engines - Magnetic particle
inspection for crankshafts and camshafts
1 Scope
This Standard specifies the magnetic particle detection and assessment
methods for crankshafts and camshafts of internal combustion engines.
This Standard is applicable to inspection and assessment of surface and near
surface defects of reciprocating internal combustion engine crankshafts,
camshafts of which cylinder diameter is less than or equal to 200mm.
2 Normative references
The following standards contain the provisions which, through reference in this
Standard, constitute the provisions of this Standard. For dated references,
subsequent amendments (excluding corrections) or revisions do not apply to
this Standard. However, the parties who enter into agreement based on this
Standard are encouraged to investigate whether the latest versions of these
documents are applicable. For undated reference documents, the latest
versions apply to this Standard.
GB/T 9445, Non-destructive testing - Qualification and certification of
personnel (GB/T 9445-2005, ISO 9712.1999, IDT)
JB/T 9744, Internal combustion engines - Magnetic particle inspection for
parts and components
3 Inspection method
According to JB/T 9744, DC magnetization is preferred for ductile iron
crankshafts and camshafts.
4 Personnel qualification
Personnel engaged in magnetic particle inspection of crankshafts or camshafts,
shall.
a) perform qualification and certification according to GB/T 9445
requirements, and obtain the corresponding level of certificate;
b) be qualified to carry out the independent magnetic particle inspection of
the crankshaft or camshaft who understands the process of forging,
casting, heat treatment, cold processing of crankshaft or camshaft, and
passes the professional training and examination of crankshaft or
camshaft magnetic powder inspection, with testing still after 400
crankshaft or camshaft testing practice;
c) obtain work authorization from employer or responsible organization.
5 Division of crankshaft, camshaft magnetic particle
detection surface area
5.1 Division of surface area of crankshaft magnetic particle detection
According to the different stresses during the operation of the crankshaft, each
crankshaft neck is divided into four areas. I, II, III and IV. The division of the
surface area of the magnetic particle detection of the crankshaft is shown in
Figure 1. The size of each area is as follows.
-- Area I is the surface of the 120° range between the crankshaft neck and
the crank. Area I is the part of the crankshaft stress concentration, and the
defects in Area I shall directly lead to crankshaft fracture.
-- Area II consists of three parts.
1) surface area within 240° of the intersection of crankshaft and crank
outside Area I;
2) surfaces of flange, pin hole, screw hole and the area within 5mm of the
keyway;
3) surface area within 2 times the oil hole diameter d1 at the oil hole.
-- Area III is the surface of each journal except I and III.
-- Area IV is the surface of the rest except I, II, III.
5.2 Division of surface area of camshaft magnetic particle detection
According to the different stresses during the operation of the camshaft, each
camshaft is divided into three areas. I, II and III. The division of the camshaft
magnetic particle detection surface area is shown in Figure 2. The size of each
area is as follows.
-- Area I is the ABC surface and two sides in the range of 45° to the left and
right of the symmetrical center line of the cam portion. Area I is the part of
C1 Single defect magnetic trace of length less than or equal to 2mm
C2 Single defect magnetic trace of length greater than 2 nm and less than or equal to 5 mm
6.2.1.2 Crankshaft journal diameter greater than 75mm
When the crankshaft journal is larger than 75 mm, the defect classification is
the same as the classification of the defect in 6.2.1.1. But, the length of the
magnetic traces of various types of defects in the defect classification is
determined by multiplying the length of each type of defect magnetic trace
specified in Table 2, Table 3, and Table 4 by the coefficient K. The coefficient K
is calculated as follows.
Where,
K - coefficient;
d - crankshaft journal diameter, in mm.
6.2.2 Classification of camshaft defects
The classification of camshaft defects is the same as the classification of the
crankshaft when the crankshaft journal diameter is less than or equal to 75 mm
in 6.2.1.1.
7 Allowable limit value of defect magnetic trace
7.1 Allowable limit value of defective magnetic trace of crankshaft
The B and C classes of defects in the whole crankshaft are not allowed to exist
laterally. The allowable limit of the defect magnetic trace is as specified in Table
5.
Table 5 -- Allowable limit value of defective magnetic trace of crankshaft
Area
Allowable existence limit of defective magnetic trace
Part Level Number of individual items in the area
Total number within the area
Single cylinder
machine
Multi-cylinder
machine
I No part is allowed to exist No level is allowed 0 0 0
II Within 2d1 of the oil hole
Defective magnetic
trace with a length
Within 2d1 of the oil
hole ≤ 1 ≤ 1 ≤ 1