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Analysis of Connecting Rod Failure Causes

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Analysis of Connecting Rod Failure Causes

2017-11-02

In 2014, the quantity of accepted returned Connecting Rods from Laidong Engine Factory is as follows:
eccentric wear of copper bush: 4
fracture of copper bush: 3
breakage of Connecting Rod bolt: 2

eccentric wear of copper bush.png

Appearance: eccentric wear of copper bush
Possible reasons:
The parallelism depth of the Connecting Rod small end hole axis and the big end hole axis is not good.
The cylindricity of the Connecting Rod small end hole is out of tolerance.
Improvement measures
1. Follow the technical requirements of the drawing and tighten inspections on depth of parallelism, small hole diameter, small hole cylindricity; the diameter and cylindricity of the small hole are checked for each piece; the Connecting Rod parallelism is checked 4 times per shift instead of 2 times per shift. All the rectifications have been finished.
2. Change the small hole boring head bearing, the cylindricity of the small hole is improved to 0.003-0.004mm from the original 0.004-0.006mm and the stability has been improved.


Fracture of copper bush.jpg

Fracture of copper bush

Possible reasons:

The connecting bar oilhole and the copper bush oilhoe are not in alignment, so the lubrication is not sufficient.

The size of semi-fine boring small hoe is large, leading to small magnitude of interference between the bush and the small hole.


Oil hole malposition: improve the process and equipment, the datum reference adopts variable locating point location, improve the alignment accuracy of two oil holes and the the alignment accuracy has been improved to 0.2mm from the original 0.5mm. The rectification has been completed.

The size of semi-fine boring small hoe is large: the tool has been changed to machine-clamped edging blades from the original welding blades and the diameter dimensional tolerance of the small hoe has been changed to 0.02mm from the original 0.03 mm; the small hole diameter size of every piece will be inspected. The blades will be changed timely according to the size so as to make the size accord with the requirements of the drawing.

Breakage of <a href=http://www.techconrod.com target=_blank class=infotextkey>Connecting Rod</a> bolt.jpg

Breakage of Connecting Rod bolt

Possible reasons:

Bolt thread size, appearance bumping problem;

The screw tap is not qualified;

Improvement measures

Tighten inspections on bolt cooperation parts, including inspections on macroscopic irregularity of bolts. And a special gauge has been customized to detect the concentricity of the thread and the positioning table.

The brand of the screw tap has been changed. And the screw gauge is used to test the qualifying condition. The threaded hole thread is checked every 8 pieces. The screw tap will be checked and changed timely according to the wearing condition.


About North Internal Combustion Engine Parts Co., Ltd

Manufactures & Exporters of Piston, Engine Valves, Connecting Rod and other Engine Parts etc.

More than 25 years ago, North Internal Combustion Engine Parts Co., Ltd, was established and ever since, it has consistently focused all its activities on the research and producing of pistons. By doing so it has grown from a small family workshop into a professional manufacturers and exporter of piston in China.

Exporters of pistons and engine parts with a wide range!

Pistons of petrol/diesel engine, Heavy Automobiles for PERKINS, MASSEY FERGUSON, MITSUBISHI, TOYOTA, MERCEDES BENZ, Isuzu, NISSAN, HINO, DAF, FORD, MAN, IVCEO, CATERPILLAR, CUMMINS, DEUTZ, SCANIA, FIAT, PEUGEOT, LISTER PETTER, LAND ROVER, MAZDA, HYUNDAI, KOMATSU, Yanmar, Chevrolet and TATA etc. We are exporting and supplying these pistons to many countries market including Asia, Europe, Middle east and others. 

 

SOURCE North Internal Combustion Engine Parts Co., Ltd

http://www.pistonsupplier.com

 
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