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Why did the lug bolts or wheel studs break?

Views:6     Author:Site Editor     Publish Time: 2021-02-01      Origin:Site

Car wheel bolts, connected to the wheel, bearing the weight of the whole car, also bearing our life safety.When the car is running at high speed, if the wheel bolt breaks, the wheel hub will fly out, the car is out of control, which will seriously threaten the driver's life.So the strength of the car wheel bolt is very important.


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Judgment of the strength of car wheel bolts generally according to the international standards, divided into 8.8, 10.9 and 12.9 grade. 8.8 grade bolts are usually made of 45# steel, which is not safe because of the low hardness and brittle cracking. So we only make 10.9 grade bolts and 12.9 grade bolts.


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How to judge whether the wheel bolts conform to 10.9 grade and 12.9 grade? 

We should not only test the hardness of the bolt, but also test the tension, torsion, guarantee load and other test values.Different thread has different testing standards. According to the following international testing standards, each value must meet the standard, so we can judge whether the product meets the 10.9 and 12.9 grade.If any item is not up to standard, it will be judged as unqualified.


Thread

GRADE

Rockwell

 hardness

Minimum

 tension load

Guarantee

load

Minimum

 tensile strength

M12x1.25

10.9 GRADE

HRC32-39

95.8KN

76.4KN

1040Mpa

12.9 GRADE

HRC39-44

112KN

89.3KN

1220Mpa

M12x1.50

10.9 GRADE

HRC32-39

91.6KN

73.1KN

1040Mpa

12.9 GRADE

HRC39-44

107KN

85.5KN

1220Mpa

M14x1.50

10.9 GRADE

HRC32-39

130KN

104KN

1040Mpa

12.9 GRADE

HRC39-44

152KN

121KN

1220Mpa



How to avoid lug bolt breakage ? How does our factory control the process quality of wheel bolts?


1、Hardness control: we will do different hardness according to grade request, also  choose different materials according to the hardness request, don't use inferior materials when you want high hardness bolts.


2. We must get rid of stress before plating, and cancel hydrogen after plating.During bolt's electroplating process, due to the dissociation of water molecules, a part of hydrogen ions will be produced, so the cathode precipitates metal and hydrogen at same time in the electroplating process. Precipitates hydrogen is easy to lead the bolt  hydrogen embrittlement, it will bring the hidden danger is bolt fracture, which is a very serious safety problem. 


Each lug bolts or wheel studs of HONISHEN has been specially treated, not only ensure the hardness but also keep flexibility of the corresponding grade: 


1. Get rid of stress before plating: we will do a temper treatment after bolt was handled by heat treatment, even some high requirement product, it need do extremely cold treatment, the temperature is﹣100℃- ﹣300℃, heat preservation time is 24-36 hours. Through the conversion of extreme heat and extreme cold, reduce the hidden danger of bolt hydrogen penetration. 


2. Cancel hydrogen after plating: Hydrogen removal is done by heating and baking within 1-2 hours after plating. The temperature is 150℃-300℃ and the insulation time is 3-24 hours. We will choose different insulation time  according to the size of the product itself.

So,don't worry about such fracture if you choose HONISHEN lug bolts or wheel studs .


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E-mail: hs@wheelnuts.cn 
Skype: tracyzhang1205 
Address:No.136,XiHu Road,Wujin Hi-tech
Development Zone,Changzhou,Jiangsu,China

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