Why the cap fell off from lug nut?

March 11, 2021

Have you ever had this experience? The acorn cap of the 2pcs lug nuts fall off easily, and then the lug nut quickly rust, making it ugly and unsafe.

 rust lug nut

How to ensure the fastness of the welding cap?

1. The shape of the semi-finished products.

Most factories only produce workblank with the flat top. (see pic 1)

If the caps weld on it directly, these two parts are flat VS flat, they can’t combine with each other completely, so it is easy to fall off.

But HONISHEN 2pcs lug nuts has bulge on the top. (see pic 2)When welding, ten thousand amperes of high temperature current will quickly melt the bulge, making it into molten iron, which wraps and blends the cap, and combines with each other firmly.

  compare lug nut

compare lug nut2

2. The welding machine

The current of the traditional welding machine is only 7-8 thousand amperes, the temperature is low, and the point of weld can’t be completely melting into molten iron. In addition, the current is constant, sometimes large and sometimes small, so the welding fastness is also unstable.

HONISHEN uses an automatic intermediate frequency welding machine, the welding current can reach 10-15 thousand amperes. It makes the bulge and the bottom of the cap can be melted instantly during welding, so that they can combine with each other. The current is stable and the melting point is uniform. Each product can be welded very tight.

ac welding machine


3. Operation

Traditional weld places the work pieces manually. But the placement angle is easy to deviate, the cap and the bottom parts are often misaligned and not vertical, which affects the firmness of the welding.

HONISHEN uses a fully automatic manipulator, with fixed angles and molds, infrared induction and calibration. It can align the two parts vertically, which not only ensures the stability of the product, but also the beauty and consistency. 

4. Detection

During the welding process, the fastness should be checked frequently. Two methods are usually used:

a.Fix the cap, clamp the workblank with pliers, tear it apart with a certain force, and judge whether it is qualified according to the intensity of use. However, the result will be very different under different forces, It’s uncontrolled,making this method not standard. So It’s unusually not adopted.

fix the cap


b.Place the lug nut on the fixture, insert an iron rod into the nut, knock the iron rod to make it penetrate the cap, but the welding part can’t fall off

penetrate the cap

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