Custom Automotive 12-Point Flange Bolts With Zinc Flake Finish

 

We had these custom automotive 12-point flange bolts manufactured in grade 8 material (4140 alloy steel) with both low head and high head options.  1/2-13 2A thread was rolled on both version slightly undersized to allow for coating thickness of the Geomet zinc flake + top coat and black sealant.  Prior versions of the bolts our automotive customer used were experiencing failures from the hydrogen embrittlement resulting from the use of black zinc electroplating - black Geomet zinc flake coating was used to eliminate this risk and increase corrosion resistance at the same time.

Custom 12 Point Flange Bolts With Internal 3/8-16 Thread

 

We supplied these custom 12 point flange bolts to our automotive customer at 5,000 pieces per size, with size ranging from 12.6MM shoulder diameter X 1.70" to 12.6MM shoulder diameter X 3.2".  4140 alloy steel material was used for the production with heat treatment to reach 39-45HRC hardness.  Black oxide finish was the last step in the production process.  3/8-16 internal thread was tapped on all size configurations to reach a minimum of 18MM in full thread depth.