I need to discuss this issue because it it very important when someone is designing a product or system that needs a friction hinge that is stainless steel. There are situations that need components made from stainless steel because of regulations and there are products that really need corrosion resistance. Do the designers realize that picking stainless should not be a no brainer situation. One point I need to drive home is that stainless steel varies dramatically in its corrosion resistance and there are thousands of variations to choose from. If the design system demands that the material to be used in all of the friction hinge components be 316 stainless steel then you need to know some important design facts about 316. We will talk a little later about them. Friction hinges made from high carbon steel achieve the greatest torque for the amount of material used because we can achieve spring tempers that other steels cannot come near. In one humorous situation I had an engineer told me he accomplished a 303 stainless steel hinge that won’t rust and can get great torque numbers.
I asked how he made this breakthrough. He had added carbon to case harden the steel! The carbon in steel and it’s reaction with the environment causes the corrosion. Well so much for his innovation! Back to 316 stainless, this grade is know for it’s great corrosion resistance, it is not known for its heat treatment properties. The vast majority of friction hinges use tempered spring steel in contact with hardened carbon steel with some sort of lubrication. Because of the physical properties of stainless steel and a given volume that the friction hinge must work within, you will never get more torque from a stainless steel friction hinge as opposed to a friction hinge made from carbon steels. So before everyone jumps on the stainless steel friction hinge band wagon you must ask yourself do I really need Stainless Steel? Will a properly engineered corrosion resistant hinge meet my needs. When I say properly engineered I mean that there are inexpensive steel coatings and materials that can achieve what stainless claims to do especially in the friction hinge realm. We also can keep cost low and performance high. If you need a corrosion resistant hinge, friction hinge or rotary viscous damper please contact us at www.mmtech.us
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