The Value of Implant Grade Alloys

More body jewelers have seen the value of using implant grade metals, like ASTM F138 316 L VM Stainless Steel, for products that will be worn in or on the body. These alloys are certified to an ASTM "F" specification, which when applied to metals, signifies that the quality of the alloy is acceptable to be used in a medical application. Some of these "F specs" indicate implant grade, while others indicate surgical instrumentation grade. It is important to make sure that the material used is to the implant grade. These grades go through an additional process called "vacuum melting" (the "VM" in 316L-VM) which not only removes impurities, but in the case of stainless steel, allows for a better surface layer on the material. This layer prevents the leeching of elements, like nickel, into the body. Very important for people with nickel allergies.

Is Inconel® 625 the same as Nickel 625?

The answer, not surprisingly, is yes and no. The chemistry, mechanical properties, and range of uses are within the same standards of quality, but Inconel® is a trademark that can only be used by one mill-Special Metals Corporation.

There's still some confusion among buyers, engineers, and machinists when it comes to superalloy grades. Why does the print say Inconel® 600 and the mill test reports refer to it as Nickel 600 or "ATI"® 600? Can one be substituted for the other? The answer to this is a definite yes. ASTM and AMS specifications guide the manufacturing of these high performance alloys. Reputable mills make absolute sure that the material they produce meets these strict standards. What's important in the name is not what comes before the alloy number, but the alloy number itself.

What is the DFARS Specialty Metals Clause?

The Defense Federal Acquisition Regulation Supplement, better known as "DFARS", is an enormous and far-reaching document. As part of the even larger 'Federal Acquisition Regulations' it covers things like how a Department of Defense purchasing contract is written, negotiated, awarded, and paid for. It's an important set of guidelines designed to protect the political interests of the United States. DFARS is aimed at keeping money and quality control in the hands of our friends, and away from threats to US interests.

430FR "Solenoid Quality" stainless steel rod is specifically formulated and treated to be used as the inner shaft of a linear solenoid.

Solenoids are, at heart, simple machines. You can make one yourself using copper wire, a drinking straw, a battery, and any magnetic metal. You can even use an ordinary nail for the shaft (or armature, as it is known). Coil up the wire around the straw, put the nail inside and attach the two loose ends of the wire to a battery. That's it. Watch the nail move in and out of the straw as the electrified wire creates a magnetic field that attracts or repels the shaft.

I'm looking for...

What do you call that highly refined grade of stainless steel that all your medical device customers ask for? If you're like us, and most people in the business, you call it "316 LVM" and never really think about it. At least not until a customer print calls for something like "316L ASTM F138" or "Implant Grade 316" or "316LS²". Then you might get out your books, search Google, check the specs and mill test reports, and make sure that what you're buying or selling is just what they need. And chances are you've got it right. But why all the names? What should it really be called?

There's only one definitive answer to that, but before I reveal that magical answer let's first look at the path we take to get there.

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