The Types of Metal we use for Threaded Inserts

Here at Fitsco, we use different types of metal to manufacture our threaded inserts, before they are distributed all over the world. The most popular metal we use for threaded inserts is brass, with steel being used for our compression limiters. Stainless steel is used for our custom-made threaded inserts, which are drawn, designed and manufactured to the customers’ requirements.

There are several advantages and disadvantages of using each type of metal to create our threaded inserts, compression limiters and speaker spikes and we look at them here.


Brass is attractive to the human eye and provides a quality look. Brass products, like our threaded inserts, provide superb corrosive resistance as well as its joining, plating, polishing and finishing qualities. Brass is also easily machined.

Brass however, requires some maintenance since many metals oxidise when they are exposed to the air, and, as such, brass is suspect to black tarnish, so it is recommended to keep on top of the removal and inhibition of tarnish.

When new projects are started, brass does not require oil to changeover to the new job, so staff in training can witness the processes involved in a changeover.


There are two types of steel; leaded and unleaded steel. Unleaded is natural steel, where as lead can be added to the steel to make leaded steel. Lead is added to the steel to act as a lubricant between the cutting tool and the steel, which, in turn, improves the machinability of the steel. Lead is added to steel to products, like our compression limiters, that will undergo machining but not welding.

Steel is preferred in our compression limiters as it is a more cost-effective metal.

Stainless Steel

There are three different types of stainless steel that we use: 303, 304 and 316. All three types of stainless-steel resist corrosion and look great, as well as being non-magnetic, they are made from 15 to 30 percent chromium and 2 to 20 percent nickel. So, they will have good surface quality, workability, wear resistance, impact resistance and strength. 303, 304 and 316 all have unique qualities and are good in their own way.

Aside from chromium and nickel, 303 stainless steel contains selenium and sulphur, making it extremely machinable. It is an ideal type of metal to make fasteners or threaded inserts that are corrosion resistant, strong and long-lasting. 303 stainless steel is not as corrosion-resistant as 304 stainless steel but does stand up well. 303 stainless steel is not good for welding.

304 stainless steel, however, is good for welding and it is great at resisting corrosion. It is not a good metal in a high-chlorine environment, such as in the sea, but other than that it is tough, strong and long-lasting.

316 stainless steel is more expensive, but it is more cost-effective in the long term. The difference is molybdenum, but only around 2 to 3 percent, which increases corrosion resistance hugely.

Blog by Dan - 9th September 2019

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