Secondary Operations

At MSI we machine many different types of parts out of many different types of metals. We perform milling, turning and screw machining operations on metals like Steel and Stainless Steel, Aluminum and Brass. Sometimes though, one of our machined metal components will require other special properties that cannot be achieved during the CNC, Swiss or Screw Machining process. This is why we are close partners with several local finishing services. A finishing service is a type of secondary process, usually performed after machining the metal, which will help add to or improve the properties of the metal as well as increase the aesthetics. We have worked closely with some of these vendors for over twenty years and have full confidence in their ability to offer high quality and fast turn-around for our customers.

There are only a few specific finishing services we normally see requested by our customers. These include Heat Treating, Plating and Black Oxide. This article will explain the properties of each finishing service so you can decide if they are right for your application.

Heat Treating

The process of heating parts to a specific temperature in order to achieve the performance and properties required of the metal parts. The properties that can be increased through heat treatment include softening the metal, improving electrical and magnetic properties and increased resistance to corrosion, just to name a few. There are 5 main types of Heat Treating that we see:

1. Annealing: the annealing process helps to relieve internal stresses in the metal, softening it and making it more docile.

2. Hardening: the opposite of annealing. Hardens metals and increases it’s strength. Case Hardening is a type of hardening that produces a wear-resistant surface over a strong core.

3. Tempering: used after hardening is performed. Hardening can cause metals to become too hard and brittle, containing internal stresses. Tempering reduces the internal stresses and reduces the brittleness of the metal.

4. Normalizing: very similar to annealing. The properties gained can be the same, but the cooling methods for the two processes are different. Normalizing can help soften metals and make them more ductile.

5. Stress Relieving: can be performed before or after parts have been machined. Machining metals can cause a lot of stress internally. The process of stress relieving can help remove these internal stresses.


The process of coating a machined metal part with another type of metal. The coating can be Zinc, Copper or Nickel, just to name a few. The plating can be deposited electrically or in a solution and then forms a thin coating on top of the machined part. The purpose of plating is to improve various properties including corrosion and rust resistance, improved visual appearance and electrical conductivity.

Black Oxide

The process of creating a black oxide finish to the surface of a machined part. Black Oxide helps increase corrosion and abrasion resistance, durability and aesthetics of the components we produce. Black Oxide is an ideal surface finish for aviation and automotive components, fasteners, springs, firearms and electronic products