Difference between Subtractive & Additive Manufacturing

The past few weeks when visiting new clients one of the questions that keeps coming up is “What is the difference between Additive Manufacturing and Subtractive Manufacturing” So I thought I would take a moment to share.

Let’s start with subtractive manufacturing, the traditional method of manufacturing.

Subtractive manufacturing usually starts with a piece of material and you remove the excess material by using machinery like computer numeric control (CNC) machinery such as lathes and mills to produce the parts. Simply, you start with a piece of material larger than required and remove material to produce the part and waste material. This method of manufacturing goes back to the start of civilisation, when they used flint hammers and chisels to sculpt / manufacture the first wheel by chipping away at stone.

Additive manufacturing (3D Printing) builds (grows) parts by adding individual thin layers of material. As each layer is added, it serves as a base for additional layers of material.

This meaning the part is grown layer by layer.  Material is only added to each layer where required so there is little waste. By growing a part in this manner it allows complex parts to be manufactured easily in one set up. This removing the need in most cases for complex subtractive manufacturing methods where several different machines are used to remove the excess material.

Additive and subtractive both have their places in the world of manufacturing and in my opinion, additive manufacturing won’t replace subtractive manufacturing completely, but will be used as another manufacturing process sitting alongside the traditional subtractive methods we are familiar with today.