Additive and subtractive manufacturing use the same preparation methods in terms of the type software which is used to programme them. Computer Aided Design (CAD) software is a tool with which a design can be drawn up electronically, then sent to the desired machine to be carried out. The benefits of this include minimised ‘man hours’, less opportunity of human error and heightened replicability. The primary differences between the manufacturing types shows itself after the blueprint is created. Where additive manufacturing builds an object by depositing layers of material, subtractive manufacturing starts with an object and cuts away until the desired design is revealed. Although it may sound like only two types of manufacturing, there are subcategories of each with various modes of function.
Types of Additive Manufacturing
- Binder Jetting (3D printing) – The most commonly used form of additive manufacturing, 3D printing works by taking turns printing a layer of powdered plastic followed by a layer of liquid bonding agents to secure and bind the layers together
- Material Extrusion – A type of 3D printing, requiring careful attention to consistent pressure on each layer to ensure the best design outcome
- VAT Photopolymerization – This fascinating form of additive machining works by curing liquid plastics, resins and polymers into a solid shape using a powerful UV light
- Power bed Fusion – This uses a laser to fuse extremely thin layers of material, once they have been deposited onto a build platform
- Material Jetting – Not too dissimilar to binder jetting, working with layers of plastics, but the materials are cures with a UV light, rather than bound with bonding agents
- Lamination – This is ultrasonic additive manufacturing (UAM) which binds sheets of metal via ultrasonic welding. This does, however, also call for CNC machining to remove unbound material
Types of Subtractive Manufacturing
- Milling machine – These machines cut away at materials by introducing a spinning cutting tool to a still object
- Lathe – Mostly used for designs of a conical, cylindrical or spherical shape, lathes function almost in an opposite way to milling machines in terms of tool/material relationship, by spinning the actual material, rather than the tool
- CNC routers- Routers work most commonly on 2D projects,cutting into sheets of metal/plastic/wood
- Laser and Plasma cutters – these machines function very similarly by cutting into materials using their respective modes, depending on the suitability of the job at hand. Lasers will usually be used for a more precise and intricate design, whereas plasma cutters can be relied upon for stronger, thicker matierals
Choosing which type of manufacturing is best is completely dependant on the job at hand, but it’s always best to contact a professional. This way, you can gain confidence in deciphering which route to go down, not only in terms of additive vs subtractive manufacturing but also the precise subcategory of machine for the job at hand.