In this guide, let’s discuss the basic forms of additive manufacturing to make it very easy for students and readers to understand.
We are going to cover the current 3D printing applications and their limitations
- In order to turn a 3D virtual model into a physical object coming out of a 3D printer, the printer has to build layers after layers until the object is formed.
- Some printers work across a level surface called build plate
- Some create objects atop successive layers of granulated material
- Cartesian, CoreXY & Delta 3d printers are the 3 most common printers that can get the job done
What Can 3D Printers Do Right Now
Cartesian, CoreXY and Delta are the three most common 3D printing systems now, and they can print pretty much everything when the material and model design files are properly set up, you can learn more about how these printers’ axis system work here.
The most common material types are:
- Granular powders
Photopolymers are materials that can transform from liquid to solid instantaneously when right amount of light hit on them, and they are great for additive manufacturing that provides excellent detail.
Stereolithography (SLA) is the process that focused ultraviolet light transform liquid photopolymer plastic into solid form, and here are the step by step process:
- Submerge build platform into the photopolymer plastic reservoir just enough to create a thin layer of liquid to build the first layer
- Lasing of ultraviolet light over the liquid to create the first hardened layer of the object
- The build platform lowers more into the reservoir as more layers are built
- Process continues until it’s complete
This process provides good details, but it requires materials that require focus light beam to harden them.
Recently, Direct Light Processing (DLP) can pretty much do the same thing with a cheaper light source to work faster and cuts down printing time significantly, Learn more about DLP here
Granular powder is good for plastics, metal and ceramics. The material solidifies in the following ways:
- Sinstering – Heating combined powders below their melting point
- Binding the granules with bonding materials
- Melting – Use laser to fuse powder above their melting point to form structure
Powder binding printers use inkjet to spray to apply a rapidly solidified binder to the power bed, so it’s like adding a layer of glue before the next layer is built.
When the print is complete, unused powder is removed or recycled for reuse.
Plastic powder objects remain granular until they are filled with resin, which the process fills the spaces between the granules.
For metal and glass casting, the solidified shapes are stabilized by heating them to fuse the binder and powder. Simple metal powder can be infused with liquid bronze to strengthen the alloy for a much cheaper cost.
Blown powder is useful for metal fabrication. It’s a technique where adding blown powder to the melt pool to create very complex parts with no more effort than creating a design that uses the same amount of material
Lamination doesn’t involve putting down layers of powders or melting pools of material. It simply cuts individual material layer and stacks them to form the shape. This is doable for metal foils, plastic sheets and even copy paper.
However, the material is only as strong as the material itself and laminated manufacturing system lacks resolution on the Z axis due to thickness of the material layer and glue.
This process is still very practical for people who just need fast prototyping without spending too much money.
The best known form of additive manufacturing is fused filament fabrication (FFF). An FFF 3D printer can squeeze out melted thermoplastics through the printer’s nozzle to create the object, then it builds layers of melted plastic to create an object that solidifies to room temperature in minutes.
We also call fused filament fabrication – fused deposition modeling (FDM). FDM is a term trademarked by Stratasys.
FDM 3D Printers use spools of thin thermoplastic filament made of ABS, PLA, PVA, Nylon or composite aterials
Pros And Cons Additive Manufacturing
- Rare shape making ability beyond what CNC machines can do
- Reduced tooling cost
- Rapid prototyping
- Print volume constraint for larger objects
- No custom alloying
- Rough surface finish that requires post processing
- Material shrinks during sintering so additional factors need to be considered before printing