Additive Manufacturing Materials3 classes of materials that make Additive Manufacturing a potentially game-changing approach
When selecting a material to use within Additive Manufacturing it’s not simply a case of selecting any material on the market, reducing it down to the correct form and pressing print, there are many considerations that need to be taken.
That’s why there are certain material classes that have been determined for AM to deliver the value it is known for.
Just considering what environments the material will endure prior to finished construction highlights the analysis required in selecting the material.
Converting the material into the correct form for the additive manufacturing process e.g. wire, powder, liquid.
Finishing of the part once constructed through curing, machining, etc, that will enhance geometric and functional properties.
Creating the part through AM to be of high structural integrity and finish quality dependent on the actual AM delivery process.
Consider that the material will undergo thermal stresses and pressures that can alter the microstructure and material properties.
In-situ operation for a determined time period under determined stress.
What environments will the material endure once the part is complete and in service? Consider the structural integrity specification, environment exposure, kinetic stresses during operation.
These factors all play a part in identifying what material is to be used throughout the manufacturing process.
Whether in powdered, wire, or liquid form, using metals within additive manufacturing is application transforming, opening doors to many solutions that were not possible previously.
Here at Freeform Technology, we strictly manufacture parts using aluminium due to the weight, corrosion, toughness, and thermal conductivity potential.
Our partners, SLM Solutions, provides our aluminium powder in various alloys, giving us a range of options to choose from depending on the application.
Other metals available to be used within AM are:
Nickel Based Alloys
With high strength, ductility, oxidation resistance, and high creep strength, Nickel is a good material for applications in Aerospace, Energy, Chemical, and turbine parts.
Cobalt Based Alloy
Used extensively in the medical industry owing to its exceptional biocompatibility, Cobalt also has high heat resistance, thermal fatigue resistance and oxidation resistance.
Titanium Based Alloys
High purity Titanium alloy is used for its corrosion resistance, high strength, high cycle failure strength, and toughness. Much like Titanium in solid form, it’s tough and hard.
Currently used in applications within Aerospace, Automotive, Medical, and Energy.
Stainless Steel 316L is used within AM for its very good corrosion resistance, as well as its high strength under elevated temperatures and high ductility.
Used predominantly in the Aerospace, Medical, Food, and offshore industries.
Due to the malleable nature of the structural and mechanical properties of polymer blends, it’s no surprise that polymers are the most widely used class of materials for additive manufacturing solutions.
It helps that polymers are amongst the cheapest materials to procure.
The main thermoplastics being used are:
Acrylonitile butadiene styrene (ABS)
Best known for its use in manufacturing lego bricks, ABS is the most widely available with many blends depending on the application required.
Polylactic acid (PLA)
Increasingly popular, PLA is available in rigid, soft, and rubbery finishes that increase flexibility levels of parts.
Polyvinyl alcohol (PVA)
An entirely dissolvable polymer, PVA is often used as structural supports throughout the AM process. Once the construction of the part is finished, these support structures can be washed away.
A new entry to the polymer market, and very much under development, Polycarbonate is deployed through a high-temperature nozzle like that used in Fuse Deposition Modelling (FDM).
Ceramics offer multiple benefits that position it as a powerful material when it can be constructed into complex shapes through the AM process.
Compared to metals and polymers, ceramics offers superior physical properties such as modulus, hardness and strength at elevated temperatures.
Ceramics also holds unique physical properties with regard to thermal and electrical conductivities, that can be tailored at broad ranges for different applications.
These factors make ceramics a popular material of choice within gas turbines, engines, batteries, and heat exchangers.
Where AM brings this material into its own is down to the limitations of ceramics as a workable material. Ceramic material is low in toughness, low in ductility and high crack damage sensitivity, which makes it difficult to work with throughout more traditional manufacturing techniques.
By deploying ceramics through additive manufacturing, these deficiencies can be overcome. Ceramics are often used in Powder Bed Fusion, Binder Jetting, Sheet Lamination, and Vat Polymerisation AM processes to good effect.