What Is Additive Manufacturing?
Additive manufacturing, commonly known as 3D printing, is a method of manufacturing a three-dimensional object by adding one thin layer of material at a time. Objects are built based on CAD (computer-aided design) models which the 3D printer then reproduces slice by slice.
Powdered materials are used by the printer as the building blocks of the objects, with each layer adhering to the one below it. Different types of 3D printers use different adhering techniques. These types include Sintering, Direct Metal Laser Sintering (DMLS), Direct Metal Laser Melting (DMLM), Electron Beam Melting (EBM), Stereolithography (SLA), and Selective Laser Sintering (SLS).
Typically, granular material is jetted from the print head at a specific temperature which allows it to remain soft; only curing and forming the object either as it cools, through UV, laser or electron curing, or by using bonding agents. Any loose powder left from the process is recycled in the next print cycle.
Materials & Applications
3D printers can use a wide range of materials as their building blocks. These include:
- Thermoplastics – the most common additive manufacturing material, ideal for lightweight, complex designs in aerospace applications. For example, NASA 3D printed a fully functional rocket nozzle in 2018.
- Metals – Steel, titanium, gold and silver are commonly used in 3D printing technologies. For example, McLaren used carbon fibre 3D printed parts to manufacture cooling ducts to enhance their automotive technology.
- Ceramics – zirconia, glass, and alumina are used to create new types of products.
- Biochemicals – silicon, zinc, and calcium phosphate are used in additive manufacturing to create healthcare products. For example, New York University created 3D printed tumour models as a part of a study into cancer.
Different materials are used based on both the application and the industry. With new advancements in 3D printing technologies such as SLS, multi-material printing is now a possibility too.
Benefits of Additive Manufacturing
- Less material waste due to only the exact object being produced
- Complex designs are permitted more easily than traditional manufacturing methods
- Fast turn-around time
- Cheaper production since manufacturing steps such as milling, moulding, machining and carving are no longer necessary
- Higher output rate than traditional manufacturing
Common Problems With 3D Printing
Although additive manufacturing provides many benefits to manufacturers, there is still much room for improvement within the field. We now explore a few of the challenges that additive manufacturers face.
Difficulty Bonding Certain Materials
PEEK
3D printing with PEEK, a high-performance polymer used in mechanical applications, imposes an issue. The very high-temperature gradients and warping forces in the printing process leads to faults in the material. Although, new developments such as SLS are allowing additive manufacturing businesses to test new multi-material printing to eliminate the issue.
ABS
ABS is a tricky material to use for 3D printing due to its complex chemical makeup and therefore difficulty to bond. However, with common use and applications such as vehicle interiors, it is likely that ABS 3D printing will be improved in the future to accommodate with the growing demand for efficient and reliable production of high-end vehicle interiors.
Polypropylene (PP)
Polypropylene is a cheap and versatile material that is prevalent among many industries. PP has very low surface energy, making it notoriously difficult to bond. This makes PP a difficult material to use in 3D printing. However, as additive manufacturing technologies advance, innovations such as SLS will make using these materials much more viable.
Snapped Filament
Every 3D printer has a filament which acts as the feedstock for the printer. Often times, these filaments can get damaged over time and eventually snap, causing the printer to fail.
Adhesives for Additive Manufacturing
Adhesives that are to be used in additive manufacturing must be flexible, durable and of high isotropic strength.
Araldite 2051
Araldite 2051 is a two-component, toughened methacrylate adhesive which provides high resilience to vibrations, impact and dynamic loading. It is pale yellow, when mixed. It is designed for service temperatures up to 120°C, making it extremely durable and suitable in high-temperature environments. Araldite 2051 can be used for pipe bonding applications within 3D printers.