Additive Manufacturing: Successively Adding Materials

Additive Manufacturing (abbreviated as ‘AM’) is a generous name describing the technologies utilizing 3D printing technology by adding successive layers of a given material. This may include decorative or functional optical plastics, ceramics, metals, concrete as well as organic or biodegradable materials.

Direct CAD-to-Object Manufacture

Commonly, AM fabrication technologies use a computer, 3D modeling software (Computer Aided Design/CAD), hardware (printing equipment) and build material, either a liquid resin or a solid filament.

Once the CAD sketch is produced by the designer, the AM equipment reads the data from the CAD file and processes it for printing. The printheads lay down or add successive layers of liquid, powder, sheet material or different, in a process that resembles printing, layer-upon-layer to fabricate a 3D object. The Luximprint process, different from others, utilizes advanced ‘Droplets-on-Demand’ technology to obtain optically clear objects and smooth surfaces, whereas conventional 3DP technologies lay down successive layers of solid material, or laser-write them in the resin itself.

Various Speedy Technologies under one Hat

The term ‘Additive Manufacturing’ encompasses various additive technologies including subsets like 3D Printing, Rapid Prototyping, Direct Digital Manufacture, layerwise manufacture and additive fabrication.

When it comes to processing optical parts, a process named ‘Additive Optics Fabrication’ – innovated by Luximprint – is used for the expedite prototyping of custom optics.

The field of application for AM methods is nearly limitless. Initially, AM was used in the form of Rapid Prototyping focussing on preproduction of visualization models. These days, the processes are even used to fabricate end-use products in aviation, automotive, medical, and even fashion applications. Whether an AM technology is suited for end products or not is heavily dictated by market requirements, most notable fire and safety regulations, but also lifespan conformity and impact resistance.

AM Technology Applications

While the basic process of ‘stacking layers’ is fairly simple, there are many applications of AM technology with degrees of sophistication to meet diverse needs including:

* Inspirational Prototyping: Visualization tool in design;
* Functional Prototyping: Validation tool for concepts – both for upfront simulations and for conventional manufacturing tooling;
* Mass-Customization: A means to create highly customized products whereby any part might be different from the other;
* Mold-making: Create industrial manufacturing tooling;
* Pre-series manufacture: Production of small lots of end parts.

Additive Manufacturing (AM) Methods

Here’s a quick overview of various Additive Manufacturing methods that are used in the market today:

• Stereolithography (SLA)
  
  Very high-end technology utilizing laser technology to cure layer-upon-layer of photopolymer resin (polymer that changes properties when exposed to light).The build occurs in a pool of resin. A laser beam, directed into the pool of resin, traces the cross-section pattern of the model for that particular layer and cures it. During the build cycle, the platform on which the build is repositioned, lowering by a single layer thickness. The process repeats until the build or model is completed and fascinating to watch. Specialized material may be needed to add support to some model features. Models can be machined and used as patterns for injection molding, thermoforming or other casting processes.
• Fused Deposition Modeling (FDM)
  
  Process-oriented involving use of thermoplastic (polymer that changes to a liquid upon the application of heat and solidifies to a solid when cooled) materials injected through indexing nozzles onto a platform. The nozzles trace the cross-section pattern for each particular layer with the thermoplastic material hardening prior to the application of the next layer. The process repeats until the build or model is completed and fascinating to watch. Specialized material might be needed to add support to some model features. Similar to SLA, the models can be machined or used as patterns.
• Multi-Jet Modeling (MJM)

Multi-Jet Modeling is similar to an inkjet printer in that a head, capable of shuttling back and forth (3 dimensions-x, y, z)) incorporates hundreds of small jets to apply a layer of thermopolymer material, layer-by-layer.

• Additive Optics Fabrication (AOF)

Additive Optics Fabrication, also known as ‘Additive Optics Manufacturing’, is a proprietary process innovated by Luximprint to obtain optically functional parts (most notable ‘printed optics’) straight from the printer.

Like the aforementioned 3D printing processes, the optical 3D printing process adds successively an optical resin that flows and merges under surface tension and then gets cured by UV-light. The resulting surfaces are smooth from the 3D printer, and with zero need for post-processing, the surfaces (such as polishing or grinding them) the custom optics are readily available for use. To date, Luximprint does not sell the equipment, nor the resin, but offers its unique fabrication method as a service to the global engineering and design community working with illumination optics.

• 3D printing (3DP)
  
  This involves building a model in a container filled with powder of either starch or plaster based material. An inkjet printer head shuttles apply a small amount of binder to form a layer. Upon application of the binder, a new layer of powder is swept over the prior layer with the application of more binder. The process repeats until the model is complete. As the model is supported by loose powder there is no need for support. Additionally, this is the only process that builds in colors.
• Selective Laser Sintering (SLS)
  
  Somewhat like SLA technology, Selective Laser Sintering (SLS) utilizes a high powered laser to fuse small particles of plastic, metal, ceramic or glass. During the build cycle, the platform on which the build is repositioned, lowering by a single layer thickness. The process repeats until the build or model is completed. Unlike SLA technology, the support material is not needed as the build is supported by unsintered material.

AM: Disruptive or Complementary?

Some may envision AM as a complement to foundational subtractive manufacturing (removing material like machining away raw material) and to a lesser degree: forming. Others point to it as a disruptive technology that outperforms conventional fabrication processes.

Whatever your position might be, AM may offer professionals in a variety of business fields the possibility to create, customize and/or repair their product and novel concepts and in the process, redefine current production technology. All in a matter of days, with enhanced flexibility, great versatility and at low(er) cost!