Disrupting the Optics Industry Layer by Layer

Enables rapid prototyping for dramatically reduced product development times

Useful for creating tooling and fixtures for lab and production use

3D models aid in selling product concepts to management and investors

Used to make both polymer and metal parts

Additive manufacturing and 3D printing have evolved over the past decade from curiosities to widely employed techniques for creating prototypes, and even actual production parts. Here you will learn the basics of how these technologies work, along with how they affect the photonics industry.

Introduction
Additive Manufacturing vs. 3D Printing
Limitations

In the broadest sense, additive manufacturing is a process for creating 3D objects directly from CAD (computer aided design) files. While there are quite a variety of additive techniques, they all share a common approach. First, the system software renders the object design into a series of slices, and then controls a machine that deposits solid material, layer by layer, in the software-generated pattern until the complete object is formed. This stands in contrast to traditional “subtractive manufacturing” technologies, such as CNC machining, which start with a solid block of material and then remove matter to produce the desired object.

Additive manufacturing and 3D printing are so dynamic that the terminology has yet to be standardized. In fact, both of these terms are still often used interchangeably, although 3D printing is typically used to refer to inkjet-type processes for producing polymer parts, and primarily oriented towards the consumer “maker” community. In contrast, additive manufacturing is more commonly applied to the various techniques for producing both polymer and metal parts for commercial use (hence the word “manufacturing”), either for prototyping or in production.

At first glance, 3D printing and additive manufacturing may seem like panaceas, enabling both designers and manufacturers to eliminate the need for traditional machining, molding, and other expensive production methods. However, there are two reasons this will not happen, at least any time soon. First, 3D printing and additive manufacturing are serial manufacturing methods that make parts one at a time. The processes are also slow - it is not unusual for the production of a single part to take several hours, or even days. Second, the mechanical precision of the resultant part is not nearly as high as those achieved using most conventional fabrication methods.

To a lesser extent, material properties for 3D printed parts may also cause a few issues in that they do not always consistently reproduce the desirable bulk mechanical characteristics of a given polymer or alloy. However, materials for additive manufacturing are an active area of development, and this situation is changing. But for now, expect 3D printing and additive manufacturing to remain largely limited to low volume applications where quality is not paramount, but turnaround time is.

Types of Additive Manufacturing

While there are a large number of distinct additive manufacturing and 3D printing methods, the processes described below are broadly representative of the technology. The most current techniques are variants of these basic methods.

Inkjet 3D Printing

Inkjet 3D printing is the most commonly employed 3D printing technology, and is a variation of the widely used inkjet printer. Except in this case, instead of ink the print nozzle extrudes a thin plastic filament that has been liquefied through heating. This can form a layer of material as thin as 0.1mm. Once a single layer has been formed, either the printhead is raised or the build platform is lowered by a distance corresponding to the layer thickness, and the process repeats. In some cases, the polymer material simply hardens as it cools. Alternatively, a photopolymer, which is hardened by subsequent exposure to UV light, can be employed.

Stereolithography

Stereolithography is the oldest type of additive manufacturing where a build platform is put in a vat of liquid photopolymer and positioned to sit just below the surface. Next, a focused ultraviolet laser beam is scanned to trace out the required layer shape. The focused spot hardens the photopolymer selectively wherever it moves. The build platform is lowered vertically to the thickness of one layer, and the next scan is performed. This step is repeated until the entire object is formed.

Powder Bed Methods

In these techniques, a thin layer of powdered material is deposited on the build platform using a roller or wiper blade. In “binder jetting,” a print head then moves over the powder bed and sprays out a binding solution, which selectively fuses the powder material into a solid in the desired shape. Alternatively, in “powder bed fusion” techniques, either a laser or electron beam is scanned to melt the material, which then quickly resolidifies. The build platform is lowered and another thin layer of powder is spread over it; the process repeats until completion.

Impact of Additive Manufacturing on the Optics Industry

As additive manufacturing continues to become more affordable, effective, and widely used, it greatly affects the optics industry, and nearly every industrial sector. The following videos feature a panel of Edmund Optics engineering, design, and R&D experts sharing their insights on the wide-reaching impact of additive manufacturing.

Part One

This video covers the impact of additive manufacturing on the optics industry, different types of 3D printing, rapid prototyping, and recent developments in additive manufacturing. Watch now for insight on how to take full advantage of this growing technology.

Part Two

This video covers the impact of 3D printing on IP protection, the future of additive manufacturing, and how additive manufacturing and automation influence the job market. Watch now to prepare for how 3D printing will potentially affect your career.

Additive Manufacturing at Edmund Optics^®

Like many manufacturers, Edmund Optics utilizes 3D printing methods to reduce product development cycle time and costs. This may involve 3D printing models of lens assemblies or mechanical components to get a quick read on form, fit, and function, which is often difficult to assess purely from CAD renderings.

Figure 1: 3D printed mechanics used for prototyping

Edmund Optics designers have utilized 3D printing for prototype packaging solutions in order to develop better ways to protect products during shipment. Packaging is often produced using molding or other techniques, which have substantial upfront tooling costs. Using 3D printing instead allows for effective and quick exploration of a wide range of potential solutions.

Edmund Optics also employs 3D printing methods to create tooling components for optics production in our manufacturing facilities. For example, specialized nozzles for optimized slurry spraying during optics polishing were 3D printed as conventional machining methods are more costly and time consuming for this application.

FAQ's

Can optics be 3D printed?

Not yet - optical components are some of the highest precision products manufactured today with surface accuracies of tens of nanometers, surface roughness values in the tens of angstroms range, and very high levels of internal (index of refraction) homogeneity being common. Current 3D printing and additive manufacturing techniques yield parts with specification tolerances that are many orders of magnitude larger than what traditional manufacturing methods can deliver. Other than select illumination or beam shaping applications, 3D printing is not going to produce precision optics within the near future.

Can 3D printing be used to “copy” an existing object?

Sometimes an existing three-dimensional object can be scanned and then reproduced using 3D printing. However, scanning will only copy the object’s external shape, not its internal components. Therefore replicating any complex piece of machinery would require disassembling it and scanning in each component individually. Depending upon the object and the 3D printing technology utilized, this might not necessarily deliver parts with the precision required to reproduce the original object’s functionality.

Can 3D printing be used to repair existing parts?

Yes - a form of additive manufacturing called directed energy deposition (DED) involves introducing metal in powder, wire, or strip form on an existing metal part, and then using a laser to melt the powder and fuse it. This approach has found use in select aerospace and automotive remanufacturing applications.

Are 3D printed parts currently suitable for any demanding applications?

Yes, certain types of 3D printed parts are ideal for demanding applications. One example is General Electric, which uses additive manufacturing to produce a fuel injection nozzle for some of its jet engines. This extremely complex part is difficult and expensive to fabricate using traditional means.

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January 2019 | See all Trending in Optics Topics