Prototyping: With the use of CAD and massive amounts of digital simulation software available, it can often seem superfluous to make early appearance models, or even undertake early testing of new designs. But prototyping remains a key factor in product design and development, and additive manufacturing continues to deliver even more agile, faster, concurrent engineering results that are needed in today’s design and engineering world.
Rapid prototyping with additive manufacturing has come a long way since the invention of Stereolithography (SLA) in the mid-1980s by 3D Systems’ founder and CTO, Chuck Hull (ultimately my boss). As a key part of the product design and development process, prototypes for fit, form, and function created as early as possible in the design process continue to shorten design times, deliver better products, and reduce product time-to-market.
While additive manufacturing (AM) is turning the corner to full production that can provide end-to-end solutions, prototyping is far from obsolete. In many ways, it is now far more crucial and advantageous to produce early prototypes to take advantage of both additive and traditional manufacturing practices.
Rapid Prototyping Today Meets Greater Demands
Product lifetimes are decreasing. We expect a new iPhone every year. Updates to vehicles are down from 10 years to two years. In the aircraft industry, engine qualification timelines have been shortened from over 10 years to under five, while major airliners and airframers are now expected to refresh internal cabin feel every few years as opposed to just maintaining traditional interiors.
Product innovation and customer expectations are feeding off each other at ever-increasing speed. The result is greater demand for variety, high expectations for customization, and near-constant innovation. That kind of velocity and limited edition parts are able to be delivered through additive manufacturing producing rapid prototypes without the time and costs required for tooling.
SLA was the first and is still one of the main processes in rapid prototyping. New innovations in Contactless Digital Light Processing (CDLP) are delivering even faster response for prototypes. What used to take weeks in the 1990s using traditional modeling methods was superseded by SLA prototyping, which can produce 12 to 15 prototypes in the same time. Today, these numbers are being supplanted by high-frequency concept model production using CDLP. This enables very rapid production of prototypes but also measurably reduces the product development timeline.
Frequency response of production of prototypes using traditional methods, then SLA, and now DLP.
Aerospace Design and Industrialization teams rely heavily on prototyping to create new AM methodologies for the industry. With recent innovations in heat exchangers using Powder Bed Fusion technology (PBF), technologies like SLA with clear resin are a part of the design and iteration workflow. This allows them to build multiple iterations in less than a week and dynamically test out internal fluid flow. While traditional design techniques would rely on simulated data, the complex geometry now possible with AM in metals make it so that each simulation will now take weeks instead of days. Instead of waiting, you can live-test products for visual fluid flow and make adjustments daily to ensure that the intended fluid flow and pressure drops are in line with expectations. For complex projects, this can enable you to iterate over a dozen prototypes in a matter of weeks, delivering the final test metal parts several months ahead of any schedule that didn’t include prototyping.
Rapid prototypes of a new heat exchanger design allowed rapid testing of the fluid and heat flow prior to the production of the final part.
Clear SLA materials for these applications are critical to providing good information in the prototyping phase. One company who benefitted from this is TecNiq, a developer of lighting solutions for watercraft. For TecNiq, it’s critical to choose a resin system that can provide truly clear lighting covers: Any opacity or color augmentation would result in a useless prototype for the final design.
TecNiq has saved time and labor costs prototyping production-quality lenses that demonstrate product performance before tooling the parts.
But it doesn’t just stop at SLA 3D printing.
Selective Laser Sintering (SLS) that uses nylon can make high quality functional prototypes that can include living hinges, bendable parts, and monolithic parts developed from an assembly. In addition, without the need for tooling and rivaling injection molding quality, nylon, and other materials with heat and chemical resistance let designers make parts for on-engine and on-rig testing and verification quickly and inexpensively.
Idaho Steel, a machine tool maker for food processing production lines, uses SLS 3D printing for both functional testing as well as production of end-use parts installed directly onto its machines. Since each production line includes customization, SLS provides Idaho Steel with the immediacy of tool-free production, plus robust parts, required to turn orders around quickly. Idaho Steel cited a reduction in time from 250 hours down to 90 hours, a two-third’s reduction for part production.
Using SLS 3D printing technology and thermoplastics such as 3D Systems’ DuraForm EX Black delivers parts which have the toughness of injection molded ABS and polypropylene, resulting in functional prototypes that can be tested in “real-world” environments.
SLS additive technology is also crucial to the success of interior cabin manufacturing companies. Our group has worked with four such companies recently to lay out fully-functional prototypes. In a recent project with a Tier 1 seating company, additive manufacturing using SLS and SLA technology enabled them to iterate and provide several versions of fully functional Super Luxury seating prototypes. The use of AM technologies like these has helped the company advance its product cycle by months in a highly competitive market, one which they hope to grow from single to double digit market share. By using AM, they avoided the high lead times in fabrication by both creating directly printed prototypes, and for larger parts, creating AM molds for casting urethane. In an environment that has only a few strong players and a high demand for refreshing luxury cabin seating, only AM provides the tools necessary for companies to aggressively improve market share, even when the final product will be manufactured traditionally.
Modular conveyor manufacture, Span Tech, uses the MultiJet Printing (MJP) platform by to prototype and test conveyor parts prior to ordering injection mold tooling. A broad range of materials are available on these types of platforms, and the materials are robust enough for snap-fit testing, sliding parts, and parts with metal bearings inserted.
Span Tech uses two different VisiJet materials to achieve optimal part properties for prototyping and testing machine parts prior to ordering injection mold tooling.
While the range of prototypes that can be made using additive manufacturing is almost endless, it’s important to note that design limitations do exist. SLA requires support structures to be pulled either down into the vat or off the print platform, which means that designers need to take into account support removal and scarring on down facing surfaces. SLS and MJP provide a support free platform, but has less accuracy than other resin-based systems If these design rules can be kept in mind, the extent of additive materials available mean you can quickly produce almost any kind of part, including rubber-like and overmolding, high strength, Ccear, or in full-color to represent the appearance of the design.
CJP has revolutionized the design process for consumer goods—such as for this bike seat prototype—as it can render a physical part possessing the color and look of a final part for testing.
Color Jet Printing (CJP) is another powerful tool in the world of prototyping. The obvious use case for CJP is to simulate full-color goods such as apparel and housing. Since its invention, CJP has revolutionized design for both architecture and consumer goods; it also has some very practical applications in engineering design. With the ability to render a 6 million color gradient (delivering the full color spectrum of a 2D printer in all three dimensions!), CJP has been instrumental in the use of topology optimization. Being able to produce full-size prototypes with different cases of stress concentration has become a staple in the design and industrialization process that aerospace groups can use to design and market new additive design strategies to conservative or skeptical companies. Having the physical part with calculated stress concentrations, in bright color, is becoming a vital part of the internal validation and sales process.
3D printing technologies can be combined with traditional manufacturing to render realistic, trustworthy prototypes that are used by production and maintenance engineers to validate the design and manufacturing process prior to investing in production tooling.
In addition, additive is also used by some on-demand services to deliver a rapid prototype of full-scale car models for hands-on functional testing and design verification. This vehicle was created using a combination of SLA and SLS 3D printing, as well as some sheet metal and machined parts, in eight weeks from receiving the CAD data. Once complete the automotive company’s design, production, and maintenance engineering teams were able to carry out comprehensive testing for appearance, production methods, and clearance and accessibility checking for maintenance.
It is also crucial to note that prototyping with additive doesn’t always mean directly producing the final part—it often means the use of tooling to enable design and testing. Eggshell molding provides the ability to design and test dynamic seal shapes using the exact seal material needed for final injection molded design. Done either on SLA or CDLP, this process uses sometimes as little as a teaspoon of resin to produce the outer mold of a seal, and after injecting the silicon/rubber material and curing, can simply be peeled off and functionally tested before investing in a complex final mold. This shaves months off the manufacturing and design cycles typically used.
This double O-ring was produced using 3D printing to deliver egg shell molds, which provides the ability to design and test dynamic seal shapes using the exact seal material needed for final injection molded design—reducing the manufacturing and design cycles by months.
Rapid prototyping also has game-changing effects on the casting industry. Using either SLA or materials jetting technology, it is now possible to print casting patterns directly with no tooling. For material jetting, wax patterns produced work with traditional foundry workflow and can be used for everything from prototyping to full production. Even simple geometries can take 8-12 weeks to manufacture before initial patterns can be injected, and for more complex geometries can cost in the hundreds of thousands and take more than six months before it can be tested. Material jetting technology can provide dozens of ready-to-cast patterns in weeks or less, saving months to years on complex castings. It also enables the use of reverse draft angles which are unheard of in traditional molding design, but very beneficial for turbine impeller and other technologies.
For larger castings, SLA can be used to produce large, complex patterns. Using a unique build style that allows for a very low-resin, light-weight pattern that, with slight modifications to autoclave burnout cycles, can be used in any casting house. Both of these options are available through machine ownership or through our on-demand services, and have been instrumental in the prototyping of castings globally.
Rapid prototyping through additive is becoming ever more rapid, accurate, affordable, and functional in a world that demands faster design response. Whether you are using prototyping to functionally design a product, produce appearance models for external or internal use, or even for design validation—regardless of the manufacturing method of your final product—additive manufacturing has a crucial role to play in product development across every manufacturing industry in the world.
Bryan Newbrite is the Advanced Aerospace Applications leader for 3D Systems, where he is working to industrialize and implement disruptive manufacturing technologies into established aerospace supply chains. Prior to 3D Systems, he brought his expertise to bear at GE, most recently in Dubai to support the GE EA fleet for Emirates Airlines. Newbrite holds a B.S. in aerospace engineering from Embry-Riddle Aeronautical University. He is based in San Diego.
