Functional Prototyping

3D Printing Protoyping Applications

Prove and perfect your designs with tough, precise testing

Iterative, agile product development is the promise of advanced 3D printing. Functional prototyping with engineering thermoplastics or digital materials reveals how your next product will perform, well before you commit to production tooling.

Find your functional prototyping application

Functional PrototypingGet to market faster by building prototypes quickly in-house. Correct errors and make improvements early in the design process when it’s least costly. For functional prototypes in production-grade thermoplastics such as ABS and PC, and for high-performance prototypes that withstand thermal, chemical and mechanical stress, rely on Stratasys Fused Deposition Modeling (FDM) Technology. Tough prototypes and custom test fixtures will help you take functional testing to a new level for superior performance data and certification confidence. For amazingly realistic prototypes with the look and feel of your next finished product, including soft-touch parts, clear components, living hinges and shock absorption, put Stratasys PolyJet technology to work. With the capability to print multiple materials in one automated build, and rubberlike materials in a range of Shore values, you can test with unsurpassed realism and experiment with greater freedom.

Overview

Custom Plastic Injection Molding 3D print molds for prototyping in the final material PolyJet 3D Printing has made it feasible to quickly create custom injection molds that produce low volumes of parts in the final production plastic. This is especially useful for prototypes, which can now be created onsite in just hours, from mold design to final test product, using the normal plastic injection molding process and production materials for accurate functional testing.

Custom Injection Molding With 3D Printed Tooling

Prototypes are most useful when they’re made of the same plastic as the final production part. And during product development, quick feedback is essential. But it’s hard to justify the cost to create injection molded prototypes when they require the same expensive, time-consuming tooling as production parts — even though you only need a small quantity of parts for testing.

3D printing your prototype molds in-house with PolyJet technology offers a fast, affordable way to produce injection molded prototypes. Designers and engineers can test their work more frequently and more accurately, and go to production with confidence. Product managers can shrink time to market and products can turn out better.

PolyJet Injection Molds

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PolyJet technology creates smooth, detailed, accurate molds. Digital ABS 3D printing material is strong enough to hold up to short injection molding runs of about 10 to 100 parts. You can install the 3D printed mold directly onto your injection molding machine. If testing reveals that you need to make a design improvement, you can alter the mold in directly in CAD and 3D print the next iteration. Depending on size, the new mold can be printed and ready to inject in just a few hours.

PolyJet 3D printed molds are not production tools. But during the design and testing phase, they offer a clear advantage over conventional injection molding. Product designers and manufacturers can use these molds to perform thorough functional testing without worrying about cost-prohibitive tooling. Flaws based on the final production process, geometry or choice of plastic can be discovered early, when they are easiest to fix. This can reduce costly, time-consuming mold corrections, increase product innovation and speed product development.

When to Use PolyJet Tooling

PolyJet 3D Printing is a good method for creating prototype injection molds when:

  • Complex geometry would make traditional tooling difficult
  • Low quantities are needed
  • Design changes are likely
  • Rapid prototyping from the final production plastic is important

Overview

Realistically simulate the mechanical function of end products by 3D printing parts using PolyJet photopolymers with precise dynamic friction coefficients — all in a single build.

3D printed prototypes and friction

Friction is defined as the force that opposes the relative motion or tendency of such motion of two surfaces in contact. The friction coefficient of a prototype’s surface is a functional component, not an aesthetic one, and simulates the end product’s mechanical properties. A well–designed prototype that takes friction into consideration can have the following advantages: an improved grip for the end user, reduced part wear, simulated movement functionality and sliding abilities.

Why Connex3 3D printing?

Connex3 printing systems provide a solution for prototyping surfaces with varied friction coefficients that were impossible or cost-prohibitive to prototype in the past. By being able to print several materials in one build process, Connex3 systems can produce prototypes with varying friction areas on one given part. Users determine the friction coefficients for different areas of a given part according to the load factor. Consequently, Connex3 systems save time and money by providing an easy solution for prototyping complex parts whose dynamic friction coefficients can be tested in a single build process.

Tips for dynamic friction coefficient in prototypes

  • Save your design in separate STL files according to the different parts. This is recommended for flexible areas, as well as for rigid parts. Later the parts can be printed in different color tones to visually separate areas of the model.
  • Label each part with its relevant shore value. Labeling will help you later easily determine which shore values received the highest score in your evaluation criteria tests.
  • Design you model in such a manner to enable the mounting of flexible parts on your full assembly of rigid and flexible parts. You can then use the Connex ability to print up to nine different materials in one build process and then assemble each part on the model for evaluation.
  • Coating: Use the Objet Studio software to coat parts with various thicknesses from 0.3-3mm with one mouse click. You may use any one of the different Digital Materials as the coating material.
  • To avoid disengagements, design the model so the rigid material extrudes as a thin core into the flexible one. This creates a connection that can withstand repeated flexing and bending.

Compact, Frictionless Flexibility


Plastic flexure bearings appear as living hinges and snap-fit closures in disposable containers, electromechanical systems and consumer products packaging. Minimal friction, compact design and the ability to manufacture them in one piece makes them a popular alternative to mechanical hinges and closures in many applications.

Prototype Living Hinges With PolyJet 3D Printing

Several PolyJet materials can produce living hinges that withstand functional testing. Endur is a tough, flexible photopolymer that mimics the appearance and behavior of polypropylene. On its own, it’s a great option for 3D printing living hinges. For users of Connex, Connex2 and Connex3 3D printers, Endur can also be combined with select Rubber-like materials to produce Digital Materials with improved toughness. These blends create the most successful living hinges of any PolyJet material option.

Other Digital Materials combine the superior elongation properties of Rubber-like photopolymers with the stability of Rigid Opaque materials to achieve toughness suitable for living hinges.

With multi-material 3D printing, you can combine several properties in the same build, so a flexible living hinge can function next to a rigid housing with no assembly required.

Build Living Hinge Prototypes With FDM Technology

Creating living hinges with FDM enables quick functional testing of hinged containers and housings, in production-grade thermoplastics. FDM living hinges and snap-fit prototypes are especially successful when 3D printed with FDM Nylon 12 material.

Design and build considerations: With a vertical build orientation and slight modifications to the hinge design, a single bead of thermoplastic can extend the entire length of the hinge. This results in an FDM living hinge that can last through hundreds or even thousands of flex cycles. In addition to hinge durability, the vertical orientation often provides a good surface finish on the rest of the part.

Functional Prototyping
PolyJet 3D Printing technology has revolutionized product design with the capability to jet two or more materials at the same time to create prototypes with ready–printed overmolded parts.

PolyJet 3D Printed Overmolding

Functional PrototypingOvermolding is a molding process in which two or more materials are combined to produce a single part. Typically the part seamlessly binds a rigid plastic with a rubber–like elastomer. The result is a soft-touch, non–slip surface common on power tools, toothbrushes, razors, consumer electronics, medical devices and more. An overmolded part begins with the molding of a rigid, thermoplastic substrate. On top of the substrate, a thermoplastic elastomer (TPE) is molded. The plastic substrate and TPE are joined either through insert molding or multi–shot molding. Insert molding is a two–step process. First, the rigid substrate is molded. It is then placed in a mold cavity on another injection molding machine and TPE is shot directly over the substrate. In contrast, multi–shot molding is performed on an injection molding press that shoots multiple materials in a single operation. This allows the TPE to be overmolded immediately following the molding of the substrate. The choice of methods is based on a number of factors including production volumes, tooling costs and part designs.

To address the challenges that arise from the design of an overmolded product, companies rely on a variety of prototyping methods.

Option 1: Prototype Injection Molds When time and expense are not issues, the ideal method is to inject mold prototype parts using the selected substrate and TPE materials. By using the production methods and materials, the prototype possesses the same qualities as the final product. The problems with this approach are that it is extremely costly, time consuming and inflexible. While cost and delivery depend on complexity and size, typically this prototyping approach costs between $6,000 and $50,000 and takes three to eight weeks to complete.

Option 2: RTV Molds As with insert molding, the RTV molding process uses one mold to form the base component and another for the overmolded area. Each mold requires a pattern into which the liquid silicone rubber is poured. The cost for patterns and molds typically ranges from $1,000 to $5,000. The lead time is usually one to three weeks.

Terminology

Overmolding and related terms are often confused or misused. This results, in part, from the broad range of multi-material applications that extend beyond soft materials on rigid substrates. Another source for the lack of clarity is that the terms may be derived from the characteristics of the molded part or base process. For example, some use overmolding as a synonym for insert molding. In this context, overmolding includes the molding of soft or rigid plastics on any type of base material, including metal.

In general, multi–material molding is the most accurate term to use when describing all injection molding processes that involve making parts with two or more materials. This term then encompasses:

  • Multi-shot
  • Multi-component
  • In-mold assembly
  • Two-shot
  • Double-shot
  • Multi-inject
  • Insert molding
  • Overmolding

Why Connex 3D Printing?

The Connex printing systems possess a unique technology that is one of the most important industrial innovations of the last five years. Jetting multiple materials enables overmolding in a single build process. A model can be constructed quickly and affordably — ideal when the design is still in flux. This solution is much less costly and time–consuming. It is rapidly replacing injection molding and RTV molding to produce prototypes. In a single build process, and with little effort, a prototype part can be printed to simulate several variations of an overmolded product. As stated in the Vista Case Study: “The Connex gives you the opportunity to evaluate more design options in less time and cost.”

Tips for 3D Printed Overmolding

Create a mechanism that enables you to mount a separate part on your full assembly of rigid and soft parts. Then use the Connex ability to print up to nine materials in one build process and assemble each part on the model for evaluation. Label each part that you evaluate with its relevant friction coefficient value. The label will later help you quickly determine which part received the best score in your evaluation criteria tests.

During the design process, nothing helps you appreciate what a product will really be like more than a 3D model that looks and feels like the end product. PolyJet technology’s wide range of rigid and rubber-like materials offer smooth finishes, fine detail and the ability to jet a variety of materials on a single build tray. Incorporate buttons, knobs and soft components —even add color – to create ultra-realistic prototypes that look and feel like your future products.

3D printing soft touch parts

Many industries use soft touch coating during their product design to validate future products. For example, the automotive industry uses soft touch in the design and development of interior products such as knobs, pulls and handles. Consumer electronics use soft touch coating for features such as rubberized buttons and coatings, typically to improve the product's ergonomic comfort. In the world of consumer goods, a vast array of products incorporate soft touch coating, including tooth brushes, shaving handles and glasses.

Why Connex 3D printing?

Connex 3D printing systems give you unmatched final product realism. You can produce prototypes with properties that mimic traditional elastomers like EPDM and NBR to evaluate designs that incorporate soft touch areas. With the Objet500 Connex3, you can even add color. In the example illustrated above, several rubber–like materials with different Shore A values were printed at the same time and evaluated on the design model. The model was then tested on a focus group as well as on potential customers to gain input regarding the product's comfort and ease of use. Issues such as a product's impact resistance can also be evaluated.

Tips for soft touch 3D printed parts

Save the design in separate STL files for each part of your assembly. This is recommended for the soft touch areas along with other rigid parts. Later the parts can be printed in different color tones to visually separate each area of the model.

Label each part that you evaluate with its relevant shore value. Labeling will help you later quickly determine which shore value represents the best score in your evaluation criteria tests. Also, create a mechanism that enables you to mount the soft touch part on your full assembly of rigid and soft parts. You can then use the Connex system's ability to print up to nine different materials in one build process and assemble each part on the model for evaluation.

Overview

Functional PrototypingThere are times when a component’s only function is to occupy the space that it will take in the final product. Claiming this space provides assessment and verification of critical installation issues such as assembly, serviceability, routing and interfaces. It also allows assessment of product performance aspects that are adversely affected by clearance from a neighboring sub-assembly.

One evaluation option is to manufacturer or purchase the component. However, for high-value parts with complex designs, and possibly long lead times, the investment may be unwarranted and ill advised. In the time span between installation assessment and final product assembly, design modifications may occur and parts may be damaged during repeated installation cycles. If this occurs, the component must be either repaired or replaced. Another downside to use of production components is that work-inprogress (WIP) expense increases, and schedules may be delayed by late deliveries of components. This is especially critical when working on new equipment designs.

Application Outline

Mock-ups may be substituted for production components during the assembly and interface evaluation phase of a project. For simple configurations, all necessary detail can be incorporated in a machined or fabricated part that is inserted in the product assembly. However, with complex, intricate subassemblies, the mock-up may be oversimplified, which can result in an oversight of installation and interface problems.

Surrogate components preserve all of the critical details for an installation while minimizing expense and lead time when they are manufactured with Fused Deposition Modeling (FDM). Produced as needed, with up-to-date configuration changes, the FDM surrogates will confirm clearances and interfaces for installation assessment; highlight serviceability issues; and validate routing interfaces for wiring harnesses and fluid conduits. As the product nears completion, the FDM surrogates may also be used as a training aid for assembly technicians or field service personnel.

FDM works by extruding small beads of thermoplastic material through a nozzle that is moved by a numerically controlled mechanism in layers that harden immediately. The additive process constructs surrogates in hours or days at a fraction of the cost of production components. This lowers acquisition cost and defers WIP expenses until final assembly while shortening lead times to validate installations.

When neighboring subassemblies are modified or the surrogate reveals clearance issues, design revisions are easily incorporated in subsequent iterations since FDM requires no tooling. New surrogates are conveniently produced to the latest design revision. The thermoplastic surrogates also offer the advantages of being lightweight and non-marring. This makes installation easier and reduces the possibility of damaging nearby components or structures.

As efforts shift to final product assembly or functional testing, FDM surrogates can highlight the need for removal. Manufactured from colored material— for example red—the surrogates are visible to assembly technicians. Optionally, embedded RFID sensors communicate the presence of non-production components. Either option will assure that all surrogates have been replaced with the production parts they represent.

Process Overview

The configuration of FDM surrogates can be adjusted to match the immediate needs. For space claim and assembly assessment, it is usually best to produce the subassembly to the final design. However, with minor CAD adjustments, the FDM part can be simplified to include only areas of interest. If evaluating interfaces of items such as fluid fittings, electrical connectors, air ducting or mounting surfaces, either include them in the CAD model or attach production fittings to the FDM surrogate. For smart surrogates, incorporate pockets in the model to accept RFID tags or sensors that will be embedded in the part. If weight or balance is important when training installation and service technicians, add strategically placed pockets in the CAD model that will be filled with ballast material.

Surrogate Configuration Options:

  • Envelope Verify fit (space claim) and access for installation and service. – Basic: simplified representation that eliminates non-functional features. – Advanced: Complete representation for assessment of functional clearances (e.g. sway and cooling zones).
  • Interface Validate routings and connections (e.g., fluid fittings and electrical connectors). – Integrated: interfaces constructed in surrogate. – Hybrid: production hardware mounted to surrogate.
  • Ergonomic Represent weight and balance in training aids. – Ballast: add sheet, bar or shot material to surrogate.
  • Smart Integrate feedback devices for surrogate detection and data capture. – RFID: encapsulate or attach tags for surrogate identification. – Sensor: embed or attach measurement devices.
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wind tunnelOverview

Wind–tunnel testing is an integral part of the design process in many industries, typically used to verify and tune the aerodynamic properties of solid objects. Whether an object is stationary or mobile, wind tunnels provide insight into the effects of air as it moves over or around the test model.

To make models for wind–tunnel testing, automotive, aerospace and architectural firms have relied on traditional manufacturing processes including milling, turning and fabrication. Typical materials are metal, plastic and composites. These operations require programming, setup and operator supervision, which adds to lead time and cost.

3D printing (also called additive manufacturing) has rapidly gained acceptance as an alternative process for constructing durable, accurate wind–tunnel test models. Compared with machining and model making, 3D printing with either PolyJet or FDM Technology is faster, less expensive and more efficient.

Additionally, 3D printing can preserve small, inaccessible features that are difficult to make at scale with traditional methods. For example, internal passages are easy to produce, whereas these features would complicate the CNC milling process. 3D printing makes it possible to easily embed equipment into the model, such as pressure-measurement devices and vents for smoke discharge.

Application Checklist

PolyJet or FDM is a best fit for wind–tunnel testing when:

  • Designs are complex or intricate
  • Challenging characteristics include internal cavities, organic shapes or fine feature detail
  • Design changes are likely
  • Designs are large or bulky

Benefits of PolyJet and FDM models for wind–tunnel testing include:

  • Time and cost savings
  • The option to embed inserts without drilling
  • Availability of lightweight materials
  • Ease of creating internal passages for smoke or ink dissipation
  • With PolyJet, the option to create transparent models

Application Outline — PolyJet

Producing hollow models is easy with PolyJet technology. This makes the model lighter and reduces material consumption. Inserts, often stock parts, can reinforce the model if needed, contributing greatly to its dimensional stability. Generally, it’s best to use the largest–diameter rod or thickest plate possible while reaching close to the tip of the model. The transparent materials available with PolyJet 3D printing can be useful when evaluating the flow characteristics of internal structures. Combining these materials with the complex internal structures that additive manufacturing allows lets designers verify complex internal designs.

Application Outline — FDM

Distinguished by its durable materials, FDM is well suited for constructing wind-tunnel models. Soluble supports allow for complex models with internal cavities to be designed without considering traditional manufacturability. Inserts, including stiffening rods, sensors and fastening devices, can be embedded during 3D printing. The robust thermoplastics used in the FDM process make it possible to assemble the parts to functional assemblies or bond multiple sections together to produce large models. Internal structures can be manipulated to conserve material while maintaining structural integrity.

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