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Key Questions to Ask When Ordering Rapid Prototyping In Automotive Industry

16, Dec. 2024

How to Determine the Best Prototyping Method? 5 ...

At last! It's time to turn your design into a physical object. While it's exciting to see something from your imagination turn into reality, there are questions that must be answered before you can begin.

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1 | Which prototyping method should you use?

This is a great first question which depends on the answers to the following four. But first, a quick tutorial in prototyping methods.

There are two basic types of manufacturing processes:

Subtractive [in which you remove material to form the part; includes computer numerical control (CNC; a computer guided machine or hand held router cuts away the unwanted material), lathing, machining, milling]

Additive [in which material is added to create the part; often called 3D printing].

It's also important to remember that certain materials lend themselves to specific processes. For example plastic is often used in additive manufacturing; CNC is used for metals; and you typically think of wood being lathed.

2 | What is the purpose of the prototype?

If the purpose of your prototype functional testing, then the method you use is critical. You don't want to physically test the part in a way that might show a false failure.

Here's an example. Let's say your prototype is made using a form of additive manufacturing called fused deposition modeling (FDM). Most people have heard of or seen this process described by the generic, and imprecise, term 3D printing. Simply put, following directions from a computer file, a 3D printer extrudes molten material in multiple layers which cool to create the form. Here's a video if you've never seen this in action:

And here's a photo of a part we printed in our lab using FDM. Look closely, you can see the see the horizontal layers. If you stress the part mechanically ' maybe try to bend it ' it might crack between layers. But maybe that's not realistic to how the actual part would break.

In this case, rather than prototyping using FDM, you might want to use a subtractive 3D method for prototyping, in which you use a solid plastic block of material and remove the material that isn't in the part. If you bend it and it breaks, it will break based on the design of the part, not on the soundness of the material.

3 | Do these parts need to be air tight?

3D printers are very good unless there is a hiccup in the process. In the absence of material being layered, you will add air. If your part needs to be airtight, you may need a part done by CNC which starts with a solid block of material. It's simple mathematics. If you're subtracting and you didn't take it away, it's still there.

4 | How many prototypes do you need?

Another thing to consider is the volume of (prototype) parts you need. Some processes are faster than others. If you need just one part, any option is good. Take your pick. But if you want a lot of parts, you're looking more for a supplier than a process. We work with companies with 3D printers as far as the eye can see. They can load your project on the printer and finish up in a couple days. If you only had access to a single printer it would take two to three weeks.

The size of the part also dictates how quickly you can build it. Most times when you're ordering a part you don't have the flexibility to change its size. That's one thing in favor of CNC. Depending on what you're looking for, you can break it into smaller parts, glue them together and get a much faster part without having to CNC a very large piece.

5 | Do you have to make your prototype out of the same material that you're making the part out of?

I have it on good authority that this is not a dumb question. Again, what's the purpose of the part? For functional testing, you want the material to be close to what you're planning to use for the final product. Maybe you want it to feel soft, you'll want to prototype in a material that will closely match the feel you're going for. But if you're trying to confirm your design, say your product is supposed to be hard/rigid, it doesn't matter if you use something that's super rigid or semi-rigid. As long as it's in the ballpark, you'll get what you're looking for.

REMEMBER:

Focus on the problem you're really trying to solve. Only prototype the part you need to have.
If you're concerned about the strength of a part, use a method and material that will give you the best information about that concern.

Prototyping is an exciting step. Doing your research, asking questions and making sure you understand the answers will keep your project moving forward.

Additional reading:

How a Startup Can Minimize Investment Cost and Start Production Sooner

How Small Design Changes Can Affect Product Development Pricing

For more information, please visit Rapid Prototyping In Automotive Industry.

Selecting a Rapid Prototyping Process | Manufacturing Guide

Definitions

Definitions vary and may differ at different organizations, but the definitions below may be used as a starting point.

Concept Model: a physical model made to demonstrate an idea. Concept models allow people from different functional areas to see the idea, stimulate thought and discussion, and drive acceptance or rejection.

Prototyping Attributes
Speed: turnaround time to convert a computer file into a physical prototype

Appearance: any visual attribute: color, texture, size, shape, etc.

Assembly/Fit Testing: making some or all of the parts of an assembly, putting them together, and seeing if they fit properly. At the gross level, this checks for design errors, such as placing two tabs at 2 in. spacing and the mating slots at 1 in. spacing. At the fine level, this is a matter of minor dimensional differences and tolerances. Obviously, any test involving tolerances needs to use the actual manufacturing process or one which has similar tolerances.

Prototyping Attributes
Form: the shape of the part: features and size

Fit: how the part mates with other parts

Functional Testing: seeing how a part or assembly will function when subjected to stresses representing what it will see in its actual application.

Prototyping Attributes
Chemical Resistance: resistance to chemicals including acids, bases, hydrocarbons, fuels, etc.

Mechanical Properties: strength of the part measured by tensile strength, compressive strength, flexural strength, impact strength, tear resistance, etc.

Electrical Properties: interaction of electrical fields and the part. This may include dielectric constant, dielectric strength, dissipation factor, surface and volume resistance, static decay, etc.

Thermal Properties: changes in mechanical properties that occur with changes in temperature. These may include thermal expansion coefficient, heat deflection temperature, vicat softening point, etc.

Optical Properties: ability to transmit light. May include refractive index, transmittance, and haze.

Life Testing: testing properties that may change with time and that are important for a product to remain functional throughout its expected life. Life testing often involves subjecting the product to extreme conditions (e.g., temperature, humidity, voltage, UV, etc.) to estimate in a shorter period of time, how the product will react over its expected life.

Prototyping Attributes
Mechanical Properties (fatigue strength): ability to withstand large numbers of load cycles at various stress levels.

Aging Properties (UV, creep): ability to withstand exposure to ultraviolet light with an acceptable amount of degradation; ability to withstand extended applications of forces to the part with acceptable levels of permanent deflection.

Regulatory Testing: testing specified by a regulatory or standards organization or agency to assure parts are suitable for a particular use such as medical, food service or consumer application. Examples include Underwriters Laboratory (UL), the Canadian Standards Association (CSA), the U.S. Food and Drug Agency (FDA), the U.S. Federal Communications Commission (FCC), the International Standard Organization (ISO) and the European Commission (EC).

Prototyping Attributes
Flammability Properties: the resistance of a resin or part to ignition in the presence of a flame.

EMI/RFI Properties: the ability of a resin, part or assembly to shield or block Electromagnetic Interference or Radio Frequency Interference.

Food Rating: approval of a resin or part to be used in applications where it will come in contact with food while it is being prepared, served or consumed.

Biocompatibility: the ability of the resin or part to be in contact with human or animal bodies, outside or inside the body, without causing undue adverse effects (e.g., irritations, blood interactions, toxicity, etc). Biocompatibility is important for surgical instruments and many medical devices.

Summary

Prototype models help design teams make more informed decisions by obtaining invaluable data from the performance of, and the reaction to, those prototypes. The more data that is gathered at this stage of the product development cycle, the better the chances of preventing potential product or manufacturing issues down the road. If a well thought out prototyping strategy is followed, there is a far greater chance that the product will be introduced to the market on time, be accepted, perform reliably, and be profitable.

What is the best way to get a prototype made? The answer depends on where you are in your process and what you are trying to accomplish. Early in the design process, when the ideas are flowing freely, concept models are helpful. As the design progresses, a prototype that has the size, finish, color, shape, strength, durability, and material characteristics of the intended final product becomes increasingly important. Therefore, using the right prototyping process is critical. In order to most effectively validate your design, pay close attention to these three key elements of your design: functionality, manufacturability, and viability.'

If your prototype can faithfully represent the attributes of the end-product, it is by definition functional.'These requirements often include such things as material properties (e.g., flame resistance), dimensional accuracy for fit-up with mating parts, and cosmetic surface finishes for appearance.

If your prototype design can be repeatedly and economically produced in a manner that supports the requirements of the end product, it is by definition manufacturable.'These requirements include the ability to maintain the functionality of the design as described above, keep the piece-part cost below the required level, and support the production schedule. No matter how great a design is, it will go nowhere if it can't be manufactured. Make sure your prototyping process takes this into consideration.

Finally, even if your prototype design is functional and manufacturable, it doesn't mean anyone will want to use it.'Prototypes are the only true way to verify the viability of the design in this sense.'If your design can also pass the challenges associated with market trials (e.g., trade show displays, usability testing) and regulatory testing (e.g., FDA testing of medical devices), you're well on your way to a successful product launch.

If you are looking for more details, kindly visit Rapid Prototyping In Aerospace Industry.

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