Rapid Prototyping FAQ

PADT has been providing Rapid Prototyping Services since 1994 to companies around the world, and over that time we have been asked a lot of questions. The lists below present the most Frequently Asked Questions, our FAQ. The list starts with general Rapid Prototyping questions and is followed by questions that are specific to working with the experts at PADT to do your Rapid Prototyping.

If you do not see your specific question, please feel free to contact PADT and we will be happy to answer it directly.

General Rapid Prototyping Questions

What is Rapid Prototyping?

Rapid Prototyping is a manufacturing technology that quickly builds a prototype part. Many different technologies are available that are considered Rapid Prototyping, and many can also be used for production manufacturing. Although most Rapid Prototyping systems use a form of layered additive manufacturing, they can also use a variety of other methods such as high-speed machining, molding, casting, and extruding.

Rapid Prototyping, often called RP, is rapid prototyping when the entire process of going from a computer design to a physical model is faster than more traditional manufacturing technologies. Wikipedia has a good article on the subject.[ http://en.wikipedia.org/wiki/Rapid_prototyping]

What is Rapid Tooling and how is it Different from Rapid Prototyping?

The only difference between Rapid Tooling and Rapid Manufacturing is the end use of the parts produced with the process. Both use rapid prototyping technologies to quickly make a part. But for Rapid Tooling, the part is used in another manufacturing process as a tool.

What is 3D Printing and how is it Different from Rapid Prototyping?

3D Printing refers to a subset of rapid prototyping that goes directly from a 3D computer model to a prototype with very little user interaction other than defining some preferences. The process is designed to be as easy as printing from a computer to paper.

In many ways the name is a marketing label to clearly emphasize the affordability and ease of making prototypes using systems that are labeled as 3D Printers. It is also meant to appeal to a larger, less engineering and manufacturing oriented audience. PADT uses 3D Printing systems as well as Rapid Prototyping and Manufacturing systems.

What are some of the other names for Rapid Prototyping?

3D Printing, layered manufacturing, additive manufacturing, direct digital manufacturing, digital prototyping, digital fabricator, desktop fabricator, desktop manufacturing, desktop prototyping.

People often use the names of various prototyping techniques to refer to rapid prototyping, and even more often the acronyms for those technologies. Examples are Stereolithography or SLA and Fused Deposition Modeling or FDM.

What is Layered Manufacturing and why do most Rapid Prototyping Technologies Use it?

Layered Manufacturing builds parts up, one thin layer at a time. Most traditional manufacturing methods start with a block and remove material, or shapes material using a tool of some kind. Layered manufacturing is often called Additive Manufacturing because it adds material rather than taking it away or molding it.

The best way to visualize layered manufacturing is to think of taking a real part and chopping it into very thin layers. Then stack those layers back up one on top of the other. Layered manufacturing does the chopping in a computer program, and tells a machine how to create each layer.

When and how is Rapid Prototyping used in Product Development?

Rapid prototyping can be used at almost every step in your product development process. At any point where you need a physical part you can benefit from Rapid Prototyping. Examples are:
Conceptualization: concept models, marketing mockups
Initial Design: form, fit, and function testing, visualization
Detail Design: testing, test fixtures, assembly testing, fit, form and function testing.
Production: tooling, mockups for process planning

What are the different types of Rapid Prototyping Technologies and their Advantages and Disadvantages?

Unfortunately there is no one technology that is perfect at everything. The following table is a basic listing of the main advantages and disadvantages.

TECHNOLOGY ADVANTAGE DISADVANTAGE BEST USE
SLA Smooth Accurate Detail Temperature Sensitive, Brittle, Brittles over Time Marketing Models Fit Checks
SLS Durable, Speed on Large Projects Rough Surface, Erratic Accuracy Functional Models
FDM Cost Effective Durable True Plastics Lower Resolution Weak Layer-to-layer Engineering Models Internal Reviews
POLYJET Adjustable Material Properties Speed Fine Layers Weak Material Properties Cost Elastomeric Models Overmold Models
CNC MACHINING Accurate True Materials Long Lead Time Cost Metal Models Precision Work

What is a STL File?

The STL file is a file format developed in the early days of Rapid Prototyping by 3D Systems as a simple and portable format that could be used across CAD systems to define the solid geometry to be made in a Rapid Prototyping machine. It is a triangular facet representation, the surfaces of the solid are modeled as a collection of triangles that share vertices and edges with neighboring triangles. Most CAD tools can output an STL file.

You should also know that there are two types, ASCII (text) and binary. Binary tends to be more compact.

Learn more on Wikipedia. [http://en.wikipedia.org/wiki/STL_file]

My part is about “this” big, how much will it cost to make a prototype of it?

It is very difficult to estimate the cost of a prototype without knowing many different factors. These include the volume of the part, the height in the “up” direction, the process being used, the material being used, and the finishing that is required. The best way to find out the cost is to send a part to PADT for a quote. If you do not have a computer model yet, then sending the basic dimensions and calling our engineers should result in a ball park estimate.

How long does it take to make a Rapid Prototyping Part?

IT can take as little as five minutes and as long as 3 or 4 days depending on the size, the process, and the amount of finishing required. However, most parts can be made within a 24 hour period.

Can I use Rapid Prototyping to make tooling for Injection Molding?

Yes you can. A special process and special materials are required, as is a special mold base. But a low volume injection mold can be made using Rapid Prototyping. PADT can also help find a supplier that can use rapid machining to make molds almost as fast as rapid prototyping.

My buddy has a MakerBot/RepRap/Build-your-Own-3D-Printer. How is that different from these commercial Rapid Prototyping systems?

There has been an explosion of do it yourself RP systems at around 2010-2011. Most of these are based on the fact that the patent for Fused Deposition modeling ran out. The majority of homemade systems, or personal systems, are variations on the systems made for decades by Stratasys. They differ from commercial or industrial systems in two ways: lower cost, and fewer capabilities. In general, the parts made on these systems are not usable for engineering or even visualization models because the material is too soft, the material does not fully harden or bond, there is considerable shrinkage or warping, and the actual precision of the device is low.

What is the most commonly used Rapid Prototyping Technology?

For many years the most commonly used technology is Fused Deposition Modeling. Originally only available from Stratasys, many other providers have adopted the technology. The best way to see how the various technologies stack up is through the Wohlers Report, an annual summary of the industry. [http://wohlersassociates.com]

Is there free software out there that I can use to look at my model before I send it to you? Can I convert a file I made for animation or rendering to a file you can use?

Yes. Meshlab is a tool for dealing with all types of faced data and it works with STL files as well. It can be sued for translating, repair and visualization. [http://meshlab.sourceforge.net/]

MiniMagics is a free STL viewer from Materialise [http://software.materialise.com/minimagics].

PADT’s Rapid Prototyping Services

I need a Quote, How do I get one?

Basically you need to send us a file containing the geometry you want prototyped and let us know what you need your prototype for, or if you already know, what technology you would like us to use. Detailed information can be found on our Rapid Prototyping support page [/support/rapid-prototyping.html]

What Rapid Prototyping Technologies does PADT have in House?

PADT currently has the following Rapid Prototyping technologies in house:

In addition, PADT offers the following related technologies that are often used with Rapid Prototyping:

Which Technology Should I use for my Prototype?

That depends greatly upon the use you have in mind for your prototype and your budget. Each technology has a variety of strengths and weaknesses as well as cost. What sets PADT apart from most Rapid Prototyping service providers is that our engineers have the experience and the expertise to work with you to determine the proper technology for your needs.

What does PADT need to Quote my Rapid Prototyping Job?

At a minimum, an STL or CAD file and a way to contact you. To speed along the process you can provide us with information about any preferred processes or the intended uses for your prototype.

What File Types (formats) does PADT Accept?

The best format to send to PADT is an STL file.

PADT currently has the ability to use the following Native CAD file formats:

  • NX
  • Pro/E or Creo
  • SolidEdge
  • SolidWorks

PADT can also usually work with the following non-native formats:

  • IGES
  • Parasolid
  • SAT (ACIS)
  • STEP

What settings should I use when making an STL file for PADT?

The default settings are generally acceptable for us. We do recommend that you use a “finer” setting if your part is complicated. If we find that your file is not refined enough, our engineers will contact you and let you know how to increase the accuracy for the CAD system you are using.

How do I Send a File to PADT?

We provide multiple methods for sending files to PADT:

Email it to rp@padtinc.com with your contact information.

Put it into a dropbox or secure file sharing location and send us a link via email to rp@padtinc.com.

Upload it to www.padtinc.com/upload

see www.padtinc.com/support/rapid-prototyping.htmlfor details.

I don’t have a CAD file, can you make me one?

Depending on what you need, PADT can quote solid modeling and design services or we can also recommend one of the local companies or individuals that we work with on a regular basis to help people create CAD models of their parts. Please speak with one of our engineers so we can better understand your needs and we will recommend the best course of action.

I don’t know what a CAD file is, or how to get one, what should I do?

Simply contact us at PADT and we will walk you through the whole process. You may also want to visit PADT’s The RP Resource, it contains a wealth of useful information for experienced users and those who are new to the technology.

My design is Confidential, how do I make sure it will stay that way?

PADT has provided prototyping services to over a thousand companies and individuals without a single confidentiality issue. We treat every customer’s part as confidential. If needed, we have a standard 2-way confidentiality agreement that we can sign to provide additional assurance that we will keep your ideas secure.

How precise are the Rapid Prototyping Technologies that PADT offers?

Precision and accuracy are very geometry dependent as well as machine dependent. Below are basic baselines to consider.

TECHNOLOGY ACCURACY
SLA +/-0.005″ plus 0.001″ per inch
SLS +/-0.010″ plus 0.002″ per inch
FDM +/-0.008″ plus 0.001″ per inch
POLYJET +/-0.008″ plus 0.001″ per inch
CNC MACHINING +/-0.003″

Why does PADT have so many different Rapid Prototyping Technologies?

Because each technology has advantages and disadvantages. By having each of the leading technologies, and multiple materials options for each, PADT can meet almost any rapid prototyping need.

The only common technology that PADT does not have is a ZPrinter. Why?

Frankly the parts are too fragile. Although the technology does allow you to print in color, the resulting parts are not robust enough for our customers.

What is the largest part you can make?

The largest part we can make in one run can fit in a 14 x 10 x 10 in volume. But PADT has made parts that are several over six feet long by simply building individual pieces together. We also partner with other service providers that have specialty very large machines.

How small of a part can you make? What is the smallest feature you can replicate?

Small features and thin walls are very geometry dependent as well as machine dependent. Below are basic baselines to consider.

TECHNOLOGY TYPICAL ABSOLUTE BEST
SLA 0.010″ 0.004″
SLS 0.020″ 0.010″
FDM 0.030″ 0.020″
POLYJET 0.010″ 0.002″
CNC MACHINING Material dependent Material dependent

My part needs to look like the final production part, can you do that? Can you paint my part? Can you put a surface finish on it?

Yes, in fact that is a specialty of PADT. Our technicians are true artists that know how to prep, sand, and paint a part so that when they are done, it looks like a final product. We can apply your specified surface finish or paint color.

My product has hard and soft pieces, can you make a prototype with different stiffness? Can you make a flexible part? Can you make a rubber part?

Yes. PADT has multiple technologies available that allow us to make parts that mimic several different soft materials, including over molding on a more rigid part.

My part needs to operate at a high temperature | in water | outside | under pressure | with nasty chemicals | around clumsy people. Can you make me a prototype that will survive?

In most cases we can. Most of our machines have materials that work well with water and pressure. Please contact us with your specifications and we will go over your options with you. For higher temperatures and specific chemicals, we will have to do a little research.

Can I use a prototype as a production part?

Yes. Using parts made on “prototyping” equipment as production parts is becoming more and more common for low volume manufacturing and certain smaller parts that can only be made using an additive manufacturing process.

Can rapid prototyping parts be used for tooling and fixtures?

Yes. In fact, this is one of the fastest growing areas of rapid prototyping: rapid tooling. It is becoming mainstream for many different manufacturing processes because the parts can be made very quickly and, if the proper technology is used, they can be made very strong.

Can you make a part that is clear or a certain color?

Yes. Several of our technologies have a clear material. In addition, several solid material colors are available. And, if needed, PADT can always paint your part any color you need.

I need more than one part, can you make multiple parts? Is there a less expensive way to make copies of my part?

PADT uses soft tooling and prototype injection molding extensively to make multiple copies of a part. Our soft tooling technicians are very experienced and skilled and are able to compete effectively on speed and cost with many other options, including off-shore manufacturing.

Do you do machining, vacuum forming, traditional model making?

In addition to the Rapid Prototyping technologies that PADT has in house, our shop is also equipped with a CNC mill and lathe, a vacuum forming machine, and all of the tools needed to do traditional model making.

Can you make sheet metal prototypes?

This is one of the few prototyping options that PADT does not offer. But if you are looking for a sheet metal prototyping provider, we have several we can recommend.

Can you make metal parts?

We do not offer metal parts at this time unless we use our CNC machining center. But we do partner with several providers that can make metal parts using rapid prototyping technology.

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3 Responses to Rapid Prototyping FAQ

  1. Pingback: Rapid Prototyping FAQ | PADT, Inc. – The Blog » greennewstweets.com

  2. raj says:

    what are the different types of testing done on surface in rapid prototype

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