This is true for any additive manufacturing project as well. Being aware of a few common mistakes made throughout the design process can help minimize costs and delays, and help prevent the creation and delivery of unsatisfactory parts that require further changes and rebuilds in order to meet the needs of the customer.

Pay close attention to not only the native CAD design of what is to be produced via additive manufacturing, but also the converted .STL version which is often required. The .STL file format is the standard data interface between CAD software and most additive manufacturing machines. A .STL file approximates the shape of a part or assembly using triangular facets.

“Even well conceived designs with the best of intentions can present a potential problem when converted to .STL format and submitted for additive manufacturing”, says Patrick Hunter, VP & General Manager of Quickparts (www.Quickparts.com). “This is why we make a point to review the files our customers submit to us, and address any issues we find before parts are built, rather than after they are delivered”.

Before submitting a design for any additive manufacturing project, keep an eye out for these seven common mistakes concerning part design and file conversion.

The part design has thin features or walls that are less than .030” for standard resolution or .015” – .020” for high resolution machines.
Due to the “layer by layer” approach of the additive manufacturing process, anything smaller or thinner that this will often times not build and will not be present in the final model. Pay very close attention to raised or recessed logos and areas of small text, “knife edge” features which taper down to zero thickness, and curvy sections of any design where thickness can fluctuate.

The native CAD model is converted to .STL format with a very low resolution, resulting in heavy faceting in the model.
If the resolution of the .STL file is too low, the model will be faceted instead of having smooth surfaces and curves. This can be quite common and produces unattractive parts. Typically, to achieve a smooth finish on a model there should be an edge-to-edge distance of less than .020” between facets on the .STL file. Check the parameters on the native CAD program being used to determine the best method of exporting acceptable .STL files.

The original CAD data has numerous unstitched surfaces (rather than solids), resulting in errors when converting to .STL format.
Make sure that the surfaces in the original CAD model are “water tight”, in that only solids are modeled. The .STL file can also be inspected to ensure that all dimensions, part volume, and surface area all appear to be correct.

The part design has an enclosed hollow space from which support and build materials cannot be removed.
Any enclosed hollow void in the design will contain support materials which cannot be removed through the finishing process. This area may also be filled with unused resin or powder depending on the selected prototyping process. Consider filling in voids to be solid, building the design in halves to allow access to the enclosed space, or adding a hole of some kind in the model to allow for the removal of the support materials.

Assemblies, threads, and mating features are designed with improper clearance.
The standard tolerances for most additive manufacturing processes start at +/- .005” and compound from there as the design increases in size. It is not uncommon for first time customers to receive parts that, while within the published tolerances of the manufacturing process, do not “fit together” or mate up as intended. Typically, there should be a .015” – .020” clearance between mating parts, which is different from what is required for traditional injection molding. This is an important point to remember when the success of the project depends on how well different designs mate up or assemble with one another.

The design includes a living hinge which needs to function.
Living hinge designs on most parts produced via additive manufacturing don’t typically function as intended. The build material involved is often too rigid, especially in such a thin section, and will break. While there have been a few materials developed that look to address this need (the Duraform EX material using the SLS process can often work well), expect limited usage from a living hinge design produced via additive methods.

The units of measurement for the .STL file differ from what was intended.
Double check the .STL files properties to ensure that the correct unit of measurement is selected. This is especially true when there is more than one design with varying units of measurement being built together. Some CAD packages also have default settings where .STL files may be exported in a different unit of measurement from what was used during the design process. When there is a tight time line and the project is on the line, it can be difficult to see the comedy in dramatically oversized or undersized parts as they come out of the box.

Keep these seven common mistakes in mind when considering any additive manufacturing project. Be careful to confirm the integrity of the original CAD data, and be mindful of living hinge designs, enclosed or trapped hollow spaces, clearance between mating features, and any features or walls that are smaller or thinner than .030”. After exporting the .STL file from the native CAD file, take time to confirm that the overall resolution of the file is sufficient and that the selected units of measurement are correct.

Not Sure Which Additive Manufacturing Technology to Use?
If you are not sure which rapid prototyping process is best suited for your project, pick up the phone and give us a call at 770-901-3200, or send a quick email to quote@quickparts.com. Our team of professionals are very well versed in the strengths and weaknesses of each rapid prototyping process, and will help you make the best choice based on your unique situation and budget constraints.

Here’s a brilliant video by Dr. Lawrence Bonassar, Associate Professor of Biomedical Engineering at Cornell University, describing a cutting-edge process he has developed in which he uses a 3D Printer and “ink” composed of living cells to create body parts such as ears.

:: Check out the mainstream love 3D Printing received from USA Today: Click here to read the full story.

Question: According to the “YouTube Videos” tab located on the Quickparts Facebook page (Watch it here!), what is the name of Johnny Quickparts’ love interest that is revealed in Episode 4: Johnny Learns About Stereolithography?

Answer: Dr. Wang

As a prize, L.G. will recieve one of our Reebok Play-Dry moisture wicking performance golf shirts, along with some other items. 

Thank you for your support of Quickparts!

Industry: Electronics

Project: iDVM Digital Multimeter    

Overview: Redfish Instruments (www.redfishinstruments.com) develops electronic devices that function in tandem with the Apple iPhone, iPad, and iPod-touch. Redfish Instruments’ iDVM device is the world’s first iPhone, iPad, and iPod-touch enabled digital multimeter that wirelessly transmits voltage, current, and resistance measurements for enhanced visualization, data sharing, and data logging. Control of the iDVM is handled entirely from within a free, downloadable application that resides on the mobile device.

The iDVM digital multimeter from Redfish makes measuring and data logging resistance, voltage, and/or current easy, allowing the user to capture, store, and share data wirelessly. Redfish Instruments is the only company offering a multimeter iPhone application, which can be downloaded for free from the Apple App Store.

Challenge: Redfish had created an initial design for the iDVM device, but needed to find a vendor who could provide them with functional prototypes for review and testing. “We needed to begin with some prototype versions to help us confirm the design, before ultimately moving on to sourcing the production parts,” said Patrick O’Hara with Redfish.

Solution: O’Hara began by using the Quickparts online instant quoting engine, QuickQuote®, to quote and buy the order for the initial ABS-like, black SLA prototypes for the top and bottom of the design case. After performing fit and form testing, Redfish, along with help from Quickparts engineers, implemented design revisions and moved on to a second order of pre-production Cast Urethane parts that allowed them to further test design, color, functionality, and finish texture.     

When the time came to produce the final production parts for the case, Redfish again turned to Quickparts for the Low Volume Injection Molded parts they needed. Today, production quantity components for the iDVM are molded out of UL94V0 black ABS off of aluminum injection molds with Quickparts. “From the personal follow up on our prototype projects, all the way to the Design for Manufacturability analysis we received with our molded parts, Quickparts continued to be the easy and logical choice to handle each phase of our production,” said O’Hara.         

Benefits: Redfish was able to directly benefit from the full “Prototype to Production” capabilities at Quickparts. Utilizing a single vendor, Redfish was able to move the iDVM device all of the way from concept through to production.  “The fantastic speed and service we received allowed us to easily navigate through the entire developmental process of the plastic components,” said O’Hara. “We couldn’t have done it without the great teamwork we experienced with Quickparts.”

More information is available at www.redfishinstruments.com.

Well here is your chance to WIN our NEWLY redesigned moisture wicking Performance Golf Shirt!

Simply Email us the correct answer to the question below by January 24, 2012 and you will be entered into a drawing to win your very own Quickparts moisture wicking Performance Golf Shirt.  It’s that EASY!

Question: According to the “YouTube Videos” tab located on the Quickparts Facebook page (Watch it here!), what is the name of Johnny Quickparts’ love interest that is revealed in Episode 4:  Johnny Learns About Stereolithography?  “Like” us to watch all the videos.

To submit your answer, please click here. 

Choosing the best prototype material for your application can be tricky.  One property that is especially difficult to understand and relate to is the Shore Hardness Value.  Shore hardness measures the elasticity of a material. 

Quickparts has created a scale that relates different Shore values to everyday products allowing you to easily compare materials and their corresponding Shore values.

Click here to use the Shore Hardness Scale in our Learning Center

   Don’t forget to check out the Print feature!  This shows you all of the values and corresponding products on one easy to use page.

Selective Laser Sintering (SLS) has become a reliable and trusted form of rapid prototyping due to its structural properties. It is particularly useful when the design is complex, custom, and needs to be functional or requires short run production.

In SLS a laser beam selectively fuses or sinters powder materials, nylon, or elastomer materials. It produces plastic or metal prototypes that closely match their molded counterparts.

The finishing time is reduced as the undercuts and overhangs are given support by the solid bed of powder which does not have to be manually removed, but the surface finishes are not as good as those produced through stereolithography. It requires no final curing, but the object is porous as it is sintered.

Once you have decided the SLS process is the best one for your part remember that there are only a select few materials available. However, those materials are as unique as they are special.

The most beneficial characteristic of SLS is how durable and functional the materials are. These materials include versions of the original DuraForm and DuraForm glass-filled (GF), which are nylon-based materials that create highly durable and functional plastic prototypes. Other materials available are Flex Plastic for elastomeric, rubber-like parts, and LaserForm, which makes metal prototypes.

ADVANTAGES

The primary advantage of SLS is that it builds prototypes in nylon material. It is possible to make structurally functional parts such as living hinges, functioning springs, and snap fit components with nylon material. The process in itself is very simple and requires no molding or tooling. The nylon material used can be easily machined, drilled, and tapped unlike those used in sterolithography, which are brittle as they are built with liquid photopolymers and cured with UV light. They continue to cure once complete and as a result become more brittle as time goes on.

All of the selective laser sintering materials can be finished in multiple ways. They can be painted, plated, drilled, tapped, or even machined, which allows for a better appearance for these parts.

Having a good understanding of SLS limitations, plus knowledge about the available materials and how and when to use them, and knowing what the finish options are for your final part, will ensure that you get exactly what you need when you are ready to begin testing for form, fit and function.

Fore more information about SLS or any other rapid prototyping technique visit www.quickparts.com.

  Every Picture Tells a Story.  Share Yours Today!!

At Quickparts, we ship over 1,000 orders of custom parts each month, each with its own story to tell. We are always amazed at the wide variety of customers that we have and all of the various uses of the parts we produce.

This month we are asking you to share your images of Quickparts parts in action, and tell the story of their use. Have you taken parts to space? The bottom of the ocean? Anywhere in between? We want to know, and we want pictures!!

Feel free to shamelessly include your website and a description of your product / company so that we can share your input with the rest of the design and development world, and make you look like a hero in the office. Earn bonus points with images that include remote locations, unique applications, or anything that makes us say “wow!”

Email your part pictures to us today!    

The typical behavior for the user is to have some experience with a particular technology, such as FDM, and then really focus on the material options of that technology.  While this approach works, it would be like a person that drives a truck to only evaluate trucks for their transportation needs, instead of considering the wide variety of cars, motorcycles, bicycles, skateboards, etc. available.

Even today, there is still not a clear-cut approach for the user to select the right process and material for their application.  Even with consultation from the experts, the guidance is typically skewed to the domain expertise of the consulting salesperson or the processes his company has to offer.

However, there are some high-level guidelines that may help put a user on the right path for their parts.  Ideally, you will be able to explore these guidelines from the wealth of information on the Internet, such as the learning center at Quickparts.com (www.quickparts.com) and the help you get from a knowledgeable sales consultant.  If you would like to know more, check out the Quickparts.com (www.quickparts.com) encyclopedia for more information.