Top 3 Considerations Before Prototyping

3D printing, like any manufacturing process, is not a completely intuitive technology. Printing requires precision: The build platform must be level, part orientation configured – even temperature plays a part in the success of a print. Once a part comes off the machine – be it a 3D printer or traditional CNC platform – it has a unique texture. This texture reveals how the piece was built, in additive or subtractive layers, and can be complementary to a project depending on its application; designers may prefer the texture, as it works well with a desired medium. When the texture interferes with the application, though, it must be improved or removed from the surface of the part. There are many “DIY” ways to remove texture, however popular options – such as acetone baths for PLA extruded parts – can diminish the tolerances of a part and wear away at important details.  Hand sanding requires a skilled hand and takes hours, making it a less popular option. When a part has critical features or tolerance requirements, it’s best to turn to a professional. The combination of Solid Concepts, Harvest Technologies and RedEye to form Stratasys Direct Manufacturing has allowed us to expand our in-house finishing services like painting, sanding, hand finishing, high gloss surface treatments, RFI and EMI shielding options. We’ve compiled a few of our favorite finishing examples which best relay the options open to you for your 3D printed, machined or cast part.
3d printing finishing

1. The End Product

At the forefront of the decisions made for rapid prototyping should be your product’s application. If your prototype needs to replicate the final product’s cosmetic looks, you may turn to a technology and material that provides a finer resolution, or you may need the prototype to be post-processed for aesthetics. If you need your prototype to simply function exactly as the end-product will; that is where technologies that offer robust materials and ideal tolerances come into play.

2. 3D Printing Technology

At Stratasys Direct we offer five 3D printing processes, each with their own unique build styles, design limitations and material properties. Depending on which method you use will determine specific design adjustments, like offsets and variances, which may need to be implemented into your CAD file. Our Design Guidelines highlight these important considerations.

We have two 3D printing technologies that offer unprecedented detail and cosmetic finish with fine resolution. PolyJet offers the ability to combine flexible and hard materials, as well as full color and transparencies. Stereolithography (SL) builds detailed parts with the smoothest surface finish. Our proprietary offerings include near-hollow builds for extremely light-weight parts. These two technologies are ideal for concept models and prototypes that need excellent aesthetics.

For functional prototypes, Fused Deposition Modeling (FDM) and Laser Sintering (LS) build strong, durable parts with engineering-grade thermoplastics. Direct Metal Laser Sintering (DMLS) is also available for metal prototypes. Produced much faster than with traditional manufacturing methods, these prototypes provide realistic simulations of the mechanical functions of your design in the same materials as the end product.

3. File Formats & Design Guidelines

3D printing methods use .STL files for set up and builds. While native CAD can be converted to .STL format, issues can arise on occasion when conversions happen outside of the native software. To help ensure a great build, send your CAD in .STL format.

Multiple shells and unshared edges on an .STL file can cause uneven surfaces that overlap or disconnect from one another. The best .STL files typically only contain one shell and no unshared edges. Files that have multiple shells will most likely not build as desired. It’s also key to indicate what unit of measurement your file was originally designed with, inches or millimeters? Noting original units of measurement can reduce potential errors.

3D printing processes are free-form production systems, allowing for incredibly intricate parts. They are accurate within thousandths of an inch but have lesser tolerance control than some traditional manufacturing methods. Each process has a minimum feature size, varying from .010″-.030″. Designers should account for slight dimensional variance for designs like interference fits and line-to-line designs, or plan to utilize CNC machining after builds for critical tolerances.

For more detailed design considerations related to each technology, download our technology Design Guidelines.

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