TIPS WITH TONY: Ribs and Radii

Designing ribs and radii into your injection-molded part is not only important to increase strength and stability — it improves material flow, eliminates thick areas that create issues like sink, and ultimately, enhances the cosmetic appearance of your part.

Ribs
A thick part will have several issues with sink or voids creating cosmetic, functional or molding concerns. The addition of ribs reduces the amount of volume in part thickness while still providing the part with the same overall height. Some believe that eliminating the volume/part thickness can decrease the strength of a part. This is not true — adding ribs can actually improve stability, strength and cosmetics depending on the material selection and part geometry.

Watch rib-to-wall thickness ratios. To prevent sink, the thickness of the rib should be about half of the thickness of the wall.

A major design consideration that is often overlooked is rib-to-wall thickness ratios. If you have a rib feature that is too thick on a wall, you’ll create thick areas that can result in unsightly sink or shadowing on the opposing surface. Avoid this by following a guide of 40 to 60 percent wall thickness for any rib.

 

 

Coring Out
Coring out is a technique where you remove material from a plastic part, leaving distinct walls and ribs that provide enough strength and mating surfaces for other parts in the assembly. It is necessary to make the part moldable and also saves cost and weight. Leave ribs in the right location and size to maintain strength, particularly in bending, and retain surfaces and features that interface with other parts in the assembly.

Ramps and Gussets
Continuing the discussion on strength and resin flow improvement, ramps and gussets are important features that you can build into your design. Sharp corners create high stress points whereas gussets and ramps are stress relievers, working to improve overall part quality.

Radii
Adding radii — edges or vertexes that have been rounded — to your part will improve how resin fills the mold as plastic can flow poorly around sharp corners. When you have sharp corners, resin can create stresses that cause the part to warp or bend, and may provide a location that can break since this is a weaker transition point. Resolve this by adding a generous angle to both the outside and inside corners.

Ideally, you should model radii so the inside and outside radii use the same center resulting in larger radii on the outside curves. This will help you retain a consistent wall thickness throughout your part.

Continue reading

EYE ON INNOVATION: Jewelbots Bring Bracelets Up To Code

Compared to a sleek Apple Watch or a sporty Fitbit, the Jewelbot charm bracelet looks rather primitive, says Wired Magazine. Basically, the bracelet, which is intended for tween and teen girls, is a semi-clear, plastic flower charm that slides onto a hair tie-like elastic bracelet.

But look beyond form to function on this one, says Wired, which calls the bracelet an example of “some truly fresh thinking about wearable technology.”

As Jewelbots’ creators contend, these technology-enhanced, programmable wristlets are “friendship bracelets for the iPhone era” that teach girls to code in a fun, engaging way. The charms talk to each other over Bluetooth, and using a Jewelbots smart-phone app, youngsters can program their charms to vibrate or light up when their friends are nearby.

The open-source software exposes users to the possibilities of coding in a fresh way. Using basic engineering logic, girls can program their Jewelbots “to do just about anything they — and their besties-turned-collaborators — dream up, opening their minds to STEM during an age when many lose interest,” according to the Jewelbots’ website.

Continue reading

TIPS WITH TONY: Design for Manufacturability (DFM) Analysis

Design for manufacturing (DFM) analysis provides information to not only improve the design of your injection-molded part at Proto Labs, but suggests improvements that can be applied regardless of your manufacturer.

Once you upload your 3D CAD model, you’ll receive an email inside of 24 hours — typically, within only a few hours — that contains a link to your quote. Quotes are generally defined as an estimated cost for a particular service, but arguably, the most valuable information that you receive in your Proto Labs quote is our automated DFM feedback.

The manufacturability feedback addresses considerations like:

  • Draft
  • Wall thickness
  • Undercut regions
  • Thin and thick sections
  • Material flow
  • Design complexity
  • Areas that cannot be manufactured
  • Gating and ejection

Proto Labs specifically uses this information to explain wall thickness and draft based on our manufacturing capabilities to machine an aluminum mold through three-axis CNC milling. These are unique to our manufacturing process, but are great guidelines to improving your part design in general.

Customers often times will begin designing a part with no draft or wall thickness concern and bring this design to our quoting software for a quick review at the end of the day. In many cases, by the time you arrive back at work, you may have your DFM analysis waiting. You can then apply those changes, or speak with one of our experienced customer service engineers who can help explain how to simplify your design or discuss why we have capability issues with how your part is intended.

Continue reading

EYE ON INNOVATION: Turning the Tables on Turntables

The resurgence of vinyl records has been well documented.

The biggest music industry comeback story is the soaring popularity of vinyl records, the Wall Street Journal recently reported. Nearly 8 million records were sold in 2014 in the United States, up 49 percent from the previous year. Indie-rock fans especially are buying records in greater numbers, attracted to the perceived superior sound quality of vinyl, the ritual of putting needle to groove and the physical connection to album art that is sometimes lost in the digital age.

One Chicago-based startup has turned the tables on record players by creating the Floating Record, a vertical turntable that sits on a simple, minimal block of wood that contains speakers and electrical components.

Gramovox, a consumer electronics company that, as its website says, “re-imagines vintage audio design with modern technology,” just closed the books on a $1.6 million Kickstarter campaign for this vertical record player. The Chicago Tribune reports that Gramovox is working with AssemTech as its assembly partner, and expects to deliver the turntables to market by December. Last year, Gramovox brought the Bluetooth Gramophone to market, a Bluetooth-enabled speaker that looks like an antique gramophone.

Continue reading

How Digital Manufacturing is Changing the Industry Forever

Our current issue of the Proto Labs Journal looks at the convergence of complex software and automated hardware bringing rise to the digital age of manufacturing. Follow the thread of a 3D CAD model from upload to digital analysis to final part, and the massive compute cluster that’s powering it all.

Along with our cover story, read about leveraging low-volume injection molding, the latest in innovative technology we’ve mined from the Internet  and new service offerings at Proto Labs.

Read the full Journal now.