Rapid Overmolding: Consider These 3 Elements

Injection molding is a common, cost-effective method for manufacturing parts, but, sometimes, those parts need a little help. Low impact or vibration resistance, slippery surfaces, poor ergonomics, and cosmetic concerns are only a few of the reasons why a second molded part is often added as a grip, handle, cover, or sleeve.

Proto Labs now offers rapid overmolding for parts, including the three samples pictured here.

The process of rapid overmolding will get the job done. This method, which Proto Labs now offers, and is the focus of our October design tip, uses a mechanical or chemical bond (or both) to permanently marry two parts together.

This month’s tip discusses:

  • Bonding: A strong bond between the two materials is critical to overmolding.
  • Materials: This is a key consideration in overmolding.
  • Principles: Overmolding uses the same playbook as injection molding, but with a few quirks.


THE ENGINEERIST: Mitigating Production Risk with Prototypes

Editor’s Note: The Engineerist is a three-part blog series written by Michael Corr, founder of Los Angeles-based manufacturing consulting firm, DuroLabs. This is part one.

Startup companies have limited time and money, and, rightfully so, treat them as precious resources. There is constant pressure to get products out to the market fast, and when cash is limited, there is little margin for mistakes.

As an engineering manager, my responsibility is to ensure that the development processes being used by my team to bring parts to production are reliable, repeatable, and properly mitigate risk. For high-volume production, injection molding is the best option for plastic parts but it can be expensive and time consuming—two factors that can severely impact the success of a product launch if there are mistakes.

Waiting 12 to 16 weeks for first articles off a steel mold can be an eternity for a company pressured to get products into production in a shortened nine-month time frame. Any delays only compound the issue, adding pressure on myself, my team, and the company as a whole.

CAD model

Analysts at Proto Labs prepare CAD models for manufacturing.

Automated Quoting
When I was first introduced to Proto Labs almost 10 years ago, I was impressed with its commitment to leveraging modern technology. Its quoting process was simple and quick due to automated online tools. This allowed me to independently configure part options without having to go back and forth with a sales rep to update quotes and lead times. The automation saves hours, if not days, in evaluating various options. Additionally, the design for manufacturability feedback tools, which automatically highlight problems and areas of concern in the parts, save days to weeks of time and potentially hundreds to thousands of dollars by alleviating the risk of re-spinning due to an erroneous part. Again, with time being a limited commodity and a close watch on development dollars, these attentions to detail were very important to me.

The Case for Milled Prototypes
Prototyping before production is necessary to mitigate this risk but it can potentially cost money and take time to produce parts, so it’s important to choose your prototype runs wisely. One risk-mitigating technique I’ve incorporated into my mechanical engineering team’s process is to always produce a CNC-milled prototype of any part that is identified to be injection molded for production. This seems like trite advice, but I was amazed at how often engineering teams overlook the value of this step. Even 3D printing, another valuable prototyping tool, is often not as effective as a milled part if a move to molding is imminent. The advantage of the milled part is a closer approximation to the final molded material properties—not only in strength but also look, feel, and toughness when handled.

CNC machining

Proto Labs has hundreds of CNC machines, which enable quick-turn milling of functional prototypes and production parts.

I have now built several dozen parts with Proto Labs, so I can attest to the quality and expediency of the parts. In just a few days and not much investment, one can have several milled parts in-hand and ready for evaluation. Proto Labs’ extensive library of material options has also allowed me to select the same exact plastic to be used in the eventual injection-molded parts. This flexibility paired with comparable tolerances and resolution to final injection-molded parts, allows me to reliably use milled prototypes for a full form and fit check. In many cases, I can even use the parts for structural and environmental performance tests, so we can evaluate and make any final tweaks before cutting steel without having to cross our fingers that nothing goes wrong.

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3D Printing Experts Discuss Technology’s Future

3D printing is the topic of conversation in our latest Journal issue, which focuses on the technology’s next dimension—how additive manufacturing is poised to make a giant leap forward in capabilities.3D printing

The cover story includes interviews with three leaders from the 3D printing industry who offer insight on a variety of topics, such as advancements in new machines and materials, a growing demand for 3D printing for production parts, and notable trends in software.

Another feature, “A Cloud-Based Future for CAD,” explores how 3D CAD design software is increasingly moving to cloud-based models, a trend with benefits for both product developers and manufacturers.

Elsewhere in the Journal, our Eye on Innovation column features a driverless bus, a 3D GoPro, and a DIY Bluetooth.

Read the entire Journal here.

We’re always on the hunt for though-provoking content, so send your cool project or article idea to our editor at angelo.gentile@protolabs.com.

Thanks and enjoy the issue!

DFM Analysis, Injection Molding Help Spring Company Reduce Costs

An Illinois-based steel-spring manufacturer recently called on Proto Labs to help reduce component count and save time and money on a device the company uses to market its services to the aerospace, automotive, oil and gas, and medical industries.

Smalley has long equipped its sales force with a small demo device, a handheld “comparator” that shows the relative size and performance of a wave spring—which Smalley manufactures—compared with a coil spring.

The company turned to Proto Labs for help with solving a cost issue when Smalley considered redesigning the comparator to “use them as ‘giveaways’ to prospective customers,” explained Lane Persky, Smalley marketing manager. “We were looking to go from about 20 of the original comparators, which each cost about $100 to produce, to an initial run of 1,000 redesigned comparators at a target cost of about $15 each.”

Proto Labs’ design for manufacturability (DFM) analysis, and its injection molding service, helped Smalley designers create a new comparator, which would require just seven parts. The original comparators each consisted of 23 parts.

“We chose Proto Labs for the company’s reputation and ability to do both advanced 3D printing for prototyping and affordable, rapid injection molding” for low-volume production, said Persky.


Webinar Round-Up: Thermoplastics, 3D Printing, and More

In last week’s webinar we were joined by PolyOne for a comprehensive discussion on selecting the right thermoplastic material for injection-molded parts. If you missed the live webinar, it’s now available on-demand. The presentation by Jeremy Bland shares the characteristics of common thermoplastics and what steps to take when determining the right material for your application. 

Upcoming Webinars
We have more webinars in the works! On October 27, we’ll hold the third and final installment in our series of ‘Designing for 3D Printing’ webinars. We’ll share tips on how to design parts for selective laser sintering. Click here to learn more and sign up.

Proto Labs’ On-Demand Webinars 
Interested in learning more about rapid manufacturing? Below you’ll find a complete archive of our past webinars (click the title to view).

Designing for 3D Printing: Direct Metal Laser Sintering

  •  DMLS design considerations including surface finishes, internal features, stresses, and support requirements.
  • Reducing multi-part assemblies into a single component

How Rapid Prototyping Accelerates Medical Device Development

  • Strategies to accelerate medical device development cycle
  • Prototyping effectively  and reduce design risk with rapid manufacturing

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