THE ENGINEERIST: Designing with Moldability in Mind

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 three. The first two installments can be found here.

Intelligence does not automatically equate to experience, and in hardware, product development experience goes a long way.

I was recently hired to take over management of an engineering team at an early-stage company. A team of mechanical, electrical, and firmware engineers was already in place, and while I noticed they were younger than most teams I’ve managed before, I was incredibly impressed with their intelligence and creativity. That energy of young and enthusiastic engineers was a convincing factor for me to accept the position.

An Introduction to Manufacturability
Since the team had already released products to customers, I took a passive approach and just observed the established processes while they worked on the next version of the product. I injected comments and feedback on occasion, but trusted them to repeat their existing methods as they prepared for production. However, the more I got involved in reviewing the designs, I realized there was a common theme across the younger engineers—moldability was not factored into their designs. Many of the mechanical prototype parts coming off the Stratasys desktop 3D printer were designed to satisfy the performance requirements, but would at best, be expensive to manufacture, and at worst, impossible.

Adding draft angles to design helps facilitate ejection of a part from a mold, and improves overall moldability. The exact degrees of draft angles are dependent on part geometries.

I took several of the MEs aside and asked a few direct questions challenging them on how they envisioned an injection mold being designed for their parts. Blank stares were the only answers I received. I pointed out that one design had an undercut and another had no draft angles for clean part ejection. Again, blank stares. That’s when I realized that these engineers had become trained on producing parts using 3D printing tools only. While 3D printing has a made tremendous impact in prototyping and even production-grade parts, it also has its caveats. Continue reading

THE ENGINEERIST: Fail Fast, Succeed Faster

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 two.

Certification testing is expensive, especially when your product fails.

I was managing an engineering team several years ago when we submitted a new product with an injection-molded enclosure to UL for certification testing. The tests included a mechanical stress test with some rather extreme impact forces. This product was a deviation to a predecessor and therefore had legacy requirements which constrained our design options. With the time pressure we had to get the product to market, the mechanical engineering team and I were hoping a few modest changes to the existing legacy injection mold would be sufficient to pass the new certification testing and go into production. They weren’t.

Logo Image: PR Newswire

Prototype Prep Before UL Testing
After a humbling blow to our egos and sizeable invoices from both the molder and UL, we took another approach. The ME team reviewed the points of failure of the plastic enclosure and came up with a few design improvements. But we didn’t want to risk failure again, and UL required testing parts fabricated from the actual production mold. It would be too expensive and risky if we were to modify the tool and fail again. Continue reading

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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