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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Awards Season at Proto Labs

Proto Labs and its employees have been lucky enough to receive recent awards from one national organization and two Minnesota-based publications.

Manufacturing Leadership Award
We took home Frost & Sullivan’s Manufacturing Leadership Award in the Customer Value category. The nomination was based on the customer value created through Proto Labs’ interactive quoting system with DFM analysis. Other winners in the same category include Cisco Systems, Diebold, Lexmark and Dow Chemical.

Community Impact Award
Minnesota Business Magazine presented us with a 2016 Community Impact Award in the Youth Initiative category for the efforts of the Proto Labs Foundation and its contributions to STEM programming. Since 2014, the Foundation has provided nearly $350,000 in large grants to nonprofit organizations, like Code Savvy, for their programs and initiatives that support STEM education.

Titans of Technology
Proto Labs’ EVP and CTO Don Krantz was selected by Minneapolis/St. Paul Business Journal as an honoree at its 2016 Titans of Technology awards, which celebrates outstanding technology professionals. Krantz was recognized in the CIO/CTO category, which honors a top IT executive of a public, private or nonprofit company.

WATCH: ProtoQuote with Design Analysis

Our automated, interactive ProtoQuotes with real-time pricing information and free design for manufacturability (DFM) analysis are one of the most valuable tools you can get at Proto Labs. You can upload a 3D CAD model online at any time to receive a quote within hours.

The DFM analysis helps eliminate potential problems like sink, challenging undercuts or walls that are too thin or thick. Once a part design is ready and a quote approved, production begins almost immediately.

See how easy it is to navigate ProtoQuote with our quick video.

 

Upload a part today for a ProtoQuote with design analysis.

TIPS WITH TONY: Mold Flow Analysis

Last week we discussed wall thickness by resin types, where we learned the importance of uniform wall thickness and provided a guideline on thickness based on your material selection. Another very useful resource in selecting materials is a mold flow simulator, which tests different resins and how they fill using accurate molding pressure.

Melt Flow Index
All materials have a different melt flow index (MFI), but what does this exactly mean? MFI is a measurement taken on how well a material flows at a high temperature through a specified diameter during a 10 minute test. This measurement for MFI is calculated into grams per 10 mins. Typically, higher numbers mean you have a much better flowing material that can fill thin wall geometry easier. But that doesn’t tell the entire story as a higher MFI doesn’t always mean that you won’t encounter any issues on thin part geometries. All materials have varying melting temperatures, so compare MFI between different families of materials such as polyethylenes and polypropylenes, which have about a 40° difference in testing temperatures.

Knowing the Material
Work with Proto Labs’ customer service engineers (CSEs) as soon as you begin quoting your parts and tell them what material you are considering having the parts produced in. Having this information early allows them to properly analyze part geometry for appropriate wall thickness using the MFI of the selected material. Often times, a part that is too large or has features that are too thin for a selected material will require an increase in wall thickness or an alternative material to be chosen.

Simulation
How does a mold manufacturer know the selected material will work? This is where the software takes over. Proto Labs uses a proprietary ProtoFlow® fill analysis program that is truly unique to our molding technique. We have several available materials that can be tested using a resin’s MFI and your CAD geometry.

The ProtoFlow simulation shows the resin fill of a part through a single gate location at the end of the part and the color represents the part filling through to completion.

After your CAD model has been uploaded, gate location and quantity of gates are selected based on your part’s geometry and material. A simulation is then run by our mold designers to review:

  • gate location
  • knit lines
  • incomplete fill
  • balanced fill
  • and most importantly, fill pressure

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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.

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