3D Printing Polymer Parts with Electrostatic Dissipative (ESD) Properties

Getting zapped by static electricity at the personal level is merely annoying; having your sensitive electronic equipment buzzed is another, highly destructive story.

Much as you’d like to send these components out into the world wearing their own little anti-static wristbands, that’s just not practical (and actually, not good enough*). During build and use, advanced electronics applications need true charge-dissipative protection that is inherent to their design and easy to achieve. However, the typical steps of painting or coating, covering with conductive tape, or wrapping with carbon-filled/aluminum-coated films incur both time and cost.

Electrostatic dissipative (ESD) polymer materials instead provide this kind of protection on a built-in basis, offering a moderately conductive “exit path” that naturally dissipates the charge build-up that can occur during normal operations. It also prevents powders, dust or fine particles from sticking to the surface. Whether the task is protecting circuit boards during transport and testing, or ensuring that the final product works as designed throughout its lifetime, ESD materials present low electrical resistance while offering the required mechanical, and often thermal and/or chemically-resistant properties.

ESD-safe fixture for testing a printed-circuit board, produced by 3D printing with Stratasys ABS-ESD7 material. (Image courtesy of Stratasys)

Combining ESD Behavior with 3D Printing

All the features that are appealing with 3D printing carry over when printing with ESD-enabled thermoplastics. You can print trays custom-configured to hold circuit-boards for in-process testing, print conformal fixtures that speed up sorting, and produce end-use structures for projects where static build-up is simply not allowed (think mission-critical aerospace applications).

Acrylonitrile butadiene styrene (ABS), that work-horse of the plastics industry, has been available as 3D printing filament for decades. Along the way, Stratasys and other vendors started offering this filament in a version filled with carbon particles that decrease the plastic’s inherent electrical resistance. Stratasys ABS-ESD7 runs on the Fortus 380, 400, 450 and 900 industrial systems, and soon will be available on the office-friendly F370 printer.

What kind of performance does ABS-ESD7 offer? When evaluating materials for ESD performance, the most important property is usually the surface resistance, measured in ohms. (This is not the same as surface resistivity, plus there’s also volume resistivity – see Note at end). Conductive materials – typically metals – have a surface resistance generally less than 103 ohms, insulators such as most plastics are rated at greater than 1012 ohms, and ESD materials fall in the mid-range, at 106 to 109 ohms.

Compared to standard ABS filament, ABS-ESD7 offers more than five orders of magnitude lower resistance, converting it from an insulator to a material that provides an effective static-discharge path to the outside world. Due to the inherent layered structure of FDM parts, the differences in properties between flat (XY) and vertical (ZX) build orientations produces a range of resistance values, with a target of 107 ohms, reflected in the product name of ABS-ESD7. Stratasys offers an excellent, easy-to-read FAQ paper about ABS-ESD7.

Printed-circuit board production tool, custom 3D-printed in Stratasys ABS-ESD7 material for built-in protection from electrostatic discharge during test and handling. (Image courtesy of Stratasys)

When ABS isn’t strong enough or won’t hold up to temperature extremes, engineers can turn to Stratasys’ ESD-enhanced polyetherketoneketone (PEKK), termed Antero 840CN03. Developed in 2016 and slated for full release in October 2019, this new filament expands the company’s Antero line of  high-temperature, chemically resistant formulations. The PEKK base material offers a high glass transition temperature (Tg 149C, compared to 108C for ABS-ESD7) while meeting stringent outgassing and cleanroom requirements. As with ABS-ESD7, the carbon-nanotube loading lowers electrical resistance values of Antero 840CN03 parts to the desirable “ESD safe” range of 106 to 109 ohm.

Setting up Parts for Printing with ESD-Enhanced Filament                                                            

Support structures in contact with part walls/surfaces can disturb the surface resistance behavior. To counter-act this condition for filament printing with any type of ESD material, users should perform a special calibration that makes the printer lay down slightly thinner-than-usual layers of support material. In Stratasys Insight software, this is currently accomplished by setting the Support Offset Thickness to -0.003; this decreases the support layers from 0.010 inches to 0.007 inches. In addition, supports should be removed (in Insight software) from holes that are smaller in diameter than 0.25 inches (6.35mm).

As more of these materials are developed, the software will be updated to automatically create supports with this process in mind.

ESD Applications for 3D Printing

Avionics boxes, fixtures for holding and transporting circuit boards, storage containers for fuel, and production-line conveyor systems are just a few examples of end-use applications of ESD-enabled materials. Coupled with the geometric freedom offered by 3D printing, three categories of manufacturing and operations are improved:

  • Protecting electronics from ESD damage (static shock)
  • Preventing fire/explosion (static spark)
  • Preserving equipment/product performance (static cling)

If you’re exploring how 3D printing with ESD-enhanced materials can help with your industrial challenge, contact our PADT Manufacturing group: get your questions answered, have some sample parts printed, and discover what filament is right for you.

PADT Inc. is a globally recognized provider of Numerical Simulation, Product Development and 3D Printing products and services. For more information on Insight, GrabCAD and Stratasys products, contact us at info@padtinc.com.

*Anti-static is a qualitative term and refers to something that prevents build-up of static, rather than dissipating what does occur


Surface Resistance, Surface Resistivity and Volume Resistivity

Surface resistance in ohms is a measurement to evaluate static-dissipative packaging materials.

Surface resistivity in ohms/square is used to evaluate insulative materials where high resistance characteristics are desirable. (Ref. https://www.evaluationengineering.com/home/article/13000514/the-difference-between-surface-resistance-and-surface-resistivity)

The standard for measuring surface resistance of ESD materials is EOS/ESD S11.11, released in 1993 by the ESD Association as an improvement over ASTM D-257 (the classic standard for evaluating insulators). Driving this need was the non-homogeneous structure of ESD materials (conductive material added to plastic), which had a different effect on testing parameters such as voltage or humidity,  than found with evaluating conductors.

Volume resistivity is yet a third possible measured electrical property, though again better suited for true conductors rather than ESD material. It depends on the area of the ohmeter’s electrodes and the thickness of the material sample. Units are ohm-cm or ohm-m.

             

Mission to the Moon: Stratasys Joins Forces with Lockheed Martin and PADT to Engineer Advanced 3D Printed Parts For NASA’s Orion Mission

Sometimes we get to help on some very cool projects and helping Lockheed Martin and NASA leverage Additive Manufacturing Technology from Stratasys on their Orion Mission is one of those special opportunities that we will never forget.  The right combination of material and 3D Printer allowed the team to create functional parts for the Orion vehicle as it prepares to journey to the moon and beyond.

Working with Stratasys, Lockheed Martin, and NASA has been rewarding and we are honored to have been part of this historic project.  I could go on and on, or you could read the details in the press release below.

A link to a PDF version is here.

PADT is unique in the world of 3D Printing because of our in-depth technical knowledge and experience. We don’t just print parts or sell machines, we provide world-class design, simulation, and testing services as well. That how we are able to contribute to projects like this.  If you are facing engineering challenges of any kind, and especially if you working to adopt 3D Printing technology to your engineering projects, just give us a call at 480.813.4884 or send an email to info@padtinc.com.

Press Release:

Mission to the Moon: Stratasys Joins Forces with Lockheed Martin and PADT to Engineer Advanced 3D Printed Parts For NASA’s Orion Mission

Stratasys 3D printers and materials provide extremely high levels of strength, durability and thermal properties to power missions to deep space

Variant of new Stratasys Antero™ 800NA, PEKK-based material offers electro-static dissipative (ESD) functionality for advanced mechanical, chemical, and thermal properties

Minneapolis, MN & Rehovot, Israel and TEMPE, AZ., April 17, 2018 – Stratasys Ltd. (NASDAQ: SSYS), a global leader in applied additive technology solutions, and Phoenix Analysis & Design Technologies, Inc. (PADT) jointly announced the companies are teaming with Lockheed Martin Space to deliver next-generation 3D printed parts for NASA’s Orion deep-space spacecraft. Key to the project are Stratasys advanced materials – including an ESD variant of the new Antero™ 800NA, a PEKK-based thermoplastic offering high performance mechanical, chemical, and thermal properties.

The Orion spacecraft leverages a variant of new Stratasys Antero 800NA to build an intricately-connected 3D printed docking hatch door

Orion is NASA’s spacecraft that will send astronauts to the Moon and beyond. Orion’s next test flight, dubbed Exploration Mission-1 (EM-1), will be the first integration mission with the world’s most powerful rocket, the Space Launch System, where an un-crewed Orion will fly thousands of miles beyond the Moon during an approximately three week mission.

The following flight, EM-2, will also go near the Moon, but with astronauts on-board, a first since 1972 and will enable NASA to prepare for increasingly complex missions in deep space. The mission will use more than 100 3D printed production parts on board – engineered in conjunction with Lockheed Martin, Stratasys and PADT.

The production-grade, thermoplastic 3D printed parts on NASA’s Orion vehicle are produced at the Additive Manufacturing Lab at Lockheed Martin in conjunction with PADT, which now includes the latest in Stratasys 3D printers and materials. Using advanced materials such as ULTEM 9085 and the new Antero material incorporating critical electro-static dissipative (ESD) functionality – NASA could meet key requirements for 3D printed parts to perform in the extremes of deep space. Antero is ideally suited to meet NASA’s requirements for heat and chemical resistance, along with the ability to withstand high mechanical loads.

“Working with PADT, Stratasys, and NASA has enabled us to achieve highly consistent builds that move beyond the realm of prototyping and into production,” said Brian Kaplun, Manager of Additive Manufacturing at Lockheed Martin Space. “We’re not just creating parts, we’re reshaping our production strategy to make spacecraft more affordable and faster to produce.”

Lockheed Martin is one of the first customers leveraging Stratasys’ Antero material – a PEKK-based thermoplastic with advanced mechanical, chemical and thermal properties.

The Lockheed Martin, Stratasys and PADT-engineered collaboration is differentiated by an ability to create consistency and repeatability in mass scale across the entire additive manufacturing part production process. Lockheed Martin is also one of the first customers leveraging Stratasys’ Antero, using the new thermoplastic for a critical part situated just outside of Orion’s docking hatch. The complex part consists of six individual 3D printed components locked together to form a ring on the craft’s exterior. The part is currently on display in the Lockheed Martin booth #603 at the 34th Space Symposium in Colorado Springs, CO April 16-19.

“The demands of space travel require extremely high performance materials and the most rigorous manufacturing processes in the industry. Part integrity and repeatability are essential and must pass NASA’s demanding testing and validation process,” said Scott Sevcik, Vice President of Manufacturing at Stratasys. “Based on decades of experience delivering strong and lightweight additive manufacturing solutions for leaders across the aerospace industry, Stratasys technology is ideally suited to match the high-reliability manufacturing processes required for production parts in space exploration.”

“It’s exciting to be a part of the Orion mission and Lockheed Martin’s efforts to transition additive manufacturing from prototyping to production,” said Rey Chu, Principal and Co-Owner at PADT. “Additive manufacturing technology and materials have come a long way to become a full-fledged end-use manufacturing option.”

PADT is currently joining Stratasys in their booth #537 at this week’s 34th Space Symposium. For further detail on how Stratasys is transforming aerospace and space exploration through 3D printing please visit: http://www.stratasys.com/aerospace.

Stratasys (NASDAQ: SSYS) is a global leader in applied additive technology solutions for industries including Aerospace, Automotive, Healthcare, Consumer Products and Education. For nearly 30 years, a deep and ongoing focus on customers’ business requirements has fueled purposeful innovations—1,200 granted and pending additive technology patents to date—that create new value across product lifecycle processes, from design prototypes to manufacturing tools and final production parts. The Stratasys 3D printing ecosystem of solutions and expertise—advanced materials; software with voxel level control; precise, repeatable and reliable FDM and PolyJet 3D printers; application-based expert services; on-demand parts and industry-defining partnerships—works to ensure seamless integration into each customer’s evolving workflow. Fulfilling the real-world potential of additive, Stratasys delivers breakthrough industry-specific applications that accelerate business processes, optimize value chains and drive business performance improvements for thousands of future-ready leaders. Corporate headquarters: Minneapolis, Minnesota and Rehovot, Israel. Online at: www.stratasys.com, http://blog.stratasys.com and LinkedIn.

Phoenix Analysis and Design Technologies (PADT) is an engineering product and services company that focuses on helping customers who develop physical products by providing Numerical Simulation, Product Development, and 3D printing solutions. PADT’s worldwide reputation for technical excellence and experienced staff is based on its proven record of building long-term win-win partnerships with vendors and customers. Since its establishment in 1994, companies have relied on PADT because “We Make Innovation Work”. With over 80 employees, PADT services customers from its headquarters in Tempe, Arizona, and from offices in Torrance, California, Littleton, Colorado, Albuquerque, New Mexico, Austin, Texas, and Murray, Utah. More information on PADT can be found at www.padtinc.com.

Lockheed Martin, headquartered in Bethesda, Maryland, is a global security and aerospace company that employs approximately 97,000 people worldwide and is principally engaged in the research, design, development, manufacture, integration, and sustainment of advanced technology systems, products and services.

 

 

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