The material properties of polymers like plastics and elastomers can be affected by their environments and weaken over time. These changes can lead to premature product failure. It is, therefore, important to perform material characterization and age testing prior to making a new product.
EWI Senior Technology Leader Jeff Ellis has written Predicting Polymer Service Life through Degradation Modeling Using Design of Experiments, which describes an informed, streamlined, way to conduct characterization and age testing that will save both time and money.
You are invited to view this paper – for free – by submitting the form on this page.
To learn more about this evaluation method or discuss a project, contact Jeff Ellis at [email protected].
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Want to contact an EWI expert about a project? Call 614.688.5152 or click here.
No More Mess: Bonding Plastic to Metal without Adhesives
By James Cruz, EWI
An example of a pvc-aluminum laser weld — just TRY to break this!
My first job out of college at Honda of America Manufacturing was a dream come true – the chance to play with robots and build cars! They handed me several crisp, white uniforms on day 1. Within that first week on the production line, however, I had soiled my pretty white pants with a huge, black, gooey streak of gunk. I had formally been introduced to one of the adhesive sealants used in automobile assembly.
Over my decade at Honda, I grew to understand what a pain adhesives can be in production, seeming so often to end up everywhere except where they’re wanted! They’re expensive and have limited shelf lives. Year-in-year-out, they were one of the top reasons for downtime in my department because they coated proximity switches or clamps and caused equipment issues.
Now, I fully appreciate the value of adhesives and understand that they – especially when combined with welding – can significantly improve joint performance. But what if you had a way to direct-bond a polymer to a metal without all the side effects of adhesives?
How to join dissimilar materials is one of the most common questions we get at EWI. In the aerospace industry, that might be Ti-6242 to Ti-5111. Among medical device makers, maybe Nitinol to stainless steel. But in both of those industries as well as others, clients ask us about polymer-to-metal bonding. Because at EWI, we have demonstrated the process of direct joining of polymers to metals with incredible results.
Recently, EWI’s Senior Technology Leader for Polymers Jeff Ellis wrote a paper about using a polymer lid on an EV battery box. While a gasket / adhesive + mechanical fastener approach would work, wouldn’t it be great if we could direct bond the lid? So, Jeff came up with two novel processes, both of which require little cycle time:
The first process is to laser etch the surface of the metal. EWI has optimized the process to melt microscale valleys. The melt from the valley is pushed up the edge of the valley, creating a protrusion with ends that overhang the valley. This enables a surface that is clean and has a mechanically functional topography. We use a Laser Marking Technologies 100W 1064 nm pulsed fiber laser for the etching.
The second process is to melt the polymer into the functionalized metal surface. This requires both force and heat, which cause flow into the microfeatures. We have used two different methods for heating with similar results. The first is through transmission laser heater. A 1µm continuous laser is shined through the polymer to the metal surface to heat it. The second method uses an induction coil to heat the metal and thus also the polymer at the interface. Both methods employ compression to encourage the viscous melt to fill the metallic microfeatures.
Resulting parts have shown shear strengths of more than 1000 psi. Also, initial testing has produced leak-free parts when tested using an air decay method. Finally, when cycled from 0 to 65°C, they and have shown no difference in mechanical strength despite the difference in coefficient of thermal expansion between the materials.
James Cruz
While there is still much to investigate with this application, but it has great possibilities for manufacturers. We look forward with working with you to explore applications of this exciting new technique. Want to learn more? Contact me directly at [email protected].
The H-coupon test, developed a few years ago to evaluate cracking behavior in spot-welded advanced high-strength steels (AHSS), has recently been applied to galvanized third generation AHSS. Two types of cracking have been observed in the tests of these steel grades – interfacial and zinc liquid metal embrittlement (LME).
This research is discussed in Application of H-coupon Testing for Assessing Cracking During Spot Welding of Third Generation Steels, written by Applications Engineer Rafael Giorjão and Senior Technology Leader Jerry Gould. You are invited to download this paper – for free – by submitting the form on this page.
If you are interested in EWI’s latest R&D for applied manufacturing, you can hear about it directly from our engineers throughout the month of March. EWI specialists will share new findings and applications at the following public forums and conferences over the next several weeks:
LaMorte
Women in Welding Virtual Conference, March 16, 2023 – Connie LaMorte, Principal Engineer for Design, Controls, and Automation will give a featured presentation on Automation in Manufacturing. She will also participate in a speakers’ panel at the conclusion of the event.
James
Mohr
AAMP Annual Conference, March 19-23, 2023 – Bill Mohr, Principal Engineer for Structural Engineering, will speak on Diffusion of Hydrogen into Pipeline Steel Around an External Weld on Monday, March 20. Joshua James, Research Leader and Principal Engineer, will discuss EWI work in three conference sessions: Cold Spray Application for In-field Corrosion and Damage Repair, The Complex Synergy of Delayed Environmentally Assisted Cracking Transmission Gear Assemblies, and Tele-Inspection Nondestructive Evaluation For Corrosion Applications.
The primary process today for robotic arc directed energy deposition (DED), used for large-scale additive manufacturing builds, is gas metal arc welding. However, two other processes, plasma-arc (PA) and gas tungsten arc (GTA) welding, have been recently studied at EWI and shown to offer greater control over power and material inputs during a build.
EWI Project Engineer J. Logan McNeil has written Plasma-arc and Gas Tungsten Arc Directed Energy Deposition Capabilities at EWI to highlight these investigations. You are invited to download this paper – for free – by completing the form on this page.
If you would like to discuss this work or want to learn more about EWI’s arc-DED capabilities, contact Logan at [email protected].
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Want to contact an EWI expert about a project? Call 614.688.5152 or click here.
EWI uses integrated computational materials engineering (ICME) methods to analyze correlations between processing conditions, thermal response, microstructures, and mechanical properties to predict performance in joining and additive manufacturing. The resulting information is used to create unique tools for modeling and simulation with the potential to deliver huge time and cost savings to manufacturers.
EWI Senior Technology Leader Jerry Gould has written Overview of Integrated Computational Materials Engineering (ICME) Tools Used at EWI. You are invited to download this paper – for FREE – by submitting the form on this page. To discuss this paper with the author or learn more about EWI’s ICME work, contact [email protected].
Complete this form to download the paper:
To view the paper, please submit the form above.
Want to contact an EWI expert about a project? Call 614.688.5152 or click here.
