Archives For George Ritter

Adhesive Joining of Thermoplastics

George Ritter —  September 11, 2012 — 2 Comments

Got a tough combination of molded components?  Normally we weld, but sometimes the two materials are welding incompatible or the welding conditions are too extreme in temperature or time for the size of the part or complexity of the design. In that case, the option is to bond the materials.

Bonding thermoplastics is a little tricky because the surface energy is low compared with a thermoset material.  It may be necessary to use a surface preparation technique to raise the wetting level. Dispensing can also be challenging, especially on small parts, but syringe units are quite sophisticated and give reproducible results. Once the components are joined, the curing can be fast if we used a cyanoacrylate or UV/VIS curable.

If you have a weird combination of materials to join, don’t be shy about asking us for suggestions. We work with all brands of adhesives and curing methods, and our goal is to get you running and successful.  If you need testing or analysis, that’s no problem – we do that too. Bring it on, bring it over.  

My name is Dr. George Ritter. I’m a materials engineer at EWI and I’ve been doing this for thirty years.  Post your materials joining question below or contact me at gritter@ewi.org or 614.688.5199.

In Aerospace, Automotive, Consumer Goods, Government, Heavy Industry, Materials Engineering, Soldering Brazing , , , , , ,
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Lightweighting for Heavy Manufacturing

George Ritter —  July 12, 2012 — Leave a comment

George Ritter
Lightweighting is a process of replacing a material with another to reduce weight while maintaining performance. Automotive reduces weight to improve fuel efficiency primarily since the payload itself is fairly constant. Aerospace uses lightweigting to increase payload and range. In that respect, the advantage of lightweighting for heavy manufacturing is closer to that for the aerospace industry: increase useful payload and range.

The efficiency increase and savings are real. Faster, more efficient work is good for the contractor and also for the customer. For every hundred pounds in weight reduction, another hundred pounds can be pulled or pushed every time there is a pull or a push.
Materials substitutions are often based on weight saved for equivalent stiffness. Replacing steel with a composite gives equivalent stiffness with 25-30% weight savings. The same holds true for replacing aluminum with composite. Replacing steel with higher strength steel gives more modest weight savings but has the advantage of not introducing a different material family.

Examples of areas where lightweighting can impact overall efficiency are:

  • Earth moving equipment – crew compartment, fenders and skirts, radiator shell, equipment housings, battery boxes.
  • Cranes – tower, booms, crew compartment. This results in easier and faster assembly on site. The tower sees mostly compressive load while the boom sees bending moment. Every lift can carry a higher payload, resulting in less time on site and faster completion.
  • Marine – replacement of superstructure with composite reduces topside load and center of gravity. It offers better corrosion resistance and less maintenance.
  • Heavy duty truck – the advantages of composites in HD trucking are legendary. Most of the industry has converted to composite cabs. Newer bonding techniques enable joining to aluminum or steel sub-components.
  • Trailer – aluminum and composites can replace steels and are making inroads.

What technologies apply?
Working with materials substitutions invariably requires working with materials joining technologies. Starting with modeling, engineered joint designs and predicted performance are needed for combinations of metals, composites, and thermoplastics. In bonded structure, it is possible to implement aluminum-composite, steel-composite, and even titanium-composite combinations as well as composite-composite bonding. Advanced reinforced thermoplastic welding is also an option.

On the metals side, newer approaches include friction stir welding (FSW) of steels, thick-section aluminum, and titanium. Upgraded welding techniques are needed for the newer high strength steels to provide minimum HAZ strength effects. Distortion control is important for welding of thick-section steels. Coupled with nondestructive evaluation (NDE), testing, and fatigue life testing capabilities, it is possible to provide a complete engineering package to enable the transition in to 21st century structure.

I’m George Ritter, Principal Engineer in EWI’s Materials and Structural Integrity group. Contact me at gritter@ewi.org or 614.688.5199 if you have any questions. Or post a comment below.

In Aerospace, Automotive, Friction Process, Heavy Industry, Materials Engineering, Modeling Simulation, NDE
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Adhesion Problems? Stuck or Unstuck?

George Ritter —  June 20, 2012 — Leave a comment

Most of the work I do involves putting things together down in the lab. If you are having problems putting things together and keeping them that way, give me a call or email. If we can’t getting you going again with a phone call, we can do a bit of forensic work here to analyze the issues. I can also come out to your place and take a look.

Phone: 614.688.5199

Email: gritter@ewi.org

 

In Aerospace, Automotive, Consumer Goods, Defense, Energy, Government, Materials Engineering, Oil & Gas, Rail
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Sticking Stuff to Stuff

George Ritter —  October 11, 2011 — Leave a comment

Adhesion is surface related. Any process depending on surfaces to stick to each other is an adhesion process: soldering, brazing, adhesive bonding, and coatings. Some things join or seal two surfaces. Others protect the surface or improve its performance for wear, thermal resistance, corrosion, or oxidation.

It is possible to join dissimilar materials using adhesion processes. It is desirable to use those methods when damage to the base material might occur from overheating or ther nastiness. It is also possible to change surface characteristics and performance by applying an adherent layer of a dissimlar material, like putting rubber onto a surface to protect it from abrasion, or putting ceramic on a surface also to protect it from abrasion. Get it?

Call me if you want to discuss an adhesion issue or troubleshoot something that is supposed to stick to something else.

In Automotive, Consumer Goods, Defense, Energy, Heavy Industry, Materials Engineering, Soldering Brazing
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Adhesion – Getting Stuff to Stick to Stuff

George Ritter —  September 10, 2010 — Leave a comment

In the previous posting, I talked about the importance of having a corrosion resistant surface for reliable bonding in any application involving adhesion — adhesive bonding, coatings, paints, or plastic components. In fact all adherent layers depend largely on the condition and stability of the interfacial surface. Much of my time is spent investigating surfaces and how to prepare them for reliable bonding. After that, the adhesive selection or application part comes into play.  The most important thing is for the surface to be clean. Beyond that, more attention may be needed.

Several papers we’ve published and presented over the years have focused on surfaces and adherence to them. We’ve worked with aluminum, titanium, carbon steels, stainless steels, composites, ceramics, plastics, rubber, and difficult bonding surfaces such as polyolefins and fluoropolymers.

Applying this understanding of fundamental adhesion and surface interactions, we have helped people with many adhesion issues, not just adhesive bonding. We field inquiries regarding coatings, however applied, and plastic-metal interfaces such as those found with molded-over plastics onto metal inserts. We’ve dealt with seal leaks for feed-through pins and have worked on polymer-metal seals for hermeticity in photovoltaics. Hermetic Seals for Organic Semiconductors

If you’re having problems with getting stuff to stick to stuff, let us know. We can discuss it over the phone or arrange to come to your facility, it that’s what’s needed. Don’t come unglued — just give us a call.

In Materials Engineering
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Advanced Bio-Mimic Corrosion Coating

George Ritter —  May 12, 2010 — Leave a comment

The Material Engineering and Technology group’s George Ritter has been working to develop anti-corrosion coatings based on the natural adhesives produced by mussels and barnacles.

Marine organisms have been fouling ships and underwater structures for millennia. Most produce rapidly cross linking, tenacious tendrils which tethers them to surfaces. These adhesives are highly adherent and obviously resistant to marine environments. However, the basic cross linking chemistry is also adaptable to corrosion protection of ferrous metals. A natural reaction takes place which converts the underlying surface to ferritic oxide. Unlike the common red rust, this phase is highly resistant to water penetration and further rusting.

Ritter has been applying this basic chemistry to developing high performance anti-corrosion coatings by introducing that chemistry into a resinous carrier. Initial results have shown good anti-corrosion properties that also exhibit some self-healing properties if the coating is damaged. Because the key materials are naturally occurring, these systems are non-toxic and readily adapted to protection of marine structures.
For more information, contact Dr. George Ritter at 614.688.5199

In Materials Engineering
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