Dexmet Corporation is a member or corporate sponsor of the following organizations:

• American Filtration & Separations Society – Where scientists, researchers, educators and manufacturers can educate and network with like-minded professionals in the filtration industry.
• American Wind Energy Association – A national trade association representing wind power project developers, equipment suppliers, services providers, parts manufacturers, utilities, researchers, and others involved in the wind industry. AWEA provides the latest information about the wind industry here in the United States.
• Society for the Advancement of Material and Process Engineering – An international professional member society that provides information on new materials and processing technology either via technical forums, journal publications, or books in which professionals in this field can exchange ideas and air their views. The only technical society encompassing all fields of endeavor in materials and processes, SAMPE provides a unique and valuable forum for scientists, engineers, and academicians.
• Connecticut Hydrogen-Fuel Cell Coalition – This CT organization works to enhance economic growth through the development, manufacture, and deployment of fuel cell and hydrogen technologies and associated fueling systems in Connecticut.

Dexmet will always be supportive of the industries we work with now and in the future. We want to ensure the growth and success of our clients by maintaining a continuous commitment to quality control and process improvement. Our ongoing innovations include introducing highly specialized and proprietary equipment to make sure that our products continue to exceed our clients expectations and our commitment to deliver quality expanded materials.

We are also proud to display our joint AS9100 and ISO 9001 certification on our website as an assurance to our customers that their success is our number one priority.

Click on this link to get to the article

There is also a downloadable PDF, clicking this link will get you there.

Image courtesy of Boeing

Click to open copy of our certification

In keeping with our mission to become the recognized worldwide leader for foil gauge expanded metal and thin film expanded polymers, Dexmet Corporation is proud to announce that we have received AS9100/ISO 9001:2008 Certification for the aviation, aerospace, and defense industries.  The company subscribes to the Standard’s requisite features, including risk management and configuration control, while maintaining a proactive commitment toward customer satisfaction.

As a quality producer of expanded foils for lightning strike protection on carbon fiber aircraft components, we have always worked closely with our customers to provide a product that exceeds their expectations.  Working as an ISO Certified facility for over ten (10) years, we recognize the value of having a Quality/Operations System that meets an established criterion for conforming to our Customer’s internal quality standards.  With the aircraft industry becoming a more prominent market segment for our company, the ability to conform to the industry quality requirements is essential for solidifying the business in years to come.  Working off a solid operational and quality foundation built around ISO, implementing the unique requirements of the AS Standard was an easy transition.  Our new Quality & Engineering Manager, Mark Murdoch, along with our former semi-retired Quality Manager and the entire management team, performed the task with minimal disruptions to the daily operation.  Working with a quality organization like Intertek, the certification registrar, can facilitate the transformation by providing great insight and value to the certification process.

Receiving this new AS9100 Certification will allow Dexmet to better conform to our Customer’s individual quality programs.  We are the only company with the breadth of experience with airframe manufacturers and pre-preg suppliers to provide technical expertise and have the capacity and capability to provide the new growing carbon fiber aircraft platforms.  We have repeatedly proven to our Customers that we can maintain the rigorous quality standards at high production volumes to keep the supply line flowing.  This is an achievement that we are dedicated to and proud of.  We look forward to working with our current and future Customers and will continue to provide the best available option for expanded foils and polymers in the industry.

The Dexmet Team

For instance Dexmet takes great pride in developing quality expanded material for their client base. There is a stringent quality control process in place to make sure that all expanded material meet or exceed customer specs and since Dexmet already has high standards our products always exceed customer specs.

However when you buy expanded material from lesser known manufacturers, the likelihood that you will get an inferior product increases greatly and many times that material will fail its intended application.

We are not trashing any of our competitors, many of them produce quality products and have in place a stringent quality control process like us that ensures that you will get a superior product.

So we are just looking at one company that caught our eye but there are many more like them that advertise on industry/manufacturing portals that exist on the Internet.

The name of the company we will look at is the Anping Yihang Gabion & Fence Engineering Co., Ltd., see the image below:

Anping Yihang Gabion & Fence Engineering Company

The Company states that they make precision expanded material. On closer inspection you will see the page is taken from our site and yes it is ours since it mentions us as the provider of precision expanded materials and not them.

While companies like this employ techniques of hijacking web pages, they were probably not thinking that they should have at least took off our name or changed the wording just a little?

The real danger does not lie with the hijacking of the webpage or wording, its knowing that some companies will purchase precision expanded material from Anping Yihang Gabion at a cheaper cost and receive an inferior product, the reality is you get what you pay for!

The good thing is that they are primarily selling heavier gauge expanded material and hopefully none of our customers will ever purchase precision expanded metal foils from them and have a major problem somewhere down the road with the material or the application that it is intended for.

The wording taken verbatim indicates that the company may be making claims that it cannot substantiate when it comes to producing precision expanded material. If fact they even take our animated image demonstrating the process, see the link here: Manufacturing Process.

So while imitation can be a sincere form of flattery, in the case of producing a cheaper or inferior product, it is not!

Dexmet produces quality expanded materials and has done so for over 60 years. So when you need expanded material for critical performing applications, you want the best and with Dexmet that is what you get!

To achieve the various tarnish levels was a simple matter of heating the samples of solid copper strip in an oven with normal atmosphere. This gave us a variety of colors from dark copper to a brilliant red and some “bluish” tints.

The adhesion test was done with a MAS epoxy  using their SLOW hardener.  This is an excellent epoxy with a very low level of VOC’s that makes it an attractive product in these days of work environment regulations. It also adheres well to a variety of substrates. The test was done with a crosshatch carbide tool with a pattern of etched lines intersecting at approximately 40 degrees. There was only the most minor of non-adhesion at a couple of intersections on the plain untarnished copper which is pretty good performance. All of the samples with tarnish showed no signs of failure at all. Conclusion: The tarnish did not adversely affect the adhesion of the epoxy to the substrate copper.

Illustration property of Dexmet

While this was somewhat a surprise, that material that was tarnished would show improved adhesion, it was not entirely unexpected. I suspect that the tarnish created a slightly rougher surface for the epoxy with the addition of the oxygen molecules.

A similar test was done using copper mesh and evaluating the surface resistance of clean and various levels of tarnished mesh. The samples were all tested in the clean state and then subsequently exposed to ever increasing temperature levels with normal atmosphere.  The results of this test were most unexpected. The general trend was that samples with increased tarnish demonstrated reduced surface resistance. The change was minimal and not statistically significant, but there was a pretty consistent trend. The conclusion: levels of tarnish appear to have little or no effect on surface resistance, and may result in some improvement. That last point, improvement, may be taken with a grain of skepticism. It was certainly not any worse.

NASA Corrosion Control and Treatment Manual TM-584C (Revision C) had indicated that a green patina would inhibit further corrosion, so the same would also apply to tarnish, one could deduce. Testing this theory proved inconclusive and will require a new approach. We were unable to produce a green corrosion on any of the samples evaluated regardless of level of tarnish.

Kirt Griffin, Quality Assurance Manager, Dexmet Corporation

Kirt can be reached at k.griffin@dexmet.com

AgieCharmilles Cut 30 P

Dexmet has brought the capability of Wire EDM (Electrical Discharge Machining) technology in-house to quicken the development process and provide better turnaround time to its customers.  The new capability will allow Dexmet to quickly generate custom expanding dies for application specific expanded products or provide custom cut geometries out of already expanded materials.

The engineers at Dexmet purchased an AgieCharmilles Cut 30 P from Ross Machinery, also located in Wallingford, CT., because of its advanced features of a simple to use graphics user interface to reduce programming time, large work area and travel capabilities and accuracy at high cut rates . The new Wire EDM technology allows the engineers at Dexmet to execute a range of jobs without any external applications handling everything from contour creation to part production.

The AgieCharmilles CUT 30 P Wire-Cutting EDM has a wide range of cutting capabilities from very hard carbide materials over 300mm thick or the ability to cut intricate shapes in thin delicate foils. Wire-Cut EDM utilizes a fine single-strand metal wire, typically brass, as the electrode and through a series of rapidly recurring electric arching discharges between the electrode and the work piece material is removed along the cutting path by melting and vaporization.  The process produces no cutting forces so there is very low residual stress put on the work piece with little to no change in mechanical properties or shape.

Dexmet new capabilities offer the following advantages to its clients:

• Rapid development of new tools to produce an application specific expanded product
• Custom cut shapes from expanded materials for prototyping
• Quick turnaround on parts – no intricate dies involved
• Ability to produce intricate detail that would be difficult to machine with traditional cutting tools
• Very accurate cutting tolerances and excellent surface finishes
• Delicate and weak materials as well as very hard materials can be machined without any distortion.

The images below are courtesy of Dexmet:

Samples from CUT 30 P

Samples from CUT 30 P

Samples from CUT 30 P

Produced by CUT 30 P

To learn more about the current developments at Dexmet contact Eric Toro via e-mail at: e.toro@dexmet.com

During the expanding process, die teeth pierce the incoming metal foil from above creating the distinctive diamond shape pattern.  Depending on the geometric configuration specified by the customer, the foil may also be put under longitudinal tension.  Both of these processes result in residual stress in the mesh, commonly known as “work hardening”.

As anyone familiar with metals manufacturing knows, work hardened material is stiffer, springier and more brittle than stress free metal.  The good news is that work hardening effects can largely be eliminated through the thermal process of annealing.  However, some amount of residual stress can be helpful.  It is usually easier to handle thin meshes without wrinkling or losing grid geometry if some stress is left in the metal.  More to the point, the amount of residual stress can usually be optimized for the customer’s particular application by controlling the time & temperature cycle of the annealing process.  Dexmet engineers are experts at annealing most metals and can help you choose the right specification for your application.
Another result of the expanding process is that the thickness of finished material is increased by up 800% as a result of the twisting of the strands.  This increase in the z-dimension is quite beneficial in some applications (e.g.; pressing battery electrode powder onto mesh current collectors), but not always.  The z-dimension is also not uniform across the width of the mesh role.  Dexmet can control this parameter to tight specifications by passing the expanded mesh through dimensioning rollers in a post processing step.  The mesh can be “flattened” back to the original incoming foil thickness or lightly rolled to ensure consistent edge to edge thickness.

Also, it is important to note that expanded mesh is anisotropic.  That is, its properties are different in different directions.  Most engineers recognize the difference in latitudinal (stronger) and longitudinal (weaker) strength. But other properties, such as electrical resistance, also vary and control of these should be discussed with a Dexmet engineer.  In roll-to-roll processes, it is important to remember that mechanical behavior is dependent on the directionality of reel.  Dexmet can re-roll mesh on new cores to ensure uniform behavior in the customer’s process.

The more upfront information that is shared with Dexmet engineers during the early product development stage, the more likely your future processing issues will be significantly reduced or eliminated.

FULL  ANNEAL

The most commonly requested process is a full anneal. The temperature to accomplish this depends not only on the alloy of the product but may, in certain cases, depend on the degree of cold work that goes into the metal prior to anneal. Copper is a prime example in that after 100% cold work, a full anneal can generally be achieved at less than 300 degrees Fahrenheit (°F). Since we generally require a fully annealed raw material, with some exceptions, the amount of cold work is rather low. Some say it is in the neighborhood of 20-25%. Under this condition, an annealing temperature of in excess of 600°F is required for full anneal. Sometimes, to get the desired softness, the metal must reach near the sintering point to get the required result. This can occur in several metals but most commonly in copper and nickel.

We have a method to numerically determine the level of softness which we call the BART number. BART stands for Bend Angle Recovery Test and is determined by a proprietary measurement device that we can supply if you desire to have your own. The softer the metal, the lower the amount the metal recovers from being bent 90°F at a distance of 1” from the fulcrum. Values therefore range from just above 0 to just below 90°F  but never at the extremes. Values for a particular mesh configuration and alloy can be developed from testing representative samples. We have predictable values for several configurations but we always run into new ones on a regular basis. Once established, the degree of anneal can be easily quantified. As far as I know, no one else has this capability.

Stress Relieve

The ideal stress relieve will result in a mesh that has the same BART number after heat treatment but lays flatter and feels softer. The ultimate tensile of the product is unchanged. Unfortunately the temperature required to reproduce the ideal situation varies with chemistry and in some cases cold work. It is useful when working the expanded metal around a form without losing the strength of the mesh.

Strand Anneal

The strand anneal is useful for metals, like stainless steel where it must be brought to a sufficiently low temperature from the anneal temperature in a short amount of time. If this is not done, inter-granular corrosion could develop and deposit carbon in the grain boundaries. This can be an issue in some applications.

Removing Residual Oil

Sometimes it is useful to insure the metal has no residual lubricants on it. Here, after degreasing the metal we put it in an oven to remove the last vestiges of any trace of lubricants. For this a temperature of 400°F will suffice.

Regardless of your needs, Dexmet can accommodate them with our oven and furnace capabilities.

Sincerely,

Kirt Griffin, Quality Assurance Manager

After doing numerous tests, we have found the aluminum to completely fail corrosion testing (in part due to dissimilar metals of stainless, brass, and aluminum). Since our system relies in part on continuity, our performance may suffer if the aluminum corrodes. Can you give me some options with stainless steel and a copper alloy? I am open to large variations in conductance but would like to see something with tensile strength comparable to our current material. I want to reduce conductance and improve corrosion resistance so stainless seems like the natural choice.

Answer From Dexmet’s Ken Mull:

First the science. When lightning strikes, the electrical energy vaporizes the aluminum taking out the initial energy punch, it then flows along the conductive surface looking for ground. The primary material characteristic then becomes the heat of vaporization. The heat of fusion and the electrical resistivity are not as important since the heat of fusion for all metals is insignificant by comparison and the electrical resistivity does not come into play until after the strike has occurred. A comparison between aluminum and copper yields a 2:1 difference by weight in favor of the aluminum since aluminum has a much higher heat of vaporization by weight than does the copper. So if you wish to switch to copper at the same weight as your current configuration the result would be a reduction in energy potential of ~50%.

You also mention switching to stainless steel for better corrosion potential. I cannot find the heat of vaporization for stainless steel but can for iron. Iron has a similar value of the heat of vaporization as does copper which would make it similar to the copper in terms of protection, however I am not sure how much of an effect the added chrome and nickel will have on the heat of vaporization since at the moment my search for the heat of vaporization for stainless steel has turned up blank.

Finally, after the strike, the electrical energy needs to flow towards ground and the electrical energy moving through stainless steel with it’s higher resistance (3x over aluminum) may heat up the surrounding material, potentially melting the surfacing layers.

I realize this may not completely answer your question and to verify any change you will need to re-test.

One last comment, changing to either copper or stainless steel will impact on the price since both materials are more expensive than aluminum.