This post by Dave Sherman originally appeared on the PORON Cushioning Blog.

Many customers are often surprised when we explain to them that all PORON® Performance Cushioning Materials are open cell polyurethane foams. It seems that the standard cushioning foams that they see on the market are typically closed cell EVA foams or closed cell polyurethane foams.

In fact, the open cell nature of PORON Cushioning foams is one of the material properties which help to make PORON Materials have the best resistance to compression set (C-Set) or for the non-foam geeks out there: resistance to break down after multiple uses.

Closed Cell Foams vs. Open Cell Foams

What do you need, a tennis ball or a spring?

EVA foams, commonly used in insoles and sports padding, are closed cell foams, meaning that all the bubbles of trapped air in the foam are complete bubbles, with cell walls all around, like a million balloons all stuck together. This kind of foam gets most of its properties from the air trapped inside the bubbles. When the foam is compressed, say when you’re walking on an insole or when you land on your elbow pad, the air inside the bubbles is compressed, and the return force is caused by the decompression of the air. This behavior is just like the behavior of a tennis ball, which gets its bounce from the air inside the ball. Like a tennis ball, the air eventually leaks out of the cell, and the foams go flat, or “take a set” in foamese. That means the foam insole is less comfortable on the next step, or less protective on the next hit.

Closed Cell Foam:

PORON Cushioning materials are an open cell foam, which has little connections or portals between the cells that allow air flow between them. So PORON materials are not dependent on the air for their properties, but instead on the properties of the materials in their cell walls. They operate more like spring, and return to their original position after being compressed, time after time because the air moves freely in and out of each cell.

Open Cell Foam:

Being closed cell offers some advantage and disadvantages in applications. The foams can be very light, as their cell walls can be very thin, but are usually stiff because of the incompressibility of the air inside them They can also be better at resisting liquid penetration.

Likewise, in addition to being resistant to taking a set, open cell foams have some other advantages, like being breathable and soft (better Compression Force Deflection – CFD). The table below summarizes some of the advantages (marked with an A) each foam has.

Foam Properties

Measures

Closed

Open

CFD Softness/Conformability A
Compression Set Resistance Life of Properties A
Anti Microbial Integral Coating
Breathability MVTR-Yes/No A
Water Absorption % Uptake After Some Time A
Washability Cycles at Setting A
Closed/Open Cell

So as you design something that will use a foam, ask yourself what are the most important properties you want. If you want light weight and great washability, then use a closed cell foam. If you want reliability over time, softness and breathability, choose PORON? Performance Cushioning Materials.

Tagged with:  

By Human Resources Department, Rogers Corporation

Earth Day This year’s Earth Day theme was “A Billion Acts of Green®,” and that is exactly how we kicked off the celebration in local communities.

On April 21, members of our Rogers Corporation team joined together for a clean-up of our local streets at the Rogers and Woodstock, Connecticut locations.  This year was extra special as Easter was just around the corner, and participants found Easter eggs along the way with great prizes hidden inside.

Earth Day may come just once a year, but it should be celebrated every day!  The Earth Day Network reminds us that “real change occurs best when millions of people commit to it with their actions.”  Every effort to help the environment, no matter how small, is important.

“Real change occurs best when millions of people commit to it with their actions”, Earth Day Network

Here are some tips we learned from our Earth Day celebration to make any clean up event “greener” and more fun:

  • Participants picking up trash received reusable shopping bags, a great reminder to keep a few in your car for shopping trips.
  • Rather than driving to a location for Earth Day, participants cleaned up their local streets and parks.
  • We had a great time searching for Easter eggs along the way!  Having fun going green with rewards and challenges encourages sustainable change.

To date, A Billion Acts of Green has reported over 45 million acts, both great and small.  Our team is working to take these acts to one billion and beyond!

Do you have ideas for next years’ celebration? Share them with your team and your local community!

Tagged with:  

By the Human Resources Department, US Career Center

Volunteers aren’t paid, not because they are worthless, but because they are priceless.  This anonymous quote truly touches upon the importance of volunteering.  Offering your time to a worthy cause, whether it’s disease research, helping a family in need, or feeding the hungry is an excellent way to feel good while helping others.

Volunteer in Your CommunityIn addition to helping your community, volunteering can serve as an excellent tool for the working professional.  In the workplace, you interact with people every day, whether it’s with a co-worker, client, or supervisor.  Volunteering offers new opportunities to meet others in a whole new atmosphere.  Enjoy a walk or 5k for your favorite charity while simultaneously expanding your network of contacts.

Another benefit of volunteering is simply learning something new.  Participating in a large food or clothing drive demands expert organization, a skill that can certainly benefit both you and your workplace.

Working in a team outside the office can also teach you new ways to approach challenges inside it.  Would you like to become a better project leader?  Consider managing a team of other volunteers working toward a common goal.  Improving your leadership skills outside the office will give you the confidence to shine at work.

Think about the skills you’d like to improve upon, whether it’s organization, leadership and team building, or simply meeting new people.  Find any one of the many volunteering opportunities available in every community and join in.  Learn something new, and feel good while doing it!

Which community projects are you involved in and passionate about?

Tagged with:  

This post authored by John Coonrod originally appeared on the Rog-Blog hosted by Microwave Journal

Performance requirements typically guide the selection of a PCB material. Some applications may also be cost-sensitive, and require evaluation of the total costs of choosing a circuit material. This includes the cost of the material as well as costs associated with processing the material. For example, FR-4 is a low-cost material with minimal processing costs. However, its performance is also low relative to some higher-costing materials, such as PTFE- or hydrocarbon-based circuit materials, although these materials can have considerably different processing requirements and associated costs. By considering the costs of the material as well as its processing requirements, it’s possible to determine if “you get what you pay for” truly applies to circuit materials.

Halogen-free Circuit Materials

For example, Theta® halogen-free circuit materials from Rogers Corporation have a slight premium in cost to FR-4 materials, but with more stable dielectric constant over frequency and lower loss. Ideal for high-speed digital circuits and multilayer constructions, they feature high heat resistance for use in lead-free applications. Theta materials exhibit a dielectric constant of 3.90 at 1 GHz and 4.01 at 10 GHz (in the z-axis), with dissipation factor of 0.0080 at 1 GHz and 0.0118 at 10 GHz. While Theta laminate does not deliver the electrical performance of a PTFE-based laminate material such as Rogers RT/duroid® 6035HTC ceramic-filled PTFE composites, its material costs and processing costs are lower.

Circuits on Theta materials can be fabricated with standard processing methods, to minimize processing costs. The materials themselves are available with a wide range of laminate and prepreg thickness options for covering widespread applications, and they can be processed with the same methods used for FR-4 circuit materials, using standard pin or slotted tooling. Theta material requires no more than a standard chemical cleaning process with micro-etch for preparing board surfaces for the application of a liquid or dry film photoresist to “image” the desired circuitry; the copper surface can even be prepared for photoresist application by means of a basic mechanical scrub without damage to the material. The photoresist can be developed, etched, and stripped (DES) using any commercial chemical treatment. In many ways, Theta material circuit processing is just like that for FR-4 but Theta material features a z-axis coefficient of thermal expansion (CTE) that is 30% lower than FR-4, with significantly more stable dielectric constant over frequency and temperature than FR-4.

PTFE-based Circuit Materials

In contrast, PTFE-based circuit materials such as Rogers RT/duroid 6035HTC provide considerably better electrical performance than a hydrocarbon-based Theta material, although the cost of processing the material, and the material itself, is somewhat higher. RT/duroid 6035HTC is a ceramic-filled PTFE composite with low-profile, reverse-treated copper foil for excellent thermal dissipation, stability, and low loss. As a result, it is designed for much higher power-handling capability than Theta material.

The higher cost of the RT/duroid 6035HTC material itself and its processing, however, delivers a laminate with extremely stable dielectric constant of 3.50 in the z-axis at 10 GHz, with low dissipation factor of 0.0013 at 10 GHz and impressive thermal conductivity of 1.44 W/m/K for outstanding performance in high-power circuits.

Between Theta laminate and RT/duroid 6035HTC in terms of performance, material costs, and processing costs lies Rogers XT/duroid™ 8000 and RO4000® LoPro™ non-PTFE hydrocarbon circuit materials. XT/duroid 8000 is a halogen-free thermoplastic material designed for ease of processing. The material has a similar dielectric constant to that of RT/duroid 6035HTC: 3.23 in the z-axis at 10 GHz. It is resistant to the solvents and reagents typically used to process PCBs, and has a higher maximum operating temperature (MOT) than PTFE-based materials for handling higher-temperature environments. It is lower in material cost and in processing than RT/duroid 6035HTC, but with a higher 0.0035 dissipation factor (for increased loss) and much lower thermal conductivity for less power-handling capability.

Also, Rogers RO4000 LoPro circuit material is based on a thermoset hydrocarbon resin system. Ideal for multilayer circuits, it features low-profile reverse-treated copper foil for low passive intermodulation (PIM) performance in RF/microwave circuits and excellent signal integrity in digital circuits. It is compatible with lead-free processing and designed for ease of fabrication to minimize processing costs. It cannot match the electrical performance of a PTFE-based circuit material like RT/duroid 6035HTC, but it is also less in material and processing costs. As can be seen from this sampling of Rogers’ materials, when considering a circuit material, tradeoffs in costs—both material and processing costs—also mean tradeoffs in performance.

Those attending the technical sessions at the IPC APEX EXPO in Las Vegas, NV (April 10-14, 2011, www.ipcapexexpo.org) can learn more about some of the performance, cost, and processing differences among circuit materials by attending John Coonrod’s presentation “Understanding when to use FR-4 laminates or high-frequency laminates.”

This post written by Dave Sherman originally appeared on Rogers PORON Cushioning Blog


Rogers and the PORON Team are continually working with a variety of equipment and apparel manufacturers. From helmets to protective vests and footwear to apparel, each market has their own set of standards and testing methods.

We can only begin to imagine how confusing this information can look from someone ‘on the outside’ or who is simply trying to compare one product’s performance and another. To make things more confusing, many markets without pre-set standards or test methods will adopt methods from similar markets.

In light of the March Madness season, we’ll call this next group of standards and test methods “The Elite Eight.” We’ll do our best to break out the types of markets who use these methods and some general information about the tests, but as always, feel free to leave your comments and questions!

Some of the test standards we’ll review are:

1- Peak G
2- HIC – Head Injury Criteria
3- EN 1621-1
4- EN 1621-2
5- NIJ Standard 0101.06
6- EN 13158, BETA 2009 and ASTM F1937
7- ASTM F1614
8- ASTM F2413

Bracket Breakdown:

Head Protection Division

1- Peak G– Peak G measures the maximum deceleration experienced by a projectile (such as an anvil or flat tup) onto the material or product being tested. The Peak G is recorded as the total force returned to the projectile or not absorbed by the product being tested. The lower the Peak G’s, the better the impact protection material. Concussions typically can be recorded around 300 G’s. SNELL M2005 standards require Peak G to not exceed 290 G and DOT standards require Peak G to not exceed 400 G.

2- HIC: Head Injury Criteria – HIC integrates deceleration over time, offering another dimension to just Peak G force. Samples are impacted with 4.6kg, 160 mm diameter projectile with an impact velocity of ~2.8ms¹. Lower HIC scores imply better impact protection and simulate a lower risk/severity of impact-related head trauma – Winner

Motorsports Protective Apparel Division

3- EN 1621-1:1997 assesses devices that are designed to protect the shoulder, elbow and forearm, hip, knee and lower leg regions. The test apparatus consists of a mass of 5kg with a 40mm x 30mm striking face, dropped onto the sample mounted on top of a 50mm radius hemispherical dome. The anvil is further mounted onto a load cell, allowing a measurement to be made of the force transmitted through the protector. The kinetic energy of the falling mass at impact is required to be 50J.

A protector subjected to this test method is deemed to conform to this standard if the average transmitted force of nine tests is less than 35 kN, with no single test result exceeding 50 kN.

4- EN 1621-2:2003 defines two levels of performance for CE approved back protectors. The test apparatus and procedure is similar to that of EN 1621-1:1997, but with a different impactor and anvil configuration that is designed to represent the back. The impactor is a rounded triangular faced prism, of length 160mm, base 50mm, height 30.8mm and radius 12.5mm. The anvil is a radiused cylinder, with its axis orientated to the direction of impact, of height 190mm, diameter 100mm and rounded end radius 150mm.

When tested to the procedure defined in the standard, the two levels of performance are:

  • Level 1 protectors: The average peak force recorded below the anvil in the tests shall be below 18 kN, and no single value shall exceed 24 kN.
  • Level 2 protectors: The average peak force recorded below the anvil in the tests shall be below 9 kN, and no single value shall exceed 12 kN. – Winner!

Protective Vest Division

5- NIJ Standard 0101.06 is the standard for Ballistic Resistance of Police Body Armor developed by the law enforcement standards laboratory of the National Institute of Justice (NIJ), US Department of Justice. The standard has been updated to include additional non-impact test methods such as: complete submersion in water, accelerated conditioning and environmental tests and increased ammunition velocities for some threats.

Depending on the level of the test, typical body armor ballistic testing standards place the body armor over a piece of ballistic clay and measures the back face deformation (or the depth of the hole) after being shot by a particular caliber gun. A Kevlar material is used to ‘catch’ the bullet, but other materials are used behind the Kevlar to decrease this back face deformation. Depending on the level of the standard, back face deformation can range from less than 25 mm to 44 mm depth.

6- EN 13158 (European Norm Certification), BETA 2009 (UK Certification) and ASTM F1937 – 04 (American Society for Testing and Materials) – All standards to specify body protectors used in horse sports and horseback riding

The impact levels are depending on the test level. In all standards, the completed vest is tested by using equipment and test methods similar to the EN 1621 standards. Yet the force that is transmitted through the product is much lower than the motorcycle EN 1621 standards. In addition other factors are recorded in the standard such as fit, minimum thickness of the foam, zipper closures, etc. – Winner over EN-1621 and Ballistic Testing

Industrial Safety Division

7- ASTM F1614 – Measures the transmission of repeated impacts such as a vibration. Often used to compare insole impact levels.
8- ASTM F2413 – Standard specification for measuring footwear protection such as metatarsal guards.

ASTM F2413 is a more stringent test as it records a pass or fail rating whereas ASTM F1614 does not have a standard specification number for pass or fail.

My picks: HIC wins over EN1621-2, and EN12158 beats F2413. Then EN 12158 beats HIC.

Tagged with:  
Page 73 of 78« First...102030...7172737475...Last »