Discussions with Attendees from Around the Globe at MD&M West

We were pleased to meet face-to-face with so many of our customers at MD&M West in Anaheim, California. We spoke to people from Brazil, Canada, China, Columbia, Germany, Japan, Korea, Mexico, and Taiwan,

Here are some of the topic we discussed at our booth:

• Three and four-point bend tests on nitinol
• Mechanical grips for pull seal tests
• Tensile tests on tubing
• Small circuit board pull tests
• Surgical glove testing
• Stent dislodgement testing and radial force
• Rheological properties of medical bags

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Comments from the booth at MD&M West

MD&M West is the Medical Design and Manufacturing Conference and Exhibition held in Anaheim, California. James Ritchey, Instron’s Director of Medical Device and Biomaterials had this to say about our recent trip there.

“I continue to be impressed by the extended global reach of this conference and exhibition. I spoke to engineers from China, researchers from Germany, technicians from Minneapolis, and investors from India. I have not found a more efficient approach to expanding our presence in the medical device and biomaterials communities.”

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Can You Give me a Letter Certifying that my Test is in Accordance with “ ASTM xxx” or “DIN yyy” ?

Well, no, we can’t do that. But before you gasp in astonishment and start to look around for a manufacturer that can, let’s discuss the reasons why.

A test standard details many things to which a material test must conform. Many of these are under Instron’s full control – for example, the rate of load application of a load frame or the software algorithm code for a particular calculation. But the test must also conform to many things outside of Instron’s control, such as the specimen alignment, the choice of grips and grip jaws, and the set-up of the test control parameters.


When Instron certifies that a test instrument “meets the requirements of ASTM xxx or DIN yyy”, we are confirming that the items under our control have been measured, validated, and verified in accordance with our ISO 9001 certification. We also publish letters of conformance that detail the extensive test processes that we apply to our software products.

The final certification of the actual test and associated test results must come from you. But you can rest assured that the test equipment that you are using, when properly maintained and regularly calibrated, fully meets the requirements of the published standards.
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What is the difference between a single-point and a 4-point flexural test?

A single-point, or 3-point, bend test uses one loading anvil, whereas a 4-point bend test uses two loading anvils. The selection of an appropriate bend fixture depends on the material you’re testing.

Type of Bend Test	3-Point	4-Point
Type of Material	Homogeneous (plastics)	Non-Homogeneous (composites & wood)
Stress Concentration	Small and concentrated under the center loading point	Larger region to avoid premature failure
Specimen Deflection	Typically measured with the crosshead position	Typically measured with a deflectometer

Did You Know: A four-point conversion kit may be available for most standard three-point fixtures. Contact us for additional information. Read more

Composite Metal Foam: A New ‘Hip’ Material

The first surgery to replace a damaged hip joint with an artificial joint was performed just 50 years ago. Today more than 190,000 hip replacement surgeries are performed in the USA alone. During this time, there have been many improvements to the surgical techniques and to the technologies and materials of the replacement joints but inherent problems remain. One of these is the slow deterioration of bone tissue around the prosthetic material due in part to uneven load distribution between the prosthetic and the bone itself.

Dr. Afsaneh Rabiei, a professor of mechanical, aerospace, and biomedical engineering at North Carolina State University has recently developed a new composite metal foam material that offers, among many other possibilities, the development of new hip joint prostheses that may overcome this problem.

Read full article

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4 Things to Consider When Testing at High Temperatures

Whether you’re testing the ceramics used in wind turbine blades for power generation or the metal used in a jet engine, high-temperature tests present some unique challenges and require specialized testing equipment and accessories. 

Do I need a Chamber or a Furnace?

• Temperature chambers are used up to 600o C (1112o F) – this is when the wavelength of the   electromagnetic radiation heat energy reaches the visible spectrum.
• Split-furnaces are used for testing between 400o C and 1200o C – this is when radiative heat transfer becomes greater then convective. Models are also available that apply heat (up to 1600°C) only to the specimen, and not the grips.

Do I need an Extensometer and What Kind?

• Various types of extensometers can be attached to the specimen before or after heat soaking.
• Water cooled extensometers are available if your test requires accurate strain measurement at very high temperatures.

How can I Improve the Alignment of my Load String?

• Alignment of the load string is very important and easily achieved with self-aligning quick-change adapters. These adapters allow quick and efficient removal of the tested specimen and pullrods so a new specimen can be promptly installed and tested.

Does Specimen Type Matter?

• Round specimens with threaded ends or flat, pin-loaded specimens are ideal for high temperatures.
• High-temperature lubricant is necessary on all threaded connections.

To learn more, read A Guide to High-Temperature Tensile Testing
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Common Sources of Error When Testing at High Temperatures

Testing at high temperatures can prove to be erroneous if you begin testing before things have stabilized. When you first turn on your chamber, the load string and temperature are not stabile. A transient temperature will cause your signal to drift and show a load when there isn’t one. Just like preheating your oven before cooking, you need to allow your load string to warm up and stabilize, as well as reaching your desired temperature before placing your specimen within the grips – this will give you accurate data.

Side tip: We have found that HVAC systems or other types of vents can impact your temperature testing. Make sure to move your system away from vents before testing at high temperatures. Read more

Why Should I Instrument My Impact Tests?

The majority of impact tests have the same goal in mind – establishing the amount of energy it takes to break a material. When conducting an impact test without a sensor on the striker, you limit the information that can be gathered. Since only the weight of the mass and drop height are known, you are merely able to calculate the impact energy. Since the falling weight will either stop dead on the test specimen or destroy it completely in passing through, the only results that can be obtained are of a pass/fail criteria based upon visual determination.


By adding a load-sensing tup, you can continuously record the load on the specimen as a function of time and/or specimen deflection prior to fracture. The best systems record load vs. time or deformation for the entire period of the impact event. This gives a better representation of an impact than a single calculated value. Instrumented drop weight and pendulum testing is considered the best testing method available. By performing multiple tests at various rates, a complete impact profile can be developed for a polymer. This approach can be useful in simulating functional impact resistance and running material comparisons.

There is enough flexibility to simulate real-life conditions and to perform audit inspections on parts or molded samples. By adding instrumentation to

impact tests the all-important energy absorbed value is established much quicker.

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The 6 Testing Standards to Consider when Developing & Manufacturing Hip Implants

Research and development of modular hip implants requires a substantial investment in testing the materials and the device itself. New materials and designs are constantly being evaluated. Standardization committees have established a variety of test protocols and procedures that ensure safe and effective development of these medical devices.

The test standards that you should consider in the development of hip replacements includes:

• ISO 7206 - Implants for surgery – Partial and total hip joint prostheses
• Part 4: Determination of endurance properties and performance of stemmed femoral components
• Part 6: Determination of endurance properties of head and neck region of stemmed femoral components
• Part 8: Endurance performance of stemmed femoral components with application of torsion
• Part 9: Determination of resistance to torque of head fixation of stemmed femoral components
• Part 10: Determination of resistance to static load of modular femoral heads
• ASTM F 1612 – 95 (2005) - Standard Practice for Cyclic Fatigue Testing of Metallic Stemmed Hip Arthroplasty Femoral Components with Torsion
•  ASTM F 1714 – 96 (2008) - Standard Guide for Gravimetric Wear Assessment of Prosthetic Hip-Designs in Simulator Devices
• ASTM F 1875 – 98  (2009) - Standard Practice for Fretting Corrosion Testing of Modular Implant Interfaces: Hip Femoral Head-Bore and Cone  Taper Interface
• ASTM F 2345 – 03(2008) - Standard Test Methods for Determination of Static and Cyclic Fatigue Strength of Ceramic Modular Femoral Heads
• ISO 14242 - 1: 2002-03 - Implants for Surgery - Wear of Total Hip Prostheses - Part 1: Loading and displacement parameters for wear-testing  machines and corresponding environmental conditions for tests

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My Load Cell Doesn’t Work … What Can I Do?

This is a very common problem and everyone (us included) has overloaded a load cell at one point in their testing career. Yes, it can be a costly mistake, but in most cases, a load cell can easily be repaired. Our service repair department will take your load cell – rebuild the internal components, test it, calibrate it, and send it back to you.



Here’s how the process works:

1. Call us for a Return Authorization Number (RMA)
2. Ship your item to us with the RMA # on the outside of the box
3. The service dept. will contact you with the estimated charges
4. Once the work is approved, the repair is completed and the item is shipped back to you

Oh, and yes, Instron can repair many other items; such as grips, extensometers, hydraulic pumps, actuators, circuit boards, power supplies, and more. Just give us a call or contact us and we’ll let you know what your best option is.

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Meet Us at MD&M West

We love to talk to our customers face-to-face. Our Instron experts will be available in Anaheim, California at the Medical Design and Manufacturing Conference and Exhibition February 8 – 10.  If you stop by booth #2578, you will have the opportunity to share your testing stories with Karl Malchar, Chuck Gleason, and Dan Raynor.

If you haven’t seen our new Instron 5900 Series Mechanical Testing Systems, you can see one in action at the show. A selection of biomedical accessories will also be available to demonstrate.


Witness one of our most innovative and quietest dynamic systems that is all electric and uses no oil. Ask Theresa Smith about the Electropuls and the benefits for your testing lab.

Please be sure post your stories after visiting our booth.
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Why Am I Not Seeing Upper Yield?

Are you testing for upper yield strength, but not seeing a “dip” in your stress/strain curve?  This is often the result of using improper test control parameters. During yielding, the strain rate needs to be as constant as possible. This is best achieved by using crosshead position or strain control*. 

For example, if you run a test in stress control at the onset of yielding, the testing machine will accelerate to maintain the desired stress rate.  Incorrectly running in load control causes unwanted acceleration. This prevents the stress from dropping relative to the increase in strain.  As a result, the upper yield strength calculation will fail because it can’t find the dip in the stress-strain curve (a zero or negative slope).



To correct this situation, set up the test to use stress control during the first half of the elastic portion.  Prior to the onset of yielding, switch to either position or strain control.  We have software packages that are designed to allow for control transition.

*Additional help for determining the allowable test rates during yielding can be found in the following Testing Solutions:  ASTM E8, ISO 6892 or EN10002.
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How often have you dropped your phone and are thankful that it still works?

We live in an electronic world with increasing dependence on our handheld devices for daily activities. These electronics, ranging from phones to cameras to game controllers and MP3 players, are subject to a variety of grueling conditions be it repetitive use or accidental damage. Most people don’t know the rigorous testing that goes on to ensure that your various electronics can withstand the various bumps and bruises that we inflict on them daily.

Damage to plastic casings, lens covers, keypads or buttons start to accumulate resulting in eventual failure of a piece part and thus rendering the device useless. To keep up with consumers ever growing demands on quality products, mechanical testing on various components and parts is necessary.


Three of the most common types of tests our customers perform on the electronic devices and components they manufacture are as follows:

1. Puncture/probe test - A puncture, or probe test, is used to test the durability of small parts such as buttons or keypads.
   
2. Impact/drop test - An impact test can replicate the way a device reacts to being dropped.
   
3. Dynamic/fatigue test – A dynamic or fatigue test helps determine how key components react under repetitive motions as well as give us an estimate of fatigue life of a device.
   

If you would like more information on the challenges of testing handheld devices and other plastics, please view our plastics brochure.
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