Tinius Olsen Plastics Expert Harry YohnHarold E “Harry” Yohn serves as Product Applications Specialist for Tinius Olsen Testing Machine Co. in Horsham, PA. Harry has been with the company since 1996. He has 26 years of experience in the field of mechanical and physical testing of plastics .In 1990, Harry became a member of ASTM International Committee D20 on Plastics, and he is now a vice chair of the committee (Programs), a group of about 1000 members responsible for 473 standards. He is also Subcommittee chairman for D20.30 on Thermal Properties of Plastics and chair of D20.10.02 Impact Properties as well as chair of several task groups within the committee.

Harry was honored with the Award of Merit in and became a fellow of ASTM International in 2013. In addition to his D20 work, Harry participates in standards development through the International Organization for Standardization (ISO). He is currently part of the U.S. delegation to ISO/TC61, serving as Convener for SC2 WG3 Impact Properties. Harry is a 1983 graduate of the Pennsylvania State University. Before joining Tinius Olsen, he served as sales engineer and then sales manager for Custom Scientific Instruments, Inc. a division of Atlas Electric Devices Co of Chicago.

  • Plastics & Composites FAQ
  • I am looking for information on how to import the information to test to the ASTM D4745.


    ASTM D4745 is a materials specification, not an actual test method. So, if you pull in the Method for D638 and modify it as required, you should be good to go.

  • What is the difference between ASTM and ISO for MFR/MFI ?


    Dear Harry,

    I want to know the differences between ASTM and ISO test procedure for MFR/MFI for PP ?


    Thanks for the question. There can be diiferences un the test results between the ISO 1133 method and ASTM D1238. These are mainly due to:

    1) there are some slight dimensional differences on the piston foot;

    2) the preheat time in ISO is 5 minutes verses 7 +/- 0.5 min in ASTM;

    3) the starting point is a 50 mm in ISO and at 46 mm in ASTM

    4) the test takes place over a 30 mm piston travel in ISO while the test is limited to 1/4" or 1" of piston travel in the ASTM method.

    These are the main differences. Hope that helps!

  • I was researching the difference between the Charpy impact test and the Izod impact testing and I was wondering why the notches face different directions for the two test.


    Thanks for your question. Impact testing was first carried out on metals and those tests were adapted to plastics. You are correct in saying that charpy is the test most often used when testing metals but it is not unheard of to do a metals izod or even a metals tensile impact test. Also, both charpy and izod are used for testing plastics. Izod historically has been the test of choice here in the US but the rest of the world tends to favor charpy testing according to ISO 179. In the past decade, more US users have started to use charpy testing, particularly those that supply the automotive industry. The auto industry is global in nature so 10-15 years ago they didn’t want data from 2 tests so they selected the ISO charpy test since it was in use globally. The point of the notch in the specimen is to try to get it to break in the same spot. For izod, the notch faces the striker so that you get a hinge type breaking action. For charpy you are getting a three point bend type action on the specimen. Hope this helps. Regards, Harry

  • I have a Tinius Olsen MP987 does the company offer any on site training?


    Hi Suzanne: Thanks for your question. Unfortunately, the MP987 has been discontinued for nearly 15 years, so not all of our current sales reps are familiar with the operation of the machine. However, give our Help Desk a call and they should be able to find someone to walk you through the basic operation. Manuals are available for a small fee.

  • How can I get a operator manual for Extruder Plastometer MP600?


    Instruction manuals are available from Tinius Olsen. Please contact your salesman or call TO's Production Department at 215-675-7100. Thanks.

  • Polycarbonate Melt Flow Test Parameters


    Harry, We have a T.O. Model MP993 Controller / Timer which serves us well on most materials. We are in the process of getting more and more jobs calling for polycarbonate material...which my OIPM does not address. What temperature, weight, release time, piston travel, melt density should I use. I need it all.

    Best Regards,

    Roger Claypool

    Hi Roger - Thanks for your question. Generally, PC is tested at 300 C with a 1.2 kg load. Release time & piston travel are based on expected melt flow. You'll have to try a few test to get the right settings. Melt density can be determined by selecting "calculated" for density type when configuring a test progam for a Method B test. You will then have to cut off and weigh the extrudate that is produced in either a 1/4" or 1" of travel and enter that weight into the MP993 controller. It will then calculate the melt density and melt flow index. There are written instructions in the current MP993 manual that will help you. If you still need help, please give us a call. Thanks again.

  • Hi Harry Can you please tell me the temperature accuracy of the Tinius Olsen HDT, I know the resolution is 0.1degree C but I need the accuracy


    Thanks for your question, Mark. In HDT and Vicat machine, temperature accuracy can refer to both the temperature measurement and ramp rate control. For HDT testing, the ramp rate for ASTM D648 is 2oC +/- 0.2oC/minute and is considered to be met if the temperature of the heat transfer medium (usually silicon oil) is made rise 10o C +/- 1o C every 5 minutes until the maximum temperature is reached. ISO 75 has essentially the same requirement but it is stated as 120o C +/- 10oC/hour and is considered met if the temperature of the heat transfer medium is made to rise 12oC +/- 1oC /6 min For vicat testing, there are 2 ramp rates for ASTM D1525. Rate A is 50oC +/- 5oC /hour, which considered to be met if the heat transfer medium is made to rise 10oC +/- 1oC every 12 minutes. Rate B is 120oC +/- 10oC/hour which considered to be met if the heat transfer medium is made to rise 12oC +/- 1oC /6 min. ISO 306, also has 2 rates, 50oC +/- 5oC /hour (5oC +/- 0.5oC /6 min) and 120oC +/- 10oC/hour (12oC +/- 1oC /6 min) For the temperature measurement system (probe & readout), ASTM D648 requires and accuracy of at least +/- 0.5oC. The Tinius Olsen 603 HDTM and 303HDTM meet this requirement with the use of individual RTD’s located by the specimen in each test frame. You may hear someone refer to temperature gradient, which is the difference in temperature displayed for a test frame vs. the temperature displayed on a test frame at the opposite side of the bath. There is no requirement for this in either the ASTM or the ISO standards for temperature gradient. It is usually a function of heat transfer medium viscosity, bath circulation and temperature. Bath temperature gradients generally do not affect test results. Typically, when the test is first started and the heat transfer medium is at room temperature, you may see some variability from test station to test station. However, any temperature gradient between stations usually goes away quickly after the heat transfer media warms and circulation starts. Also, all TO equipment produced since 1994 has an RTD at each individual station to monitor and record the temperature of penetration or deflection of each individual specimen under test. Hope this helps.

  • Is there any standard for measuring the spiral flow of polyethylene?


    Thanks for your question. I spoke with a colleague at ASTM D20 who works with polyethylene. He told me that it is a common test in the industry (and PP as well) but there are a number of different moulds and procedures. There is no standardized procedure in ASTM for the test. I'm not sure about ISO. I\'ll check on that and if I find something, I'll let you know. Thanks again. HEY

  • How much time do I have to fill the Melt Indexer Barrel and start the test in a Method A Test. I have heard 60 Seconds to fill and then wait 300 Seconds or 420 Seconds. What is the proper procedure?


    ASTM requires the operator to fill the bore, insert the piston and start the test within a minute. As soon as it is finished, the test is started on the machine and the preheat countdown begins. Generally, ASTM D1238 requires 420 seconds +/- 30 seconds for the pre-heat period but that can be overruled in the materials specification if there is one.

  • Is there an equivalent test for Plastic products that would be similar to N-Value in the testing of metals?


    ASTM D638 does reference a Poisson\'s Ratio test which is similar to the N-value test. ASTM D20.10 ran a round robin a year or so ago and I know the results were pretty scattered among the participating labs. I believe the next revision of D638 will remove reference to the Poisson\'s Ratio test in the main body of the standard, but it will reference it in the appendix section of the standard incase anybody wants to use it. Hope this helps!

  • We are a small recycling company and have need of a device to test plastics for different grades. i.e. injection grade HDPE, HMW, ect. Is a melt flow index tester what we need, or is there a more economical product we can use?


    Hi guys - Thanks for the question. I'm very sorry for the delay in getting back to you. A melt indexer is one of the more economical ways of determining flow rates of plastics.

  • Aside from buying an expensive micrometer, how do you suggest measuring the bore of the barrel in an MP600 MFI?


    Thanks for your question.  At TO we use a bore gage in combination with a ring gage to check verify the bore.  We actually sell them   P/N's 90004730 & 90004899. I believe there are some gages that use air but I am not too familiar with them.  Sorry that I can not be of more help.

  • Hi there, is there a problem with putting a melt indexer orifice in a muffle furnace for 5 minutes at 600 C, to burn off resin? I've heard this could be a problem if the metal is hardened.


    Thanks for the question.  Some people do this routinely but they may use a lower temperature.  If you choose to use this cleaning practice, make sure that you check the ID with a go/no-go gauge. - Harry

  • Is there a calculation to use if my HLMI is 11.9 and I want to know how that translates to MI?


    Thanks for the question but, unfortunately, there is no formula for relating 2 different flow rates under 2 different sets of test conditions.  You can do a flow rate ratio by following Procedure D of ASTM D1238.  Best regards - Harry

  • I am required to determine yield strength at 0.6% EUL. As this value in the chart is drawn against stress. We are using Horizon Software with Epsilon(3542-0200-050-ST) Extensometer. material is high strength steel manufacture & sub-size specimens.


    Here are the 2 results you need to get Yield strength at 0.6% EUL.

    Take the attached* results files and import them into your Horizon software.  To do that, first copy the attached files to a location on the PCs Drive.  Then, in the Horizon software,  navigate to the Library tolos Tab. Then click on the Results button.  Make sure that the Library of Working Methods is selected.  Click on the <Import from file> button.  Browse to the files attached to import them.  Then you can add them to the report.  You need both files to be imported.

    Horizon Software

    *contact us for attachments.

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