Complex Round Test Bars

November 1, 2017

In addition to being able to turn perfect shouldered, button head and threaded tensile bars, Tensilkut’s CNC Tensilathe has been used for preparing more complicated, proprietary test specimens.  This one is a fine example:

Tapered stress test bar

Tapered stress test bar

This is a bar designed by a customer for a specific test of longevity of Hastelloy.  Each of the end sections on both ends is tapered, as is the gauge section.  This test specimen is beautiful in its complexity.

Ends of tapered stress test bar

Ends of tapered stress test bar

Of course, because it was turned from Hastelloy, accommodations had to be made in the program; when the program would turn steel or stainless specimens perfectly, the deflection from the Hastelloy caused it to be oversized.  When we program your specimens for the CNC Tensilathe or the CNC Tensilkut III, we want to receive several samples of your actual material, so our programs will accurately prepare your test bars, regardless of its properties.  Machines which accurately prepare physical test specimens are the only things we’ve ever built, and we pride ourselves on offering the best sample preparation equipment available.


40-75 Tensilbis

October 11, 2017

The 40-75 Tensilbit is our carbide burr Tensilbit.  It is .500″ diameter, suitable for use on all Tensilkut I or Tensilkut II machines.  The 40-75 Tensilbit is suitable for cutting test specimens from fiberglass, composites, filled and similar materials; the cross cut effectively cuts the fibers in these materials, ensuring a smooth finish for the best possible test specimen.  Note, however, that Kevlar does require one finishing pass of .002″ with the 40-76 Tensilbit, to clean up the lower edge of the specimen before it’s removed from the template.

40-75 Tensilbit end view

40-75 Tensilbit

Early Tensilkut Machines

October 9, 2017

When Tensilkut was first created, in 1953, there was one model, with a maximum capacity of .250″, and limited ability to cut tensile samples from harder materials.  Within a few years, this changed, and a machine with the capacity of up to .500″ on softer metals was added.  This is the press announcement:

Tensilkut press release from the late 1950s.

Tensilkut press release from the late 1950s.

Thereafter, Tensilbits and templates for preparing plastic, fiberglass and other nonmetallic tensile bars were added.  Today, our line includes the traditional Tensilkut I for cutting test specimens from flat metals and plastics, along with the Tensilkut II and CNC Tensilkut III, along with machines for turning round tensile specimens and notching impact and shear bend test bars.  How far we have progressed.

Guide Sleeves

October 4, 2017

It’s not terribly uncommon for the guide sleeve on the Tensilkut I or Tensilkut II to be worn.  The guide sleeve is integral to the Tensilkut machine’s ability to create the same specimen repeatedly, without the skills a full charge machinist offers.

Guide sleeve on the Tensilkut machine, showing early signs of wear

Guide sleeve on the Tensilkut machine, showing early signs of wear

We do keep guide sleeves in a variety of sizes in stock for shipment when our customers need them.  They’re easy to replace, keeping your testing program running smoothly.

Guide Sleeves for the Tensilkut I and Tensilkut II

Guide Sleeves for the Tensilkut I and Tensilkut II


CNC Tensilkut III For Multiple Samples

October 3, 2017

Often, our customers are interested in the CNC Tensilkut III to gain the ability to clamp multiple blanks into the machine, start it and have the freedom to do other things while the machine cuts specimens unattended.  To that end, we typically set up the CNC Tensilkut III with multiple work stations, so several specimens (typically between 4 and 6, depending upon the size) can be cut at once.  This is a typical table, configured to clamp 6 strips for the preparation of ASTM E8 samples.

The table for the CNC Tensilkut III, configured for multiple tensile specimens

The table for the CNC Tensilkut III, configured for multiple tensile specimens

Once the strips are clamped to the table, the specimens are chosen on the included computer, using our Windows-based point and click system; the machine then runs through its cycle without any operator interaction.  When it’s finished, the CNC Tensilkut III shuts down, indicating that it’s safe to open the front door and remove the specimens, at which point it can be reloaded for another set of specimens. When located in the testing lab, a Tensilkut machine lets you cut your tensile bars as you need them, on your schedule.

Turning Round Tensile Bars

September 29, 2017

Turning round tensile test bars has always been a difficult and tedious process.  A full charge machinist can turn a test specimen using a lathe, but it will take some time, and, unless the machinist is fastidious, it may not be within the tolerances required by the specification.  Additionally, since machinists will often turn bars using only the largest possible passes, the bar will likely need hand finishing to remove distortion caused by the turning process.

Tensilkut has two machines designed to allow you to turn round tensile bars in accordance with ASTM E8, ASTM A370, JIS, DIN and ISO specifications in the lab.  Technicians without previous machining experience can learn to run these machines in short order; as with our other machines, these machines are supplied with a self-instruction manual, so it can be used by different operators as time goes on.

The Tensilathe/505 is our semi-automatic tracing lathe.  It operates from a Master Template, which controls the shape and dimensions of the specimen.  The operator needs only to dial in each cut to prepare a perfect tensile bar.

Tensilathe/505 semi-automatic tensile sample turning machine

Tensilathe/505 semi-automatic tensile sample turning machine

The CNC Tensilathe is the automated round test specimen preparation system.  This machine runs on a Windows-based microcomputer; specimen preparation is accomplished with a point and click software system.  After setting up the specimen, the operator is free to complete other tasks while the sample is turned automatically.

CNC Tensilathe for the automatic turning of round tensile specimens from most metals

CNC Tensilathe for the automatic turning of round tensile specimens from most metals

Please call 865-982-6300 for further information, or fill in the contact form below for a speedy response.

CNC Tensilkut III for Hardened Steel

September 26, 2017

This is a video demonstration of the CNC Tensilkut III cutting out the gauge section for one specimen of 1.4mm thick hardened steel. The starting size was 3/4″; the finished specimen is in accordance with ASTM E8, with the .500″ x 2″ gauge section, and the included .003″ taper.

This demonstration is 8 minutes long, and shows the entire cutting process.  Please contact us for more information or a quotation.

RIP, Cassini

September 15, 2017

In 1997, the Cassini spacecraft was launched, with the expressed mission of exploring Saturn.  For the past 7 years, it has done that, sending back spectacular images of our ringed neighbor, along with chemical details about the atmosphere of the planet and its moons, and the composition of its rings.  Today, it crashed into the surface of Saturn, sending a bit of final information on its way to oblivion.

Why does this matter to Tensilkut?  Because the Jet Propulsion Lab was a customer, as were many of its suppliers, and the Tensilkut system was used to test the materials traveling into space for nearly 20 years.  We are proud to have contributed to this exciting voyage in our own, peripheral way.  RIP, Cassini, and thanks for the memories.

10-33 Tensilkut I

Tensilkut I

How Long will a Tensilkut Machine Last?

September 13, 2017

We had an inquiry from a customer for replacement templates for their Tensilkut I.  They couldn’t find a nameplate containing the model and serial number of the machine, so they sent us a photo instead.

Tensilkut I from the early 1960s

Tensilkut I from the early 1960s

Judging from the color and the lack of a stainless steel top plate, this machine was built in the early 1960s.  A corner is missing, the phenolic plate is broken on one corner, yet the machine still works well.  There is at least one other unit of this vintage still in everyday use.  After 50 plus years, that’s pretty good.

And, yes, we were able to supply templates to this customer.

To Cut Straight Strips

September 12, 2017

Straight strips are a very valuable commodity in the laboratory.  In addition to needing a straight strip as the basis for cutting a test specimen, whether tensile, compression or another test, the straight piece is necessary for flexural testing, and is very valuable for other tests, including hardness testing.  The Tensilsaw is a very convenient way to cut strips from small plaques of plastic, fiberglass, composites, glass laminates and other non-metallic materials.

Visit our website or our YouTube channel for more video demonstrations of the Tensilsaw and our other equipment.