TTR2 - Radial Force Tester

Model TTR2 Tensile Testing Machine

The Blockwise Tensile Testing Machine Model TTR2 is a tabletop machine designed to measure the radially-outward force of a stent or similar device, as a function of its diameter
  • Purpose-Built Software
  • Easy to Learn
  • Easy to Calibrate

The TTR2 uses a rotating-nut-type stepper motor linear actuator to move the input arm of a low-friction radial compression mechanism. Motion of the input arm causes the opening diameter to change. The diameter of the opening is measured by an encoder on the stepper motor. The linear force is measured by a precision force transducer and converted to radial force Knowledge Base: Measuring Radial Force.

Various sizes of Blockwise metal compression stations may be attached to the machine. Compression stations can be quickly removed and replaced. All of the compression stations feature low friction and linear relationship of stroke to diameter. To obtain the lowest friction and lowest purchase cost, choose the smallest mechanism that accommodates your size range. Temperature control systems are optional, and are sold as part of the compression stations. Some compression stations use heaters embedded in the dies, while others use an overall oven-type enclosure. Temperature may be set in the range of room temperature to 50C (most typically 37C).

Radial Force Software

TTR2 includes a laptop PC with “Blockwise Radial Force” application software preinstalled. The software is intuitive and powerful; new users can get meaningful results within a few minutes. Context-sensitive help concisely describes all controls and displays.

The software helps the user calculate “radial strength” of balloon-expandable stents, and “chronic outward force (max and min)” of self-expanding stents, as described in the testing standard ASTM 3067.

Several types of test sequence are available, including manual settings of diameter or radial force, ramp, cycle, or arbitrary user-defined diameter sequences. Test data can be written to .csv files for analysis by a spreadsheet program.

Radial force can be displayed, graphed, and saved in various forms and units, including radial force per length, hoop force, hoop force per length, and pressure.

For test very low-force devices, a “Friction Compensation” feature can be used to remove most of the compression station’s internal friction from the results.


Calibration is very quick and easy, for both diameter and force. Calibration standards (pin gage for diameter and weight for force) are supplied with the machine, or you can use your own. Only one pin is needed for complete diameter calibration. The machine can be calibrated without removing the compression station. Calibrating the diameter does not necessitate a force recalibration, or vice-versa.

The TTR2 requires no maintenance. The radial compression mechanism also requires no maintenance - just keep the mechanism clean. Do not use in a dusty or dirty environment. You may clean the mechanism by blowing with compressed air. You may clean the center opening with 99% isopropyl alcohol on a lint-free swab or cloth.


Required Installation Connections – Model TTR2

Description Physical Specs Functional Specs Comments
Electric Power Powers the force signal conditioner, actuation motor, heaters, etc. C13 Coupler (IEC 60320) 100-125 VAC 6A 50-60 Hz or 220-240 VAC 6A 50-60Hz See the label on the compression station; heaters are wired for EITHER 110V or 240V
Compressed Air Not Required

Model TTR2 with J-Crimp™ Compression Station

With a decade of service in radial force testing the J-Crimp™ is a proven choice. We recommend you select this model unless you need a bigger size, higher force, or special features. High precision, very low friction, no die-to-die wear, high durability.

Diameter: 0-16 mm
Length: 62, 124 mm
Max Radial Force: 660 N
Radial Force Typical Friction Level: +/-0.4 N
Diameter Resolution: .00074 mm
Radial Force Resolution: .006 N

Model TTR2 with Twin-Cam™ Compression Station

For measurement of very large diameter products,, the Large Twin-Cam™ compression station provides the lowest friction in its size range. Small gaps, no die-to-die wear, high durability

Diameter: 0-30 mm
Length: 124, 310 mm
Max Radial Force: 980 N
Radial Force Typical Friction Level: +/-0.8 N
Diameter Resolution: .00091 mm
Radial Force Resolution: .005 N

Model TTR2 with Large Twin-Cam™ Compression Station

For very large diameter measurements, the Large Twin-Cam compression station provides very low friction and wear, and the best process control available for the size range. Small gaps, no die-to-die wear, high durability

Diameter: 0-60 mm
Length: 124, 248 mm
Max Radial Force: 930 N
Radial Force Typical Friction Level: +/-1.5 N
Diameter Resolution: .00095 mm
Radial Force Resolution: .005 N