Specification builder · Tier D
Stent radial force tester (iris-type radial compression) for radial resistive force, chronic outward force and crimp profile of vascular stents at 37 deg C
A stent radial force tester squeezes a stent evenly with a multi-segment (iris-type) head and records force against diameter, giving the radial resistive force of balloon-expandable stents and the chronic outward force of self-expanding stents at body temperature (37 deg C). It is bought by medical-device testing laboratories, stent manufacturers and research groups to check stents against ASTM F3067 and ISO 25539-2. Very few companies make this instrument, so competition in tenders is limited.
What this equipment will do
- Stent types: balloon-expandable and self-expanding coronary stents, diameters up to 14 mm.
- Stent types: peripheral stents, diameters up to 30 mm. (with the optional module)
- Stent types: stent grafts and large self-expanding frames, diameters up to 60 mm (ISO 25539-1). (with the optional module)
- Force-diameter curve while the head closes on the stent and opens again (ASTM F3067).
- Radial resistive force / radial strength of balloon-expandable stents at set diameters (ASTM F3067, ISO 25539-2).
- Chronic outward force of self-expanding stents at set diameters (ASTM F3067, ISO 25539-2).
- Testing at body temperature, 37 deg C: dry in a heated head or chamber, or immersed in a water / saline bath. (with the optional module)
- Programmed diameter ramps, holds and crimp-release-reload cycles saved as test methods. (with the optional module)
- Radial stiffness and hysteresis, curve overlays and batch statistics (mean, SD). (with the optional module)
- Crush resistance between flat plates and local (pinch) compression of stents (ISO 25539-2). (with the optional module)
- Film-loop (sling) radial force of stents and stent grafts. (with the optional module)
- Crimped and expanded outer diameter (crimp profile) by laser micrometer (ASTM F2081), and elastic recoil from expanded and recoiled diameters (ASTM F2079). (with the optional module)
Not covered: Stent securement (force to dislodge the crimped stent from its balloon, ASTM F2394) needs the stent securement tester.; Stent durability over hundreds of millions of pulsatile cycles (ASTM F2477) needs a stent/graft pulsatile durability tester.; Delivery-system trackability and pushability need a trackability test system; balloon burst and inflation tests need a balloon burst / leak tester.; The radial head is not a precise dimensional gauge: strut and wall dimensions need a measuring microscope or video measuring system.
Loading the builder...
Standards this specification draws on
- ASTM F3067-26 Current guide for radial loading of balloon-expandable and self-expanding vascular stents (radial strength, collapse pressure, chronic outward force); defines what the tester must be able to do.
- ISO 25539-2:2020 International standard for vascular stents; requires evaluation of radial force / radial resistive force, chronic outward force, crush resistance and dimensions.
- ISO 25539-1:2017 Standard for endovascular prostheses (stent grafts); includes radial force testing of large self-expanding devices.
- ASTM F2079-09(2022) Test method for intrinsic elastic recoil of balloon-expandable stents, measured from expanded and recoiled diameters.
- ASTM F2081-06(2022) Guide for measuring and reporting dimensional attributes of vascular stents, including crimped profile.
- FDA guidance: Non-Clinical Engineering Tests and Recommended Labeling for Intravascular Stents (2010) FDA guidance that asks for stent diameter versus uniformly applied radial pressure, recoil and crimped profile data.
- ISO 7500-1:2018 Method for verifying and classifying the force-measuring system of testing machines.
- ASTM E4-24 US practices for force calibration and verification of testing machines, accepted alternative to ISO 7500-1.
- ISO/IEC 17025:2017 Accreditation standard for testing and calibration labs; requires calibrated, traceable equipment and controlled records.
- 21 CFR Part 11 US FDA rule on electronic records and signatures; applies where electronic radial force results are used for batch release or regulatory decisions.
- IEC 61010-1 Electrical safety standard for laboratory and measuring equipment, including heaters and chambers.
- IEC 61326-1 EMC standard for laboratory and measuring equipment.
Common mistakes in tenders for this equipment
- Copying one maker's station names, diameter ranges or exact force figures (for example a specific 16 mm / 660 N head) so only that brand can comply; state the device sizes you will test and use "not less than".
- Requiring audit trail and electronic signatures, wet-bath testing and a flat-plate crush fixture all together, which leaves only one or two possible bidders; separate the true needs from nice-to-haves.
- Asking only for "radial force at 37 deg C" without an independent temperature probe, pin gauges and calibration weights, so the lab cannot prove its results to an ISO/IEC 17025 assessor.
- Buying a single large head and one high-capacity load cell for coronary stents whose radial force is a few newtons, giving noisy and unreliable results.
- Ignoring after-sales reality: these makers rarely have Pakistan engineers, so tenders without depot-repair times, shipping cost, a loan head and 10-year parts commitment leave the tester idle for months.
- Forgetting crimp profile and recoil: the radial head is not a precise diameter gauge, so a laser micrometer is needed if crimped profile is a test item.
- Asking for DRAP medical-device registration or ISO 13485 for the tester itself; it is laboratory test equipment and this demand only confuses bidders.
- Comparing bids on headline force capacity instead of empty-head friction, low-force accuracy and temperature control, which decide the quality of results.