Ball Rebound Tester

The instrument is two units: a test stand that carries the down-pipe, and an electronic console that reads each rebound and calculates the result. The test stand measures 7.87 x 9.84 x 23.6 in (200 x 250 x 600 mm) and the electronic unit 7.87 x 6.73 x 3.54 in (200 x 171 x 90 mm), so the pair sits comfortably on a standard lab bench.

The steel ball weighs 16.3 ± 0.2 g and, in the standard set-up, falls freely from 19.7 in (500 mm) onto the specimen. Both values are fixed by the hardware, so every operator runs the test the same way.

The console runs on 100-240 VAC at 50/60 Hz, which covers mains supplies in North America and most other regions. The electronic unit is rated IP 30 and the down-pipe IP 20, a rating meant for a dry indoor laboratory rather than a wet production area.

Every result appears first on the console's 4-line LCD, which shows the test cycle, the measured values, the median value in %, the status and the operating instructions. For many routine checks the operator simply reads that median and records it.

For electronic records the console has a V24 RS 232 output running at 9600 baud with 1 start bit, 8 data bits and 1 stop bit, plus a USB port for transferring results off the instrument.

Those are ordinary serial settings, so a PC or a laboratory system can receive the readings once its port is set to match. If you want the results to land in a spreadsheet without retyping, the cable, adapter and Excel transfer software are listed among the accessories for this tester.

The standard instrument is ready to test as delivered. The accessories extend it in two directions: a second drop height, and electronic transfer of results.

For a second drop height we offer the EKF 18.1 in (460 mm) down-pipe with its own magnetic system, together with a works calibration certificate for 460 mm ball rebound. Labs that report to more than one specification can keep both pipes and fit the one the method calls for.

For data, the options are a data output cable, a USB adapter and GKB03 software, which carries results from the console into Excel.

Tell us the foam you test and the standard you report to in a request for a quotation, and we will confirm which of these items your lab needs.

A single drop takes seconds. The magnetic system releases the ball, it falls down the pipe onto the specimen, the rebound is measured, and a sensor placed close to the holder returns the ball to its home position, ready for the next drop.

The console does the arithmetic as the readings come in and gives the average as a percentage, so there is no hand calculation at the end. That is why we describe the instrument as having a short measuring cycle.

Total time per specimen is set mostly by your test method rather than by the tester. The standard you report to defines how many rebounds are taken on each specimen and how the specimens are conditioned beforehand, and that preparation usually takes longer than the drops themselves. For a batch, plan the time around cutting and conditioning; the rebound series itself moves quickly.

As standard, the instrument ships with the main unit test stand, the electronic console, the EKF 19.7 in (500 mm) down-pipe with a magnetic system, and a works calibration certificate for 500 mm ball rebound. That is everything needed to start testing to the standard method.

The design aim is an instrument that is switched on and used. It is a plug and play system, extremely easy for a new operator to learn, and it has no calibration requirements in normal use, so there is nothing to adjust between tests.

Anything beyond that set is ordered only when your method or your reporting calls for it, such as a second drop height or transfer of results to a computer. The accessories question on this page lists those items.

A ball rebound result is defined by three things: the ball, the height it falls from and the specimen it lands on. The tester fixes the first two by design, with a toleranced steel ball and a down-pipe of set length whose magnetic system releases the ball the same way on every drop.

Each instrument ships with a works calibration certificate for the drop height it is supplied with, so the set-up is documented from the first test.

The third factor sits with the lab. Foam results are sensitive to specimen condition, so cutting and conditioning to the standard you report to matter as much as the instrument. When two sites disagree, compare specimen preparation and conditioning before anything else.

If you need the certificate details for an accreditation file, get in touch with our team and we will go through what it covers.

The tester is built for flexible foams: polyurethane foam and similar flexible cellular materials, the class covered by DIN EN ISO 8307 and ASTM D3574. Typical work is incoming inspection of foam sheet, batch-to-batch comparison in production and screening of new foam formulations.

Specimens are 3.94 x 3.94 in (100 x 100 mm) and 1.97 in (50 mm) high, so the material has to be available as a block or sheet that can be cut to that size.

Solid rubber compounds call for a different rebound method. For those we offer the GenRebound vertical rebound resilience tester, which uses a falling hammer, and the Pendulum Rebound Resilience Tester for elastomers, with a heater option for testing warm samples.

The ball is 0.63 in (16 ± 0.2 mm) in diameter. It is a magnetic steel ball, which lets the magnetic system in the down-pipe hold it and release it cleanly at the start of each drop.

Diameter matters because the size and mass of the ball together set the energy delivered to the foam and the area it lands on. The ball rebound standards fix both, which is what makes results from different labs comparable.

Keep the ball clean and free of damage, since dirt or a dent changes the contact with the foam surface. For the other instruments we build to measure foam and rubber resilience, see our rebound testing equipment range.

Yes. The tester comes certified in accordance with ASTM D3574, the ASTM collection of test methods for slab, bonded and molded flexible polyurethane foams, and it runs the ball rebound resilience procedure in that standard.

ASTM D3574 contains many separate procedures, including indentation, tensile and tear tests, and each needs its own equipment. Indentation force deflection, for example, is run on a compression set-up, not on a rebound tester.

When you send us your specification, name the D3574 test it cites and we will match it to the right instrument. Our ASTM D3574 standard page lists the NextGen equipment that supports this standard.

Yes. The tester comes certified in accordance with DIN EN ISO 8307, Flexible cellular polymeric materials, Determination of resilience by ball rebound.

The method drops a steel ball of set size and mass freely from a fixed height onto a foam specimen and expresses the rebound as resilience in %. Our standard configuration, with its down-pipe, magnetic release and works calibration certificate, is set up for this method out of the box.

The standard is most useful as a comparative check between foam lots, suppliers and formulations, and it works best when specimen preparation and conditioning are kept the same from test to test. Many of our customers run it alongside indentation and compression set tests, since rebound does not replace full cushioning characterization.