Rebound Testers

Physical Mechanics & Detection Technologies

Dynamic rebound testing evaluates material structural integrity without surface destruction by measuring the coefficient of restitution, defined as the speed ratio of rebound velocity (v_rebound) against initial contact velocity (v_impact). When an impact mass strikes a material surface, absorbed energy goes into localized surface deformation or heat dissipation, while restored elastic energy propels the body upward. Recording this velocity or height ratio yields immediate quantitative data across structural metals, flexible foams, rubber elastomers, and concrete.

Qualitest rebound instruments utilize four core detection mechanics aligned with specific material categories:

A. The Leeb Velocity Principle (QualiTip™ Series for Metals & Alloys)

For structural steel components, heavy castings, and field machinery, the QualiTip™ Series (including the QualiTip™ Plus, QualiTip™ II-Plus, QualiTip™ III, and compact QualiTip™ Lite) calculates surface hardness using the Leeb rebound equation:

HL = (v_rebound / v_impact) × 1000

An internal permanent magnet inside the impact probe shoots past an induction coil during impact and rebound strokes, generating a precise voltage pulse (electromotive force). Built-in signal processors capture peak voltage amplitudes to determine exact velocity ratios, displaying values on high-contrast OLED screens with automatic conversion to HRC, HRB, HB, HV, HS, and tensile strength values. This dynamic depends on the material’s yield strength to elasticity ratio (R_y / E), impact mass, contact speed, and indenter radius. Interchangeable impact probes, including the slender DL Probe variant, allow operators to measure inside narrow grooves, gear teeth, or internal pipe walls without special setups.

B. Photoelectric Automated Drop Mechanics (Qualitest Ball Rebound Tester for Foams)

For polyurethane foams, footwear midsoles, and flexible cushioning, resilience is measured as percentage rebound (R):

R = (h_rebound / h_drop) × 100%

The Qualitest Ball Rebound Tester drops a standardized steel test ball down a vertical column onto the specimen under pure gravity. Firmware controls the automated drop cycle to eliminate operator-to-operator variation, while an automated magnetic return system returns the ball to home position after each drop. A 4-line LCD screen reports individual test values, median results, and test status, while 1% graduation markings along the measuring column allow visual cross-checks. Built-in USB output exports results directly to LIMS databases without requiring external calibration.

C. Pendulum & Vertical Resiliometer Mechanics (QualiRebound™ Series for Elastomers)

Evaluating rubber compounds requires measuring dynamic energy return during high-rate impact. The QualiRebound™ Series offers specialized instruments built for specific elastomer requirements:

• Schob Pendulum Rebound Resilience (QualiRebound™ GB and pneumatic QualiRebound™ RDA): Utilizes a calibrated pendulum impact mass to evaluate elastomers within the 30 to 85 IRHD hardness range. Optical angle sensors measure energy returned after impact, while built-in digital controllers compute mean resilience percentages across test runs. Pneumatic clamping on the RDA model secures samples to eliminate slippage.
• Vertical Rebound Resiliometer (QualiRebound™ V1): Measures vertical bounce resilience by dropping a guided plunger mass vertically onto rubber specimens.

D. Mechanical Impulse Springs (Qualitest Concrete Rebound Hammer Series)

For field inspection on buildings, bridges, pillars, and structural masonry, the Qualitest Concrete Rebound Hammer Series (including the QualiCRH-2000A analog, QualiCRH-2000D digital, and QualiCRH-1000A High-Strength model) utilizes a spring-driven internal weight that strikes a plunger held flush against the concrete. The distance the internal weight rebounds along a calibrated mechanical slider or digital encoder yields a Rebound Index (R) correlating directly with concrete compressive strength.

Comparison of Qualitest Rebound Tester Lines & Technical Specs

Calibration Protocols & Overcoming the "Mass Effect"

Maintaining measurement integrity across production runs requires strict calibration routines and proper component support.

Addressing Energy Loss on Small or Thin Components

When testing lightweight or thin-walled metal components with a Leeb rebound probe (such as the QualiTip™ Series), the impact stroke can induce structural vibration in the specimen. This chatter drains energy away from the impact body, producing artificially low hardness readings, a physical phenomenon known as the mass effect.

• Sample Requirements: Accurate Leeb measurements require solid specimens meeting a minimum thickness threshold of 10 mm (3/8") and a minimum mass of 5 kg (11 lbs).
• Solid Rigid Coupling: Lightweight specimens under these thresholds must be clamped firmly onto a heavy steel support anvil using a high-viscosity acoustic coupling fluid to prevent energy leakage.

Electronic Sensor Calibration

For the Qualitest Ball Rebound Tester, the firmware-controlled drop system eliminates operator-to-operator variability and requires no external calibration tools, relying on factory-calibrated optical sensors to track ball bounce trajectory accurately over long production cycles.

Material Correlations & Testing Parameters

Rebound numbers provide direct quantitative material metrics when evaluated under standardized testing parameters:

• Viscoelastic Rubber Losses: Rubber resilience testing captures energy returned versus energy absorbed during high-strain impact. Selecting the correct system, such as the QualiRebound™ GB for Schob pendulum testing or the QualiRebound™ V1 for vertical drop resilience, ensures accurate characterization of dynamic dampening in tire compounds, seals, and flexible polymers.
• Concrete Strength Mapping: Rebound indices (R) measured with the Qualitest Concrete Rebound Hammer Series correlate directly to compressive load capacity via established empirical calibration curves, providing rapid non-destructive verification on job sites before proceeding with further construction steps.