How Does a Falling Dart Impact Tester Work?

What Is a Falling Dart Impact Tester?

A falling dart impact tester is a specialized instrument used to determine the energy required to cause a plastic film or sheet to fail under a defined impact. Instead of applying slow, steady force like a tensile tester, it simulates sudden, localized shock events—for example, a pallet corner striking a bag, or a filled pouch dropping onto a hard surface. The result is a quantitative measure of impact toughness that correlates more closely with real packaging failures.

Basic Principle of Operation

The core principle is simple: a hemispherical dart of known geometry and mass is dropped from a fixed height onto a clamped film sample. If the film ruptures, the test is recorded as a failure; if not, it is recorded as a pass. By adjusting the dart mass according to a staircase (up-and-down) sequence and tracking pass/fail outcomes, the tester calculates the characteristic failure mass (often referred to as M50), which corresponds to the level where roughly 50% of specimens fail.

MLB-01 Mechanics: From Clamping to Release

The MLB-01 combines controlled mechanics with guided software to make this process precise and repeatable.

1. Pneumatic Clamping

The film sample (typically at least 150 mm × 150 mm) is placed between two annular clamps. A pneumatic system applies a consistent clamping pressure around the circumference, ensuring that the film is held firmly and does not slip during impact. Compared with manual screw clamps, pneumatic clamping reduces operator-dependent variability and helps satisfy the clamping requirements described in standards.

2. Three-Jaw Pneumatic Dart Release

The dart must start its fall from a stable, centered position and be released cleanly. Instead of using an electromagnet, which can suffer from residual magnetism and inconsistent release of very light or heavy darts, the MLB-01 uses a three-jaw centering pneumatic gripper. The jaws grip the dart mechanically, then retract symmetrically when the test is triggered, allowing the dart to fall freely without induced rotation or delay. This supports a true free-fall condition at the specified drop height.

3. Solid Aluminum Foundation

Impact tests are sensitive to vibrations and movement of the test frame. To minimize these effects, the MLB-01 is built on a 20 mm thick solid aluminum alloy base that rests directly on the lab bench. The high mass and rigidity reduce resonance and unwanted motion during impact, helping ensure that the energy is absorbed by the film and not dissipated through a flexible or hollow chassis.

4. Staircase Calculation: The “Brain” of the System

In the staircase method, each impact outcome determines the mass for the next test:

• If a specimen fails, the dart mass is decreased by a fixed increment.

• If a specimen passes, the dart mass is increased by the same increment.

After a sufficient number of tests (typically at least 20), the sequence of masses and outcomes is used to calculate the impact failure mass M50. The MLB-01 guides the operator through this sequence on the touchscreen, records each result, and performs the calculation automatically. This eliminates manual spreadsheet work and reduces the risk of arithmetic errors.

Why Use an Instrumented Tester Instead of Manual Rigs?

Compared with improvised or manual test setups, a dedicated instrument such as the MLB-01 offers several advantages:

• Reduced calculation errors: The staircase algorithm and final M50 calculation are applied consistently by the software, independent of the operator.

• Improved safety: Pneumatic clamping and remote release keep hands away from the drop zone, and the dart path is controlled by the test frame.

• Higher repeatability: Standardized clamping, clean release, and a rigid base structure minimize variability caused by equipment and handling, so differences in results reflect the film, not the test rig.

For labs and factories that rely on impact data to make design and release decisions, these mechanical and software features are critical to obtaining reliable, audit-ready results.