Selection considerations
In the evaluation of the safety performance of packaging transportation, the drop testing machine is the key testing equipment. When selecting a model, users are often faced with the choice of single-arm and double-arm structure. In fact, this choice is not determined by the equipment itself, but mainly by the size and weight parameters of the package to be tested. Understanding this core principle helps users make informed decisions based on actual testing needs.
Principle
Single-arm drop testing machines usually use a column support release mechanism, and the packaging is pneumatically or mechanically clamped or placed on the bracket, lifted to a predetermined height and released. Its relatively compact structure makes it suitable for packages with a symmetrical center or even weight distribution.
The double-arm drop tester uses two parallel columns to secure the package with a two-point lifting and release mechanism. This design provides better balance and stability, especially for packages with larger sizes, irregular shapes, or a pronounced center of gravity.
Determine the core parameters of selection
The maximum outline size and gross weight of the package are the primary technical indicators that determine whether to choose a single-arm or two-arm model. The following relationships can help you decide:
The mass of the package is m (kg) and the maximum side length is L (mm). The maximum carrying capacity of the device is noted as Mmax, the effective table size (or clamping range) is denoted as Smax。 The selection must meet the following requirements:
m ≤ Mmax And L ≤ Smax
When the package is lighter (e.g. m < 50 kg) and smaller in size (L < 800 mm), a single-arm construction usually meets the requirements. When the packaging is of large mass or long size, the double-arm structure is a safer choice due to its better rigidity and balance, which can effectively prevent tilting or overturning during the drop process and ensure that the falling posture meets the standard requirements.
Selection reference for different application scenarios
The following table compares the suitability of the two structures under different packaging parameters and can be used as a basis for initial screening.
| Packaging feature parameter tendency | Recommended types of structures to prioritize |
| Lighter mass, regular shape, small size | Single-arm structure |
| Larger mass, or longer in size, or irregular in shape | Double arm structure |
| Directional drop tests such as edge and corner drops are required | Double arm construction (better stability) |
| Laboratory space is limited and testing is not frequent | Single-arm structure |
Test effectiveness
The selection must ensure that the equipment capacity meets the requirements of the relevant test standards. Domestic and foreign standards such as GB/T 4857.5 and ISO 2248 have clear regulations on the drop height, the flatness of the impact surface, and the momentary posture of release. Dual-arm construction is often more advantageous in guaranteeing smoothness and attitude accuracy at the moment of release of large packages, which is crucial for ensuring the validity and repeatability of test results. Users should carefully check the specific description of the specimen fixation and release method in the standard.
Other auxiliary selection factors
In addition to size and weight, test efficiency, subsequent expansion needs, and safety protection must also be considered. Dual-arm models typically lift more smoothly and are helpful for high-frequency or automated testing needs. At the same time, the range of package sizes that may be tested in the future should be taken into account to reserve an appropriate capacity margin for the equipment. The safety protection devices of the equipment, such as the anti-secondary fall mechanism, fence, etc., are also an important part of ensuring the safety of the operation.
Conclusion
Drop testing machine selection is a technical decision-making process oriented by testing requirements. The choice between single and double arms is fundamentally determined by the size and weight of the package to be tested, taking into account standard compliance, test validity and operational safety. It is recommended that users clarify the parameter range of their own conventional and maximum test packages before selection, and use this as the core basis to choose the equipment structure that matches the capability, so as to ensure the accuracy and reliability of the packaging transportation safety test.
References
GB/T 4857.5 Packaging - Basic tests for transport packaging - Part 5: Drop test methods
ISO 2248 Packaging Complete, fully packed shipping packaging Vertical impact drop test
ASTM D5276 Standard Test Method for Testing Drop Tester for Fully Loaded Boxes and Products