In the complex world of distribution, ensuring the safe delivery of products depends heavily on the ability of packaging systems to withstand the physical stresses encountered during transportation. One critical factor that affects product integrity is vibration. Whether products are being moved via trucks, railcars, or forklifts, the vibrations during transport can pose significant risks to packaged goods. Understanding the vibration environment during distribution is therefore essential to designing packaging systems that can protect products from damage. This article delves into the findings of CPULD’s graduate student, Yu Yang Huang’s study aimed at measuring and analyzing vibration levels during forklift handling and its implications for pre-shipment testing.

Forklifts are an integral part of the distribution process, performing a variety of handling tasks such as loading, unloading, and organizing goods in warehouses. While much research has focused on the vibrations produced by large transportation vehicles like trucks and railcars, forklifts present unique vibration environments that must also be understood. The purpose of Huang’s study was to analyze the average vibration levels generated by forklifts and to provide insights that can be used for pre-shipment testing of packaging systems. By accurately simulating the vibration environment that occurs during forklift handling, packaging engineers can better assess the durability and suitability of their packaging systems.

To obtain a comprehensive understanding of forklift vibration, various forklifts were observed and measured. The acceleration-time data collected during these tests were analyzed using power spectral densities (PSD), a tool used to represent the distribution of power across different frequencies. The data revealed that the vibration levels peaked between approximately 2.5 and 5 Hz, after which the intensity of vibration continuously decreased to around 120 Hz. Beyond this point, very few vibration peaks were recorded, indicating that high-frequency vibrations above 120 Hz are rare in forklift handling environments.

Image 2. Representative pictures of the forklift simulator jig. The main components of the jig are: 1) Forklift Carriage, 2) Fork Tines, 3) Accelerometer, 4) Angle Adjustment Shims, and 5) String Potentiometers.

Image 1. Representative pictures of the forklift simulator jig. The main components of the jig are: 1) Forklift Carriage, 2) Fork Tines, 3) Accelerometer, 4) Angle Adjustment Shims, and 5) String Potentiometers.
Image 2. Representative pictures of the forklift simulator jig. The main components of the jig are: 1) Forklift Carriage, 2) Fork Tines, 3) Accelerometer, 4) Angle Adjustment Shims, and 5) String Potentiometers.
Image 3. Representative pictures of the unit loads used to conduct the experiments in the across the length orientation: (a) unbounded unit load, (b) bounded unit load.
Image 3. Representative pictures of the unit loads used to conduct the experiments in the across the length orientation: (a) unbounded unit load, (b) bounded unit load.

Huang’s study also compared the vibration levels observed in forklifts to those measured in other transportation vehicles. Interestingly, forklift vibration levels were found to be 1.2 to 1.3 times lower than those produced by trailer trucks and small transportation vehicles. However, the vibration levels were roughly equivalent to those found in railcars, suggesting that forklifts create a relatively gentle vibration environment compared to other types of transport.

Based on the data collected, Huang proposed a recommended vibration test spectrum for forklifts. This spectrum covers the frequency range of 1 to 120 Hz and includes six smoothed breakpoints. The overall Grms (root mean square of acceleration, a measure of vibration intensity) for the spectrum was found to be 0.29. This recommended spectrum can be used for the forklift vibration testing of packaging systems in pre-shipment testing, much like the standards set by organizations such as ASTM International and the International Safe Transit Association (ISTA) are used for truck and railcar vibration testing.

One of the key contributions of this research is its focus on forklifts, a transportation method that has often been overlooked in vibration studies. Forklifts, while less likely to produce extreme vibrations, when compared to trucks or railcars, still generate significant stresses on packaging systems. Packaging engineers must therefore ensure that their packaging designs can withstand these vibrations, especially for products that spend considerable time being handled by forklifts. Huang’s research highlights several critical considerations for packaging engineers and supply chain managers tasked with designing and testing packaging systems for forklift transport. The recommended vibration spectrum provides a valuable tool for pre-shipment testing, allowing engineers to simulate forklift vibration levels and assess the suitability of their packaging designs.

As a next step, the researchers plan to publish further results focusing on shock-like events, such as those caused by potholes or sudden stops, which can occur during forklift transport and handling. These shock events, which can occur in both the lateral and longitudinal directions, are just as important to consider as vibration when evaluating the durability of packaging systems.

In conclusion, Huang’s research provides a solid foundation for improving packaging design and testing for forklift transport. By understanding the vibration environment specific to forklifts and using the recommended test spectrum, packaging engineers can enhance the safety and durability of their packaging systems, helping to ensure that their products reach the destination without damage.

Read the full research article here: https://asmedigitalcollection.asme.org/testingevaluation/article-pdf/doi/10.1520/JTE20210293/7144991/10_1520_jte20210293.pdf