ASTM D5331 Mechanical Handling of Unitized Loads

ASTM D5331 package testing evaluates and compares unitizing films by assessing their ability to withstand various types of mechanical handling. As an ISTA and ISO 17025 certified lab, we realize the importance of mechanical handling testing. Meeting the ASTM D5331 requirements can be difficult. We understand the challenges and guide companies through the process.

Keystone takes a consultative approach throughout the entire test program. When packages do not meet the requirements, we assist with finding solutions. We are in constant communication throughout the test process. Our engineers take pride in delivering quick and accurate ASTM test results.

Request a quote to receive testing services customized to your specific needs. Have a question about unitized loads wrapped with films? Contact us and we will determine the best course of action.

Summary of ASTM D5331 Mechanical Handling of Loads Secured with Stretch Wrap Information

The test method applies to common means of handling which include forklifts, push/pull, clamp trucks, cranes, and spade lift-type handling systems. The test levels can change to better reflect known levels of intensity in the field. ASTM D5331 focuses on sample preparation and evaluation when assessing the performance of stretch film for load unitizing.

For this standard the following terms are defined:

          Large shipping case or create – a shipping container (any material) of size and weight that requires mechanical handling. This unit can weigh from 100 lbs to many tons. It can be secured or carried by a base or pallet. A frame may be provided to stabilize rigidity throughout the container.

          Spade lift attachment – a lift truck attachment that is used for top handling products. The products can include interlocking flange cartons (IFC), folded caps, or folded flap-style cartons.

          Unitized load – two or more packages that are wrapped or banded together as one shipping unit. 

Scope of ASTM D5331 Mechanical Handling Package Testing

When unitized the packages normally weigh more than 100 lbs. The packages can be unitized using shrink wrap, banding, strapping, taping, or gluing. The unitized load can but does not necessarily have to include a pallet or slip sheet.

ASTM D5331 is often used to compare the performance of unitizing films. However, it can also be used to compare one kind of wrapping material used in different wrap cycles.

It is important to note that there has not been a direct correlation established between test results and field performance. Rather, the ASTM D5331 integrity test simulates mechanical handling during all distribution phases. A user can customize the test to simulate a particular distribution environment. To do this the user may use discretion to establish test levels and the number of test cycles.

Significance of ASTM D5331 Unitized Loads Package Testing

The two apparatuses used in this test are the load-wrapping apparatus and the mechanical handling apparatus. A load-wrapping apparatus is a machine that wraps the test load. This method should be as close as possible to the actual method of wrapping that is used in production before shipping.

The mechanical handling will be determined by the test method. To prepare the test loads, begin by arranging the packages in a manner that is similar to actual production. They may be loaded in layers or stacked on a pallet or slip sheet. The load should then be wrapped with the unitizing film using a predetermined percent stretch and wrap cycle. 

Again, this is predetermined by the user using their discretion. Then, the unitized load should be left untouched for a minimum of 16 hours before conducting the test. This time allows the stretched wrapping material to reach an equilibrium of its stress retention forces. The test will then be conducted according to the test procedure chosen.

The test procedures include palletized load, spade lift, clamp handling, and push/pull handling. ASTM D6055 provides more information on compliance procedures of palletized loads, spade lifts, clamp handling, and push/pull handling

After the test, the laboratory will record data and compile a test report that includes all the information outlined in the ASTM D5331 standard. This includes:

  • Dimensions of the unit
  • Weight of each unit
  • Procedures used
  • Height of rotational drop

Expert Unitized Loads Secured with Stretch Wrap Films Package Testing

Keystone Package Testing can accommodate flexible and rigid packages of all sizes, including large pallets. Our team strives to give our customers more time and energy on product development instead of testing. In addition to ASTM D5331 testing, Keystone has a full scope of expertise including drop, vibration, and sterile barrier.

Request a quote or contact us at (724) 657-9940 to learn first hand why so many companies partner with Keystone to achieve their package testing certification needs.


For more referenced ASTM standards and similar testing, please follow the links below:


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