June 29


How to Design Puncture-Resistant Fabric Dunnage

By Steve Melito

June 29, 2017

puncture-resistant fabric dunnage, rack bag design

Fabric dunnage that’s not puncture-resistant can shred the best packaging designs. For example, in the automotive and heavy truck industries, parts that are designed to lock into place can tear rack bags during parts loading and unloading. Small rips can become big holes, and parts bags that lack sufficient strength won’t last long. Torn fabric dunnage can also fail to protect the parts themselves.

For packaging engineers, preventing punctures starts with analog design. Instead of just looking at your digital files, Hold-True loads and unloads sample parts into prototype WIP bags. Part drawings contain important information, but working off-line will reveal problems like point loading. Choosing a puncture-resistant base material is important, but you’ll also need to follow some design guidelines about protective panels, structural members, bonding, and fabrics.

Protective Panels

Protective panels that are made of high-density polyethylene (HDPE) provide protection against point loading and abrasion. Hold-True sews HDPE panels onto rack bags and can recommend the right sheet thickness to use for your application. With steel sun visors and other parts that have sharp metal corners, it’s important to avoid using HDPE sheets that are too light. Otherwise, the plastic can crinkle or bend. If additional support is required, structural members offer a solution.

Structural Members

CON-Pearl® is a structural plastic that’s both strong and lightweight. Unlike Pcorr, a type of corrugated plastic sheeting that’s used with sewn fabric dunnage, CON-Pearl® provides strength in every direction. Depending on the application, Hold-True may recommend using sheets of CON-Pearl® in thicknesses of 3/8” or 1/16”. Thicker sheets aren’t necessarily better, however. If a plastic sheet is too thick, parts like a cabinet with attachment points may dig through.


As some packaging engineers have learned the hard way, it’s difficult to bond HDPE to CON-Pearl® with regular glues. Most bonding agents that adhere to one substrate won’t stick to the other. Even plastic glues don’t work well because the two substrate materials are so dissimilar on a molecular level. That’s why Hold-True uses a specialized glue to achieve strong, reliable bonds. This bonding agent costs more than regular glues, but provides a strong return on investment (ROI).


Finally, Hold-True can incorporate thin pieces of fabric into your fabric dunnage design to support parts loading and unloading. Design houses that only look at digital files can tell you how much a part weighs, but they lack the application knowledge to support ease-of-use for assembly line workers. To learn more about how Hold-True uses analog design to make puncture-resistant fabric dunnage, please contact us.

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