Design Guide for PP Industrial Dunnage and Handling Trays in logistics and warehousing: Draft, Radii and Draw Ratio

Thermoforming rewards designs that respect how a heated sheet stretches. These rules prevent most tooling rework and most thickness complaints.

This guide is written for engineers, purchasers and project managers who need a practical answer, not a resin data sheet.

Product Overview

This category covers a family of products rather than a single item. In practice a buyer defines industrial dunnage and handling trays by three things: the base resin, the format or dimension, and the performance or certification level it has to meet. Typical options in this category include returnable and reusable designs; gauge 1.5 to 8.0 mm; ESD and conductive grades. Materials most often specified are Polypropylene, High Density Polyethylene, Polycarbonate, Acrylonitrile Butadiene Styrene, and the choice between them changes stiffness, temperature resistance, chemical behaviour and price.

In the logistics and warehousing sector the decision is usually driven by stackability and returnability, with traceability as a secondary requirement. Typical end uses include dunnage trays, parts supermarket trays, returnable trays.

Key Material Properties

These figures are typical for commercial grades and should be confirmed against the supplier's certificate for your specific lot.

Polypropylene is frequently the default selection here: PP is the lightest mainstream packaging resin and keeps its shape under repeated flexing.

Design Rules for Thermoformed Parts

A few geometry decisions made on the drawing save weeks of tooling adjustment later.

• Avoid undercuts unless the tool has moving sections, which adds cost to every cycle.
• Use a draft angle of at least 3 degrees per side so the part releases without vacuum locks.
• Keep the draw ratio moderate: deep cavities thin the sheet and force you to start with a thicker gauge.
• Design uniform wall thickness by avoiding abrupt depth changes in the same cavity.
• Leave a flat sealing flange of at least 6 mm when the pack has to be heat sealed or lidded.
• Make corner radii at least equal to the sheet thickness; sharp corners are where holes start.

Send these rules to your designer together with the sheet gauge and the target cycle time; most tooling modifications come from ignoring draft and corner radii.

Common Grades and Variants

• Polypropylene based: lowest density among commodity plastics
• Polyethylene Terephthalate based: excellent barrier to CO2 and moisture
• Polycarbonate based: outstanding impact strength (250x glass)
• Acrylonitrile Butadiene Styrene based: high impact toughness

Beyond the base resin, most suppliers offer UV stabilised, food contact, flame retardant, anti-static and recycled content versions of the same product. Ask which additive package is included, because it is often the difference between a part that lasts three years and one that lasts ten.

Processing and Finishing Options

The route below is the one most factories use for this type of part.

• Assembly
• Cnc trimming
• Twin sheet forming
• Thick gauge thermoforming

Secondary operations such as printing, welding, machining and assembly are often cheaper to do in the same factory, and they reduce the risk of mismatch between components.

How to Specify Industrial dunnage and handling trays Correctly

Work through these points in order and most specification mistakes disappear.

1. validate washing and drying resistance
2. check stack load and conveyor compatibility
3. define the number of returnable trips expected
4. specify ESD grade if electronics are handled
5. design locating features that survive repeated use

Send this list to your supplier with the drawing and you will receive comparable quotations from every factory you contact.

Frequently Asked Questions

What packing and shipping options are available?

Standard packing is export cartons on fumigation-free pallets, with custom labelling, barcode and retail packing available. We also handle consolidated containers and door to door delivery.

Do you offer samples?

Yes. Standard samples are normally free of charge and shipped within three working days; custom samples are charged at cost and credited against the first production order.

What is the minimum order quantity for industrial dunnage and handling trays?

For standard sizes and colours the minimum is usually one pallet or one production run; for custom tooling the economic minimum depends on the tooling cost amortised over the expected volume. Send us your annual volume and we will calculate the break even point.

How long does tooling and sampling take?

A new tool typically takes 25 to 45 days depending on cavity count and complexity, followed by T1 samples within one week. Existing tools can usually start production within 10 to 15 days of order confirmation.

What tolerance can be achieved?

Standard production tolerance follows the relevant ISO or DIN tolerance class for the process; tighter tolerances are possible after machining or grinding, but they add cost. Define the tolerance only on the functional dimensions.

Conclusion

Our team supplies industrial dunnage and handling trays to logistics and warehousing customers worldwide, with samples, material certificates and full inspection reports available before mass production.