For automated pick-and-place applications, knowing the dimensions of a thermoformed tray isn't enough. The automation needs a repeatable reference that establishes where the product cavities are located. That reference should come from the formed geometry of the tray—not simply the die-cut flange.
Why Not Locate From the Flange?
Thermoforming and die cutting happen at separate stages of production. Because of form-to-cut registration tolerance, the formed tray can shift slightly relative to the outside die-cut flange.
If the automation locates the tray from the flange, that variation can change where the cavities are positioned relative to the programmed pick points.
Locate From Formed Geometry
Instead of locating the tray from the die-cut flange, automation can locate it using formed features that have a fixed relationship to the product cavities.
The cavities, sidewalls, and locating features are produced from the same hard tooling. This means their positions relative to one another remain consistent. When the fixture locates the tray from a formed feature, it isn't simply establishing where the tray is—it is establishing where the entire cavity pattern is positioned.
For automation, the relationship looks like this:
fixture → locating feature → cavity → product
One way to do this is to design formed locating features into the tray that work with the customer's fixture. Chamfered locating pins can account for some initial tray offset and guide the tray into position as the pins engage the formed locating features.
Once the tray is located in the fixture, the automation has a repeatable reference for where the cavities—and the products inside them—are positioned.
Depending on the application, the same principle can be applied using the tray's formed outside walls. Fixtures positioned at known locations can guide or center the tray from these formed surfaces rather than relying on the die-cut perimeter.
Design For the Gripper
How the robot picks up the product also needs to be considered when designing the tray.
Engineering needs to know how far the gripper opens and closes, how deeply it enters the cavity, where it contacts the product, and how much clearance it needs around the product and tray.
This information can affect cavity spacing and geometry. A tray can hold the product correctly but still cause problems in automation if the gripper doesn't have enough room to access, pick up, and release the product.
Engineering also needs the product's dimensional tolerances when designing the cavity. The cavity needs to accommodate acceptable product variation while maintaining the positioning or retention required for automated handling.
Considering Automation Early In Design
For automated applications, information about the locating method, fixture, grippers, suction cups, or other end-of-arm tooling should be shared with engineering at the start of the tray design process.
Ideally, the thermoformed tray and its critical geometry are established before the automation system is finalized. This gives the automation designer a defined tray to work from, while allowing the locating method, product orientation, and gripper clearance to be considered during tray development.
When possible, Dordan evaluates the tray alongside the customer's fixture and end-of-arm tooling in 3D CAD before production tooling is built.
Establishing the tray geometry first—and sharing automation requirements early—creates a more reliable foundation for the system built around it.
Designing a tray for automation?
Download our Dunnage Tray Design Guide for key questions and considerations when designing a custom thermoformed tray for manufacturing and automated handling.