Functional trays: how to specify by life cycle

What is a functional tray?

A functional tray is specified to do a job in your operation, not just to hold the part. It has four functions: it protects, organizes, speeds up counting, and simplifies transport. Each one has a direct effect on operating cost, even when that cost doesn't show up in the unit price.

Protecting means keeping each part in its own cavity, with no contact between parts, and guarding against electrostatic discharge when the component requires it. Organizing means giving each part a fixed position, so a missing part shows up immediately and poka-yoke (error-proofing) becomes possible: the cavity accepts the part only in the correct position.

Speeding up counting means locking in the quantity per tray and per box. With 24 parts per tray and 10 trays per box, for example, every box carries 240 parts, and the receiving team already knows the count. Simplifying transport means stacking well, fitting the box you already use, and making good use of space, with more parts per shipment.

What is your tray's life cycle, and why is it the first question?

A tray's life cycle is how long it needs to last and how many trips it needs to make. That might be a single shipment, from the supplier to the customer's assembly line, or years of use between departments in the same plant. The answer changes almost everything in the specification, from material to wall thickness to the type of anti-static protection.

The most common cycles fall into three groups. An expendable tray makes one trip and ends its life at assembly. An in-plant returnable circulates between departments and comes back to the start of the process. A closed-loop returnable travels from supplier to customer and comes back empty, cycle after cycle.

The same part may need two different trays. A thicker process tray can circulate inside the plant for years, while the tray that ships to the customer is expendable and lighter. Giving both the same specification usually makes one more expensive than it needs to be and the other too weak. These questions help define the cycle.

• How many trips does the tray need to make, and over what period?
• Does it circulate only inside the plant, or does it go to the customer?
• Who disposes of or returns the tray at the end of its use?
• Will it be washed, and how often?
• Is handling manual, robotic, or both?

Material, wall thickness, and application: how do the three work together in a thermoformed tray?

Once the life cycle is defined, the specification moves on to three core variables: material, wall thickness, and application. All three work together. A tough material with too little wall thickness cracks before the end of the cycle, and a thick tray made from a material that can't stand up to the oil on the line fails as well. There's no single best material, only the one best suited to the job. These are the most widely used.

• PS (HIPS): economical with good formability; the base material for black conductive trays and process trays.
• PET and PETG: clear and rigid, used in inserts and blisters when visual inspection matters.
• ABS: resists impact and oil; a good fit for returnable trays.
• HDPE: resists chemicals and impact; suited to heavy-duty use.
• PP: withstands higher temperatures and chemicals.

Wall thickness follows the cycle. Trays used inside the plant for production tend to be thicker and more durable, while an expendable tray can use thinner sheet without losing function. In thermoforming, the sheet stretches, and the corners end up as the thinnest points of the tray. Termotray sets itself apart by controlling wall thickness distribution across the tray instead of reinforcing only where the part makes contact.

Application is the third variable. The tray has to fit the box you already use, whether that's a KLT bin (small load carrier), a rack, or OEM-standard packaging. It also has to stack without sticking together and, when there's automation, hold every cavity in the exact position the robot expects. For a full table of materials and their typical uses, see our thermoformed tray materials page.

Does your part need ESD protection? Conductive or dissipative? Topical or in-resin?

Not every part needs protection against electrostatic discharge (ESD). In general, exposed components such as assembled PCBs (PCBAs), bare die, memory modules, and sensors require protection, while encapsulated parts often don't. Your customer's requirements also count and should be written into the specification. To see where these trays are used, visit our ESD trays page.

When protection is needed, there are two decisions to make. The first is the class. Conductive material drains charge quickly. Static dissipative material releases it gradually and in a controlled way, which in many cases is enough. Because conductive material costs more, the class deserves careful attention, as our article on conductive vs. dissipative trays shows.

The second decision is duration. A topical anti-static coating has a limited shelf life and works well for single-use or short-cycle trays. An in-resin anti-static additive keeps protecting for years (the so-called permanent effect) and suits trays built for many use cycles. Our article on topical vs. in-resin anti-static has the details.

Expendable or returnable, virgin or recycled: how do you choose by application?

Neither option is better than the other. An expendable tray is usually the better choice when the tray ends its life at the customer's assembly line and there's no return loop. A returnable tray makes sense when the tray comes back, within the plant or between companies, and its cost is spread over many cycles. Our article on expendable vs. returnable trays runs the full numbers, including freight, disposal, and part damage.

Virgin and recycled material both work. Recycled material is supplied to specification, with limits defined in advance, since it can show dark specks and lower gloss. For low-cost expendable trays, it's often the better choice. What doesn't work is using just any recycled material with no lot control.

Agree on the limits for recycled material before the sample is approved, not after the first lot. Define which color and gloss variations are acceptable, whether inspection requires transparency, and whether the material needs ESD protection. With that settled, every lot is checked against the same reference.

Which specification mistakes drive up tray cost the most?

Problems that show up after approval usually come from a decision made out of order. When the material is chosen before the life cycle, or the ESD class before the component has been assessed, the tray may pass at the prototype stage and fail in day-to-day operation. A few mistakes come up again and again in tray specifications.

• Requiring ESD protection for every part as a precaution, including encapsulated ones, without assessing the component.
• Specifying conductive when dissipative would do, and paying more with every reorder.
• Using a topical anti-static coating on a returnable tray that will circulate for years.
• Increasing the wall thickness of the whole tray when the weak point is at the corners.
• Approving recycled material without agreed limits on color and gloss.
• Designing the tray without considering the box or rack it will travel in.

All of them trace back to a specification that starts with price or material instead of how the tray will be used. When the first question is the life cycle, most of these decisions are settled at the design stage, before the mold is built, which reduces rework and cost.

What should you bring to the conversation with your supplier?

Termotray's engineering team starts with the discovery stage, held as an on-site visit or a technical meeting, and follows up if it needs more information. Specifying a tray goes faster when that first conversation already covers four basics.

• The part: a physical sample, or a drawing or 3D CAD file (STEP, IGES, or PDF).
• The volume: quantity per lot and frequency of use.
• The workflow: where and how the tray will be used, and its expected life cycle.
• The requirements: ESD protection when needed, technical cleanliness, a standard box or rack, and anything your customer specifies.

If you already use a tray for this part, show it to us: it tells us what works today and what needs to change. From there, our engineers present an initial tray proposal, with a 3D model showing your part already in place, before the mold is built. Once you have this information, request a quote.