Design Guide for PETG Thermoformed Medical Device Trays in electronics and electrical: 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.

The notes below come from day to day production and export work with overseas buyers.

Product Overview

This category covers a family of products rather than a single item. In practice a buyer defines thermoformed medical device 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 gauge 0.40 to 1.50 mm; rigid and semi rigid designs; custom cavity and instrument layouts. Materials most often specified are Polystyrene, Polycarbonate, Polypropylene, Polyethylene Terephthalate, and the choice between them changes stiffness, temperature resistance, chemical behaviour and price.

In the electronics and electrical sector the decision is usually driven by ESD protection and dimensional accuracy, with cleanliness as a secondary requirement. Typical end uses include accessory blisters, component trays, device inserts.

Key Material Properties

The table below summarises the values that usually decide the material choice.

Polyethylene Terephthalate Glycol is frequently the default selection here: PETG forms at lower temperatures and holds detail well, which is why it dominates medical trays.

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.
• Make corner radii at least equal to the sheet thickness; sharp corners are where holes start.
• Leave a flat sealing flange of at least 6 mm when the pack has to be heat sealed or lidded.
• Design uniform wall thickness by avoiding abrupt depth changes in the same cavity.
• 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.

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

• Polyethylene Terephthalate Glycol based: excellent clarity with no stress whitening
• Polycarbonate based: outstanding impact strength (250x glass)
• Polyethylene Terephthalate based: excellent barrier to CO2 and moisture
• Polypropylene based: lowest density among commodity plastics

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

Processing method drives both cost and performance, so it should be fixed early in the design.

• Tyvek lidding
• Die cutting
• Validation sealing
• Pressure forming

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 Thermoformed medical device trays Correctly

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

1. confirm the sterilisation method with the material
2. validate the seal process to ISO 11607
3. specify particle and cleanliness requirements
4. run peel strength testing on every production lot
5. control tooling wear to avoid trim burrs

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

Frequently Asked Questions

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.

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.

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 thermoformed medical device 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 do you control colour consistency?

Colour is controlled with a masterbatch reference approved by the customer, and every production lot is checked against the approved sample under standard lighting before shipment.

Conclusion

If you are planning a new electronics and electrical project, send us your drawing, annual volume and target properties, and we will come back with a material proposal, a tooling plan and a budget quotation.