Can a custom EVA foam insert for cases be a single layer?

Answer: Yes, for simple shapes under 1 kg one 30 mm die-cut layer is enough. Every model change then replaces the whole sheet.

Does higher density always mean better shock protection?

Answer: No. Density carries load but shortens travel, so a light part on dense foam transmits more shock. Density and thickness have to be paired.

How is the die charged?

Answer: By pocket count and complexity, 600 to 900 RMB for a 480 by 360 mm sheet with a dozen pockets, one-time and not repeated on reorders.

Should the insert be glued to the case?

Answer: Spot-glue the four corners; a full bond tears the lining at the next replacement. Use 3 mm locating pins where movement matters.

Can colour and hardness be specified?

Answer: Black, grey and white are standard, other colours need 200 square metres. Hardness is quoted in Shore A at ±3, and batch spread belongs in the acceptance clause.

Custom EVA Foam Insert for Cases: Size, Wall and Load

Quick answer: A custom EVA foam insert for cases is specified by four numbers: cavity size, total thickness, density with hardness, and die clearance. Thickness runs 2 mm under cavity depth, 60 kg/m³ at Shore A25 holds about 3 kg, and cuts hold ±0.8 mm.

What Sets a Custom EVA Foam Insert for Cases
Density and Hardness to Load
Layer Count and Thickness
Die Clearance and Cut Tolerance
Temperature Humidity and Recovery
FAQ

1. What Sets a Custom EVA Foam Insert for Cases

Four numbers decide a custom EVA foam insert for cases: cavity size, total thickness, density with hardness, and the clearance at each pocket.

Order matters. Measure the cavity, set total thickness to depth minus 2 mm of preload, then pick density against item weight and clearance against how the part is picked up. A 480 by 360 by 180 mm cavity carries 178 mm of foam.

Parameter	Sets	Usual value
Cavity	Outline and nesting	Measured at the tightest point
Thickness	Preload, travel	Depth minus 2 mm
Density	Load, recovery	38 to 90 kg/m³
Clearance	Grip, release	1 to 2 mm a side

2. Density and Hardness to Load

Density sets weight, hardness sets how far a thumb sinks, and the pair has to match. 38 kg/m³ at Shore A18 suits parts under 1 kg, 60 at A25 is the general grade, and 90 at A35 takes components above 5 kg. Raise density without hardness and the pocket walls slump under load.

Custom EVA Foam Insert for Cases: black case open on a wooden desk, egg-crate foam and clear bag in the lid, soldering iron beside it

Load is simple to estimate. A 100 by 100 mm bearing face at 60 kg/m³ and A25 holds about 3 kg at 25 percent compression; more compression carries more, but recovery drops with it. Past 3 kg, widen the face or step up to 90 density. Extra thickness adds travel, not capacity.

3. Layer Count and Thickness

Most runs build three layers: a flat lid sheet, a die-cut middle, a flat base. The lid presses, the middle locates, the base absorbs impact, and a model change replaces the middle alone.

Work thickness back from the cavity. 178 mm splits into 95 mm of pocket, 20 mm of lid and 63 mm of base. Pocket depth is item height plus 5 mm so fingers can reach the part, and the lid closes onto that gap: a 90 mm item sits in a 95 mm pocket.

Under 20 mm of base, drop energy passes straight to the case wall; 63 mm acts as a crushable column and cuts peak acceleration in a one metre drop by roughly thirty percent.

4. Die Clearance and Cut Tolerance

Clearance follows handling: 1.5 mm a side for fingers, 1 mm for tweezers, 2 mm for gloves. Under 1 mm the foam grips the part too hard to pull out; over 2 mm it slides in transit and wears against the pocket wall.

Custom EVA Foam Insert for Cases: closed light grey case on a ribbed van floor, a carton beside it, pallets and straps behind

Cuts hold plus or minus 0.8 mm, with 1 mm per 100 mm of squareness. Bridges between pockets stay 8 mm or wider, since a 5 mm bridge is what fails first in vibration. Pocket corners take R3, because a square corner cracks after repeated handling.

Item	Value	Check
Clearance	1 to 2 mm	By handling method
Cut tolerance	±0.8 mm	Five points, caliper
Bridge	8 mm minimum	Visual and caliper
Corner	R3	No sharp edge

5. Temperature Humidity and Recovery

Service life follows the environment. A custom EVA foam insert for cases runs from minus 20 to 60 °C: above 60 it softens and pocket walls creep, below minus 20 it stiffens and parts jam. A sea container reaches 65 °C, so export orders need that limit in the specification.

Recovery is measured as compression set: 70 °C, 25 percent compression, 22 hours, thickness back to 90 percent or better. Water absorption stays under 1 percent, or moisture sits in the pocket and hardware rusts first. Six months of sunlight yellows and embrittles the face, so inserts ship wrapped in black PE.

Conclusion

A custom EVA foam insert for cases comes down to four numbers and three layers: cavity size sets the outline, total thickness sets the preload, density with hardness sets the load, clearance sets the feel. Put those on the drawing and the first sample fits, and the custom EVA foam insert for cases project avoids a second round.

This article discusses only the container (case body) side of specifications and design intent, and does not cover any handling, loading or use of the contents.