How much protection does Foam Cutting give up?

Answer: At 1.2 m the insert peaks at 62 g against above 120 g for a moulded tray. Moulding still locates 12 kg to 0.1 mm, which foam cannot.

Is it always the small-batch answer?

Answer: Below 300 pieces, almost always. A CNY 36,000 tool over 300 parts is CNY 120 each, against CNY 120 for one program.

Why not switch to moulded pulp?

Answer: It suits shallow cavities above 2,000 pieces. Deep pockets tear, and wet strength drops about 30 percent.

Can corrugated dividers replace it?

Answer: Only under 2 kg and only for rectangular parts. A 140 g peak stops scuffing rather than impact.

Does mixing two systems cost more?

Answer: One extra assembly step, but foam plus a bracket is routine from 500 to 3,000 pieces and lands 40 percent under all-moulded cost.

Foam Cutting vs Alternative Inserts: Where the Real Gap Is

Quick answer: Foam Cutting is weighed against moulded trays, moulded pulp, corrugated dividers and air pillows. Under 800 units it wins; above 10,000 units, moulding takes over.

Where Foam Cutting Draws the Line
Two Cost Curves and One Hidden Line
Drop Performance at the Same Height
Revisions and Lead Time on the Third Drawing
When to Walk Away from Foam Cutting
FAQ

1. Where Foam Cutting Draws the Line

Most comparisons begin with one unit-price table mixing four forming logics. Foam Cutting is subtractive: pockets come out of a block. A moulded tray is additive: melt fills a steel tool. Pulp is slurry sucked onto a screen. A corrugated divider only folds and slots.

The cut route holds 120 mm of pocket depth, a 3 mm wall and plus or minus 0.5 mm on the outline. It cannot hold a threaded insert. Foam sits near 3 MPa, so one M6 screw crushes the wall, and locating 12 kg to 0.1 mm needs a bracket underneath.

Option	Forming logic	Minimum	Unit price, CNY
Foam Cutting	Subtractive	1 piece	2.4
Moulded tray	Melt in a steel tool	3,000	4.6
Moulded pulp	Slurry on a screen	2,000	3.2
Corrugated divider	Folded and slotted	200	1.1
Air pillow	Inflated film	500 m	0.6

2. Two Cost Curves and One Hidden Line

There is no tool, only CNY 120 of programming per revision. The steel tool is CNY 36,000, the pulp tool CNY 11,000, a corrugated die CNY 300. One line is quoted as sampling, the other as tooling, which is how the cheap route starts to look dear.

Foam Cutting: a grey case open on a plain backdrop, convoluted foam in the lid above a grid of square cutouts

A 300 by 250 by 40 mm insert in 38 kg per cubic metre PE costs 2.4, of which 1.7 is material. The curves cross near 780 pieces; past 3,000 pulp and moulding pass it. Weight is the hidden line: 90 g against 240 g, or CNY 18,000 across ten thousand sets by air.

3. Drop Performance at the Same Height

On one rig, 4.2 kg dropped from 1.2 m, a 30 mm insert peaks at 62 g. EVA reads 85 g, pulp 108 g, corrugated 140 g.

Item	Foam	EVA	Pulp	Corrugated
Peak acceleration at 1.2 m	62 g	85 g	108 g	140 g
Compression set, 25 percent, 70 C, 22 h	5.8 percent	4.2 percent	9.5 percent	21 percent
Attenuation by the eighth drop	12 percent	18 percent	corner crack	collapse
Insert weight	90 g	130 g	165 g	45 g

4. Revisions and Lead Time on the Third Drawing

Moving one pocket is 40 minutes of programming and one scrap sheet. A mould means stripping, welding and repolishing: five days and CNY 4,000. Pulp means a new screen: seven days.

Foam Cutting: a closed grey case on a scarred bench, two front latches, a blurred workshop with an orange rack behind

Lead times stack the same way: fifty pieces in three days, moulding 22 days to first batch. Only the cut route can run 5 mm oversize and finish the pocket once the hardware freezes.

5. When to Walk Away from Foam Cutting

Four requirements end the discussion: a threaded insert, a clear window, 0.1 mm repeatable location, or 20,000 pieces in one order. Compression also drifts, so a pocket that grips today can loosen 0.2 mm in three months.

Requirement	First choice	Second choice	Reason
Under 300 pieces	Foam Cutting	Corrugated	Revisions are program edits
300 to 3,000 pieces	Moulded pulp	Foam Cutting	Pulp passes foam after 3,000
Above 10,000, hard location	Moulded tray	Foam plus bracket	Foam cannot hold an insert
Above 4 kg, six-face drop	Foam	EVA	Lowest peak of the four

Under 500 pieces, a 4 mm wall between pockets or a weight target, the cut route wins. A tray 0.3 mm off will not seat, while foam absorbs that error. A 5 mm ABS plate at the locating points closes the stiffness gap for about 40 percent less than all-moulded cost.

Conclusion

No alternative wins on every axis; order quantity and locating requirement decide. Moulding wins on stiffness, pulp on the sustainability story, corrugated on price, Foam Cutting on revisions. That is why, in a pilot build, Foam Cutting remains the hardest option to replace.

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.