Does a Case Internal Divider always need tooling?

No. Slats need no tool and start at one set; EVA and trays do. Below 200 units, take slats.

Is the EVA die charge refundable?

No. The supplier keeps the die and bills it in the first invoice. A split is negotiable: seventy percent up front, the rest per set.

Why does a tray start at 1,000 units?

Tooling. A 3,500 tool adds seventeen per tray at 200 units; at 1,000 it drops under six.

Can the three routes be combined?

Yes. Slats divide, EVA cushions, a tray locates a precision part. A hybrid is charged only for the tooling.

Which route is fastest?

Slats, at three to five days with no tooling queue. EVA takes 8–12 days, trays 15–20.

Case Internal Divider Selection: Slats, EVA or Blister Trays

Quick answer: Choose a Case Internal Divider by volume, then tolerance. Slats need no tooling, cost 6–12 per set and ship in three to five days. EVA liners pay off from 200 units at 22–40 per set, with the best cushioning. Blister trays start near 1,000 units, where a 3,500–9,000 tool spreads thin and accuracy reaches ±0.3 mm.

Three Routes and Their Boundaries
Adjustable Slats Without Tooling
EVA Die-Cut Liners From 200 Units
Blister Trays From 1,000 Units
A Decision Tree by Volume and Tolerance
FAQ

1. Three Routes and Their Boundaries

A Case Internal Divider is quoted as slats, EVA liners or blister trays. Slats interlock from grooved sheet, EVA is punched and stacked, and a tray is vacuum-formed over a tool. The route fixes tooling, batch floor and accuracy before price.

The costly mistake is revision, not unit price. A layout change means a new drawing for slats, a new die for EVA, a repair for trays. Small batches feel that most, so Case Internal Divider projects fail on change orders, not quotes.

Route	Tooling	Economic batch	Unit cost	Accuracy	Lead time
Adjustable slats	none	1–100	6–12	±2.0 mm	3–5 days
EVA die-cut liner	800–1,800	200–800	22–40	±0.8 mm	8–12 days
Blister tray	3,500–9,000	1,000+	9–16	±0.3 mm	15–20 days
Slats plus EVA	800–1,800	100–300	26–48	±1.0 mm	9–14 days

2. Adjustable Slats Without Tooling

Slats are the cheapest Case Internal Divider: grooved sheets interlocking on a fixed pitch. No tool is needed, quotes follow sheet area and cutting time. Six compartments in 3 mm PP hollow sheet use 0.35 square metres and cost 6–9 per set; 5 mm raises it to 9–12.

The strength is revision: shift one slat or add spares when the layout changes.

The weakness is fit. Slots need clearance, joints leak, stack-up reaches ±2 mm, and vibration lets compartments drift; long parts need a foam strip. Ask for slot pitch and spare slats.

3. EVA Die-Cut Liners From 200 Units

An EVA liner is punched to the outline and stacked. A die costs 800–1,800 and takes 3–4 days; production runs 8–12 days.

The curve breaks near 200 units. With a 1,200 die and 18 per set, fifty sets carry 42 each, two hundred 24, five hundred 20.4, one thousand 19.2. Past 200 the line flattens.

Batch	Tooling per set	Unit cost
50	24.0	42.0
200	6.0	24.0
500	2.4	20.4
1,000	1.2	19.2

Closed-cell EVA spreads impact across the contact face; a tray of the same wall concentrates it on ribs, where a sharp corner punches through. Cameras and instruments default to this Case Internal Divider style. A new outline re-cuts the die from 800.

4. Blister Trays From 1,000 Units

A tray is formed by heating PETG or PET sheet onto an aluminium tool. Tooling runs 3,500–9,000; a prototype tool lasts a few hundred cycles. Lead time is 15–20 days.

Accuracy is what the buyer gets: the locating face holds ±0.3 mm, and the thousandth tray matches the first. A Case Internal Divider for automated loading has no other option at this tolerance.

With a 6,000 tool and 7 per tray, 200 trays cost 37 each, 500 cost 19, 1,000 cost 13 and 3,000 cost 9. 1,000 is the gate; above 3,000 the price undercuts slats.

5. A Decision Tree by Volume and Tolerance

Two questions come first: annual sets and tolerance. Under 300 sets at ±2 mm, take slats. At 200–800 sets needing cushioning at ±1 mm, take EVA. Above 1,000 at ±0.5 mm, take a tray.

Bands overlap between 300 and 500 sets. Build a hybrid: EVA body with a tray insert under the critical part, or slats as a frame with EVA on six faces.

Scenario	Annual volume	Recommended route
Prototype	1–20	Adjustable slats
Pilot build	50–200	Slats plus EVA
Stable mid-batch	200–800	EVA die-cut liner
Production	1,000+	Blister tray
Precision run	3,000+	Blister tray plus EVA lid

Give five facts in every enquiry: annual and first-batch volume, tolerance, cushioning, case model and revision frequency. A bare quantity forces the most conservative quote, so most Case Internal Divider quote spreads come from missing information.

Conclusion

Pick a Case Internal Divider by volume, then tolerance, then price. Under 300 sets, slats keep revisions free. From 200–800, EVA balances cushion and cost. Above 1,000, a tray amortises its tool. Know both thresholds, and Case Internal Divider selection stops being guesswork.

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.