How much clearance should a cartridge box cavity leave?

Answer: 1.5 to 2 mm per side, 3 mm between neighbours, 5 mm around the block. It covers shrinkage loss, not assembly slack.

Can a 3.0 mm wall simply be raised to 3.5 mm?

Answer: Not directly. The extra 0.5 mm brings 0.4 mm sink marks at the bosses and ruins lid-line accuracy before it adds stiffness.

How is the stacking height decided?

Answer: By the bottom side wall: five layers unribbed, seven with vertical ribs, always on loaded weight.

Why cap the unit weight at 25 kg?

Answer: It is the practical ceiling for one-person carrying.

IP65 or IP67 for the seal class?

Answer: IP67 wherever standing water or immersion is possible; IP65 suits dry indoor cycles. ---

Cartridge Box Specifications: Dimensions, Wall Thickness and Load

Quick answer: Build a cartridge box specification from the inside out: 1.5 to 2 mm per side, walls of 2.5 to 3.5 mm, a loaded unit under 25 kg, and no more than 2 mm of set after a five-high stack sits for 72 hours.

Sizing a Cartridge Box from the Inside Out
Dividers and Insert Fit
Wall Thickness and Rib Geometry
Load Rating, Stacking and Unit Weight
Seal Class and Temperature Window
FAQ

1. Sizing a Cartridge Box from the Inside Out

Enquiry sheets usually list outside length, width and height. The supplier copies them, the mould is cut, and then the cavity turns out not to hold the layout. A cartridge box specification starts at the cavity; the outside is cavity plus wall.

Draw the layout to scale first, item by item. Allow 1.5 to 2 mm per side on the largest diameter, 3 mm between neighbours, 5 mm of cushion. Shrinkage and warpage take 0.3 to 0.5 mm off a moulded cavity.

Item	Value	Basis
Cavity length	Layout length + 4 mm	2 mm per side
Cavity depth	Tallest item + 6 mm	Lid foam pre-load
Wall thickness	2.5 / 3.0 / 3.5 mm	Tiered by loaded weight
Outside footprint	600 × 400 mm	Pallet module

2. Dividers and Insert Fit

How finely a cartridge box is divided follows the changeover rate, not the catalogue photo. Long runs get individual pockets; a mixed programme gets a through-channel plus swappable inserts, so a changeover swaps foam, not the body.

Cartridge box: cream rotomoulded case closed on a beige backdrop, two front latches with a round knob between them, folding handle and raised lid rim

PP honeycomb board is commonly 8 mm, EVA runs at 38 kg/m³ and PE at 30. Cut pockets 2 mm deeper than the item and give the wall a 2 degree draft.

An insert sits 1 mm inside the cavity on a 5 mm pad, with the handle within 20 mm of the loaded centre of gravity.

3. Wall Thickness and Rib Geometry

Wall thickness on a cartridge box falls into three tiers: 2.5 mm below 15 kg loaded, 3.0 mm up to 25 kg, and 3.5 mm beyond that or past five-high stacking.

Ribs do more than thickness: height at twice the wall, pitch at 90 mm, root radius R2, 1.5 degree draft. Ribs meeting at the corners close a ring, lifting torsional stiffness about forty percent for six percent more weight.

Injection moulding holds wall variation inside 0.15 mm; rotomoulding runs 4 to 6 mm at 0.8 mm. Past 3.5 mm, sink marks gather at the bosses and 0.4 mm shows daylight through the lid line.

4. Load Rating, Stacking and Unit Weight

Load splits into two tests. Static: five-high stack, 400 kg on top, 72 hours, 24 hours of recovery, set under 2 mm. Dynamic: three drops from 1.2 m on a corner, an edge and a face, latches still closing.

Cartridge box: silver case standing at a slight angle, a combination lock on the side edge, vertical shell ribs, four casters

Stacking height on a cartridge box is set by the bottom side wall: five layers unribbed, seven at 90 mm rib pitch, a pallet board beyond seven.

Unit weight is ergonomics, not materials: above 25 kg the drop rate climbs, so a heavier build wants casters or a two-person lift, and at least seventy percent of the base should sit on the pallet.

5. Seal Class and Temperature Window

Sealing runs in two steps, water then pressure. IP65 covers jets from any direction; IP67 covers 30 minutes at 1 m. Most cartridge box programmes take IP67, since standing water and brief immersion both occur.

Three things deliver IP67: a continuous gasket, even latch clamping and a relief valve. Compression belongs at 25 to 30 percent; the valve opens at 0.35 bar, so a temperature swing cannot pull the lid down under vacuum.

The window follows the route, usually -40 to +71 °C. Impact strength at -40 °C is about a third of room temperature, so cold drop is its own test: four hours of soak, then 1.2 m, no cracking and no latch release.

Test	Condition	Pass criterion
Water ingress	IP67, 1 m for 30 min	Dry interior
Cold drop	-40 °C soak, 1.2 m drop	No cracks
Salt spray	96 h neutral	No red rust

Conclusion

The hard part of a specification is sequence, not arithmetic: layout, cavity, wall, outside. Dimension chain, stacking and seal class pull against each other, so a change in one sends you back to the other two. With a test method against each line, they make a cartridge box drawing a tool shop and a line can both hold to.

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.