Is a thicker wall always better on a Large Protective Case?

No. Eight to ten millimetres buys 30 percent more stiffness and 5 kg, changing wheels and pallet load.

Why is rib pitch 300 mm?

A 300 mm bay deflects 0.9 mm under 20 kg; 400 mm doubles it.

Can lift points double as tie-downs?

No. A tie-down pulls sideways, the insert is designed for vertical load, and side pull creeps the plastic.

What tolerance does a rotomoulded wall hold?

Plus or minus 0.8 mm, 1.2 mm at corners, so drawings call out minimum thickness.

How high can a Large Protective Case be stacked?

Three empty, two loaded. Once rim flatness passes 2 mm, two is the limit.

Large Protective Case: Wall Thickness, Ribs and Lift Points

Quick answer: A Large Protective Case is sized in order: length and total weight first, wall thickness second, ribs and lift points last. Past 800 mm outside length and 12 kg empty, rotomoulded walls run 8 to 10 mm, ribs sit on a 300 mm grid, and each lift point is rated at four times its working load.

Where a Large Protective Case Begins in Size
Wall Thickness from 6 to 12 mm
Rib Grid and Rib Height
Lift Points: Position and Load per Point
Rim Flatness and Three-High Stacking
FAQ

1. Where a Large Protective Case Begins in Size

A Large Protective Case has no fixed threshold: outside length past 800 mm, cavity over 120 litres, empty weight over 12 kg. Past two markers, handling needs two people or a trolley.

Scaling is not proportional: stiffness rises with the cube of thickness and falls with the cube of span, so doubling the length deflects a panel eight times as far.

Class	Length	Cavity	Empty	Process
Large	700–1000 mm	80–150 L	8–15 kg	either
Extra large	1000–1500 mm	150–350 L	15–28 kg	rotomoulding
Special	>1500 mm	>350 L	>28 kg	rotomoulding + frame

2. Wall Thickness from 6 to 12 mm

Rotomoulded walls follow the powder charge: 6, 8, 10, 12 mm. A 1000 mm body starts at 8 mm; ten suits bases over 0.6 square metres, where impact bending grows fast.

Every millimetre costs weight: a 1000 by 600 by 500 mm body carries 2.8 square metres, so 1 mm is 2.5 kg of PP. Corners at 12 mm save 18 percent of material.

Wall	Process	Length	Empty	1.2 m drop
6 mm	injection	<700 mm	6 kg	corner cracks
8 mm	injection	<1000 mm	10 kg	passes
8 mm	rotomoulding	<1200 mm	14 kg	passes
10 mm	rotomoulding	<1500 mm	19 kg	passes
12 mm local	rotomoulding	>1500 mm	24 kg	passes

3. Rib Grid and Rib Height

Ribs fight panel bulge, not overall stiffness. A 1000 mm Large Protective Case with bare walls bulges 3 to 4 mm at mid-panel under 20 kg, and past 5 mm the gasket leaks.

Pitch is 300 mm: such a bay in 8 mm wall deflects 0.9 mm under 20 kg, while 400 mm jumps to 2.1 mm. A 1200 mm Large Protective Case takes four ribs on the long side.

Height runs 8 to 10 mm at 0.8 times the wall, R3 at the root, 1.5 degrees of draft: thick ribs sink the face, thin ones void at the crest.

4. Lift Points: Position and Load per Point

Lift points are sized on dynamic load: 2 g at pickup and 1.15 for a 60 degree sling, so weight times 2 over points, times 1.15. An 80 kg case on four points carries 46 kg each, rated 185 kg.

Position fails more often than rating: four points sit a fifth of the length in from each end, their quad enclosing the centre of gravity.

Inserts are moulded in: an eye bolt bites 8 mm of wall and lets go below 1.5 kN, while a 12 mm stainless insert with a 2 mm boss holds on a Large Protective Case. Castors carry rolling weight only.

Total	Points	Static	Design	Insert
40 kg	2	20 kg	46 kg	M8
80 kg	4	20 kg	46 kg	M10
150 kg	4	38 kg	87 kg	M12
250 kg	4	63 kg	145 kg	M16
400 kg	6	67 kg	154 kg	M16

5. Rim Flatness and Three-High Stacking

Long rims are hard to hold flat: a 1200 mm rim shrinks 1.8 percent as it cools, so 1.5 mm of flatness comes from a mould cut 1 mm low in the middle.

Flatness is sealing: a 30 percent squeeze on a 12 mm gasket leaves 8.4 mm, and a 2 mm low spot leaves 13 percent.

Stacking is set by the bottom rim: 120 kg on a 1.4 m length bends 0.6 mm at 8 mm wall. A lid recess with a boss 3 mm smaller keeps the tier aligned, and a Large Protective Case needs both.

Conclusion

Three numbers decide it: thickness from span and load, ribs on a 300 mm grid, lift points at four times the working load. Get them right and a Large Protective Case keeps its stiffness as it grows.

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.