What is the minimum specification from a custom hard case manufacturing company?

Answer: Ten fields across three layers, or four at a pinch: cavity, outside, wall, load. Miss one and the quote carries an assumption.

Why give both cavity and outside size?

Answer: The cavity decides what fits, the outside decides the tool and the loading count. With cavity alone the toolmaker guesses the wall, usually 15 mm short.

Is a 3.0 mm wall always safer?

Answer: No. Another 0.5 mm adds 12 percent to weight and sink risk. At 3.0 mm with 1.8 mm ribs a case already carries 45 kg.

How is the 45 kg rating proven?

Answer: A spread load on the base for 24 hours, and 180 kg on the lid for 24 hours, both at 40 degrees Celsius.

How many sample rounds are needed?

Answer: Two normally, three with inserts, the third adjusting foam and latch preload only, so the body tool stays untouched.

Custom Hard Case Manufacturing Company: Size, Wall, Load Specs

Quick answer: A custom hard case manufacturing company fixes a specification with three blocks: cavity against outside size, nominal wall against rib root, load against stack height. A 520 x 380 x 190 mm cavity becomes 580 x 435 x 215 mm outside at 3.0 mm wall, and 45 kg stacks five high.

What a Custom Hard Case Manufacturing Company Must Specify
Converting Cavity Size to Outside Size
Wall Thickness, Ribs and Press Tonnage
Load Rating and Stacking Verdicts
Tolerances and Sample Approval
FAQ

1. What a Custom Hard Case Manufacturing Company Must Specify

An enquiry reaching a custom hard case manufacturing company often reads "a box 500 mm long inside". That cannot be quoted, because three blocks are missing: geometry, material and mechanics.

Geometry needs cavity, outside size, corner radius and land width. A 520 x 380 x 190 mm cavity becomes 580 x 435 x 215 mm outside, built from 3.0 mm wall, 8 mm land and R25 corners. Material fixes grade and shrinkage: PP copolymer runs 1.4 to 1.8 percent, ABS 0.4 to 0.7, so a grade change moves the cavity over 3 mm.

Layer	Fields	Example	If missing
Geometry	cavity, outside, land	520 x 380 x 190 mm, R25	quote off by 15 percent
Material	grade, shrinkage	PP copolymer, 1.6 percent	cavity off by 3 mm
Mechanics	load, stack, drop	45 kg, 5 high, 1.2 m	ribs undecided

2. Converting Cavity Size to Outside Size

Conversion starts at the wall: the cavity is functional, the outside is the mould, and one wall plus one land sits between them.

Custom hard case manufacturing company: close-up of a black case edge, two latches framing a three-knuckle hinge, tight lid seam, fine matte texture

Example: a 520 x 380 mm cavity gains 3.0 mm per side for 526 x 386 mm, 8 mm of land for 542 x 402 mm, then 19 mm and 16.5 mm of latch boss, reaching 580 x 435 mm. Round any step and the outside misses by 5 mm after the tool is cut.

Depth adds more: the 190 mm cavity sits inside a 215 mm outside carrying a 12 mm base, a 10 mm lid crown and a 3 mm land. With 30 mm of foam only 160 mm remains, so tall contents quote against 160. Past 1.5 mm of diagonal difference the gasket leaks at one corner.

3. Wall Thickness, Ribs and Press Tonnage

The ladder runs 2.5, 3.0 and 3.5 mm: base and lid at 3.0, walls at 2.5, bosses at 5.0. A step over 2.5 mm between zones cools unevenly and leaves a sink mark behind the thick zone. Ribs run at 0.6 of the main wall, so 1.8 mm, at 6 mm height and 45 mm pitch.

Cavity long side	Wall	Rib	Press
380 mm	2.5 mm	1.5 mm	160 t
520 mm	3.0 mm	1.8 mm	250 t
680 mm	3.5 mm	2.1 mm	450 t

Tonnage follows clamping force: at 45 MPa and 0.25 square metres a single cavity needs 1125 kN, about 113 tonnes, and a 1.4 factor lands on 160 tonnes; two cavities need 350. A 12 percent spread between quotes usually sits on that line.

A 680 mm cavity forced onto a 250 tonne press comes out whitened, and the stress marks show after 48 hours of neutral salt spray.

4. Load Rating and Stacking Verdicts

Base load looks at deflection: 45 kg spread evenly may not sag the base over 2 mm. Stack load looks at the lid, because five high puts 180 kg on the bottom case, about 0.9 MPa of contact stress.

Custom hard case manufacturing company: open black case, camera body and long lens in foam cutouts, foam pad in the lid, two latches

Testing replaces calculation: 180 kg on top, 40 degrees Celsius, 24 hours, one hour of rest, then permanent set under 1.5 mm. Room temperature gives 0.6 mm and hides the problem.

The handle boss is a stress riser, so 500 pulls at 45 kg must leave no root crack, a tenth of the 5000 cycles two years implies.

5. Tolerances and Sample Approval

The tolerance sheet carries cavity plus or minus 1.0 mm, outside plus or minus 1.5 mm, wall no thinner than 90 percent of nominal, lid gap 0.6 to 1.0 mm, flatness 0.8 mm, diagonal 1.5 mm.

T1 proves the tool fills in about twelve days; T2 adds a CMM report five days later. Keep three approved samples, each marked with date, shot and compound batch, and seal one for the customer.

The sheet is also the acceptance basis: no standard says whether the cavity runs at 1.0 or 1.5, or that a lid under 60 N opens itself in transit.

Conclusion

A custom hard case manufacturing company with a disciplined sheet quotes on one page and argues less. Geometry and mechanics pin size and load, the tolerance sheet pins acceptance, sealed samples pin every later batch. Whether a custom hard case manufacturing company writes those numbers down first matters more than machine age.

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.