Can a Case Showroom sample be the acceptance standard?

No. It was hand dressed; colour and hardware came from single lots. Acceptance needs a sealed sample, a drawing and an AQL plan.

How many trial rounds before approval?

Three rounds of 25 shots: fill, dimensions, stability. If the spread moves, add a round.

Can a lot above ΔE 2.0 be accepted by concession?

Not advisable. Above 2.0 it is a different colour, visible side by side. Consent covers hidden surfaces only.

Why replace hand-cut liners with a die?

Hand cutting holds 1.5 mm and varies across parts. A die holds 0.3 mm but needs sharpening every 5,000 strikes.

How long does a sealed sample stay valid?

Twelve months. Plastic yellows and plaques fade, so an older sample no longer matches a lot.

Case Showroom Samples: Four Gaps From Sample to Mass Production

Quick answer: A Case Showroom sample is one hand-finished part; a production part comes off a settled mould and a material lot. Four gaps follow: tooling, masterbatch, bought-in hardware, liner cutting. Lock them as numbers: three trial rounds, colour within ΔE 1.2, die-cut liners, AQL 2.5. The sample defines the standard; production defines delivery.

Where Case Showroom Samples and Production Parts Diverge
Tooling and Trial Shots: Hand-Finished First Parts
Masterbatch and Batch Colour Drift
Hardware, Gasket and Liner: Supplier Lots and Dies
Approval List, Sealed Samples and AQL
FAQ

1. Where Case Showroom Samples and Production Parts Diverge

Every case in a Case Showroom was built one at a time: a mould on trial, an engineer dressing each shot, a small masterbatch blend, a knife-cut liner. Production runs a settled tool, continuous mixing and a die. At two thousand pieces the gaps show as harder lids, darker colour, looser latches.

Gap	Sample	Production	Fix at approval
Tooling	First shot, dressed by hand	Settled tool holds flash	Log rounds and repairs
Colour	Small blend, weighed by hand	Continuous mixing, drift	Set ΔE limit
Hardware	One purchase, one lot	Split lots, plating drift	Lock grade and supplier
Liner	Hand cut to fit	Die cut to drawing	Issue die drawing

2. Tooling and Trial Shots: Hand-Finished First Parts

A first shot carries 0.15 to 0.25 mm of stock on the parting line, taken down with P400 paper before the part reaches the Case Showroom. The drawing says 3.2 mm; the dressed sample reads 3.1 mm, the settled tool 3.35 mm, enough to demand a new liner fit.

Hardening moves the cavity 0.2 to 0.4 percent: on a 600 mm case that is 1.2 to 2.4 mm no fitting removes. Run three rounds of 25 shots and ban hand work on parting lines.

3. Masterbatch and Batch Colour Drift

Sample colour is a small blend at 2 percent masterbatch. Production mixes continuously, and a change of carrier grade or pigment source moves ΔE by 0.5 to 1.0 between lots. An unpurged barrel leaves the first fifteen shots dark; a white case that looked neutral in the Case Showroom reads yellow under plant light.

Judge against the sealed sample, not a chip, at 4000 K and 500 mm. Hold ΔE at 1.2; between 1.2 and 2.0 is a concession, above 2.0 the lot returns. Keep three 80 mm plaques per lot for twelve months.

4. Hardware, Gasket and Liner: Supplier Lots and Dies

The latch on the Case Showroom sample: 12 microns plating, 96 hours salt spray, 45 N. Production plating can fall to 8 microns and rust at 48 hours, force swinging 38 to 52 N.

The gasket is judged on hardness and set: Shore A 65, within three points. A die holds 0.3 mm where hand cutting holds 1.5 mm, but the die dulls after 5,000 strikes.

Item	Sample	Drift source	Control
Latch	12 microns, 45 N	Die revision, plating bath	10 microns, 45 ± 5 N
Hinge pin	304, 0.05 mm gap	Material swap, heat lot	0.1 mm max
Gasket	Shore A 65, 25% set	Compound lot, cure	65 ± 3, 30% max
Liner	Hand cut, ± 1.5 mm	Die wear, density	± 0.5 mm, 45 ± 3

5. Approval List, Sealed Samples and AQL

What was approved in the Case Showroom needs eight values: dimensions, wall spread at six points, ΔE, plating and opening force, gasket hardness, liner density, cut tolerance, print, packing. Each needs a method; as sample means nothing.

Seal three samples for file, customer and line, labelled with date, tool, masterbatch and die. Inspect to ISO 2859-1, level II, AQL 2.5.

Lot size	Code	Sample	Accept / reject
151 to 280	G	32	2 / 3
281 to 500	H	50	3 / 4
501 to 1,200	J	80	5 / 6
1,201 to 3,200	K	125	7 / 8

Sharp edges, latch failure, hinge fracture and gasket release reject a lot on one find; a wall range above 0.15 mm across twenty cases stops the line.

Conclusion

Approval builds a standard that repeats, not a handsome case. Record the trial rounds, lock the masterbatch and ΔE, lock hardware grades and the liner die, and let AQL and sealed samples carry the judgement. Convert all four gaps into numbers, and the case seen in the Case Showroom arrives two thousand times.

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.