Is writing or equivalent into case tender specs enough?

Answer: No. The phrase states an attitude, not a test. It needs the 4 evidence items and a 5-working-day window behind it.

Can we keep one reference model?

Answer: It costs responses. Once a model sits beside the dimensions, bidders treat it as the default and every alternative needs extra paperwork.

Only 3 suppliers can respond. Is that lock-in?

Answer: Look at what removed the others. Capacity and test gear are fair filters; model codes are not. Rewrite them and the pool usually returns above 6.

Is a ±1.0 mm tolerance too loose?

Answer: No. Shrinkage runs 0.4% to 0.8%, or 2.4 mm to 4.8 mm across a 600 mm edge, so ±1.0 mm after mould compensation is normal practice.

Will 5 evaluators wave equivalence through?

Answer: Only if the evidence cannot be paged through. With page numbers on all 4 items, 12 rows take under 40 min to read.

Writing Case Tender Specs: Avoiding Lock-In

Quick answer: Case tender specs escape lock-in when model codes, trade names and dimension stacks become measurable limits plus four provable equivalence items.

Three lock-in patterns
Six parameter groups
Making or equivalent provable
A deviation sheet reviewers can score
Three disqualification lines
FAQ

1. Three lock-in patterns

A 38-row parameter table with 11 rows only one supplier can meet has already turned a tender into a price talk. Score the technical side at 40 points across 5 evaluators and those rows open a 6-point gap. Most documents carry 3 disqualification lines. Nobody prints exclusivity on the cover. The table looks neutral. Case Tender Specs hide the lock in model codes, trade names and dimension stacks.

All three swap a verifiable result for a source only one factory can match. A model code is an internal drawing number, a trade name is a trademark, a dimension stack is one supplier's structural habit. None of them describes the case body, only who made it.

Original wording	Why it locks	Neutral rewrite
Model XG-6040, lid thickness per OEM drawing	Internal code, no outside bidder can match it	Outer 620×480×230 mm, inner 570×430×195 mm, ±1.0 mm
Uses a named brand sealing strip	Trademark names a single source	EPDM strip, compression set ≤25% to GB/T 7759.1
Cavity, foam thickness and divider pitch all fixed	Three linked values leave one internal layout	Fix net inner size and wall ≥3.0 mm, inserts as options
Colour code plus a named masterbatch supplier	Code and channel locked together	ΔE ≤2 against the retained sample
Latches to a specific hardware model	Any substitute counts as a deviation	Latch pull 45 N to 70 N, 5000 cycles without failure

Model codes are hardest to see because they look like specifications. XG-6040 carries no dimensions, so bidders guess 600 mm or 604 mm, and a wrong guess becomes a negative deviation. Three dimensions plus a ±1.0 mm band fix that: wide enough for shrinkage, narrow enough to keep the process window.

Dimension stacks are quieter. Fix cavity, foam and divider pitch at once and the internal layout is decided too; a rival 3 mm off on slot pitch cannot fit the divider at all.

Keep the result, drop the source.

2. Six parameter groups

Six groups let bidders answer case tender specs line by line: outer and inner size with ±1.0 mm, wall ≥3.0 mm with measuring points, ingress per IEC 60529 at 30 min and 1 m, hardware by material and latch pull, environment at -20 °C to 60 °C with a 1.5 m drop onto 9 kg plus 48 h salt spray, marking and packing by character height and gross weight.

Case Tender Specs hardware line shown on a closed black flat case with two red latches, recessed grip and short embossed bars on the lid

Ingress is the group most often cut to a scatter. Three characters hide how deep, how long, and whether the sample is empty, and changing one of them flips the verdict. Empty case, 30 min at 1 m, opened within 5 min and checked for water tracks, gives every bidder one target.

Wall thickness needs points. Without a location a supplier reports 4.2 mm on the thickest rib while the thin wall sits near 2.6 mm; 5 readings per face judged on the minimum closes it.

Parameter group	Limit	Test basis	Evidence
Outer and inner size	620×480×230 mm, inner 570×430×195 mm, ±1.0 mm	Three-point measurement	First-article record
Wall and weight	Wall ≥3.0 mm, unit ≤5.8 kg	Ultrasonic gauge, 5 points per part	Thickness log, weighing slip
Ingress protection	30 min at 1 m, no water entry	IEC 60529	Third-party report
Hardware	Latch pull 45 N to 70 N, 5000 cycles	Tensile rig, cycle bench	Type test report
Environment	-20 °C to 60 °C; 1.5 m onto 9 kg; 48 h salt spray	ISO 2233, ISO 9227	Three test reports
Marking and packing	Embossed characters 8 mm, gross ≤6.5 kg	Visual check, weighing	Pack artwork, weighing slip

Environment needs three numbers and each maps to a failure mode: -20 °C to 60 °C for cold embrittlement, 1.5 m onto 9 kg for impact fracture, 48 h salt spray for hardware corrosion.

3. Making or equivalent provable

Or equivalent completes half the job in case tender specs. The other half turns equivalence into evidence, and one missing item drops the clause back into a lock.

A third-party report on immersion and salt spray comes first, with test conditions matching the table word for word. Then 2 samples, one cut open for wall thickness, one retained. Process documents naming mould count and the clamping range used follow. Two comparable supply records close the list.

Keep that list in the clause, not in an annex, and answer every doubt in writing within 5 working days to all bidders at once. The window is the cheapest block of time in the process. Expect one side effect too. An open clause moves work from bidder to buyer, since someone must read 4 items per bid across 6 groups, so name that reviewer before the document is issued.

4. A deviation sheet reviewers can score

Deviation sheets for case tender specs run one row per departure, 12 rows maximum, three columns: clause, type, and substitute with evidence page. Type is none, positive or negative, with no room for largely compliant.

Case Tender Specs internal volume check on an open black case, moulded carry handle inside the lid, two red latches at the rim

Twelve rows keep the reading finite. Five evaluators hold the same sheet, walk the rows and turn to the page; a page that cannot be found scores as missing.

A 4.5 mm wall reads as generosity until unit weight passes 7 kg and breaks the gross ceiling, so a positive deviation must state its effect on neighbours.

A negative on a critical limit disqualifies. Three negatives on the rest may convert.

5. Three disqualification lines

A disqualification line judges results, never sources. A wall under 3.0 mm, a failed immersion condition, or a latch pull below 45 N ends the bid on the spot.

Thin evidence comes second: 2 of the 4 items missing. Silence through the clarification window counts as dropping the claim.

Run 6 checks before opening. Any model code or trademark left in case tender specs, tolerances consistent, all 6 groups present, the evidence list attached, the deviation sheet labelled with rows and columns, and lines that describe results only.

Conclusion

Lock-in in case tender specs is not a wording problem. It is the swap from source to result: model codes become three dimensions with a ±1.0 mm band, trade names become material plus test method, dimension stacks shrink to net inner size and a 3.0 mm wall. Group the table into 6 blocks, back equivalence with 4 evidence items and 5 working days, cap the deviation sheet at 12 rows, and write lines that judge results only. A 3-supplier field then returns above 6, and the meeting argues about wall thickness, not brands.

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.