How many units make a plastic carrying case bulk buy worthwhile?

Answer: A single-cavity tool runs about 28,000 CNY: 56 CNY per case at 500 units, 14 CNY at 2,000.

How much clearance should the cavity allow?

Answer: 10 to 15 mm per side and 20 mm on top, compressing 3 to 5 mm at closure.

Are two latches enough?

Answer: Up to 18 kg and 560 mm, yes. Above 20 kg or 600 mm, specify four. POM latches hold about 40% more force than PP when cold.

Which resin suits a bulk order?

Answer: ABS indoors where gloss matters, block copolymer PP below minus 10 degrees C, HDPE for heavy items stacked three high at most.

What lead time should 1,000 units expect?

Answer: 18 days moulding on an existing tool, 5 for cartons and pallets, 2 to load: 25 days. A new tool adds 22.

Plastic Carrying Case Bulk Buy: Five Checks Before You Order

Quick answer: A plastic carrying case bulk buy is settled by five checks in order: internal size, wall and lid thickness, latch count against handle load, resin grade against service temperature, then carton loading and sampling. Size first, price last.

Five Checks That Drive a Plastic Carrying Case Bulk Buy
Outside Size Versus Usable Volume
Latch Count and Handle Load
Resin Choice and Wall Thickness
Carton Loading and Incoming Inspection
FAQ

1. Five Checks That Drive a Plastic Carrying Case Bulk Buy

A bulk buy fails differently from a sample. At 1,000 units the returns come from drifting cavities, thin walls away from the gate, and latches that let go under load.

The sequence: size tier, wall and lid thickness, latch count against handle load, resin grade for the coldest service, then carton counts and sampling. Reverse it and each mould change costs 28,000 CNY.

Check	Benchmark	Failure at 1,000 units
Internal size	3 mm diagonal spread	Foam bottoms out
Wall and lid	3.0 and 2.6 mm	Drop height -0.3 m
Latch	180 N per latch	Pops open below 150 N
Resin	Split at minus 10 C	Wrong grade for cold
Sampling	AQL 2.5, 80 pieces	Cosmetics only

A diagonal spread past 3 mm keeps the gasket from reaching 25% compression, and a latch under 150 N opens by itself in a 1.2 m drop.

2. Outside Size Versus Usable Volume

A 560 x 350 x 230 mm shell with 3.0 mm sides, 2.6 mm lid and 3.4 mm base yields a 505 x 292 x 194 mm cavity, 28.6 litres. The 480 x 330 x 195 mm model gives 19.2 litres, so 9.4 litres separate the tiers across an 11% price step.

Plastic carrying case bulk buy: two black cases side by side, left lid flat over grey foam, right insert tray and coiled cable, two latches

Work back from the item. A 460 x 250 x 150 mm block needs 15 mm of foam per side and 20 mm above, so the cavity must reach 490 x 280 x 190 mm.

Polypropylene shrinks 1.5% to 2.0%; with 1.7% compensation the cavity holds plus or minus 1.2 mm, and a spread above 1 mm points to mould temperature moving 8 C.

3. Latch Count and Handle Load

At 18 kg loaded, one-handed lifting concentrates torque at the handle boss: 4.5 mm of wall and a 6 mm 304 pin. Hang 30 kg for thirty minutes and check for permanent set.

Two latches at 180 N each suit a 560 mm case at 18 kg. Past 600 mm or 20 kg, use four and offset the centre pair by 8 mm so the lid cannot bow on a plastic carrying case bulk buy.

A full-width hinge with a 5 mm pin should clear 500 cycles under 0.5 mm, with the gasket groove at 3.2 mm and 25% compression.

4. Resin Choice and Wall Thickness

Homopolymer polypropylene at 3.0 mm cracks in a 1.2 m drop at minus 10 degrees C; block copolymer pushes embrittlement past minus 25. ABS needs 2.8 mm for stiffness and gloss.

Plastic carrying case bulk buy: close view of grey foam pressed around a pale device shell, a grey seal running along the rounded corner lip

HDPE at 3.5 mm survives 1.5 m, yet its 900 MPa modulus lets a five-high stack sag 1.8 mm.

Resin	Wall	Drop height	Modulus	Best fit
PP homopolymer	3.0 mm	1.2 m	1500 MPa	Indoor
PP block copolymer	3.0 mm	1.2 m at -25 C	1200 MPa	Cold stores
ABS	2.8 mm	0.9 m	2200 MPa	Glossy shells
HDPE	3.5 mm	1.5 m	900 MPa	Heavy loads

Removing 0.4 mm saves 62 g per case, 62 kg across 1,000 units, roughly 78 CNY, and takes the drop rating from 1.2 m to 0.8 m on a plastic carrying case bulk buy.

5. Carton Loading and Incoming Inspection

Each case is 2.6 kg net, two per 575 x 365 x 250 mm carton, 24 cartons per pallet: 48 cases. A 40 ft high cube holds 1,008 cases; a 20 ft holds 432.

Sampling at AQL 2.5 over 80 pieces covers 20 latch cycles, 3 mm diagonal spread, 0.5 mm hinge clearance and 48 hours of salt spray on a plastic carrying case bulk buy.

Conclusion

The five checks work as a sequence, not a menu. Internal size decides fit, resin and wall decide survival in a drop, latch and handle decide lift safety, sampling decides rework. That order is what a plastic carrying case bulk buy rewards.

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.