Why can plastic case pictures and prices differ threefold for one size?

Answer: Route and batch: the same envelope differs threefold in tooling, and 100 pieces cannot absorb a mould.

Why is a rotomoulded case dearer per unit yet cheaper at volume?

Answer: Material and labour per unit run higher, since 13 kg of LLDPE costs three times the resin in an injection shell. Above 300 litres, though, injection needs a 2500-tonne press and tooling from 350,000 RMB, so amortised rotomoulding stays 8% to 15% cheaper.

Is injection tooling worth it for a 100-piece order?

Answer: An 80,000 RMB mould over 100 units adds 800 RMB each, more than the case; stay with rotomoulding below 500 units.

Can castors be added to a case later?

Answer: On an injection case yes, on a rotomoulded one no: its floor is a solid 6 mm wall, and drilling breaks the load path.

Which line is most often missing from an offer?

Answer: Inserts and tooling: an insert moves from 35 to 180 RMB, and an 80,000 RMB mould over 300 units is 267 each.

Plastic Case Pictures and Prices by Size Class and Moulding

Quick answer: Four bands cover most enquiries: injection hard cases 85 to 380 RMB, rotomoulded cases 650 to 1200 RMB, wheeled cases 380 to 760 RMB, stackable bins 900 to 1500 RMB, ex-works at 100 pieces.

Plastic Case Pictures and Prices by Class
Injection and Rotomoulding Cost Structures
Where Accessories Add Cost
Volume Bands Versus Weight
Five Inquiry Parameters
FAQ

1. Plastic Case Pictures and Prices by Class

Case-class products share no price list with small boxes: a 400 mm case and a 1200 mm bin differ fivefold in material and tenfold in tooling, so plastic case pictures and prices compare only by class.

Class	Size band, mm	Empty weight	Price, RMB per unit
Hard case, PP	400×300–700×500	2.2–7.0 kg	85–380
Rotomoulded case, LLDPE	800×600–1000×700	11–19 kg	650–1200
Wheeled trolley case	550×400–650×450	5.5–8.5 kg	380–760
Stackable bin, HDPE	1200×800, pallet base	22–32 kg	900–1500

Prices track PP and LLDPE spot prices and the settlement rate; only a written offer binds.

2. Injection and Rotomoulding Cost Structures

Injection tooling carries the money: a 700×500 mm mould with slides and etched texture runs 80,000 to 350,000 RMB against 40,000 to 120,000 RMB for the rotomoulding tool, which sees no injection pressure.

Plastic case pictures and prices: two silver hard cases on a wooden bench, the upright one on four black castors

Batch size divides them: a colour change takes 1.5 to 3 hours of purging against 20 minutes, and the economic batch runs 500 to 1000 units against 30 to 80, so plastic case pictures and prices tilt to rotomoulding on small orders.

Cost item	Injection	Rotomoulding
Tooling, RMB	80,000–350,000	40,000–120,000
Material per unit	8.5 RMB/kg, 4.8 kg = 41 RMB	9.2 RMB/kg, 13 kg = 120 RMB
Labour per unit	90–150 s, 0.3 RMB	18–25 min, 3–6 RMB
Economic batch	500–1000 units	30–80 units

3. Where Accessories Add Cost

A 300 RMB shell with a PU insert, four castors and an aluminium plate quotes at 600 RMB: accessories are priced as a share of the case, so the dearer the shell, the smaller the share a wheel set takes.

Accessory	Uplift, RMB	Share of case price
Flat EVA or XPE insert	35–110	8–18%
PU foam cut to shape	80–180	15–25%
Reinforced nylon handle	18–35	4–7%
Wheels and handle, two or four	120–320	20–40%
Pressure relief valve	12–25	2–4%
Stainless padlock hasp	25–60	5–9%
Anodised name plate	8–20	2–4%

Inserts are the largest line: a cut insert replacing a flat pad lifts price 15% to 25% and adds 3 to 5 days. Wheel sets need extra floor and moulded bosses, buried in the 20% to 40% uplift. Valves, locks and plates stay under 15% yet are most often missing; pin wheel diameter before comparing plastic case pictures and prices.

4. Volume Bands Versus Weight

Price tracks empty weight more than volume, and weight tracks skin area: double the volume and the surface grows 60%. A 500 litre bin works out near 1.9 RMB per litre, a 20 litre one near 5.4 RMB.

Plastic case pictures and prices: a beige rotomoulded case on a ribbed metal van floor, two grey straps across the lid

Stacking is a calculation: with empty weight plus payload, keep bottom-wall stress below 0.35 MPa, capping a stack at three or four tiers. Wall thickness climbs from 2.5 to 3.0 mm at 20 litres to 6.0 to 8.0 mm at 500 litres.

5. Five Inquiry Parameters

Inaccurate quotes come from incomplete inquiry sheets. Five items bring the first reply within 8%: outside and internal clear size, wall thickness with rib pitch, resin grade with route, accessory list, batch and delivery.

Lid depth is what people forget: two cases marked 600×450×250 with 60 mm and 90 mm lids differ by 30 mm of usable height. Tooling lead time runs 25 to 35 days for injection, 12 to 18 for rotomoulding.

Conclusion

Plastic case pictures and prices reduce to a class table and two curves: class sets the band, tooling sets the entry quantity, accessories set the landing point. Fix those three, and plastic case pictures and prices tell you which offer is worth a second call.

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.