How far apart are per kilo and per case quotes from a rotomolded protective case manufacturer?

Answer: A per kilo quote at 32 CNY lands near 358 CNY against 553 per case, but the gap is the wall.

Answer: Under 1,500 cases a year, three arms cover a 700 x 450 mm mould. Four add about 30% real output, not the 33% on paper.

What wall thickness passes?

Answer: A 4.3 to 4.7 mm average across nine points, none under 4.1. A rim above 5.3 mm means build-up.

Can the 300 piece MOQ drop?

Answer: To 150 with a 1,200 CNY purge charge, about 8 CNY each, waiting for another order to share the oven.

Rotomolded Protective Case Manufacturer: Arm Count and Tooling

Q: Aluminium or steel tooling?

Answer: Aluminium under 1,000 cases or with frequent changes; steel for a long run, where 20,000 cycles bring tooling to 1.6 CNY.

Quick answer: Audit a rotomolded protective case manufacturer by arm count and oven volume: three arms on a 26 minute cycle give 166 cases a day on paper, 122 after loading. Then check tooling and powder grade.

What the Rotomolded Protective Case Manufacturer Quotes Against
Machine Arms and Real Capacity
Aluminium or Steel Tooling
Wall Uniformity and Powder Grade
MOQ, Unit Cost and Lead Time
FAQ

1. What the Rotomolded Protective Case Manufacturer Quotes Against

Quotes come per case or per kilogram, and the kilogram version hides wall thickness. A 700 x 450 x 300 mm case weighs 11.2 kg at 4.5 mm and 9.9 kg at 4.0 mm, so a per kilo quote drops 12%.

Eleven kilos of LLDPE at 13.5 CNY per kilogram is 151 CNY, and an arm hour at 260 CNY adds 113 CNY, so 264 CNY is the floor.

Cost block	300 pcs	1,000 pcs
Powder	151 CNY	151 CNY
Moulding	113 CNY	113 CNY
Hardware	32 CNY	30 CNY
Tooling	183 CNY	55 CNY
Total	553 CNY	405 CNY

Tooling sets the other end. A 55,000 CNY aluminium mould is 183 CNY per case at 300 pieces and 55 CNY at 1,000, so ask what quantity a lump sum is spread over.

2. Machine Arms and Real Capacity

Arm count is the first capacity variable, not the only one. Three arms on a 26 minute cycle give 166 cases a day, four give 221. A 700 x 450 x 300 mm mould displaces 0.11 m3, so it fits a 3.2 m3 oven.

Rotomolded Protective Case Manufacturer: warehouse stacks of khaki cases nested eight high, wrapped in clear stretch film, a darker stack at left on a concrete floor

Arms	Cycle	Paper output	Real output
2	26 min	111/day	82/day
3	26 min	166/day	122/day
4	26 min	221/day	163/day

Check arm load rating too: at 250 kg per arm a 68 kg mould plus powder leaves margin, while a 120 kg machine forces a 34 minute cycle. Schedule on 2.2 arms, not three.

3. Aluminium or Steel Tooling

The difference is heat transfer and life, not price. A 6 mm aluminium mould conducts at 200 W/mK and heats in 11 minutes; a 3 mm steel mould at 45 W/mK needs 15, or 20 extra oven hours across 300 pieces.

Item	Aluminium	Steel
Thickness	6 mm	3 mm
Heat-up	11 min	15 min
Tool cost	55,000 CNY	32,000 CNY
Wall range	0.4 mm	0.7 mm

Below 1,000 cases a year with frequent changes, aluminium wins because patching is quick. On a long run, steel spread over 20,000 cycles brings tooling to 1.6 CNY.

Aluminium is easy to modify and reuse, so a buyer who pays should hold the tool number and storage location, with a clause barring other orders.

4. Wall Uniformity and Powder Grade

Wall uniformity is where a rotomolded protective case manufacturer is most often vague. Target 4.5 mm at nine points: 4.4 to 4.6 on the side, 4.1 to 4.9 in the corner, 4.6 to 5.3 at the rim.

Rotomolded Protective Case Manufacturer: workers on orange stools finishing black cases at benches, a stack of black cases at left, two blue overhead signs, yellow floor markings

Rotomolding grade LLDPE runs a 3.5 g/10min melt index at 35 mesh and 0.935 g/cm3; below 2.5 the powder will not flow out at 280 C and pinholes follow. Put that in the contract.

Test powder three ways: batch number, moisture under 0.05%, and a 200 mm plaque for fish eyes.

5. MOQ, Unit Cost and Lead Time

MOQ follows how many moulds fill one oven: three arms carry three moulds, so under 300 pieces leaves an arm empty. A colour change costs a rotomolded protective case manufacturer 90 minutes and about 1,200 CNY.

Batch	Tooling	Processing	Unit price
300 pcs	183 CNY	370 CNY	553 CNY
1,000 pcs	55 CNY	350 CNY	405 CNY
2,000 pcs	28 CNY	337 CNY	365 CNY

Lead time is 28 days: 20 for the tool, 3 for trials, 3 for production, 2 for inspection. Payment runs 30/40/20/10, the last tenth held 60 days, and the wall is judged on the nine point average.

Conclusion

Audit a rotomolded protective case manufacturer in this order: quote basis, arm count, tooling, powder. A per kilo basis makes prices incomparable, and an unverified arm count turns a lead time into a guess. Ask for oven size, tool number and powder batch before signing with any rotomolded protective case manufacturer.

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.