Case Study: 8-Cavity Refrigerated Container Lid Mold

One machine producing about 23,000 pieces per day, with unit cost reduced by around 40%

By Zhang, Senior Sales Engineer at H T Mould

Product type: 8-cavity thin-wall PP refrigerated sealed lid mold
Applications: food packaging, especially refrigerated sealed box lids
Customer region: large packaging manufacturer in South China

1. Customer Challenge: Lid Output Could Not Keep Up with Base Output

We had previously supplied the customer with a 4-cavity refrigerated sealed container base mold producing about 9,874 pieces per day. The customer soon came back with a new problem: "Box output is up, but the lids can't keep up."

Base mold: 4 cavities, 35-second cycle, about 9,800 pieces per day
Old lid mold: 4 cavities, 38-second cycle, about 9,100 pieces per day
Result: around 700 container bases per day had no matching lids and could not be shipped as complete sets

The customer was very clear: lid output had to exceed base output, and unit cost had to come down, because lids often sell for 20-30% less than the box base and leave much thinner margins.

So I recommended H T Mould's high-cavitation thin-wall PP lid solution: 8 cavities, a 30-second cycle, and the same 400T press class used for the base mold.

2. Solution Core: Pushing Efficiency to the Limit

Lids differ from bases: larger projected area but thinner walls (often 0.4–0.55 mm), demanding fill balance and even cooling. The 8-cavity tool redesigns gating, cooling, and ejection—not a simple double-up from four.

1. Process data (actual production)

Item	Value	Item	Value
Cavities	8 CAV	Cycle	30 s
Mold size	450×720×498 mm	Press	400 T
PP melt	310 °C	Cooling water	18–22 °C
Water pressure	0.5–0.6 MPa	Production yield	99.3%

2. Why this lid mold is a “throughput machine”

8 balanced cavities—analysis-tuned runner length and gate sites; cavity-to-cavity fill spread <0.2 s
30 s cycle—uses thin lid geometry; beats typical 36–40 s
400T footprint—compact, easy changeover, no extra capital

3. Three thin-wall lid design challenges—and our answers

Challenge	Symptom	H T Mould response
Unbalanced fill	Remote cavities short or unfilled	Symmetric H runner + valve gates, timed sequencing
Warpage	Lid not flat, poor seal	Conformal cooling + zoned mold temp; deflection <0.12 mm
Demolding	Stick or stress whitening	Air pins + precision ejector layout

3. Field data: ~23,040 pcs/day—one press does two presses’ work

Daily output: ~23,040 pcs/24 h (3600 s / 30 s × 8 × 24); steady 22,500–22,800

Yield: 99.3%; defect rate <0.7%

Metric	Old (4 cavities)	H T Mould (8 cavities)
Daily output	~9,100	~23,000
Output multiplier	1×	2.5×
Yield	97.5%	99.3%

4. Cost: lids are thinner—margins are tighter

Power: 410 kWh saved per 10k pcs—$47.46 per 10k
Labor: three headcount-equivalents—$2,604.41/month
Maintenance: $2,893.79 saved per million shots
Material: hot runner, zero cold runner—127 kg/day saved—~$4,340.69/month

5. Profit: lids can still earn

Item	Old	H T Mould
Daily output (pcs)	~9,100	~23,000
Total cost/pc (USD)	0.73	0.528
Profit/pc (USD)	0.22	0.422
Daily profit	$289.67	$1,404.36

+$1,114.69/day; ~$33,423.31/month
Mold investment $46,300.69—payback in ~1.5 months

6. 3M shots guaranteed; 5–6M is routine

We warrant 3 million shots; this customer passed 3.8M and remains stable. At 5M shots, mold cost per part is only $0.0012.

7. Customer feedback

“I worried eight cavities would be unstable—yet 30 s is steadier than our old four-cavity at 38 s. We’ve bought three sets.”
“99.3% on a thin lid—we didn’t think it was possible. Less scrap, more margin.”
— Director of production

8. Base + lid = matched line

Part	Mold	Daily output	Press
Refrigerated sealed base	4 cavities, 35 s	~9,874	400T
Refrigerated sealed lid	8 cavities, 30 s	~23,040	400T

9. Who should buy this 8-cavity lid mold?

Lid demand 15,000–25,000/day
Current cycle >36 s or fewer than six cavities
Running 400T for maximum output
Thin margins—need cost down
Must pair with base production

Closing

Base and lid look like two molds—it’s really one capacity equation.

Base: 4×35 s; lid: 8×30 s. Same equipment class—double lid output, roughly half lid cost.

H T Mould—solutions for the highest output per square meter of shop floor.