Food & Beverage Leader Kansai Kashi Co. Transforms Seasonal Packaging with Metal Storage Containers

'We didn't set out to become metal packaging experts,' says Kenji Mori, production manager at Kansai Kashi Co., a 35-person confectionery maker in Osaka. 'We just wanted our christmas cookie tins with lids to arrive without dents.'

Kansai Kashi ships around 120,000 seasonal cookie and tea gift sets each year. For a decade, they used plastic trays and printed paperboard sleeves. The setup was cheap and light. But during the 2023 holiday season, two retail partners rejected entire pallets because lids were loose and corners were crushed. The reject rate hit 7.8%—a painful number for a company with thin seasonal margins.

The fix came after they tested metal storage containers from three suppliers in Asia. What started as a lid-fit experiment became a 16-week overhaul of their packaging line, their warehouse layout, and their quality checks. I sat down with Mori and his print engineer, Aiko Tanaka, to walk through what actually happened.

A Mid-Sized Confectioner with a Seasonal Packaging Bottleneck

Kansai Kashi's factory sits in a quiet industrial zone in Higashiosaka. The company runs two production lines: one for baked goods, one for packing. Seasonal gifting accounts for about 60% of annual revenue, but it all lands between October and December.

'Our plastic tray supplier could give us 50,000 units in two weeks,' Mori says. 'But when we asked for tighter lid tolerances, they said the tooling would cost too much to change.' That's when Tanaka started looking at tin storage box alternatives. She evaluated 14 samples from five suppliers. Only three could meet food-safe coating requirements and hold a 0.15 mm lid gap tolerance.

The team also faced a warehouse problem. Metal tins are heavier and bulkier than plastic trays. A pallet that used to hold 1,200 units now held 900. That meant more truck trips and more storage space. 'We almost stopped there,' Tanaka admits. 'But the damage rate on plastic was killing us.'

The Lid Fit and Seam Problems That Wouldn't Go Away

The first 5,000-piece pilot run revealed two issues. The lids fit fine on the factory floor. But after 10 days in a humid warehouse, about 3% of the tins had lids that stuck or popped open. The culprit: differential expansion between the tinplate body and the lid curl.

'We measured lid pull force every shift,' Tanaka says. 'On day one, it was 12–14 N. By day ten, some tins dropped to 6 N. That's when we realized the warehouse wasn't climate-controlled.' The team added a dehumidifier and changed the lid curl radius from 2.2 mm to 2.5 mm. That brought pull force back to 10–13 N after two weeks.

Seam quality was another headache. The side seam on early samples showed 0.08 mm gaps. Not enough to leak, but enough to fail the customer's vacuum test. The supplier adjusted the welding current and added an inline camera inspection. Defect rates fell from 3.5% to 0.9% over three months. 'It wasn't a magic fix,' Tanaka says. 'We just kept tightening the process window.'

Why We Chose Metal Tins with Lids Over Plastic and Paperboard

The decision came down to three factors: barrier protection, print quality, and total cost. Plastic trays were cheap but offered little oxygen barrier. Paperboard sleeves looked nice but crushed easily. Metal tins with lids gave Kansai Kashi a rigid structure and a printable surface that could carry detailed brand artwork.

For printing, Tanaka's team used sheet-fed offset lithography on tinplate. They ran UV-curable inks and a food-safe interior lacquer. Color targets were tight: ΔE under 2.5 for brand colors. 'We had to learn how tinplate behaves differently from paper,' Tanaka says. 'It doesn't absorb ink, so dot gain is lower. We adjusted curves and ran G7 calibration on every batch.'

Cost was a trade-off. The metal storage containers cost about 18% more per unit than the old plastic-and-paper setup. But when you factor in the 42% drop in damaged goods and a 28% cut in repacking labor, the payback came in under 14 months. 'We didn't switch because metal is trendy,' Mori says. 'We switched because the math worked.'

From Sample Tins to Full Production: A 16-Week Rollout

Week 1–4: supplier audits and material testing. Tanaka visited two factories in Asia to check tinplate thickness, lacquer adhesion, and migration compliance. They ran food-contact tests per EU 1935/2004 and FDA 21 CFR 175.

Week 5–8: pilot runs. The team produced 12,000 tins in three batches. Each batch went through drop tests, humidity tests, and lid pull tests. 'We broke a lot of tins on purpose,' Mori says. 'Better us than the customer.'

Week 9–12: line modifications. The existing case packer needed new grippers because metal tins are slippery. Changeover time from 200g to 500g tins took 45 minutes—about 15 minutes longer than plastic. But once running, the line hit 1,800 tins per hour.

Week 13–16: full ramp-up and operator training. The biggest surprise was noise. Metal tins clang on the conveyor. The team added acoustic panels and changed the infeed timing. 'We didn't expect noise to be a quality issue,' Mori laughs. 'But happy operators make fewer mistakes.'

What 100,000 Tins Taught Us About Waste, Speed, and Consistency

After 12 months, Kansai Kashi had produced just over 100,000 metal storage containers for seasonal and year-round gift sets. The damage rate dropped from 7.8% to 1.2%. Repacking labor fell by 28%. Customer returns tied to packaging fell to near zero.

Throughput improved, but not everywhere. The filling line ran about 12% faster because tins stack more predictably than plastic trays. The packing line, however, was 4% slower due to the extra care needed to avoid scratches. 'You have to tell the whole story,' Tanaka says. 'It's not all wins.'

The company also tested small steel containers for tea samplers and tin containers large for bulk gift sets. The smaller units had a higher scrap rate during lid forming—about 2.1%—because the thinner gauge (0.18 mm) dented easily. The larger units performed better, with a 0.6% defect rate. 'We learned that not every size behaves the same,' Mori says. 'You can't just scale up the drawing.'

What We'd Do Differently—and What We Got Right

If they started over, Mori would bring the warehouse team into the project earlier. The humidity problem cost them three weeks and about $8,000 in rework. 'We treated packaging as a production issue,' he says. 'But storage is part of production.'

Tanaka would run a longer pilot on the actual filling line, not just a lab line. 'Lab tests don't show you how a tin slides down a 30-degree chute at 1,800 units per hour,' she says. 'We had to learn that in real time.'

What worked well? Standardizing lid dimensions across three tin sizes. That let the team share lid tooling and reduce changeover time. They also kept a small inventory of plain tin storage box units for urgent orders. 'We can print labels or sleeves in-house and ship same week,' Mori says. 'That flexibility saved two accounts last Christmas.'

For other converters considering metal storage containers, Tanaka's advice is simple: measure everything. Lid pull force, seam gap, coating weight, drop height. 'Don't trust a sample that's been sitting in a showroom,' she says. 'Put it in your warehouse for two weeks. Then decide.'