# 進化し続ける EVA ケース：革新と適応の歩み

Canonical URL: https://evacasemanufacturer.com/ja/news/the-ever-evolving-saga-of-eva-case-a-story-of-innovation-and-adaptation
Published: 2024-09-09 11:14:00
Author: Dongguan Lianping Luggage Co., Ltd.
Publisher: LIANPING
Keywords: eva case manufacturer, custom eva case, compression molding eva shell, die cut foam insert, eva case drop test, eva sheet density g/cm3, oem eva case china
Views: 2,077
Language: ja

LIANPINGのEVAケースラインが簡単な成形ポーチからダイカットフォームシェルへ進化した経緯と、次回発注で密度・硬度・落下試験スペックが持つ意味。

The oldest tooling still in service on our mold rack is a single-cavity aluminum tool stamped 2016. It was cut for a plain black earphone pouch, 165 x 95 x 55 mm (roughly 6.5 x 3.7 x 2.2 in), with nothing inside but a thin velvet lining. Ten operators could finish that job in a day. When we pulled it out for a maintenance check this spring, the parting face had worn enough to leave a 0.4 mm flash line along the seam, so our tooling technician skimmed it, polished the cavity and put it back on a small reorder.

## From Sewn Pouches to Compression-Molded Shells

EVA (ethylene-vinyl acetate) came into our line as a replacement for sewn nylon pouches that lost their shape after a few weeks in a bag. Compression molding is what changed the material's usefulness: a flat blank goes into a heated cavity, the press closes at roughly 150-180 degrees C depending on the compound, and the sheet comes out as a three-dimensional shell with walls typically 1.5-2.5 mm thick. Early shells were single-density, around 0.20 g/cm3, with hardness near Shore C 55. Too soft and it slumps under pallet load; too hard and the zipper tape tears at the corner radius.

## What Actually Changed Between 2022 and 2024

Three shifts moved the product range. Buyers started specifying interior geometry instead of an empty box, which turned die-cut foam and egg-crate foam from an optional extra into the default. The outer laminate moved on from basic polyester to 600D Oxford and PU leather surfaces that hold up better against conveyor abrasion. And drop performance became a written line in the specification rather than a verbal assurance: most electronics and medical orders now quote 1.0-1.5 m drops across six faces, three drops per face, packed in the customer's own shipper.

Hardware followed. A mid-range nylon coil zipper typically survives about 5,000 open-close cycles on our bench rig, and the failure is almost always the slider body rather than the tape. For anything carrying a retail service-life claim we now specify YKK or an equivalent and log the cycle count on the QC sheet that travels with the pre-production sample. Webbing handles are pull-tested to 20 kg on the larger tool shells, because a handle tearing out in a store is the complaint buyers remember.

The tooling approach changed as well. Our [EVA tool case line](https://evacasemanufacturer.com/ja/products/sub/eva-tool-case) now runs on a set of modular base molds, so a customer asking for a 300 mm or a 380 mm shell is not paying for an entirely new cavity. The same logic was applied to [the medical case range](https://evacasemanufacturer.com/ja/products/sub/eva-medical-case), where an insulin cooling kit needs an insulated cavity kept separate from the pocket that holds syringes and test strips.

## Where the Material Specs Sit Today

General-purpose shells run sheet density of 0.18-0.22 g/cm3. We go denser, closer to 0.25, for heavy tool sets and drone bodies where the case itself carries part of the load. Anti-static versions for board-level carriers are checked against the surface-resistance limits in IEC 61340-5-1. Every compound we run arrives with RoHS and REACH documentation from the sheet supplier, and CA Prop 65 statements are available when a US retailer's compliance portal asks for them. Outdoor designs are verified to IP54; reaching IP65 needs a gasketed zipper track and a formed lip, and that is a real cost line rather than a wording choice. Distribution testing moved in the same direction. Parcel and less-than-truckload shipments are qualified to ISTA 2A or 3A, and where a customer's own protocol references ASTM D4169 we build the test plan to that instead. The difference shows up in corner crush more than anywhere else: a shell that survives a bare drop can still fail once the carton above it in a stack adds load.

The 2016 tool is booked for another refurbishment in November. Two new cavities for a European power-tool distributor are being cut in the same workshop, and the first samples from that run go out by Friday.

## FAQ

**How has EVA case construction changed since 2016?**

Three changes dominate: interiors moved from empty shells to die-cut and egg-crate foam layouts, outer laminates shifted from basic polyester to 600D Oxford and PU leather, and drop performance became a written specification, commonly 1.0-1.5 m across six faces with three drops per face inside the customer's own shipping carton.

**What EVA sheet density should I specify for a hard case?**

Most general-purpose molded shells use 0.18-0.22 g/cm3 sheet with hardness around Shore C 40-70. Heavier contents such as tool sets or drone bodies justify 0.25 g/cm3. Lower densities save weight, but the shell slumps under pallet stacking and the corners lose shape first.

**Do EVA cases meet RoHS and REACH for EU import?**

Yes. Compounds run on our lines carry RoHS and REACH declarations issued by the sheet supplier, and we keep current versions on file with the order record. CA Prop 65 statements are available for US shipments. Material testing goes through CTI, and the quality system is certified to ISO 9001.

---
Contact: anton2@qq.com