How a Nantong Mould Shop Quietly Supplies Battery-Pack Foam Pads To Top EV Programs

Application case study, EV thermal-runaway protection

If you open the floor of a modern battery-electric vehicle, the long black pad sitting between the cells and the cold plate is almost always expanded polypropylene foam. Density 50 to 70 g/L, thickness 18 to 30 mm, compression set below 12% at 70 °C. Every major Chinese cell maker is buying it by the million.

Nantong Bainuo Mould Co., Ltd. (https://www.bainuomoulds.com/) has been running one of these mould programmes since 2022. The first tool was a 4-cavity EPP family mould for a 1.5 kWh pack spacer. Cavity size 620 × 220 × 26 mm, shot weight 380 g, cycle 110 s, P20 steel with copper-beryllium inserts in the high-wear corners. The tool is now on its 1.2 millionth shot and still inside the original wall-thickness tolerance of ±0.15 mm.

What is interesting is what is around the foam tool. The same shop is making the precision checking fixtures for the spacer — aluminium jig with 12 Renishaw reference points, used by the cell maker's Tier-1 in Wuhan to keep dimensional drift inside 0.1 mm across an 8-hour shift. They also supply 3D-printed sand moulds for the small aluminium coolant distribution plates that sit underneath the foam pad, which means one supplier can quote the foam tool, the checking fixture, and the prototype cast plate as a single package.

For an EV programmes team that is tired of juggling three vendors for one battery pack, that consolidation is the actual story. Ask Mr. Wu for a sample kit of three foam densities plus a CAD of the checking fixture, email bainuo@bainuomould.com, call +86 153 7171 3697, or message via WhatsApp +86 199 4201 0686. Do this before your next pack concept freeze, not after.