EV Battery Cell Holder Mould Injection Molding Key Points – A 21-Drop Hot Runner Case Study

In EV battery cell holder mould injection molding, the hardest challenge is often not the part design — but how to stably fill a "long and thin" product. Recently, JunSun Mould completed a representative project: an EV battery long thin cell holder with a length of over 1200mm and wall thickness of just 1.2mm, made of ABS+PC (flame-retardant grade, poor flowability),The solution was a 21-drop hot runner system. This article walks through the key technical points.

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1. Three Key Points for EV Battery Cell Holder Injection Molding

For EV battery cell holder mould design and injection molding, three core key points need priority attention:

JunSun Mould has a mature design methodology for all three key points.

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2. Project Background: Long Thin EV Battery Cell Holder

The product is a long strip cell holder for an EV battery module. Customer requirements:

• Length: 320mm

• Wall thickness: 1.0mm (0.8mm at thinnest)

• Material: ABS+PC (flame-retardant grade, UL94 V-0)

• Cavities: 16

• Dimensional tolerance: ±0.05mm

Core challenges:

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3. The Solution: 21-Drop Hot Runner System

To address these challenges, JunSun Mould's design team did not go with a conventional 2 or 4-drop solution. Instead, we implemented a 21-drop hot runner system.

Why 21 drops?

• At 320mm length, single-side gating would make the flow path too long

• We used a staggered, dual-side gating approach: 10-11 drops per side, 21 drops total

• Drop spacing was kept at 30-40mm to ensure the melt front does not freeze at the far end

Hot runner specifications:

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4. Moldflow Analysis: From Simulation to Validation

Before machining the mould, JunSun Mould ran a full Moldflow analysis.

Key findings:

1. Fill time: 21 drops filling simultaneously, fill time ≈ 1.8 seconds — much lower than 4.5 seconds with single-side gating

2. Injection pressure: Peak pressure kept under 120MPa, within machine limits

3. Weld line location: Adjusted gate timing to move weld lines to non-stress areas

4. Warpage: Predicted 0.12mm, within tolerance

Actual trial molding results closely matched the simulation — validating the 21-drop approach.

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5. Why is ABS+PC a Common Material for EV Cell Holders?

ABS+PC is a common engineering plastic alloy, combining the toughness of ABS with the strength of PC. For EV cell holder applications, it has clear advantages — but also special considerations:

JunSun Mould's countermeasures:

• Increase drop count to shorten flow length

• Strictly control melt temperature and residence time

• Use valve gates to reduce shear heating

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6. Summary of Key Design Points for EV Cell Holder Moulds

Based on this 21-drop project experience, JunSun Mould summarizes several core design points for EV battery cell holder moulds:

1. More drops, not fewer
   For thin-wall long parts, better to add more drops than to risk short shots. 21 drops may sound like a lot, but it's far cheaper than mould rework.

2. Sequential valve gate timing is critical
   Not all 21 valve gates open at once. Use staged opening: middle gates first, end gates later, to avoid trapped air.

3. Balanced cooling system design
   Cooling channels on long moulds must be evenly distributed along the length to avoid warpage from hot spots.

4. Mold steel and polishing matter
   To ensure smooth ABS+PC flow, all runner and cavity surfaces are mirror-polished to reduce flow resistance.

5. Document every trial parameter
   Create a complete process parameter sheet for each mould to enable repeatable mass production.

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7. JunSun Mould's Positioning

JunSun Mould is a China Battery Housing Mould Supplier & Battery Cell Holder Mould Manufacturer focused exclusively on new energy battery structural components.

This 21-drop EV cell holder project is just one example from our portfolio. If you are developing similar thin-wall cell holders or battery housings, feel free to reach out with your drawings.

Contact Us:

• Website: www.junsunplast.com

• Email: mould@junsunplast.com

• WhatsApp/WeChat: +86 152 05867586