Plastic Coffee Dripper – From 95% Rejection to Mass Production

PLASTIC COFFEE DRIPPER
From 95% Rejection to Stable Mass Production

A thick-wall moulding challenge solved for a home lifestyle e-commerce brand.

*[Hero Image: 成品图，白底，电商风格产品摄影]

THE CHALLENGE

Our client, a home lifestyle e-commerce brand, wanted to launch a premium plastic coffee dripper. The part features an extremely thick wall—a classic "thick-wall injection moulding" challenge.

The client initially tried a two-shot overmoulding process. The results:

⚠️ Rejection rate hit 95% — nearly every batch was scrapped
⚠️ Poor surface finish — unacceptable for high-res e-commerce product photography

They came to us for a complete solution.

OUR SOLUTION

We recommended switching from two-shot overmoulding to single-shot injection moulding, taking full responsibility for mould design, process optimisation, and post-moulding handling.

[Image: 冷却治具或模具结构图]

THE DIFFICULTIES

Once we moved to single-shot moulding, the thick wall created a new set of problems:

▸ Void bubbles formed inside the thick section
▸ Severe warpage across the part
▸ Obvious sink marks on the aesthetic surface

These three defects are the classic triad of thick-wall moulding—fixing one often makes the others worse.

OUR APPROACH

Our engineering team attacked the problem from two directions:

1. Fine-tuned the injection process — through repeated DOEs, we optimised fill speed, holding pressure, and cooling time to minimise shrinkage and internal stress at the source

2. Developed a proprietary post-mould cooling fixture — after ejection, parts go through a precisely controlled external cooling station that we designed in-house, ensuring stable geometry and eliminating voids during the critical solidification phase

After multiple validation rounds, we cracked all three problems.

THE RESULTS

Metric	Outcome
Internal quality	Zero voids — fully eliminated
Surface quality	Smooth finish, sink marks completely resolved
Dimensional stability	No warpage, all dimensions within drawing specifications
Production status	Stable yield, smooth mass production, on-time delivery

[Image: 良品与不良品对比图]

The client launched the product immediately upon receiving the first mass-production batch, with positive feedback from end-users.

PROJECT SNAPSHOT


Industry	Home lifestyle / E-commerce
Product	Plastic coffee dripper
Key challenge	Thick-wall moulding (voids / warpage / sink marks)
Our solution	Single-shot moulding + process optimisation + proprietary post-mould cooling fixture
Outcome	From 95% rejection to stable mass production