Case Study: Eliminating Black Marks on White Plastic Components

Introduction

A Tier-level automotive component supplier was producing white plastic connector parts with strict appearance requirements.

However, during ultrasonic welding:

• Black marks appeared on the surface

• Defects increased during continuous production

• Multiple machines failed to meet quality standards

 Result: Products could not pass OEM inspection.

After evaluation, the issues were not material-related, but process-related:

• Unstable pressure from pneumatic systems

• Excessive localized heat causing surface contamination

• Lack of precision control for sensitive materials

• Poor repeatability during long production cycles

For white or light-color parts, even minor instability = visible defects.

We provided a customized solution based on:

Key Technical Features

✔ High Frequency 35kHz

• Lower amplitude → reduced surface damage

• Ideal for precision & thin-wall plastic parts

✔ Servo-Driven System

• Accurate pressure control (vs pneumatic)

• Programmable welding profiles

• Stable and repeatable output

✔ Multiple Welding Modes

• Time / Energy / Distance / Absolute

• Flexible for different materials

✔ Consistent Energy Delivery

• Prevents overheating

• Eliminates discoloration and burn marks

After Implementation:

• Black marks → Completely eliminated

• Surface quality → Clean & consistent

• Production → Stable under continuous operation

Business Impact:

• Higher product qualification rate

• Reduced scrap & rework

• Improved end-customer satisfaction

This solution is ideal for:

• Automotive plastic components (connectors, interior parts)

• Medical devices

• Electronic precision components

• Appearance-sensitive products (white / light color)

Ultrasonic welding is widely used because it enables:

Fast bonding without adhesives

Localized heat generation

High efficiency for mass production

But for high-end applications:

Control precision determines final product quality

That’s why:

✔ Servo system = precision
✔ 35kHz = gentle + clean
✔ Process control = stability

Having Similar Welding Issues?

• Black marks on white parts

• Inconsistent welding quality

• High defect rate in mass production

Get a customized welding solution within 12 hours

Contact us now →