From Sampling to Certainty – How 100% Inline Thermography Transforms Plastic Weld Quality and Process Control

In a world of rising quality standards, regulatory audits, and increasing production complexity, plastic laser welding faces a fundamental challenge: random sampling is no longer enough. Conventional test strategies leave too much to chance - and too much waste. Discover how TherMoPro, LPKF’s inline thermography system, delivers full transparency and opens new dimensions in quality assurance and process optimization.

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The Risk of Sampling-Based Inspection

In many laser welding applications, quality control still relies on visual inspections, destructive testing of random samples, leak checks based on AQL standards and one-time thermal stress. While this approach has been widely accepted, it comes with hidden risks.

Even statistically acceptable processes can miss critical defects when:

material batches vary in transmission or fiber content/ distribution,

tools or clamping systems cause inconsistent pressure,

part positioning fluctuates slightly over time,

or thermal input drifts during long production runs.

In such cases, good parts may be rejected unnecessarily - while defective parts slip through unnoticed.

100% Inline Thermographic Inspection

TherMoPro changes this paradigm by introducing full-field thermal inspection directly after the weld. Using long-wave infrared cameras, it captures the surface temperature distribution of every part and interprets the thermal signature using intelligent analysis.

Unlike basic process metrics like weld time or collapse control, TherMoPro delivers more than 20 thermal characteristics per part. These include the homogeneity of energy input, potential underheating, and critical overheating zones.

All data is processed in real time, and each part is classified as OK or NOK—before it moves on to the next step.

From Inspection to Optimization

Beyond quality assurance, TherMoPro provides deep insight into the laser welding process. Subtle changes in thermal patterns often reveal root causes for performance issues long before defects occur.

For example:

Uneven heat distribution might point to misaligned tools or worn components.

Local overheating may indicate incorrect energy input or process speed.

Cold zones could be caused by poor material transmission or clamping issues.

With this level of detail, process owners can shorten setup times, validate new tooling without destructive testing, and fine-tune machine parameters for more stability and yield. It also enables faster and easier approval of new material batches or second-source suppliers - based on objective thermal data rather than trial-and-error.

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Built-in Traceability and Documentation

Every thermal profile is linked to a unique part ID. This creates a digital fingerprint for each component—documenting that the right amount of energy was delivered to the right area.

Such traceability enables:

Audit-proof documentation for regulated industries,

Retrospective analysis in case of customer claims,

Performance comparisons across suppliers, shifts, or tooling variants.

In safety-critical sectors like automotive, medical devices, or aerospace, this level of documentation is not just helpful—it’s essential.

Minimizing the risk of Quality Loss

Random sampling introduces risk. 100% inline thermographic inspection replaces uncertainty with insight - and enables a new era of quality-driven production.