The Challenge

Many medical device manufacturers use thermal transfer printing to produce UDI labels.

At the beginning of a production run, the labels are clear and easy to read.

However, after several hours of continuous printing, operators begin to notice something unusual.

The labels still pass visual inspection, but barcode read rates start to decline.

The printer hasn't stopped working.

The barcode hasn't changed.

Only the print contrast has gradually decreased.

Why It Happens

As the ribbon and print head wear during long production runs, black bars become lighter and white spaces become less distinct.

To the human eye, the UDI label still appears normal.

But for a barcode scanner, the difference between black and white becomes too small, making barcode boundaries more difficult to identify.

This problem becomes more obvious when:

• Labels are very small

• Products move continuously on the production line

• The scanner has only milliseconds to capture the image

Engineering Considerations

Replacing the printer is not always necessary.

Instead, manufacturers should:

• Monitor ribbon quality during long production runs

• Clean the print head regularly

• Verify barcode quality at scheduled intervals

• Use an industrial barcode scanner capable of capturing subtle grayscale differences

By identifying low-contrast labels before they interrupt production, manufacturers can reduce unnecessary downtime and avoid repeated scanning attempts.

Recommended Barcode Scanner

For medical device UDI verification and traceability systems, the XTIOT XT8601B provides high-resolution industrial imaging designed for demanding production environments.

Key advantages include:

• Reliable reading of low-contrast UDI labels

• Support for GS1 DataMatrix, QR Codes and 1D barcodes

• High-speed decoding for automated production lines

• Industrial Ethernet and serial communication

• Suitable for medical device manufacturing, pharmaceutical packaging and laboratory automation

When UDI labels begin to lose contrast during production, capturing more image detail becomes more important than increasing illumination. The XT8601B helps manufacturers maintain stable barcode reading throughout long production runs.