Improving in-mould labelling accuracy through controlled static charging

In-mould labelling (IML) is a widely used technique in the automotive and consumer goods sectors to permanently embed labels onto plastic components during the moulding process. The quality of an IML application depends on one critical factor: accurate label positioning inside the mould cavity. Any movement or misalignment during moulding can cause labels to shift, curl, or detach, resulting in quality issues and higher rejection rates.

A key enabler of accurate IML is static electricity. Electrostatic force is used to temporarily bond the printed label—often referred to as a decal—to the right location on the mould surface before molten plastic is injected.

The challenge: inconsistent label adhesion

One of India’s leading two-wheeler manufacturers faced recurring issues of inconsistent label adhesion during their IML process. Despite using automated robotic pick-and-place systems, labels were not holding firmly enough inside the mould cavity. This resulted in misaligned labels, aesthetic defects, and productivity loss.

The root cause was identified as inadequate and inconsistent charging of the labels prior to placement. Without sufficient electrostatic force, the labels could not maintain their position during mould closing and injection.

The solution: controlled static charging integration

AxisValence studied the application and implemented a controlled static charging solution using Valstat VC60 static charging bars paired with PC65 power generators. The system was seamlessly integrated into the existing robotic pick-and-place operation.

In this process, uncharged labels are first placed on a dedicated bed. This bed then moves beneath the static charging bars, where a uniform and controlled electrostatic charge is applied to each label. Once charged, the labels are picked by the robotic arm and accurately placed into the mould cavity. During moulding, the electrostatic force ensures that the label remains securely in position until it is permanently embedded into the plastic component.

The outcome: consistent quality, lower rejection

By applying controlled static charges, the labels become temporarily adhesive, due to electrostatic attraction. This ensures accurate placement throughout the moulding cycle without residue or permanent bonding. The result is improved label alignment, enhanced aesthetic quality, and a significant reduction in rejection rates.

For manufacturers using IML, controlled static charging is not just a supporting process—it is a critical step that directly impacts productivity, consistency, and overall output quality.