Laser Welding of Plastics

Control Micro System’s custom laser plastic welding systems bring economy, speed, accuracy, and repeatable welds to your plastics production requirements.

Laser plastic welding is becoming increasingly popular in several industries including medical device manufacturing and automotive manufacturing. The advantages of laser welding over traditional methods of plastic welding are numerous and have led to enormous savings for companies who are embracing this modern technology.

Advantages – Laser Welding of Plastics:

Seam Quality – Weld seam structure is excellent, and often secondary finishing is not required.

Non-Contact Welding – There is no need for tooling replacement due to wear and tear and laser welding puts less stress on weld pieces.

Cleaner Processes – Laser welds can typically be done without filler material or additives and leave virtually no debris.

Precision – A laser’s localized energy means excellent thermal control, low distortion, very close tolerances, and a very repeatable and consistent weld.

Easy Automation – Laser plastic welding can be easily integrated into an automated system.

Methods – Laser Welding of Plastics:

There are several laser welding methods available, depending on the materials being welded. Most materials that can be welded to each other through traditional methods can also be welded using one of the following laser welding methods.

Heat Conduction Welding – Heat conduction welding is used when both plastics being welded absorb the laser energy (as opposed to being transparent to the laser wavelength). In this method, as the beam follows the weld path, the two plastics are brought to melting temperature but stay well below the vaporization temperature. The weld is achieved through intimate contact of the two parts at the melted weld path; a butt weld. A conduction weld creates a weld at or just below the surface and is prevented from traveling deep into the bulk of the materials. The weld seam is smooth and should not require any additional finishing.

Transmissive Welding – Widely used in manufacturing, transmissive welding was the first method to weld plastics using lasers. The process requires a transparent (to infrared range light) upper part and an absorbing (to infrared range light) lower part, held with consistent, tight contact to each other. The beam passes through the upper layer to heat the lower. As the lower plastic reaches melting temperatures, the heat is passed to the transparent upper plastic. When both are at the melting stage, the weld is achieved at the interface. For transmissive welds to occur, both plastics must have similar melting ranges.

Transparent Plastic Laser Welding (“Clear-on-Clear” Plastic Welding)

Transparent laser welding can be used when both plastic pieces being welded together are mostly transparent, or in the infrared wavelength range. When two transparent parts are placed in intimate contact, the laser energy transmits through the upper layer, as in transmissive welding, and meets the interface between the two parts. Instead of simply passing through the second layer as well, some of the energy is absorbed solely due to the interface between the parts. Both layers heat to the melting point at this interface and allow a weld to form under specific conditions with little to no color change, based on the material cooling properties. Transparent laser welding is now gaining dominance in the medical device manufacturing industry where clear parts are often required.

Plastic Laser Welding Images