Clearweld Products and the Laser Welding Process

Clearweld allows the near infrared (NIR) and infrared (IR) laser welding of clear IR and NIR transparent plastics. Clearweld can be coated onto parts or used as an additive compounded into resins. While there are many established methods to weld plastics, each with its own advantages and disadvantages, Clearweld offers a dynamic, plastic welding technology to provide you with greater design, engineering and manufacturing flexibility. The image to the right shows how a Clearweld solution can be coated and laser welded using Clearweld solutions. The Clearweld is coated, leaving a green layer on the surface of the part. A second top part that is IR transparent is placed above the coated part and pressure is applied. The laser welds the two parts together, and when performed correctly, the Clearweld coating is both transparent and colorless.

Clearweld makes near infrared transmission laser welding of transparent plastic parts fast and easy.

Our Products

Sonotek ultrasonic spray systems allows uniform films of Clearweld allowing transmission near infrared laser welding of Clearweld solutions with minimal variations.

Clearweld Coatings

Clearweld coatings offer a simple approach to laser welding NIR transparent plastic parts. The Clearweld 100 and 900 series are applied to the part as a coating. Typical application methods are: ultrasonic sprayer system, precision fluid dispenser, inkjet printing or any method that would commonly deposit solvent-based solutions.  See our Distributers and Equipment page for more information. 

Clearweld additive compounded with plastic resin for injection molding of parts used with near infrared transmission laser welding

Clearweld Resins

When Clearweld resin is used, the additive material is compounded into the resin using loadings between 0.015 and 0.1 weight % depending on part thickness, part geometry and type of resin. The Clearweld additive efficiently converts laser energy to heat.  The user has the flexibility to compound Clearweld into nearly all thermoplastic resin materials. Clearweld resin, when laser welded, will not lose color.  We recommended use of the lowest loading that reliably welds.

Clearweld and the Laser Welding Process

The parts to be welded are placed in a clamping system that allows for pressurized contact. Many laser welding systems come with the feature already built in, as seen in Leister’s Maxi Laser welding system for Large Components. A laser ranging from 900nm to 1100nm used with a Clearweld product produces melting at the interface between the two parts. The laser welding is complete in seconds.  However, allow the part to cool before removing from the clamping system. Cooling systems can be used to expedite the cooling process.

 

Labeled near infrared Laser Beam
Thermal imaging of two plastic parts welded using Near infrared transmission welding, heat isolated at weld interface.

Laser Welding Parameters

Laser welding occurs at the interface between two parts. The two parts melt due to the laser heat generated. As the parts cool, they fuse creating a bond that is as strong as the base material itself. The heat generated during the weld is determined by the energy density of the laser and the amount of Clearweld deposited. Energy density is determined by laser power, scan speed and the spot size of the laser. For example, to increase weld speed use a more powerful laser or use a larger amount of Clearweld. It is important to use a laser welding system to weld plastic.  While laser welding using a laser engraving system is possible, we do not recommend this practice due to the smaller spot size of these systems. When using a laser welding machine, make sure to follow the manufacturer’s suggested parameters.

Energy density is determined by laser power, scan speed and the spot size of the laser. For example, to increase weld speed you can use a more powerful laser or use a larger amount of Clearweld. When using a laser welding machine, make sure to follow the manufacturer’s suggested parameters.