What are the causes of cold welding caused by plastic laser welding?

During the plastic laser welding process, cold welds are a common problem, which may lead to insufficient welding strength and affect the overall quality and performance of the product. There are many reasons for the occurrence of cold welds, mainly including the following aspects:

1. Improper laser parameter settings

Insufficient power

Insufficient laser power will lead to insufficient heat in the welding area, and the plastic will not be fully melted, resulting in loose welding and the formation of cold welds.

Welding speed is too fast

Welding speed is too fast, which makes the laser stay in the welding area too short, unable to provide enough heat to melt the plastic, resulting in poor welding quality.

Incorrect focus position

Inaccurate laser focus position will cause the energy to be concentrated in the wrong position, unable to fully melt the plastic in the welding area, resulting in a false weld.

2. Material problem

Material absorption rate

Different plastic materials have different absorption rates for lasers. Materials with low absorption rates are insufficiently melted under the same laser power, resulting in cold welds.

Material Thickness

Material thickness has a great influence on laser welding. Too thick material may not be completely melted, and too thin material may easily overheat and deform.

Material Compatibility

When welding plastics of different types or batches, if the physical or chemical properties of the materials do not completely match, it may result in poor welding strength and form a false weld.

3. Welding environment and preparation

Surface cleanliness

If there are pollutants on the plastic surface before welding, such as dust, oil or moisture, it will affect the conduction of laser energy and the melting of plastic, resulting in a cold weld.

Clamp pressure

Uneven or insufficient clamp pressure will result in poor contact in the welding area and failure to form a strong weld joint.

4. Process parameters and equipment problems

Welding path

The design of the welding path is unreasonable, and the laser beam fails to cover all areas that need to be welded, resulting in some areas not being welded or incomplete welding.

Equipment calibration

Inaccurate calibration of laser welding equipment, such as uneven spot quality and energy distribution of the laser beam, will lead to unstable welding results.

Cooling time

Insufficient cooling time after welding, the weld is not fully solidified, resulting in insufficient welding strength.

5. Operator skills and experience

Operation experience

The operator's mastery of laser welding equipment and process parameters is insufficient, and they are unable to adjust them according to the actual situation, which easily leads to false welding.

Monitoring and feedback

The lack of real-time monitoring and feedback mechanism makes it impossible to detect and adjust problems in the welding process in time, resulting in poor welding quality.

Plastic Laser WeldingThere are many reasons for cold welding, involving laser parameter settings, material properties, welding environment, process parameters and equipment conditions, as well as operator skills and experience. To solve the problem of cold welding, it is necessary to comprehensively consider the above factors. By optimizing laser power, welding speed, focus position, ensuring material compatibility and surface cleanliness, and strengthening equipment calibration and operator training, the welding quality can be effectively improved and the occurrence of cold welding can be avoided.