What Is Energy Director In Ultrasonic Welding?

The energy director is a common joint design in ultrasonic plastic welding. It is a protruding triangular column on the welding surface of a plastic part. Its function is to gather the vibration energy at the tip of the triangle, and the accumulated heat forms a uniform plastic melt flow on the entire welding surface of the plastic part. So what is the advantage of the ultrasonic welding energy director?

Increase The Strength Of Ultrasonic Welding

The energy director is conducive to the fusion of two plastic parts and improves the strength of ultrasonic welding. If false welding occurs in ultrasonic welding, there will be a break between the two plastic parts, and it is easy to find the defect of the false welding as the plastic parts have the energy director, then you can avoid false welding. And the energy director in ultrasonic welding is useful for ultrasonic welding troubleshooting. In the case of no energy director, if the ultrasonic welding has false welding, it is difficult to identify by the appearance of the product.

energy director in ultrasonic welding2
energy director in ultrasonic welding

Reduce Flash, Improve Appearance

The energy director shortens the contact time between the welding head and the plastic part, so fewer plastic overflows. In addition, plastic overflows are reduced due to the smaller welding area to avoid material build-up. Through reasonable energy director and welding structure design, ultrasonic welding can achieve a high-quality appearance of plastic products. So the energy director design for ultrasonic welding is important.

Reduce Welding Time

The energy director reduces the overall energy required to melt and fuse the plastic, thereby shortening the welding time. At the same time, the shortening of the welding time helps to avoid the over-welding problem caused by the long-term welding of plastic parts.

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ultrasonic welding gap not uneven

Is the welding line of plastic products after ultrasonic welding uneven?

Ultrasonic welded plastic products sometimes have uneven welding lines, that is, the welding lines are large in some places and small in some places, resulting in unsightly products. If the ultrasonic welding machine can work normally, it is necessary to analyze and solve this problem from the design of the plastic weldment itself.

1 Unreasonable energy director design for ultrasonic welding

If the ultrasonic welding energy director design is too thick, it will be difficult for the welding head of the machine to press down. A common ultrasonic energy director structure is a triangle with a side length of 0.5mm. In addition, welding at the corners is more difficult. Usually, the corners cannot be welded successfully.

2 Ultrasonic welding for different plastic materials

The two weldments that are ultrasonically welded should use the same material as possible, such as ABS and ABS, PS and PS. If the materials of the two weldments are different, consult the professional team for welding advice first. If they can be welded together, it is recommended to make the plastic structure into a mechanical interlocking type.

3 Plastic products are wet or have additives

Ultrasonic welding plastic parts are too wet or there are chemical components such as glass fiber or other flame retardants in the plastic parts, which will also cause difficulties in ultrasonic welding.

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