When Ultrasonic welder welding plastic, sample was damaged?

Ultrasonic welding,Ultrasonic welding horn and product surface contact, high frequency vibration, unreasonable design will lead to poor welding effect. How to achieve high precision and stable plastic welding? How to avoid damage to welded plastic due to excessive energy? When using ultrasonic welding machine, how can we avoid damage and complete the welding more efficiently? First of all, we need to understand the principle of ultrasonic welding.

Ultrasonic welding principle: Ultrasonic wave ACTS on the thermoplastic plastic contact, will produce tens of thousands of times per second, the high frequency vibration, this reaches a certain amplitude of high frequency vibration, through the weldment sends the ultrasonic energy to the welding area, due to the welding area is two welding interface of the acoustic resistance is big, so can produce local high temperature, the two plastic contact rapidly melting, coupled with a certain pressure, make its merging into one. When the ultrasonic stops working, let the pressure continue for a few seconds to solidify, forming a solid chain of molecules that can be welded with a strength close to that of the raw material.

Cause of damage to the welded sample

The power output of ultrasonic welding equipment is too strong

When the output power of ultrasonic plastic welding machine exceeds the need of rubber parts, rubber parts can not withstand the high pressure beyond their capacity, stress is destroyed and cause internal damage;

The energy output of the ultrasonic amplifier is too strong

The expander fails to match the transducer and the welding head successfully, and the increase ratio leads to too high energy transferred to the welded adhesive, which leads to internal damage due to the stress difference.

The force point of the bottom die is suspended

The welding horn, the bottom die and the welded glue need reasonable force design, because the ultrasonic energy is much greater than the ordinary voltage capacity, the welding head and the bottom die need to match the force design. When the stress point is suspended, it is subjected to ultrasonic conduction and vibration, resulting in uneven stress and damage;

Stress concentration failed to buffer and channel

Plastic products are high and thin at right angles to the bottom, without R angles to buffer and channel energy. Plastic right Angle allows stress to be concentrated at one point, without cushioning and dispersing energy buffer design;

Incorrect ultrasonic welding operation

The improper operation of the operator leads to the failure of the ultrasonic welding equipment to properly play its utility.

 

 

 

Improvement Plan:

(1) Advance the ultrasonic vibration time;

(2) reduce pressure, reduce ultrasonic welding time;

(3) reduce the number of power segments or use low-power machines;

(4) reduce the expansion ratio of ultrasonic amplifiers;

(5) Cushion the buffer rubber at the force of the bottom mold;

(6) avoid suspension or clearance between the bottom mold and the product;

(7) Retest the frequency after the upper mold is cut out;

(8) Affix elastic materials (such as silicon Likon) after cutting holes in the upper mold.


Post time: Aug-26-2022