All kinds of plastic welding process application

A finished plastic product may be made from a variety of materials or parts, which can be combined using mechanical fixtures, adhesives and welding processes. Among the three kinds of joints, the welding process has the best effect, and the welding forms are diverse, and different welding processes can be used according to different materials, sizes and uses.

Mechanical fixtures, adhesives and welding processes can join the two engineering plastics. Mechanical fasteners can quickly connect the two components, but the joints are poorly leak-proof and local stresses can disengage the polymer materials.

Adhesives provide good properties to form excellent leak-proof joints, however, adhesives are difficult to handle and slow to cure. At the same time, when using adhesive bonding, joint preparation and surface cleanliness requirements are higher.

Welding produces firmly bonded joints with mechanical properties close to those of the parent material. Plastic welding is limited to thermoplastic polymers because thermoplastic materials can be softened by heating. Thermosetting polymers cannot be softened by heat after hardening. Compared with metals, thermoplastic polymers require less heat to weld.

Ultrasonic welding

Ultrasonic welding is formed by mechanical high frequency vibration. The part to be assembled is pressed and clamped between the oscillating welding head and the fixed welding head, and then at a right Angle to the contact surface, receiving ultrasonic vibration with a frequency of 20~40KHz. Alternating high frequency stresses generate heat at the joint interface, resulting in excellent welding. The tools used for this process are expensive and are therefore suitable for large production volumes.

This welding method is only suitable for welding small parts not more than a few centimeters in length. Applications include valves and screening programs for welding medical devices on multi-head machines, boxes, automotive parts, vacuum cleaner housings, etc.

Friction welding

Friction welding of thermoplastics (also known as "rotary welding") works in the same way as metal welding. In this welding process, one piece of substrate is fixed and the other rotates at a controlled angular speed. When the parts are pressed together, frictional heat causes the polymer to melt, which, when cooled, forms a weld. The main welding parameters include: rotation speed, friction pressure, forging pressure, welding time and melting length.

Friction welding can produce excellent welding quality, simple welding process and strong repeatability. However, due to its simple process, it is only suitable for applications where at least one part is round and angular alignment is not required.

Vibration welding

Vibration welding is also called linear friction welding. The two thermoplastic parts rub against each other at the right pressure, frequency, and amplitude until enough heat is generated to melt the polymer. After the vibration stops, the parts align with each other, and the melted polymer solidifies to form a weld. Vibration welding is similar to rotary welding, the difference is that the motion is linear motion instead of rotary motion. This welding method is very fast, the vibration frequency is generally 100~240Hz, the amplitude is 1 mm ~5 mm.

The main advantage of this welding process is that it can weld large complex linear parts at high speed. Other advantages include: simultaneous welding of multiple parts, simple welding tools, welding of almost all thermoplastic materials including injection molding parts, extruded parts, blow molding parts, thermoforming parts, foaming parts and stamping parts, mainly used in the automotive and home appliances industry.

Vibration welding is especially suitable for thermoplastic materials, including amorphous resins such as ABS/PC, PVC, PMMA and PES; Semi-crystalline resin such as HDPE, PA, PP, TPO. Dukane's welder joints automotive parts, such as the intake manifold, dashboards, taillights and bumpers; Aviation applications such as HVAC pipes, interior lights and storage bins; Home appliances are dishwasher pump and water spray arm, detergent sprayer and vacuum cleaner casing.