Ultrasonic welding machine

Ultrasonic welding machine

Ultrasonic welding machine is a process used to join two plastic parts together to form a strong, finished assembly. The process relies on high-frequency (ultrasonic) vibrations being generated and applied to the parts via a horn. Welding occurs as the vibrations are absorbed in the interface between the two parts, generating friction and causing the plastic to melt. The ultrasonic vibrations are generated by a series of components, including the power supply, converter, booster, and horn, ultimately delivering the mechanical vibration to the parts.

Ultrasonic welding machine principle

The power supply’s role is to convert the incoming line voltage (at 50 or 60Hz) into a new frequency. This electrical energy is then sent to the converter, which, as the name implies, converts the electrical energy into mechanical vibrations. The converter consists of piezoelectric ceramic discs, which expand and contract at the supplied electrical energy rate. The magnitude of the vibrations is referred to as amplitude, a term that becomes very important when specifying an ultrasonic system for a given application. The vibrations are transmitted through the booster, which typically increases the amplitude by a predetermined multiple, also known as gain. Finally, the booster’s output amplitude is transmitted through the horn, where it can then be delivered to the plastic parts.

Ultrasonic welding machine composition

An ultrasonic generator (power supply)

ultrasonic generator

The ultrasonic generator converts the 110VAC or 220VAC electrical supply current into a high frequency, high voltage electrical signal.

An ultrasonic converter (transducer)

The ultrasonic converter utilizes the high-frequency electrical signal from the generator and converts it into linear, mechanical movement. This conversion occurs through the use of piezoelectric ceramic disks that expand when a voltage is applied.

ultrasonic transducer

An ultrasonic booster

Ultrasonic booster and round flange

The ultrasonic booster is a tuned component that mechanically adjusts the amount of linear vibratory movement from the converter to the required level for the specific application to produce optimal welding performance. The booster also provides a safe, non-vibrating location to clamp onto the welding tools.[/one_half_last]

An ultrasonic welding tool (horn/sonotrode)

The ultrasonic welding horn is a custom-made tool engineered to vibrate at a specific frequency. These tools are painstakingly designed using computer modeling technology for optimum performance and longevity. Ultrasonic tools must be tuned to match the frequency of the system. This tuning procedure requires consideration of the horn’s mass, length, and geometry. Common tool head sizes are 150 * 40mm and 110 * 20mm.

ultraosnic tool head

A sectional view of ultrasonic welding machine WW1530L

aotomatic welding machine 15K
A sectional view of ultrasonic welding machine WW1530L

Longer service life

Transducer prestress

All piezoelectric transducers for ultrasonic welding are of the Langevin type — i.e., one or more piezoceramics that are mechanically compressed (prestressed) between a front driver and a back
driver.

Transducer cross section
Transducer cross-section
Transducer Relative axial amplitudes
Transducer Relative axial amplitudes

Because piezoceramics are weak in tension, a static compressive prestress must be applied to prevent the piezoceramics from experiencing tensile stresses when the transducer vibrates ultrasonically. Also, the prestress assures that the piezoceramic interfaces make good contact so that the acoustic waves are transmitted well with minimum loss. We use the most convenient center screw design.

A specific prestress can be obtained by tightening the transducer center screw to tighten the transducer. The traditional method is to use a torque wrench for tightening, but this parameter is
affected by many factors and often has deviations.

Prestress vs torque Langevin type transducers
Prestress vs. torque Langevin type transducers

When the tightening of the ultrasonic transducer is insufficient, its impedance is large, which will cause serious heat generation; when the tightening is excessive, it is easy to cause problems such as damage to the ceramic sheet (crystal crack) and durability. The transducer is the most important part of ultrasonic welding equipment. So it is essential to tighten the transducer and obtain the best prestress accurately.

Get the best prestress of the transducer
Get the best prestress of the transducer

Piezoelectric ceramic sheet

Piezoceramics are typically classified as “soft” or “hard.” Hard piezoceramics are used for power applications. Among hard piezoceramics, there are two basic types, generally designated as PZT4 and PZT8 (PZT stands for lead-zirconate-titanate of which the piezoceramics are composed). Different manufacturers may have their own designations for these types, but the general performance is similar. Our device uses PZT8 piezoelectric ceramics, which has better relative performance.

Nominal piezoceramic properties at low electric field conditions
Nominal piezoceramic properties at low electric field conditions

Advantages of ultrasonic welding

  • Does not need an external heat source: Ultrasonic welding’s primary advantage is that it doesn’t need an external heat source. The heat is self-generated between the materials.
  • Fast: Since vibrations’ frequency is very high, ultrasonic welding is one of the fastest welding methods available in the industry.
  • Possibility of automation: Ultrasonic welding being uncomplicated in many ways, is easy to automate. The ultrasonic machine comes with sensors that constantly monitor the temperatures.
  • Clean and strong joint: The contact surfaces melt/fuse upon welding, and it produces a very clean and strong joint.

Ultrasonic welding has many advantages when compared to traditional welding technologies. Many industries use it due to these specific combinations of merits.

Application of ultrasonic welding

Ultrasonic welding is an eco-friendly process that takes seconds, consumes very little energy, and reduces costs while maintaining a high degree of quality. The equipment fuses contact points on cell phones and other consumer electronics that are generally inaccessible with other welding methods. These techniques can be adapted to a wide range of commercial and industrial applications. In the food industry, the ultrasonic welding process is used to create a hermetic seal. It can fasten blister packs and facilitate various products, including toys, disposable lighters, pipettes, and intravenous catheters.

Ultrasonic welding is commonly used in the plastics, aerospace, and automotive industries to join similar materials. It is handy in the production of medical products. Since the process does not introduce exhaust or other contaminants and the welds do not degrade, the manufacturing equipment can be used in a clean-room environment.

Ultrasonic welding machine tips

Ultrasonic welding is very effective at sealing or welding plastics. However, you cannot weld all types of plastics.  Like metals, plastics also have different types. And it is essential to ensure that the plastics to be welded are chemically compatible. If you try welding polyethylene and polypropylene, they may melt together, but there will be no chemical bond. A chemical bond is important for creating strong weld joints. Another factor to keep in mind while welding any material through welding is maintaining a uniform contact area.

Attributes Parameter Attributes Parameter
Brand HCSONIC Item Model WW1530L
Maximum Power output 2200W Frequency 15KHZ
Maximum Amplitude 10µm Working model Continuous, intermittent
Weldable materials Thermoplastic materials Welding Head Material Steel
Welding Head Size 270*25mm  Driven Type Electric
Technical Support Video, mail, phone Warranty One year, except the horn
Full Set Weight 21KG Place of Origin China
hcsonic naming rules hcsonic ultrasonic equipment naming rules

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