AWS G1.1M – G1.1 pdf free download
AWS G1.1M – G1.1 pdf free download.Guide to Ultrasonic Assembly of Thermoplastics.
In each of these processes. the thermoplastic parts are subjected to low-amplitude, high-frequency mechanical vibrations. This energy is converted into heat within the thermoplastic through intermolecular friction, which softens or melts the polymer. The processes of welding, insertion, staking, swaging, and degating use essentially the same equipment. The joint requirements. materials and geometries determine which of these processes will best meet the final assembly needs
1.4 Process Description
Ultrasonic assembly is the joining or reforming of thermopi astics using high -frequency vibrations to generate heat. For example, a metal object becomes warmer when repeatedly struck with a hammer. The kinetic energy of the hammering transforms into thermal energy (heat) as the molecules in the object move more vigorously. These molecules are likewise excited to move vigorously when subjected to the impact (hammering) of high-frequency ultrasonic vibrations.
An ultrasonic welding system applies high-frequency energy (vibrations) through one part, focusing the energy into the junction of the two pans. The focusing of the energy is critical. The details of this method are presented elsewhere in this document.
1.6 Systems for Applying Energy to Work
A press system is recommended for critical, precisely controlled applications. When consistency and appearance are not critical, a hand-held unit may be adequate. Many manufacturers use compact actuators in applications where an automated press system would he too large. These actuators offer press control in a smaller package that is better suited to custom mounting. When production rates demand faster speeds than standard press systems can provide, rotary index systems can be used. Fully automated systems are available for ultrahigh-speed assembly operations.
1.7 Process Advantages and Limitations
1.7.1 Advantages. Ultrasonic assembly can have the following advantages over other joining techniques:
1. Uniform joining is achieved because heating occurs rapidly and is confined to the immediate joint area:
2. The weld strength can be as strong as the unreinforced base material;
3. No solvents, adhesives, or external heating are required:
4. Dissimilar materials can be assembled using ultrasonic process; and
5. Ultrasonic assembly is considerably faster than other methods, resulting in higher efficiency and greater economy.
1.7.2 Disadvantages
I. Ultrasonic assembly equipment is moderately expensive:
2. Initial equipment and process setup can be complicated: and
3. Flash, particulates. and stresses occasionally appear at the joint after welding.
1.8 Safety and Health
Ultrasonic assembly operations involve potentially hazardous equipment and materials. Personnel should be trained in the proper use of the equipment. and the safety and health practices mandated by OSHA and local codes. and those recommended by the equipment and materials suppliers. Proper work attire, including safety glasses and hearing protection, should he specified and enforced. Material safety data sheets (MSDSs) should be available to personnel for all materials and chemicals used in the manufacturing area. For additional help on improving plant safety, consult ANSI Z49.I, Safer’ in Welding, Cutting, and Allied Processes, available from American Welding Society. Some basic safety rules to observe include:
1. Keep hands away from under the horn. An energized horn in contact with skin can cause burns. Also, a moving horn can cause rapid, crushing forces:AWS G1.1M – G1.1 pdf download.
