Study on Heating Process of Ultrasonic Welding for Thermoplastics

Abstract

Heating mechanisms of ultrasonic welding for thermoplastics were studied via numerical simulation and experiment. Relationship between dynamic modulus and static relaxation modulus of thermoplastics was theoretically analyzed. Segment time—temperature equivalency equation for different temperature ranges and a method for directly separating viscoelastic heat from strain energy were used in the simulation. Temperature measurement tests with poly(methyl methacrylate) specimens were carried out to verify the simulation results. Results of simulation and experiment reveal that interfacial friction rather than viscoelastic heat initially start the whole welding process. Viscoelastic heating becomes dominant when temperature reaches Tg (glass transition temperature) of the material. And viscoelastic heat provides most required heat during welding.

Bonding of planar poly (methyl methacrylate) (PMMA) nanofluidic channels using thermal assisted ultrasonic bonding method

“…For thermoplastic polymers, T g is an important point at which some physical and mechanical properties dramatically change. During ultrasonic bonding, the temperature rising rate drastically increases when the temperature is above T g , which could be explained by viscoelastic heat (Zhang et al 2009). Higher preheating temperature makes the interfacial temperature easier to reach T g .…”

“…According to our previous study (Zhang et al 2009), the interfacial temperature during ultrasonic bonding was influenced by the amplitude of ultrasonic. Theoretically, the peak temperature of the interface was much influenced by the amplitude of ultrasonic.…”

“…However, the amplitude step value of our bonding machine is 0.6 lm. Based on our temperature tests, the peak temperature increment was about 10°C with the amplitude increment of 0.6 lm (Zhang et al 2009). So the interfacial temperature can be more precisely controlled using preheating temperature than using amplitude.…”

Investigation on Ultrasonic Welding Attributes of Novel Carbon/Elium® Composites

“…Welding attributes of thermoplastics aids in the cost-effectiveness of the composite part to be manufactured in an industrial environment from forming until the finishing steps [3][4][5][6]. The most feasible welding techniques available for fusion bonding of thermoplastic composites are resistance [7][8][9], induction [8,[10][11][12][13][14][15] and ultrasonic welding [6,[16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. These behave differently in the way the heat is generated at the welding interface.…”

A Numerical Analysis of the Temporal and Spatial Temperature Development during the Ultrasonic Spot Welding of Fibre-Reinforced Thermoplastics

“…By implementing a time-temperature superposition, the curves have been extrapolated to the ultrasonic welding frequency of 20 kHz. Zhang et al [19] measured the relaxation modulus curves at various temperatures for polymethylmethacrylate (PMMA) and used the data to calculate the dynamic loss modulus as a function of time. Another promising approach is the inverse determination of material properties using experimental measurements and computational simulation, such as the methods proposed by Jedrasiak et al [17] and Willis et al [20].…”