Heating to Curing Temperature

Speaker basket and diaphragm are positioned in the induction coil

Objective
In this application test, we are heating to curing temperature using induction, to attach a speaker diaphragm to a speaker basket. The adhesive will be applied to the speaker basket, and the speaker diaphragm placed immediately above. The adhesive has an activation temperature of 57° C, or 134° F.  The customer wants to use induction for heating the speaker basket to the curing temperature.  This will activate the adhesive, and create the bond to the rubber speaker diaphragm.

This application test will confirm that the speaker basket will heat to the bonding activation temperature of 134° F within 2-3 seconds.

Equipment
UltraFlex UPT-S2
HS-4 Heat Station

Material
Two-Turn Induction Coil

Key Parameters
Temperature: just above 134°F (57°C)
Power: 0.5 kW
Time: 2 seconds
Frequency: 118 kHz

Process:

  1. The speaker basket was carefully positioned immediately below the induction coil, making sure that there was no contact between the basket and coil.
  2. Several tests were run to determine the appropriate power level and operating time to achieve the necessary temperature, with power levels ranging between 40% and 60%.  Temperature was monitored with an infrared temperature gun.  Video was taken with the gun, to verify the temperature and timing.

Results/Benefits:

  • Precise control of the time and temperature
  • Power on demand with rapid heat cycles
  • Reduction in defects due to overheating
  • Minimal handling of speaker diaphragm, reducing potential damage
  • Repeatable process, not operator dependent when parts are set in a nest or fixture

Pictures

Video