Question

Which of the following Thermal techniques utilizes the mechanical hammering for conversion of vibration energy to heat energy for bonding the fibrous web?

• A. Area
• B. Through air
• C. Belt
• D. Ultrasonic

Hint:

Ultrasonic bonding uses high-frequency vibrations to generate heat within the fibers, causing localized melting and bonding. Think of it as very rapid, microscopic hammering.

Answer 1

The Correct Option is D

Step 1: Understanding Thermal Bonding in Nonwovens: Thermal bonding is a process used to bond nonwoven webs (sheets of fibers) by applying heat. This melts thermoplastic fibers or a thermoplastic binder, fusing the fibers together.
Step 2: Analyzing the Options: Area Bonding: This is a general term that doesn't specify a particular heating method. Through-air Bonding: Hot air is passed through the web to melt and bond the fibers. No mechanical hammering is involved. Belt Bonding (Calendering): The web is passed between heated rollers (calenders) under pressure. This uses heat and pressure, but not mechanical hammering. Ultrasonic Bonding: This uses high-frequency vibrations (ultrasonic waves) to generate heat within the fibers. A vibrating horn (sonotrode) applies pressure and ultrasonic energy to the web, causing localized melting and bonding at the fiber contact points. This is effectively a very rapid, localized "hammering" action at a microscopic level.