Mechanical bonding is when the fibers are not altered by either heat or chemicals and are instead bonded by an alternate method. 
Hydro-Entanglement bonding (also called spunlace), bonds the fibers by mechanically intertwining the fibers with water jets. Similar to spunlace there is also needlepunching/needlefelting which uses needles to intertwine the fibers as opposed to water jets. Also there is ultrasonic pattern bonding for use in materials that need to be a bit softer than other nonwovens.
The oldest technique for consolidating fibers in a web is mechanical bonding, which entangles the fibers to give strength to the web. Under mechanical bonding, the two most widely used methods are needpunching and spunlacing (hydroentanglement). Spunlacing uses high speed jets of water to strike a web so that the fibers knot together. Nonwoven fabrics made from this method are generally softer and more have more drapability.
Ultrasonic bonding system consists of an engraved anvil drum and an ultrasonic system with acoustic stack (converter, amplitude coupler and sonotrode). The acoustic stack is mounted above the rotating anvil drum leaving a small gap between the surface of the rotating anvil and the sonotrode. The sonotrode constantly expands and contracts (amplitude) 20,000 times per second. As material passes through the gap, force and amplitude are applied to the material. During the expansion cycle, sufficient compression is applied through the material against the raised bonding points of the anvil drum creating surface friction to melt the nonwoven materials. During the contraction cycle the gap is increased allowing the material to move through the gap without material jams. Ultrasonic bond strength is controlled by constant web speed, constant amplitude and consistent force applied to a specific anvil drum pattern.