Sonobond, a leader in the application of ultrasonic bonding and welding technology, will showcase its ultrasonic equipment for assembling body armour, including the SeamMaster High Profile Ultrasonic Sewing Machine, at the Shooting, Hunting, Outdoor Trade (SHOT) Show that will take place from 14-17 January 2014 in Las Vegas.

Ultrasonic technology is increasingly being used as an assembly method for body armour. “One of the reasons behind the growing preference for ultrasonic assembly is the National Institute of Justice (NIJ) wet-conditioning standards that require ballistic vests to be waterproof, even after submersion for 30 minutes,” explained Sonobond Vice President Melissa Alleman.

“More than 30 manufacturers now use Sonobond equipment because it reliably seals the outer nylon shell, protecting the ballistic-resistant material inside from the damaging effects of exposure to moisture.”

Personal protection capability

Body armour is used for protection by law enforcement, military personnel, Secret Service agents, emergency responders and CIA and IRS employees.  Over the years, the standards set by the NIJ to ensure personal protection capabilities have become more and more stringent. 

“Since the bullet-proof materials – such as Spectra-Shield and Kevlar – contained in the vest lose their life-saving effectiveness when exposed to water, it’s absolutely critical that the seams in the outer nylon shell are perfectly fused,” said Alleman. 

Ultrasonic bonding creates a strong molecular bond that’s impervious to moisture and eliminates stitch holes, glue gaps, fraying and unravelling, reducing risk of damage to the interior contents of the vest.

Ultrasonic bonding

Ultrasonic bonding occurs when woven or nonwoven synthetic materials or blends with up to 40% natural fibres are placed between the machine’s horn and anvil or, in the case of the SeamMaster, rotating wheel.

High-frequency vibrations result in localised heat buildup that causes the synthetic fibres to soften and fuse, creating a durable seal without needles, thread, glue or other consumables, the company reports. 

Ultrasonic equipment

The SeamMaster High Profile Ultrasonic Sewing Machine is suitable for sealing the exterior nylon shell of body armour systems.  Its rotary system bonds and trims synthetic materials in one step and its large, high-clearance wheel is said to provide easy access for bulky materials and hand-guided operations.

The machine is up to four times faster than conventional sewing machines and 10 times faster than adhesive methods, according to the manufacturer.

Attaching synthetic straps

Sonobond’s SureWeld 20 Ultrasonic PlungeBonder, which can seal large, multiple-layer or difficult-to-bond materials, is said to offer manufacturers a number of advantages for attaching coated straps within the seam of a ballistic vest’s outer shell.

By placing the outer shell material and strap between the machine’s horn and anvil, the high-frequency vibrations channeled to the materials create a heat buildup in just one pulse that seals without compromising the integrity of the seam, ensuring the vest’s ability to satisfy NIJ submersion standards.

www.sonobondultrasonic.com