While the concept of noncontact might seem to be out of place at an ammunition factory, it actually fits very well there for certain assembly processes, such as
sealing bullets. Nearly three years ago, several of the largest U.S. ammunition manufacturers were looking for a way to automate the process, make it less hazardous and improve sealant performance. The manufacturers met with several dispensing equipment and material suppliers, including Hernon Manufacturing Inc.
Since the 1940s, assemblers used their fingers to apply a thin coating of asphalt inside the bullet’s mouth casing prior to the insertion of gun powder and the bullet. The major problem with the process is that manufacturers had to wait 24 hours for the asphalt to dry before completing the assembly. Equally problematic was that the asphalt often failed and the bullet did not pass the leak test.
Since 2010, these manufacturers have used an automated dispenser to apply a very thin adhesive to seal each bullet. The SS3500 dispenser from Hernon is stationary and shoots a 0.5-microliter dot onto each bullet as it passes underneath. Capillary action causes the dot to disperse around the bullet.
The Ammunition Primer Sealant 59621 (also from Hernon) is based on an acrylate ester. Because it has both ultraviolet and anaerobic cure mechanisms, it cures within 3 seconds. It is available in red, green and clear for usage identification. These sealants are used by the U.S. military, police departments and FBI.
“This dispenser seals more than 280 bullets per minute and requires just 1 liter of sealant to seal 1.4 million 5.56-caliber primers,” says Harry Arnon, president of Hernon. “It is about the size of a matchbox, but features a circuit board that allows it to be easily programmed and extremely precise.”