WATERVLIET ARSENAL, N.Y. (May 1, 2018) -- When the Army’s fleet of 155mm self-propelled howitzers, called the Paladin, faced a significant readiness challenge two years ago, the Army turned to its oldest arsenal to quickly remedy the problem. But sometimes even well-experienced Army units, such as the Watervliet Arsenal, create new challenges when they try to correct old ones.
The gist of the readiness issue has been years in the making, said Col. Joseph Morrow, the Watervliet Arsenal commander, as he described the extensive corrosion issue that developed under what is called a bore evacuator on a howitzer tube.
A bore evacuator is used on the gun barrels of the Abrams tank and the M109A7 self-propelled howitzer to help reduce propellant gases and pressure from venting back into the vehicle’s firing compartment, Morrow said. But due to age of the barrels, maintenance procedure challenges, and changes in propellants over the years, hundreds of barrels suffered extensive corrosion of the bore evacuation holes, such that Soldiers’ safety and the accuracy of the round may be affected.
After several studies were conducted as to how this readiness issue may have happened, some came to the belief that because the bore evacuator was very heavy, that the time and effort to remove the evacuator after every firing was untenable.
The Arsenal, working hand in hand with the Army’s Benét Laboratories, quickly came up with a fix.
“By using a manufacturing composite winding process that was being used on the 120mm tank cannon, we were able to quickly modify that process for the self-propelled artillery system,” said Gregory Marcklinger, the Arsenal’s division chief for Manufacturing Support. “As a result, we were able to lower the weight of the bore evacuator from approximately 203 pounds to 110 pounds.”
“We believe that by producing a lighter bore evacuator a rather difficult maintenance job should become much easier for artillery crew members,” Marcklinger said. “In fact, we had our first million-dollar contract for light-weight bore evacuators not long ago.”
But, sometimes, there are unintended consequences that arise from good intentions.
“We believed that we could do more to support the Soldiers in the field than just lightening the evacuator,” Marcklinger said. “So, working with Benét Laboratories, we decided to use a Cerakote coating under the evacuator to further reduce the opportunity for corrosion.”
Cerakote is a ceramic-based coating that provides an improved hardness and longer-lasting abrasion resistance to the treated surface, Marcklinger said. Not that the Arsenal didn’t treat the area under the evacuator before, but it did so with a dry film coating that does not have the same tough characteristics as Cerakote.
“Before I came to the Arsenal three years ago, I painted ships for the Navy for 15 years,” said Thomas Barnes, an Arsenal production painter. “But I have never painted with a coating as difficult to apply as Cerakote.”
With Cerakote, the Arsenal had to work with tolerances that were tighter than what was required of dry film, and the painters had to develop a new quality test procedure, Barnes said.
“If you try to apply Cerakote too much at one time, it immediate starts running,” Barnes said. “We had to purchase new tooling and then apply Cerakote in four layers and in very thin coats.”
Barnes said that he was very frustrated until the process and techniques were finally achieved.
“I take a lot of pride in my work,” Barnes said. “My work has got to be perfect, because it is going out to the troops. And when it (my work) is not right, I get angry, which makes me work harder to find a solution.”
When tolerances are one to two-thousandths of an inch, there is not much room for human error, said Kenneth Prescott, the Arsenal paint supervisor. The Arsenal now has a good handle on this process and the goal going forward is to train more painters to meet this high standard.
After several months of trial and error, new Cerakoted-barrels, with light-weight bore evacuators are now going out to the troops in significant numbers, Prescott said.