The Proof Firing Test Simulation program conducted by Benet Laboratories at Watervliet Arsenal fully tests a product for fit, form, and function before it receives any added value and is shipped to other activities for further processing or proof firing. Both mortar tubes and the cannon breech mechanisms are hydraulically at the same stresses induced by live firing. Possible hydraulic loads are in excess of 100,000 psi.
Cannon tubes, however are not proof simulated; they are Proving Ground Lot Accepted (PGLA). With the PGLA program, only one out of seven tubes is proof fired and the rest are accepted in a sampling basis. The rationale for sampling tubes is based on a swaying process performed by passing a .1-inch diameter mandrel down the bore. This process is equivalent to approximately 150% pressure over the proof firing test which also increases the fatigue life of the tube. Fit and functional testing for breech mechanisms are performed by an automated process using a gymnasticator - or by using a manual process. During this simulation of the loading and unloading of a round, all required forces for the moving components of a breech unit are measured and recorded. The gymnasticator was developed in-house and simulates the load, fire, and unload sequence for most breeches in WVA's inventory.
Full-scale simulation was initiated with the operation of the Acceptance Test Facility (ATF). The ATF has capability to proof-accept a wide range of breech mechanisms, mortars, and components ranging from 60mm M2 mortars to the eight-inch M201 A1 Howitzer. Since 1977, over 19,000 items have been accepted through simulation testing with an estimated savings of over $15M.
The simulation process is also an effective way to screen for production defects. This screen has prompted corrective action to be taken before costs and delays are incurred by shipment for proof firing. These delays can total from six to nine months. After the hydraulic test and the automated gymnastication test or a manual test, the breech units are broken down, cleaned, visually inspected, and undergo a magnetic particle inspection. With the inspections completed and passed, the unit is ready for shipment to the next step in the process.
This simulation proof testing program has significantly reduced the requirement for live proof firing and its associated testing costs. The process allows problems to be quickly identified and corrective actions taken. Further developments for this process include accepting newer cannon breech designs and automating a number of the database entries.