Assembly in Action: Mixer Ensures Armor Integrity
October 29, 2007
Textron Inc. manufactures a wide range of products, including everything from airplanes to boats to lawnmowers. Subsidiaries include Cessna Aircraft Co. and golf cart manufacturer E-Z GO.
Textron Inc. (Providence, RI) manufactures a wide range of products, including everything from airplanes to boats to lawnmowers. Subsidiaries include Cessna Aircraft Co. (Wichita, KS) and golf cart manufacturer E-Z GO (Augusta, GA).
At its Textron Marine & Land division (New Orleans, LA), the company manufactures the M1117 armored security vehicle (ASV) for the U.S. military. Because the vehicles provide protection for soldiers on patrol in hotspots like Iraq, the Army has been ordering an unprecedented number of the vehicles in recent year. In 2005, the Army ordered 724 of the vehicles. In 2006, the order grew to 1,200, and Textron found itself assembling up to 48 ASVs per month.
Incorporated into each ASV’s body armor is a thick layer of Kevlar fiber. During production, approximately 30 different Kevlar shapes are pre-cut and assembled on a table. The panels are then attached to the interior of the vehicle using two-part SIKA Biresin brand elastomeric urethane casting resin in 5-gallon pails with viscosities of 7,000 cps for part A and 250 cps for part B. The mix ratio is 1.5:1 by volume and has a 15- to 20-minute work life.
To ensure that the adhesive is correctly mixed, Textron employs a See-Flo 7 Meter Mix Dispense System from Sealant Equipment & Engineering Inc. (Plymouth, MI). During production, an operator selects a specific shot size, and the See-Flo 7 dispenses a precise volume of mixed material into a container. A flame retardant and curing accelerant are added, the adhesive is applied to the Kevlar, and the Kevlar is then applied directly to the body of the ASV. As part of this process, the ASV is rotated on its axis to facilitate operator access. C-clamps, vise-grips and column jacks are put in place for 2-hours to hold the Kevlar panels in position during the adhesive curing cycle.
The See-Flo 7 is a continuous-flow, adjustable-ratio meter system with precision shot volume controls. Textron’s system is cart-mounted, so that it can be easily moved where needed. Material is placed in 10-gallon pressure tanks, agitated and degassed. The tanks are pressurized with nitrogen.
In the Textron operation, the system has been pre-set with 15 shot sizes ranging from 360 to 3,600 cc. The system’s Program-A-Shot controls incorporate a linear-transducer to precisely measure the selected volume of mixed material. The See-Flo 7 meters the material on-ratio to a 2200-245 No-Drip Mix-Dispense Valve with disposable static mixer, which delivers the material at a rate of 22 cc per second. A ratio-check is performed regularly to verify the 1.5:1 material ratio accuracy.
For more on two-part dispensing, visit www.sealantequipment.com or call 734-459-8600.