Original Date: 07/21/2003
Revision Date: 01/18/2007
Best Practice : Powder Paint
Electric Boat Corporation, Quonset Point Facility utilizes a powder paint process to eliminate the long process time associated with liquid paint’s drying cycle time and coverage properties. This process has reduced the cycle time of painting small and large parts as much as 98%.
With the success of its automated powder coat system, implemented in 1994, for hangers, sound damp plates, and small parts, Electric Boat Corporation, Quonset Point Facility (EBQP) decided that developing a more ambitious system to handle larger parts would have merit. In 1996, EBQP responded to an urgent request from the Groton shipyard to apply 10 to 20 mils of epoxy powder to two, 750-pound torpedo tube doors using a makeshift set up of existing powder coat application equipment and portable heaters. Both doors were degreased, abrasive blasted, coated, cured and shipped back for installation on the ship within 10 hours. Application and curing of the traditional liquid epoxy paint to these doors would have taken four days. The success and lessons learned from powder coating these doors prompted an investigation of a powder coating facility that could handle larger and heavier assemblies.
The ensuing investigation determined the size, weight, and the number of assemblies for powder coating. From this investigation and meetings with consultants on paint finishing process systems, the size and capacity requirements for the new powder coating facility were established. Construction on the new facility began early 2001, and opened for production in September of that year.
The Powder Coat Facility (Figure 2-1) consists of a large batch-type oven, a powder coat booth, computer controls, and two powered rail carts to move parts between the oven and the powder booth. The system accommodates parts weighing up to 40,000 pounds with a maximum size of 14' wide x 20' long x 12' feet high. The oven heats the parts to 4500 F, and the temperature is monitored and controlled by a computer through a series of thermocouples attached to the part. The operator programs recipes into the computer to control the part temperature and length of time the part is at that temperature to ensure proper curing of the paint. The powder booth supports the use of four manually- operated powder spray guns at a time and also allows changes in powder colors.
EBQP powder coats more than 2,000 parts a year. The process time for powder coating parts can be up to 98% faster than liquid painting, and the total labor, material, and operating costs are typically 50% less. The significant decrease in process time is not only obtained using powder paint, but also EBQP’s innovative method of mounting and transporting the parts allowing total coating coverage without flipping or handling the part while it is at high temperature. Pre-heating the parts allows a thicker coat than a typical single coat, enabling the assemblies to be returned to the trades sooner, thereby accelerating fabrication schedules. At the same time, the quality of the coating is greatly improved because powder coating is harder and more durable than liquid coatings.
EBQP’s use of powder coating is also helping improve the environment by reducing the amount of Volatile Organic Compounds (VOCs) released into the atmosphere by 3,400 pounds a year. Unlike liquid paint, powder coatings contain no VOCs, eliminating noxious emissions. In 2001, EBQP was awarded the Governor’s Award for Outstanding Achievement in Pollution Prevention in recognition of its powder coating facility for large submarine parts.
Figure 2-1. Powder Coat Facility
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