Original Date: 02/23/1998
Revision Date: 01/18/2007
Best Practice : Plural Component Paint Dispensing for Touch-Ups
Plural component metering, mixing, and dispensing for touch-up primer is an alternative to buying touch-up kits from an outside vendor and significantly minimizes waste generation. Advantages of the Plural Component Paint Dispensing kits include: the components are proportioned, mixed, and dispensed by the system instead of an individual; hundreds of one-half-to two-ounce batches of mixed, ready-to-apply primer can be obtained in less than an hour; the system can be flushed and cleaned with water; and only one container is used for disposal.
Primers applied to aircraft generally consist of two/three-component, catalyzed, corrosion-inhibiting, epoxy polyamide products. The primer process requires specific proportioning of each component plus proper mixing. Mixing instructions are based on the assumption that these products will be used in a spray application. Water reducible primer formulated for spraying causes problems when used in a brush touch-up application. The low viscosity of the spray grade primer produces sags and runs, and does not cover the sealant, fasteners, and scratches as required.
Northrop Grumman selected Sealant Equipment and Engineering’s See-Flo 387 equipment (Figure 2-5) to meter, mix, and dispense primer in sizes suitable for touch-ups. Characteristics of the unit include:
Precision metering Components are kept separate prior to entering the mix chamber
Components are held in pressure pot reservoirs or gravity feed hoppers
Adjustable dispensing of material
Operable by push buttons on the control panel or by foot pedals
No-drip nozzle assures that the dispensing tip does not drip paint after each dispense cycle
The cycle time for this unit is less than ten seconds. Hundreds of one-half- to two-ounce batches of ready-to-apply primer can be dispensed into touch-up plastic bottles and made available to Northrop Grumman’s assembly workers in a very short time.
The assembly workers also needed a brush grade primer which met all the requirements of a spray grade primer, but with more viscosity. This product had to be a ready-to-use item that did not require proportioning, mixing, or reliance on another organization to supply or mix the primer. Northrop Grumman worked with Deft Coatings, Inc. to produce a touch-up water reducible primer formulated for brushing. The resulting primer is specification approved for military and commercial programs; works in plural component dispensing systems; and can be packaged in three- component kits, usually in one- to two-ounce sizes.
Advantages of Plural Component Dispensing kits are: The three components are proportioned, mixed, and dispensed by the system instead of an individual.
Hundreds of one-half- to two-ounce batches of mixed, ready-to-apply primer can be obtained in less than an hour.
The system can be flushed and cleaned with water.
Only one container is used for disposal.
Disadvantages of off-site purchased, three-component kits are: Three separate components need to be manually mixed to produce one ounce of primer.
Shaking the components excessively reduces the pot life, while insufficient mixing produces a non- acceptable finish.
High cost associated with off-site purchased kits.
Three separate components per kit produce an abundance of hazardous waste containers for disposal
Purchasing three-component primer kits from outside vendors costs $96,000 per year. By producing the Plural Component Paint Dispensing kits in-house, Northrop Grumman spends only $25,000 per year for a net savings of $71,000. Total investment cost for the equipment needed to produce the in-house primer kits was $30,000. The company recouped its investment cost in approximately 106 days.
Plural component metering, mixing, and dispensing for touch-up primer is an alternative to buying touch-up kits from an outside vendor. Northrop Grumman evaluated various factors prior to its decision including total costs from outside vendors versus in-house equipment and labor costs; and the volume of material used per application. In the case of producing touch-up quantities of water reducible primer, the advantage is clearly in favor of purchasing equipment and dispensing the material, rather than buying kits from an outside vendor.
Figure 2-5. Plural Component Mixing and Dispensing System
For more information see the
Point of Contact for this survey.