Sealant Removal Systems
Alternatives to hand scraping
By Barb Zuehlke
Sealant removal can be a tedious maintenance task. A good amount of time and energy can easily be spent trying to remove old sealant when performing maintenance on an aircraft. In the past, removing this tough material usually meant using a Plexiglas scraper to manually scrape off old sealant. These days, you don't have to revert to the tried and true Plexiglas scraper anymore. There are several products available that offer viable solutions for sealant removal.
Rotary removal tools
3M offers a one-two punch with its SR Cutter and SR Radial Bristle discs. The SR Cutter is a plastic rotary cutting tool with an integral metal mandrel. It's available in .40- and .83-inch diameters. With the use of a low speed, high torque drill it removes thick polysulfide and polythioether sealants greater than 1/16 inch. And used with the SR Radial Bristle disc, remaining sealant, under 1/16 inch, is removed. Discs are available in 2- and 3-inch diameters and the flexible bristles can access hard-to-reach areas.
According to 3M's Larry Ptasienski, 'Customers stress productivity gains from using the product, with up to 60 percent savings. And what used to take eight hours now takes two and one-half to three.'
The problem with scraping by hand is that damage can occur to the substrate along with health hazards due to the many hours involved that could cause carpal tunnel syndrome. The 3M tools can be used in tight spaces and around fasteners to minimize these effects and reduce possible rework.Part of 3M's one-two punch: the SR Cutter.
The SR Cutters require a pneumatic right-angle drill with 1/4 inch-28 female threads with recommended speeds of 850 to 1,200 rpm. The Radial Bristle discs mount on the mandrel #990 in a straight shaft or right angle pneumatic tool rated at 10,000 to 12,000 rpm. Dynabrade offers a 950-rpm drill, Model 53455, to use with the SR Cutter, and a 12,000-rpm die grinder, Model 50000, for the SR Radial Bristle discs.
Vibrating sealant removal tool
Another product solution offered by Kell-Strom Tool Co. is a Mastic Removal System that will remove PRC, RTV, silicone, glues, fabric, Velcro, leather, veneer, tape, seals, gaskets, carpets, and all general mastic and caulking from aircraft metal, plastic, and composite surfaces.
'With PRC, coatings are applied very thick and they're very elastomeric,' says Thomas Kelly, sales manager for Kell-Strom. 'There is a need for hand-held tools. You don't want to damage the substrate surface.'Kell-Strom's Mastic Removal System includes the Vibro-Gun, Vibro-Blade sharpener, blades and blade bags..
The system, Model OZ700, includes the air-powered Vibro-Gun, a 16-foot air supply hose for use in and around hangars, and a built-in Vibro-Blade sharpener with a vacuum bag to make it easy for mechanics to use as needed in the hangar or on-board the aircraft. The Vibro-Gun has an adjustable speed control to allow the operator to adjust the number of strokes per minute to match the job requirements.
The sharpener features a grounded air hose to prevent static buildup. The operator inserts the blade and presses a switch to activate the motor. An abrasive removes just enough to sharpen the blade. Residue is vacuumed off the surface and deposited into the electrostatically treated vacuum bag for easy disposal.
According to Kelly, the time required for sealant removal varies by application but total time savings can be reduced by up to two-thirds of what it took with previous methods.
The kit includes 1/2-, 1-, and 2-inch blades. Some blades have notches to go around fastener heads without damaging them. 'If you have a flat spot you can use a 2-inch blade and the smaller ones in tight spots,' Kelly says. Kell-Strom also has bottom head blades and high-lock blades with custom blades available in plastic, steel, brass, and aluminum bronze.
Kelly also stressed the ergonomic and safety benefits of the system. The rubber grip on the Vibro-Gun is ridged to prevent slipping and the vibration is confined to the blade to reduce operator fatigue.
The bottom line is you want to remove sealant as quickly as possible without damaging the substrate. Now when you are faced with a sealant removal task, you don't have to just rely on that hand scraper. There are solutions available that can save you time, increase productivity, and improve safety conditions.
St. Paul, MN
Kell-Strom Tool Co. Inc.