Paint Shop Innovations

Reflective guardrails. Sandpaper. Masking tape. Thinsulate. Post-its ...This array of products seems a little dull ... Yet these products are in the portfolio of a firm that has competed on the edge probably longer than any other major company."-Shona L Brown and Kathleen M. Eisenhardt, Competing on the Edge: Strategy As Structured Chaos (Harvard Business School Press; 1998).

Indeed, to the uninitiated, masking tape probably does seem dull. But John Sheridan of the Industrial Tape & Specialties Div. within 3M (St. Paul, MN) notes the lack of glamour of masking tape may mask the importance of the product in automotive assembly plants. An exaggeration? Far from it. As Sheridan notes, "$1.05 or so worth of masking tape on a $45,000 car doesn't mean much-"and here's where the other shoe drops-"unless the tape doesn't work right."

If the tape doesn't work right, then there is, quite simply, a mess. The problem occurs in or after going through the paint baking oven. Generally, masking tapes have a natural rubber adhesive.

3M, as might be expected, offers a whole range of these tapes. But Sheridan points out that there can be a problem, particularly when it is necessary for a vehicle (or component) to go through a bake oven more than once. One problem is that the adhesive transfers to the surface of the body. Which can be tricky to remove from the freshly cured paint.

Or, another problem is simply that when the tape is being removed from the surface, when the demasking is taking place, the tape slivers. Whole pieces stick to the surface. Once again, the issue here is to remove the slivers of tape without damaging the surface of the painted body. This can be time-consuming, which has a negative effect on productivity.

Or, there is still another problem that can occur, which is known as "lifting." What happens here is that as the tape is being baked in the oven, it lets go. Which can lead to what is known as "blow-by. " What gets blown by is paint onto a surface that is supposed to be masked from paint. Which means rework.

The solution devised by the clever people at 3M is designated "2693 High Temperature Paint Masking Tape. 2693, instead of using natural rubber, has a proprietary synthetic rubber, a co-polymer. It was specifically developed to stay in place in paint ovens and to come off only when, it is supposed to, without any slivering or adhesive transfer. The tape, which is 8.5 mils thick, provides instant adhesion and it is rated to handle a maximum temperature of 325°F. it is highly conformable, which means that it can provide masking over irregular surfaces. It will even be removed cleanly from most rubber moldings.

Of course, this new tape costs slightly more than the generally available product. But given the aforementioned issues that may crop up, it is hard to imagine that it isn't worth the extra cost.

Speaking of paint, there is still another 3M product that can improve the operations in paint shops (as well as other places where full-spectrum lighting is useful). The product is the 3M Light Pipe, led Construction which is offered by the 3M Specified Products Dept. The product is being tested in the Chrysler Warren Truck Assembly Plant's paint inspection area.

Those familiar with paint inspection areas know that there is typically a bank of fluorescent lights used to illuminate the surfaces of painted vehicles. The Light Pipes are an alternative. They consist of two elements: a microwave-powered full-spectrum sulfur lamp developed by Fusion Lighting Inc. (Rockville, MD) and a clear, air-filled polycarbonate tube-which can be up to 66 ft. long (it comes in 6ft. lengths) and is 10 in. in diameter-that's lined with 3M Optical Lighting Film.

The light bulb is smaller than a golf ball, yet when the microwaves hit it, 135,000 lumens are produced. This light is flicker-free and is said to have little in the way of heat-generating infrared or fabric-fading ultraviolet rays. This light is bounced along the inside of the tube; light of a prescribed angle passes through the walls. The amount and the location of the light emission is controllable.

The lamp bulb is rated at 60,000 hours. Essentially, it doesn't wear out because there is no filament. The microwave source, a magnetron, does wear out; it has a life of 20,000 hours, so it needs to be replaced a couple of times during the life of the bulb.

As with the tape, there is a cost issue. A section that's about 60 ft. long costs on the order of $6,000. However, there are several benefits, such as reduced maintenance costs, and reduced electricity requirements.