Written by: Matt Dearman, Mcloones Process Engineering Technician
Have you ever worked on a project and been challenged with making one of your identification products stand out yet be durable at the same time? Doming is the answer!
The term Doming in the labeling industry refers to the process of applying a transparent resin onto the surface of a two dimensional part, giving it a three dimensional or domed appearance (Figure 1).In the most stripped down explanation of the process, a catalyst and a resin are mixed and then poured onto the surface of a part which cures to form a clear lens. A typical lens thickness would be .070 and can be applied to encapsulate the whole top surface of a part or selectively over just a portion of a part to accentuate an individual feature.
The machine that is used to dispense the doming is equipped with two large holding tanks, one for resin and another for the catalyst where the liquids are degassed to remove all of the air bubbles. This is very important as bubbles in either of the two-parts of the mixture will be highly visible if they become trapped in the lens when the doming is poured and cured due to its see-through properties. After the degassing occurs, each component is sent, in a ratio of 1:1 by weight, to a mixing chamber that is in close proximity to the dispensing nozzles. Small batches of the resin and catalyst are then mixed together and are ready to be applied.
Mixing only small amounts of the catalyst and resin at a time reduces the amount of wasted product due to routine purging cycles that are necessary to keep the system free of clogs. In order to improve production speed the dispensing head consists of multiple injection nozzles which are affixed to a traveling arm driven by a computer program, not unlike many CAD/CAD based CNC driven machine tools. This allows for a precisely distributed amount of resin onto the surface of a substrate in an endless variety of shapes and sizes in a repeatable manner. After a job is complete the system is thoroughly cleaned to eliminate the possibility of hardened resin in the system.
The Doming process not only augments your identification product appearance but also creates a protective cap which makes it an economical solution for many extreme environment applications. For example, a Urethane resin will resist many chemicals, solvents, and cleaners creating a label that is impermeable to a wide array of liquids. The resin also shields the part from surface defects such as abrasions. Doming is also a great way to protect an ink systems integrity. With a cured lens directly on top of printing there is no chance of ink being rubbed off of your part like you commonly see on push buttons, keyboards, and hand instruments/tools. Complemented by all of the previous benefits of part durability, doming resin will not yellow, crack, or fall victim to tinting when exposed to the UV rays of the sun. This is very desirable for usage that may be located in direct sunlight or harsh environments.
Because of this resilience, domed parts are widely used on products where frequent cleaning takes place or where waterproof labeling may be necessary. Doming is an ideal application for kitchen appliances, bathroom fixtures, sporting goods equipment, electronics, fire apparatus, cabinetry, marine and medical environments. While the automotive industry uses doming to increase the durability and life expectancy of their appliques with polyurethane doming resin, it not only protects from scratches but also demonstrates self-healing characteristics.
Now that homage has been paid to the durability advantages of the process lets take a look at why most of our customers at Mcloone choose domed labels . . . it makes their identification products pop! Many of our POP (point of purchase) customers make use of doming for advertising displays or product identification not due to durability concerns but wanting an upscale look that is appealing to the end user. Doming is an inexpensive means to make a plain flat label look sophisticated and when applied over an embossed part, the variance in height is magnified for a more dramatic appearance.
As mentioned earlier some customers choose to dome only selective features on their parts to emphasize that area. This can be achieved by either embossing a thin border around that feature which acts as a dam to stop the resin from flowing past the border or some customers prefer the use of a stop ink because it doesnt require additional tooling cost. Stop ink is screen printed onto the substrate material as a ring that matches the periphery of the desired domed pattern ranging from .060-.125 wide () dependent on the amount of resin that it needs to hold back.
Doming can be utilized on a wide variety of materials including various metals, polycarbonate, vinyl, mylar, and coated paper. A substrates surface energy along with the resins surface tension correlate to determine the success of the doming process in regards to the resin flowing to the edge of the part. To example this relationship I will use the age-old scenario of your car in a rain shower
If you were to wax half of your car and it began to rain you would notice on the waxed side of your car the water would pull itself together and form near spherical droplets. This is due to the low surface energy (surface wetting capability) of the waxed surface and the surface tension (force that holds the liquid together) of the water. The rain on the un-waxed side of the car acts differently, it tends not to form droplets but instead to spread out to form a thin film of water. This happens because the surface tension of the rain water has been overcome by the surface energy of cars paint allowing for wettability of the car surface. Accordingly, when doming a material that exhibits too low of surface energy, the resin will flow past the edge of the part and will not form the desired domed appearance. Material texture, surface cleanliness, and part contour can also adversely influence doming success. An ideal application would include a smooth substrate free of surface contaminates, such as oil, and a periphery free of square corners with a minimum of .0625 (1/16) corner radii.
The next time youre looking to add appeal and distinction to your identification products, consider the use of doming. The 3D appearance and depth will distinguish your products from your competitors while providing a durable solution.
Contact Mcloone today to get quotes on all your doming needs.
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Based in La Crosse, WI, Mcloone (aka Mcloone Metal Graphics) is a manufacturer of custom decals, custom nameplates and pressure sensitive labels. Founded in 1954 by James E. Mcloone, we are now recognized as one of the worlds leading providers of high-quality identification graphics.
Mcloone is a business of JSJ of Grand Haven, Michigan, U.S., a privately held corporation that actively designs, develops, markets and brands a group of durable goods and services throughout the world.
Our specialties include metal labels and nameplates, vinyl decals, self-adhesive vinyl labels, doming, asset tags, metal signs and polycarbonate identification graphics. Materials available for your identification labels include aluminum, stainless steel, vinyls, foils, polycarbonates, polyesters and many more.
All this and great customer service means that Mcloone is there when customers need us the most. Artwork services, in-house tooling, fast turnaround time and a dedicated staff all result in a stress-free customer experience. With Mcloones guidance, customers identification products arrive as designed and on time.
Thats peace of mind. Thats Mcloone.
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