EPOXIES
Epoxy comes in a variety of forms and is used for many applications. The most basic use epoxy has is for electric and electronic machines. Epoxies provide structural support and protect the vital components of these machines and devices that are generally subject to destructive forces in their applications.
Epoxy adhesives offer a strong, rigid, chemically resistant bond to various substrates in electromechanical devices. They also protect machines from heat, moisture, chemicals, dust and dirt, vibration, and other mechanical shocks. Epoxies are applied as adhesives, coatings, trickle, dip, and impregnating resins, varnishes, bonds, seal potting compounds, and encapsulants.
The offerings (Figure 1) from our suppliers range from watery liquids to thick pastes that will fill large gaps. These can often be sanded, drilled, and tapped once cured. Cure time can vary from a few minutes to several hours, depending on the product.
Epoxy paints and coatings generally offer the best environmental and chemical protection compared to polyester, polyurethanes, and other alkyds. Offerings here include one-part aerosols and sprays, as well as two-part coatings that require a catalyst to cure appropriately—seen in Figure 2 and Figure 3.
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Trickle and roll through applications require low viscosity resins with the high bond strength and quicker than average cure times. While polyester resins and varnish are more often used, Epoxies such as Elantas E-230, Dolph’s CC-1095, and Star’s ST-36-2 are also used, particularly in rewinds where the quick-cure products are needed to speed up the turnaround time.
Epoxy potting, casting, and encapsulating resins seal and protect the vulnerable windings and components in a rigid, moisture, and chemically resistant mass (Figure 4, 5, and 6.)
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Motor end turn encapsulants can be poured, requiring a form or mold, or buttered in place with a spatula.
Nearly all electric motors and dry-type transformers are treated with an impregnating resin or varnish toward the end of the manufacturing or repair process. This is because the wire and insulation necessary to build an electromagnet device must be flexible enough to form the needed shapes. For these flexible materials to then survive in the presence of vibration, heat, moisture, chemicals, and mechanical shock, the machine is treated with a polymer-based liquid that saturates and coats the wire, insulation, and magnetic steel. When the polymer cures, the materials are bonded to each other, often steel and iron.
Epoxies offer the highest level of chemical and moisture resistance in these applications and are typically applied by dip or vacuum pressure impregnation (VPI).
Epoxies offer customers a broad range of solutions to everyday applications. When determining what the appropriate epoxy to use is, relevant questions include: the quantity of resin needed (per part), available cure time, temperature sensitivity, expected operating environment. EIS supplier’s technical representative are helpful resources to find the right business solution