How does viscosity control wire coating control coating on wire thinner than a human hair? This is the challenge faced by manufacturers of wires with a diameter of 30 – 300 microns (known as winding wire, magnet wire or fine wire). These wires are key components in the electric motors, transformers and electrical coils needed in appliances, automobiles and other powered equipment.
Enamel coatings control the dielectric insulation properties of wires and have a significant impact on wire quality. The viscosity of an enamel fluid is a direct measure of the coating solids content of the fluid. By controlling the viscosity of the coating during the process, wire manufacturers can control the uniformity of insulation on the wire.
In the past, many manufacturers have relied on visual monitoring of viscosity. To avoid coatings that are too thin, engineers err and make coatings thicker than necessary, resulting in wasted coating fluid and less flexible wires that impact performance. Cambridge Viscosity's oscillating piston viscometer technology enables manufacturers to more accurately control coating thickness in real time over a wide range of temperature variations.
Temperature Compensated Viscosity (TCV) is a mathematical representation of the viscosity a process fluid will have at a user-selected reference temperature. TCV allows wire rod manufacturers to monitor viscosity regardless of temperature fluctuations. With the viscometer automatically adapting to temperature changes, manufacturers don't have to worry about less variables in highly variable processes. By keeping this factor constant, manufacturers can easily fine-tune their process, such as changing the coating thickness or the speed at which wires are drawn through the coating bath.
A leading North American fine wire manufacturer was trying to control the viscosity temperature of its enamels. Difficulty maintaining target viscosity specifications despite tight temperature control was the reason for the constant failure of their syringe sampling method. Another leading fineline manufacturer in CHINA and Japan used a paddle viscometer to control enamel viscosity and found that evaporation on the paddle and changes in enamel level caused significant errors and product rejection. Both companies turned to Cambridge Oscillating Piston Viscometers to solve their problems.
The accuracy and temperature compensated viscosity control capabilities of the Viscosity viscometers allow both companies to reliably produce viscosity readings using in-line viscometers that are directly compared to in-house specifications. This results in reliable achievement of quality targets while reducing the cost of enamel and solvents and significantly reducing rejects caused by air bubbles and other defects on the surface of the wire due to improper coating. The Cambridge system also allows users to store up to 1,000 data points in memory for troubleshooting with readily available reference data.
The ability to monitor viscosity in real time and precisely control coating thickness also helps save resources. Manufacturers can use just the right amount of paint, which saves cheap paint fluids from being wasted, and can better improve the flexibility of the wire for more efficient winding around the core diameter. The oscillating piston viscometer also monitors viscosity 24/7, so coating thickness can be controlled throughout the manufacturing process.
Cambridge's technology is used by wire manufacturers all over the world, most of them located in the US, Europe, CHINA and Japan. "We tried a number of viscometers but found Cambridge's technology to be very reliable in meeting our accuracy targets," said the director of engineering at the Asian fine-wire manufacturer. The viscometer also has integrated temperature compensation, which mathematically adjusts the viscosity to suit temperature changes, allowing tight control of viscosity."