Informational Resources on Industrial Infrared Heating Solutions

All infrared heaters have the ability to be attuned to a specific wavelength. The infrared wavelength produced by a heater is inversely proportional to the heater’s output temperature.

Electric heaters have an infinite ability to be adjusted within heater temperature limits. This permits a greater amount of flexibility for matching a heater’s output with an industrial application’s requirements. Gas heaters, on the other hand, have less capability for adjustment. Generally, the output produced by a gas heater can range from 100 percent to 70 percent. Below that point, gas heaters will usually shut off.

Many professionals think that an optimal goal is to match the output wavelength of a heater with a product’s absorption. Although it can be a good starting point, this principle is not always helpful. Short-, medium-, and long-wavelength heaters can often be used for most applications. Generally, shortwave heaters will heat, cure or dry the product in the shortest amount of time; mediumwave heaters will take slightly longer; and longwave heaters will require the most time.

Certain factors can, however, make the above statement incorrect. An example is the process of heating a white plastic sheet, common in thermoforming applications. Because shortwave infrared is color-sensitive, black colors will quickly absorb shortwave infrared, but white colors will reflect a much larger amount of the energy. In this case, a medium-wave heater can actually heat a white sheet of plastic faster than a shortwave heater. Because of this tendency, testing is the only way to effectively determine the results.

All heaters currently in use worldwide do not output their energy at a single wavelength. Rather, every heater’s output energy distributes across multiple wavelengths, although it usually has a peak wavelength that relates to the emitter temperature. A number of factors affect a decision to determine which wavelength emitter is appropriate. These considerations include the initial cost of the system, operating cost, available space, process speed and maintenance costs.

The choice of Solar Products’ panel heaters for industrial applications is due to their high radiant efficiency (typically 80%), long life (25,000 hours), durability, flexibility in available sizes and temperature uniformity.

Infrared heat does penetrate a sheet of plastic within certain limits. Studies have previously shown that infrared energy will penetrate it up to .015 inches. Past that point, the sheet is only heated via conduction. The real penetration amount will depend, however, on a number of influential variables, such as heater output energy, wavelength, sheet type, sheet characteristics and sheet color.

Heat cycle times depend on the sheet’s conduction and the amount of power that it can absorb before its surface begins to overheat and possibly burn.

When ABS plastic (acrylonitrile-butadiene-styrene) and HDPE plastic (high density polyethylene) are compared, we have found that ABS will burn at a much lower temperature than HDPE. For this reason, the heater temperature for ABS applications typically does not exceed 800°F.

On the other hand, when a sheet of HDPE is heated, the temperature of the heaters can be raised to 300 to 400°F without causing any damage to the sheet’s surface. This increased temperature permits more energy to be absorbed by the sheet. HDPE is a crystalline material that requires more energy to heat the sheet than ABS, an amorphous material.

The ability to raise the temperature higher with HDPE is important because it reduces the heating cycle time. Even with more power, HDPE typically needs one second per mil to be heated, whereas ABS can be heated in .5 seconds per mil. The heating rate for ABS is accomplished with a lower heater temperature and, therefore, a lower energy output. The above considerations are only general rates for heat transfer, however. The rate of heat transfer will increase as the sheet’s thickness decreases, and decrease as the sheet’s thickness increases. In other words, heating cycle times are proportional to the square of the sheet’s thickness.

The choice of a heater’s size depends on the type of heater required for a given application. The F-Series model is our most commonly produced heater because of its high radiant efficiency (typically 80%), long life (25,000 hours), durability, flexibility in available sizes, temperature and uniformity. Heaters in the F-Series product line can be constructed in standard sizes between 6″ and 12″ wide and 6″ increments in length up to 60″ for the 6″ wide heater and up to 84″ for the 12″ wide heater.

Because we are a custom manufacturer of heaters, both the heater’s length and width can be customized to your exact requirements within good engineering limits. The width can be constructed from 3″ to 30″, and the length can be constructed from 6″ to 84″, though we prefer not to build a heater 30″ x 84″ because of its reduced durability.

Our G and M series of glass and metal face heaters have more limits on their lengths and widths. Glass face heaters typically are not longer than 36″, and metal face heaters are usually not longer than 48″.

Our Q-Series heaters are restricted further in size. Because of a limit on the size of the quartz used to build the heaters, the Q-Series heaters are commonly built in smaller sizes, such as 6″ x 12″ and 12″ x 12″. Q-Series heaters have been manufactured in sizes up to 15″ x 16″.

Note: The size limits for all the heaters mentioned above will vary depending on the particular application requested. The sizes given are only intended to be general guidelines to abide by.

If you know the wattage, voltage and phase, this is a simple calculation. Assume for the purpose of this example that you have a heater rated at 6480 watts at 480 volts. For single phase, the amp draw is simply the wattage (6480) divided by the voltage (480) so 13.5 amps. For three phase, the calculation starts the same wattage (6480) divided by voltage (480). That result is then divided by the square root of three (1.732) so 7.8 amps.

Assuming the heater was designed originally to run on 480 volts, the output will change by the ratio of the voltages squared.

Assume the original heater was 6480 watts at 480 volts. Connecting it at 460 volts will result in a reduction in power (460 divided by 480) squared so 91.8% of the original output, or 5951 watts.

If the situation was reversed – original design at 460 volts and moving to a 480 volt facility, the power would increase (480 divided by 460) squared to 108.9% or 7057 watts.

A related question is whether those changes will impact the process. In the first case, lower output, the answer will depend on whether the heater is currently being run at full power all the time. If that is the case, then yes, there will be a change – less throughput, longer dwell time, etc. However, if the heater is being controlled at a certain temperature set point (below its maximum temperature) there is a fair chance that the slightly lower output can still reach the set point temperature. Initial machine startup maybe slightly slower put production operations should be unchanged.

When moving to a facility with higher voltage, if the heater is being controlled at a given temperature set point, there should be no problem operating at the higher voltage, and initial machine startup will probably be slightly quicker. If the heater was being run wide open at the lower voltage, you should give us a call to discuss the change. We will see if the heater at the higher voltage would still meet our design criteria.

There are two alternatives. One is through the use of individual heaters, each of which can be controlled individually to meet your needs. It is also possible to have multiple zones in a single heater.