In this video, Kyle Otte, an engineer here at Thermal Corporation, addresses a question we receive often regarding Ease-Aid. Ease-Aid is a release and heat transfer agent made by Thermal Corporation for use with cartridge heaters. He also demonstrates the correct way to apply it to a cartridge heater and provides some helpful tips about this product.
Click here to view a list of all Thermal Corporation cartridge heater configurations.
Ease-Aid is listed under our General Accessories page. Please call, email, or chat with us to place an order for Ease-Aid today!
A customer was having some issues with a set of cartridge heaters in a mold. The mold had two sides, each side contained four cartridge heaters. The technician would start the process and the heaters would all come on and begin heating the mold. Then, after about 45 minutes, the heaters would begin blowing the fuses. Once the fuse blew, then power would stop flowing and the heaters and mold would cool down. What was going on?
Leads and Fuses
I went to visit the customer and looked at their actual machine as well as some old heaters that had been taken out of the mold. The first thing I noticed was that the leads were black where they exited the heater. The second thing I noticed was that the heaters still had the correct resistance. So, the heaters were not burned out, the power was somehow returning to ground and blowing the fuses (which is the equivalent of tripping the breaker).
The Explanation
This is what was happening: the mold was getting hot and because the heaters were not long enough to stick completely out of the mold, the fiberglass leads were getting hot and the insulation was breaking down. The particular leads we use at Thermal Corporation are rated at 600V, but as the fiberglass insulation breaks down, it is not a stretch to think that 480V could jump to ground through the broken down fiberglass.
Another issue is that the heaters had a silicone boot on each lead end as well as ex-flex. In the first picture, the silicone boot is the shiny black material over the leads. Silicone boot is used as a protector for the leads and is rated at 500°F. Ex-flex is a high-temperature fiberglass product that is shown in the second picture as the white sleeving. It is rated for a similar temperature as the silicone boot. While these additions can certainly protect the leads from damage, especially from mechanical or cyclic wear, in this particular situation they were really acting as a thin layer of insulation inside the mold and causing the leads to hold more heat. This was also contributing to the breaking down of the fiberglass and causing the leads to arc.
Solution to the Problem
The solution was to add a 1-1/2″ long cold section to onto the lead end of the cartridge heaters. This got the leads completely out of the mold and out into the cooler air. This stopped the leads from breaking down due to heat and kept the fuses from blowing.
Have a question about a heating application?
Contact our engineers for advice! Our engineers excel at problem-solving heating application issues. Don’t hesitate to shoot us an email (engineering@thermalcorp.com) or give us a call ((800) 633-2962) and we will be happy to answer any questions you are having about any industrial heating application.
Written by Kyle Otte Date Published: 10.10.2019 Last Updated: 10.10.2019
In this how-to video, our Thermal Corporation engineer, Kyle Otte, explains how to correctly insert a cartridge heater into a mold, block, or any other heating application.
This case study was the first of many to come, recorded on May 24, 1996, by Thermal Corporation engineer, Jim Dixon. Over the last fifty years, the great team of Thermal Corporation employees has helped many countless customers with heating applications. One of the byproducts of being an established company is having an extensive library of past solutions to lean on.
When we entered the quote into our tech sheet program, the program was unable to choose an internal resistance wire for these specific cartridge heater values. This caused us to ask three questions:
Why is this a problem?
If the program could pick a wire, why would this probably not be a good heater?
What would we recommend?
Think About the Formula for Wattage
To begin, think about the formula for wattage.
Wattage = Current x Voltage
Heaters that have low wattage and relatively high voltage are typically a problem. If wattage is low and voltage is high, then what is the current? The current would be very low. How do you make a current very low?
I (Current) = E (Voltage) / R (Resistance) OR R = E / I
If the current is low and the voltage is high, what does R need to be? R needs to be very high. How do you make the resistance high? Think of electricity as water flowing through a heater. What diameter water hose has high resistance to the flow of water? A very small diameter hose will resist the flow of water. Thus, we have to use a very small wire and a LOT of it. In this case, we did not have any wire on hand that was small enough to make this particular case work.
Why Would This Not Be a Good Heater?
This leads into our second question: if we did have a small enough wire, why would this not be a good heater?
Remember that as heaters age, an oxide coating builds up on the surface. Temperature cycling accelerates this. Under a certain set of circumstances, the nickel-oxide will build up a constant rate. At some point, the oxide coating cuts off the path for electricity to flow- just like cholesterol clogging up an artery.
The oxide coating on each wire is the same thickness. So, which size do you think would fail first? If you thought the small wire, then you are correct.
What Would We Recommend?
Now, to address the question of what should be recommended. First of all, to cause the wire size to increase, what needs to be changed and how? The answer is the resistance must decrease.
W = E2 / R
If W does not change, and R goes down, what happens to E? E must also go down, as well. This means the customer must go to a lower voltage.
208 Volts, 3 phase power, is common in small industrial plants.
If 208V is a voltage from one hot-line to another hot-line, what is the voltage from a hot-line to the ground?
Line to Ground Voltage = Line to Line Voltage / √3 = 120V
Therefore, wherever there is 208V there is probably 120V, also. If we recommend 120 volts, how much does it help the resistance?
Initially: R = E2 / W 2082 / 75 = 577Ω
Now: R = E2 / W 1202 / 75 = 192Ω
Thus, resistance is decreased by a factor of 3. This is what we recommended to our customer.
Have a question about a heating application?
Contact the Thermal Corporation engineers! We can help you solve any issue or any question you may have regarding your heating application. Get in touch with us by email at engineering@thermalcorp.com, by phone at (800) 633-2962 x152, or chat with us using the instant chat feature located at the bottom of the page.
Written by Jim Dixon Edited by Shelby Reece and Kyle Otte Date Published: 08.23.2019 Last Updated: 08.23.2019
Our resellers, along with our other valued customers, are one of the major parts of Thermal Corporation and what help keeps our company going. We, at Thermal Corporation, are always looking to reach out to new resellers for our products. Our goal for this post? To grab your attention — if you are a part of an industrial heating sales company who is interested in buying and reselling Thermal Corporation products, then this post is for you!
What We Sell
As you may already know (or not), Thermal Corporation designs, manufactures, and sells industrial heating products. The types of industrial heaters we manufacture can be standard, or designed to exact customer specifications. Our products are used mainly for the plastics industry, but can also be used for other industrial applications such as food processing. These products include:
Our delivery time is second to none! Ask about our express line of heaters that ship on the same day with no extra cost! Limitations do apply. We also specialize in custom and unique heaters. We can provide these heaters with short lead times.
How to Become a Reseller
So, are you an industrial heating sales company looking for new product categories to offer or who wants more of a variety of brands to sell? Then, contact Thermal Corporation today and chat with us about becoming one of our resellers! Don’t forget about the discount you can receive if you decide to resell Thermal Corporation products. Resellers have the opportunity to get the largest available discount from Thermal Corporation. Discounts are based on annual sales of Thermal Corporation products.
Thermal Corporation is looking to reach out to new possible resellers right now! Need more specific information on our products? Check out the products page on our website at www.thermalcorporation.com/products.
Interested in chatting with us and getting more information about doing business with Thermal Corporation? Contact Ushma today by email at ushma.s@thermalcorp.com or by phone at 256-837-1122 x127.
Written by Shelby Reece Edited by TC Marketing Team Date Published: 03.04.2019 Last Updated: 09.04.2019
Watt density is a measure of the rate of heat being transferred through the surface of the heater.
For example, if you were to draw a 1″ x 1″ square on the surface of the heater, how much power (or heat) would pass through that area? The answer is the heat per unit area, so basically the watts per square inch.
So, How Is it Related to Heater Life?
Basically, the higher the watt density, the higher the temperature is inside the heater (assuming all other variables are constant). As the temperature inside the heater increases, the materials inside the heater are operating closer to their breaking point. This results in shorter heater life.
We received a question from a customer the other day regarding how to check whether or not a heater is operating correctly on the line. This is a great question! But, how do you actually know if a heater is operating correctly or not? Our answer is this: The best and safest way to check a single phase heater that is still on a machine is to…
Turn off power to the heater and disconnect the lead wires.
Find the number engraved on the heater specifying the watts and volts. (See photo)
Measure the resistance between the two lead wires or two post terminals, depending on the heater.
The resistance should be close to the voltage squared divided by the wattage (for you mathematicians out there, here is a formula: R = V^2 / W)
For example: You have a 500 W – 240 V heater.
R = 240^2 / 500
R= 115.2 omhs
Standard tolerances allow for resistance to measure between -10% and +5% of this total when the heater is at room temperature. If the heater is still at operating temperature expect resistances in the range of -5% to +10% of the calculated total.
So, what exactly is a Split Sheath Cartridge Heater?
Spilt sheath cartridge heaters are tubular heaters that have been formed in to a half circle which is then folded in the middle with the two halves now making a circle. Their claim to fame is that they are easier to remove from a hole. This is true – but more on this later.
The drawings that usually accompany the advertisement show the two halves expanding as the heater heats up with the heater more completely filling the hole. The amount of expansion is actually a function of the thermal expansion of the metal sheath. Different metals expand different amounts, but all of the expansions are rather small, at least compared to the drawings, which are exaggerated for clarity. All of the sheath materials are either one of the stainless steels or incoloy steel.
The main point here is that a split sheath cartridge heater will expand the exact amount as a regular cartridge heater made of the same steel. The amount of expansion is a function of the thermal expansion of the sheath and the diameter of the heater, which is the same for both types of heaters. Thus, they are the same.
Ease of Removal
While it is possible to manufacture a heater in a near perfect circle, when you form the circle into a half circle it is not a near perfect half circle. When you put the two halves together, the resulting shape is slightly football shaped. That is, the diameter in one direction is not the same as the diameter if you rotate the measurement by 90 degrees. The difference is something on the order of 0.015 to 0.020 inches. What this means is that the AVERAGE diameter is smaller than a regular cartridge heater. THIS is why it is easier to remove. The smaller the diameter the easier the removal.
Disadvantages
With a slightly football shape, the heater is not making as good of contact with the hole and thus poorer heat transfer. The internal temperature of the heater will be higher and the heater will have shorter life.
Also, tubular heaters have more magnesium oxide insulation between the element wire that generates the heat and the inside of the sheath compared to a regular cartridge heater. This means the heater can more likely be run in air because of the higher breakdown due to the thicker MgO, but also means that this thicker insulation reduces the rate of heat transfer. Again, poorer heat transfer means that the heater will have a higher internal temperature and resulting shorter heater life.
Edited by Shelby Reece Date Published: 07.19.2018 Last Updated: 09.09.2019
I hope 2018 has started with many blessings for you already! We are in the starting gate, ready to offer you some NEW SIZES in Cartridge Heaters. We now have a more complete line with 22 different diameters in Metrics and Inches. Some of these we have not been able to offer in the past, but are well equipped to handle all of your needs!
Our customer service team and engineering tech team are available for you when you have questions about ordering, or placing an order. We have already had customers taking us up on these new sizes, and we hope you will too. We try hard to please our customers and meet your needs. This is a request that customers have been making for a few years, and we have been working hard on being in this position.
We will also be offering a new Band Heater experience soon. Please keep yourself informed with our announcements.
I do hope you will take advantage of these new Cartridge Heater Sizes. Have a wonderful New YEAR!! We look forward to hearing from you.
Written by Jennifer Taylor Edited by Shelby Reece Date Published: 01.02.2018 Last Updated: 09.06.2019