This guide is intended as a companion post to our YouTube video explaining the same. I recommend you give that video a watch and then read this guide for a full picture of what is involved in installing MoSi2 heating elements in your dental sintering furnace.
Typically, furnace manufacturers design their furnaces so that the heating elements are installed through the heated chamber, up through the insulation of the furnace. I’ve used this picture in many places on our site, but it is a great illustration of what the top – where the element connections are electrically terminated – of many dental sintering ovens looks like:
The elements were inserted through the heated chamber up through the furnace insulation.
Occasionally, the furnace manufacturer will design the furnace such that the elements may be inserted from the top. You will be able to tell if this is the case by looking for a slot in the furnace insulation between the element holes. The slot allows the body of the element to be inserted first, leaving the terminals protruding like shown in the video as well as the above picture.
It is important to follow the advice in the video regarding the positioning of the element taper. As shown in the video, the taper must be all of the way inside of the furnace. If not, you are risking premature failure of your heating elements. For more information on this topic, check out our blog post on the topic, which provides some more detail.
The fiber insulator is not strictly necessary, but it does aid in both the performance and the efficiency of the furnace. The primary purpose of the fiber insulator is to keep the hot air present in the furnace from escaping by using the element holes in the furnace insulation as chimneys. Hopefully, your dental furnace came with some type of ceramic fiber insulation material already installed with the stock elements, but if it didn’t it is not the end of the world. We sell this type of insulator as an accessory – just drop us a line if you can’t find it on our website.
A quick note on the insulators – depending on how sealed the terminal box is on your furnace, the fiber insulator may be a more critical item. If the terminal area is tightly sealed and there is no fiber insulator on your elements, the heat escaping from around the elements could cause problems with the electrical terminal straps. The straps are braided Aluminum and are not designed to see temperatures higher than ~350F. If they see temperatures higher than that, they will start to degrade from excessive oxidation and will cause premature element failure.
At Dental Furnace Elements, we prefer to use single shank element holders rather than dual shank element holders. Dual shank holders – as you may have guessed – hold both of the element terminals rigidly together. Like anything that gets hot, the elements do expand and contract during their thermal cycling, and being that the elements are basically glass (they are a ceramic material), they are quite brittle at low temperatures and do not like mechanical stress.
The single shank holders allow the element terminals to move independently, and in our experience, the use of single shank holders is correlated with longer heating element life.
From a tightening torque standpoint, be firm, but be gentle. Remember, these elements are basically glass!
This part is fairly straightforward. The straps that you buy from us along with your elements just slide onto the element terminals, and are fixed in place by appropriately sized spring clips.
One thing to keep in mind is how much stress the straps are applying to the element terminals. You should be working to reduce the amount of stress the straps place on the elements – given the inherent brittleness of MoSi2, it doesn’t take much leverage to cause stress risers on the elements, causing micro cracks, and eventually, premature element failure. use the shortest length straps possible, and if you can, try and make sure that the connections are supported on insulated brick.
Feel free to reach out to us, we would love to help! Also, we would love to hear your tips and tricks for element installation. You never know – we may just feature your on our blog.
Thank you for your business!
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Dental Furnace Elements LLC
17621 Narragansett Avenue
Lakewood, OH 44107