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Can someone recommend a C & B casting investment that is good for implant abutments? I've used GC Fugivest II w/ full strength liquid and they still come out tight. — tagged Crown and Bridge and Abutments
Are you looking for a pressing oven with features others do not have? What makes the difference from pressing oven to pressing result? What is it that really matters? Do you know?
When you are pressing...See more for consistent success, you want predictable results. However, you must understand the function of your tools in order to achieve consistency. On this forum and others, I have seen many posts asking questions in preparation for furnace purchases. Those questions are usually open ended and non-specific in terms of features, quality or price point.
Although most of the furnaces on the market function in much the same way, utilize many of the same types of components, the quality and configuration of these components coalesce to differentiate each furnace.
Unfortunately to adequately understand the difference you will probably have to get a degree in engineering, but lets start with some simple things to look for that may shorten the list dramatically.
1st - Price - for the most part you get what you pay for.
2nd - Who manufactures most of their own parts, even down to the electronics. Ultimately, the more the company actually produces their selves, the better quality control they have.
3rd - What features are important is the oven able to be utilized for both pressing and ceramics or just on or the other?
Those first three steps will dramatically shorten the list. To further shorten the list, look for innovative design concepts. Know that patents and unique design elements usually indicate attention to product detail and usually translate into higher product quality and better firing/pressing results.
Principle design criteria. These are the main ideas behind a products design. Most manufacturers always use a certain type of chamber design, thermocouple type, press methodology and lift design. Using common sense on some of these design items can also help.
1st there is chamber design. Many types of chambers have been introduced, some with embedded winding, quartz spiral tubing with a spiral element inside, exposed spiral windings, the list goes on. Ultimately it is hard to say what the best winding is, but more important that how it is installed is how close it is to your work and how much of the ring does is heat. The trick with chambers is heat radiation, making sure the heat is radiated as evenly as possible throughout the chamber and as uniformly as possible across the firing tray. In this instance, bigger tends to be better. However, if the no matter the chamber configuration the thermocouple must be of high quality and well calibrated.
Common thermocouple types used in pressing and ceramic ovens are Type K and Type R other medium level P variations exist for cost savings purposes. Type R tends to be the most popular, Type K the second and the P type the least. Type R has the best accuracy through the most commonly used temperature ranges for the application and is made with a combination of metals that make it also a very reliable thermocouple for the application. To find a difference in quality, look at the thickness of the wire and the packaging of the thermocouple itself. Too much exposed wire can be problematic, to thin will bring short life and too little exposure will not read temperature adequately enough.
Calibration is one of the most confusing topics to cover with many technicians. To understand the function of calibration you must understand why you need to calibrate. When a furnace is new the motherboard (mainboard) is programmed with a reference chart the furnace uses to tell you the temperature based on the voltage output from the thermocouple. As all thermocouples vary slightly it is necessary to calibrate to correct for any variance. In order to truly calibrate an oven, there must be a controlled device used. This device is usually a secondary thermocouple that is itself calibrated and set as the standard for a certain number of uses before it itself is retested. Some furnace manufacturers will sell you calibration kits, these kits may help you slightly in certain situations, but are not controlled the same way. Be wary of these manufacturers and kits, they tend to be another consumable.
Pressing methodology is something I discuss from time to time. Whether it be a stepper motor, motor driven, air driven piston or other, make sure you can control either the speed, the pressure or both. What's more important than the mechanism itself is the furnace's ability to know what is going on in the ring while it's pressing. Intelligent press technology varies from furnace to furnace, most of the better pressing ovens have some sort of sensor that tells the furnace when the unit is done pressing so that the furnace does not continue to push un-necessarily.
Lift methodology is not typically thought much about, but none the less can be an important attribute or detriment to an oven. Keeping the heat centered over the unit, or ring can ensure more even heat distribution and better results. Some lift mechanisms are incorporated into pre-dry and cooling features that make their accuracy and placement critical. Use your common sense when looking at the lift.
Finally, those individual features are nice, but do they really work? Ask for proof. Be tough of the sales people, ask them for video, pictures, testimonials or better yet, ask them if you can try it. Some manufacturers will let you try before you buy. This is usually dependent on your relationship with the manufacturer and their ability to get it back from you should you decide to not keep it.
In the end, the furnace is usually only as good as the user of the furnace. Understanding the furnace, the physics and the chemistry always makes things go more smoothly. Good luck.
For Sale: Origin Pro 3000 Mill. Works terrific. Includes computer, tooling, and suction unit. Cost new - $73k, sell for $35k. Call Jimmy at Sherer Dental Lab, Rock Hill, SC 803-324-4040 — tagged B&D Technologies ORIGIN® Pro Series
For Sale: Two (2) Roland DWX-50 milling machines, DentMill CAM Software, (1) 3M ST scanner, and (3) Lava Therm ovens. Mills were just factory refurbished (new collets, tension cables and spindles) and...See more all equipment is in great working order. This is a great opportunity to move into milling at a more economical price point. Asking $22,000/Mill, $4,000/CAM with computer, $4,000 for 3M ST Scanner, and $3,000/Lava Therm. We will entertain all serious offers. Call Alex or Lonnie at California Dental Arts at 408.255.1020.— tagged 5 members3M ESPE Roland DGA 5-Axis DWX-50 Milling Machine Delcam DentMILL Roland DWX-50 Milling Machine
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