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June 29, 2014
The turbine is the heart of the high-speed handpiece and bearings are the heart of the turbine.
Bearings are the most common failure point of a turbine and are often the primary differentiator between one turbine and another.
Way back in Practice Tips #22, “High-speed Handpiece Design,” we covered all of the components that make up a complete bearing assembly. For ease of reference, we’ve included the diagram of a bearing assembly below. For further explanation of the components, check out Practice Tips #22.
Today, we’re going to look at some of the different bearing materials and designs on the market.
Many turbines use stainless steel bearings that require lubrication. The balls, inner ring, outer ring, and shield are all made of stainless steel. The ball cage will be made of a polymer (there are a few more variations within this broad category and different types of polymers for the cage, but all these permutations require lubrication).
Stainless steel bearings have been in use for decades and are a proven design with good performance and good reliability. They are manufactured in large quantities for dental turbines and many other industries so cost is comparatively low. As these turbines incorporate metal bearings in metal housings, they require lubrication. Most handpiece lubricants on the market are designed to withstand the rigors of sterilization, but these turbines should still be lubricated every time they are used (see our handpiece maintenance products here). Lubrication after using and before sterilization is generally adequate, but consult the manufacturer of your turbine and lubricant to determine if post sterilization lubrication is required as well.
Many turbines currently on the market are advertised as “lube free.” There are 2 primary methods of manufacturing lube free bearings:
LTL bearings are still the same basic stainless steel design so they share many of the features of standard stainless bearings. The greasing and sealing process adds to the cost (and they aren’t manufactured in quantities like the standard bearings), so they will add to the cost of the turbine or handpiece that uses them. The sealing process, also, prevents debris from getting into the center of the bearing assembly and on the actual steel balls, so maintenance is a little easier. Nonetheless, these bearings (or, more accurately, turbines that incorporate these bearings) still need to be cleaned after every use and before sterilization.
Last of all, there are ceramic bearings. Ceramic bearings are actually made of a ceramic silicon nitride, so they have a very smooth low-friction surface. The low-friction surface removes the need for lubrication and also minimized heat build-up during use. They, also, withstand high temperatures very well, so they withstand repeated sterilization better than stainless steel bearings.
Both LTL and ceramic bearings will run at higher rpm than stainless bearings and are better able to handle higher air pressure (they typically require in excess of 40 psi drive air pressure). The higher rpm can help these turbines cut faster so some practitioners feel they perform better (naturally, this is subjective).
In summary, the materials and techniques used to manufacture lube free bearings are more costly than standard stainless bearings, so these bearings (or the turbines that incorporate them) often cost twice as much as turbines that need to be lubricated. It’s up to the practitioner if the advantages are worth the expense.
January 29, 2014
A dentist's handpiece is one of the ultimate tools in his dental office. Making sure it runs smoothly is very important.
The primary function of a handpiece is to provide power for rotary instruments, i.e. burs. If your handpiece won’t hold the bur, or won’t release the bur (so you can’t change burs) it effectively ceases to function.
Regular readers of Practice Tips will know that the chuck is the part of the turbine responsible for bur retention. Consult our issues on handpiece design and chucks for more information on this component.
There are basically two reasons for a chuck to cease functioning. One is simple break-down of the chuck itself: wear, breakage, or other alteration from the original specification preventing it from functioning as designed. The other is simple debris. If the chuck is clogged with debris, this will impede proper function.
This month we’ll show you how to properly maintenance the chuck in an auto-chuck handpiece to minimize debris build-up and eliminate it when present.
The steps illustrated below should be taken at least once a week on all auto-chuck handpieces to keep the chuck working as well as possible for as long as possible.
Materials required (see image below):
Step 1. Place a drop or two of lubricant into the chuck. If using a spray lubricant (such as Once-A-Day), a quick shot of lubricant should be sprayed into the chuck.
Dropping lubricant directly into the chuck
Step 2. Activate the chuck and insert a bur.
Inserting a bur
Step 3. While activating the chuck, (hold down the button if a push button handpiece) work the bur in and out to loosen any debris.
Working the bur in the chuck
Step 4. Remove the bur and clean any debris off of it with the swab. Some debris may be on the exterior of the handpiece, swab this off as well.
Remove and check the bur
Step 5. Re-insert bur and verify proper function. Bur should be held securely and remain in place if tugged.
Verifying proper function
Step 6. Repeat the above steps as needed. It is not uncommon to have a significant debris build-up so you may need to flush the chuck several times.
NOTE: We’ve demonstrated the technique with a Star 430 push button handpiece. We encounter clogged chucks on this make and model of handpiece frequently, but chuck cleaning should be a part of your regular weekly routine with all models of auto-chuck handpieces, Lares, Kavo, Midwest (push button or Power Lever™) or any others in your inventory. Add chuck cleaning once a week to your handpiece maintenance routine to help keep your handpieces functioning well.
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December 19, 2013
Maintaining your handpieces can often be overlooked. Hot gears from lack of oil and flattened bearings from overuse can easily be avoided. Dentists rely on high-performance handpieces to provide the best quality care to their patients. Even the best equipment can malfunction due to the lack of proper care, so American Dental Accessories is here to help you maximize the potential of your dental handpieces in a cost-effective and preventive way.
We suggest you print and post the following step-by-step list near your sterilization area as a handpiece care reminder and for easy reference.
Step 1: Clean the exterior of the handpiece using a mild soap and water solution to remove the gross debris in accordance with CDC guidelines.
Step 2: Once the handpiece has been thoroughly cleaned, a few drops of handpiece lubricant (or a quick spray) should be placed into the drive air hole of the handpiece per the following diagram:
Run the handpiece until nothing but clean lube comes out (all debris has been flushed). Continue to run until all excess lube has been expelled as well. NOTE: It may be necessary to repeat this step to expel all debris.
Step 3: For lube-free handpieces, perform the above procedure using a handpiece cleaner, rather than a lubricant.
Step 4: The above procedure is for high-speed handpieces and slow-speed motors. For slow-speed and electric attachments, lubricant should be sprayed into the handpiece from below and the attachment installed on a motor and run to expel any debris and distribute the lubricant.
Step 5: Once all debris has been flushed from the handpiece, sterilize it in a chemical vapor or steam sterilizer at or below 275º F, according to the sterilizer manufacturer's instructions.
Step 6: After sterilizing, remove the handpiece from your sterilizer and allow to cool completely.
Step 7: Most lubricants currently on the market will not break down in the sterilizer, so you should no longer need to lubricate your handpiece again after sterilization.
Your handpiece is now ready to use!
If you still need help, please look at our post on Dental Handpiece Maintenance tips or call us with any other questions you might have.
For additional handpiece maintenance and repair information see: The Blue Handbook: How to Care for Your Dental Handpiece.