Customer Service: 1-800-331-7993
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 Tech 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 Tech 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.
April 30, 2014
Before we get started, we want to reiterate our number one objective with Tech Tips (and when you call us): to empower your practice with basic maintenance, installation, and repair knowledge, so that you're not paying full-service distributors exorbitant fees on a regular basis. While taking the time to familiarize yourself with your equipment will have a learning curve, you'll be glad you did. Once you get it down, you'll be saving lots of money and will feel more in control of your practice. Without further adieu:
Order today and receive a $150 Merchandise Credit! Call 800-331-7993 to place an order and mention the code: TECHTIPS (order must be placed by May 5th, 2014)
February 27, 2014
Air water syringe tips are one of the most common products dentists and hygienists use in dental offices. So let's get to know more about the differences between syringe tips and which ones will work best for your practice.
The basic design of the standard air water syringe tip has remained unchanged for decades. The air water syringe has two concentric passageways, one for air (usually the outer passage) and one for water (usually the inner passage).
The central tube (see image below) is for water. On most standard tips, this tube is longer and projects out the back of the tip. This design allows the water tube to penetrate a small o-ring (#01-06) inside the syringe head to help keep the air and water separate.
On many disposable tips, the inner water passage is the same length as the rest of the tip; this means that these tips will require a special adaptor to help keep the air and water separate. If used without an adaptor, they are much more prone to cross-over (See Tech Tips #50 & Tech Tips #51). This is one reason that autoclavable tips will usually deliver superior performance.
On most syringe tips, air moves through the outer passage of the tip coming out at the end. Sometimes the air is expelled through a simple gap but sometimes several holes are used (this aspect of the design can vary widely). Most metallic tips will have a series of holes regularly spaced at the end of the tip to allow expulsion of air (see image below). The regular and consistent spacing of these holes provides a consistent spray pattern (when spraying both air and water mist). As a cost saving measure, many disposable tips simply use the natural “gap” between the inner water line and outer air line of the tip to allow air to escape out the end. Relying on this gap provides inconsistent spacing and an irregular and inconsistent spray pattern.
As mentioned, syringe tips at their most basic are simply an assembly of two concentric tubes. These are round. They go into a round passage in the air water syringe and are normally secured with o-rings. This means you’ve got a round tube in a round hole. It will spin. Many practitioners like to use the syringe tip for retraction and will push on the cheek with the syringe tip. If pushing with the tip, rotation is not desired. Most syringes are designed for quick changing of tips (as the tip should be changed after each patient) which does not normally allow for a mechanism to reduce the ability to spin if pushed on. The DCI rotation lock tips (#01-97) are an exception to this.
The rotation lock tips have a series of “dimples” (see image below) around the perimeter of the tip which will lock in with the ball bearings of the DCI syringe holding mechanism (“collar”) making it harder for these tips to spin. These tips will only work in a DCI syringe (#01-01Q or #01-85) which has 6 ball bearings in the collar to secure the tips. The ball bearings are retracted to change tips, so using a design that incorporates the ball bearings does not preclude quickly changing tips either.
With most other syringes, two o-rings (#01-04) are used to hold the tips in place. On some of these, one o-ring may be replaced with a cone (#01-21 or #01-23). Along the length of the cone is a slit (see image below). This slit provides lateral tension making it harder to spin the tip. Some syringes can be adapted to use a cone instead of an o-ring if you wish to minimize tip spin. Normally, use of a cone will make it more difficult to change tips, but it shouldn’t prevent quickly changing tips. Consult with our staff and we will help you determine if you can incorporate a cone in your syringe.
As you can see, many aspects of the tip design affect syringe performance. Keep your needs and uses in mind when purchasing tips and syringes.