Frequently Asked Questions

1. How quick will my orders be shipped?
   
   FirstAMDental.com usually ships in-stock items within 24 hours (one business day).
   
   
2. How should I do choose different types of bearings?
   
   If a customer is experiencing premature failures, switching the bearing cage types may increase the life span. Radial and angular bearings are engineered differently and switching from one to the other may eliminate turbine failures. If a customer is operating in a particularly dirty environment, switching to bearings with integral shields (Ameriden™'s Intergral Dust-Free Series) should prolong turbine life.
   
   
3. Why are 7-ball bearings better than conventional 8-ball bearings?
   
   Flexible O-ring seating frequently causes bearing misalignment when the outer ring cocks or tilts relative to the inner ring. To alleviate this, our bearings utilize 7-ball geometry to minimize such damaging effects. This geometry is more forgiving toward misalignment than conventional 8-ball complements. At the same time, this geometry leaves more material between the ball pockets for greater cage strength.
   
   
4. What is the difference between Radial and Angular contacts?
   
   Basically, dental bearings are manufactured using two different methods of ball contact to the outer race; Radial and Angular. Angular style bearings are the industry standard, for they are usually quieter and tend to last longer. Radial style bearings are easier to handle during assembly, which is more desirable to the beginning repair technician. Radial style bearings are usually cheaper to purchase .vs angular style bearings.
   
   
5. Why should I try angular contact bearings for lube-free bearings?
   
   Angular contact bearings feature symmetrical cages. This enhances performance and extends bearing life as each ball is fully supported and completely surrounded by the cage. Angular contact bearings must be axially preloaded with a spring or O-rings to assure contact with the full unrelieved shoulder.
   
   
6. Should I choose Torlon® or Phenolic bearing cage (retainer)?
   
   Torlon® is a polyamide-imide (PAI), and is primarily used for wear and friction parts. It offers a very low expansion rate, low coefficient of friction and exhibits little or no slip-stick in use. Its maximum operating temperature is 500F. FirstAMDental's own Ameriden™ bearings use Torlon 4301 PAI. This grade excels in severe service wear applications such as non-lubricated bearings, and in high temperature environments.
   
   Phenolic cages are used primarily for angular contact ball bearings. Its light weight makes it ideal for high speed applications. Some of phenolic's other desirable characteristics as a cage material are: low coefficient of friction, non-galling, ability to absorb lubricants, dimensional stability in presence of lubricants and moisture. It does well in where lubricant is scarce as it has a wicking effect to retain and absorb lubricants when present. It should not be used in temperatures in excess of 225°F (107°C)
   
   
7. What is “Maintenance Free” ?
   
   Integral Shield, or as known in the industry as “maintenance free”, bearings are bearings that have a one piece shield, a combination of the outer race and shield. This design is intended to keep debris out and lubrication in. Integral shield, greased bearings are considered maintenance free. These bearings are considered by many to be the most durable, and should be used in high debris and/or excessive side load environments.
   
   

  Still couldn't find the anwers? Send an email to our dental parts experts: service@firstamdental.com