1. Tolerance: refers to the maximum limit of allowable departure of a part from its nominal size. The tolerance is sometimes expressed as a plus and minus value, such as +0.005/-0.002. This would mean the maximum departure from the nominal size for that part would be +0.005 and the minimum would be -0.002.
2. Fit: The designation of how two parts fit together typically fall into four classifications: interference, clearance, transition, and slip. An interference fit is one in which two parts must be forced together, while a clearance fit allows two parts to slide together without force. A transition fit falls between the two, and a slip fit is one where there is a higher tolerance for the part so that, when assembled, movement or sliding can occur.
3. Dimensional Stability: Refers to a component’s ability to maintain original size and shape. Various factors such as changes in temperature, humidity, and other ambient factors affect dimensional stability.
4. Preload: Refers to an amount of force applied to a bearing assembly to reduce axial and radial play between the part surfaces. Preload increases bearing stiffness and helps ensure contact between surfaces.
5. Hardness: Refers to a materials resistance to indentation by a sharp object under a known static load. Hardness is usually expressed in terms of Rockwell Hardness, Vickers Hardness, or Brinell Hardness.
6. Load Rating: Refers to the maximum amount of load a bearing can safely handle over a specified period of time. The size of the load is proportional to the contact area of the bearing surface, the type of load, the speed at which the load is applied, the bearing internal clearance, and the lubrication used.
7. Pre-lubricated: Applied to a bearing that is lubricated at the manufacturer with oil or grease to increase its performance and longevity.
8. Runout: Refers to the departure of a cylindrical or spherical surface from its ideal form which is usually due to wear and tear.
9. Seal: A thin ring which is designed to keep out dust, dirt, and contaminants while allowing a bearing to turn with minimal friction and forces.
10.Micron: Unit of measure often used to describe the level of contaminant particles found in lubricants, sealants, and other mechanical parts. 1 micron is equal to one-millionth of a meter.
