10 PCS - MR74ZZ (4x7x2.5 mm) Metal Double Shielded Ball Bearing MR74z 4*7*2.5mm

Description

Miniature Bearing Types & Features
Miniature and instrument ball bearings can be divided into two basic types, deep groove and angular contact. The first (deep groove) can also be classified as "Open", "Shielded", or "Sealed" depending on the existence and type of seal or shield. Deep groove ball bearings have two inherent advantages; they can sustain some axial load in either direction as well as radial loads, and the two raceway cross-sections are simple circular arcs which can be very precisely finished so the bearings have low friction and very little noise or vibration. Several different cage designs are available with different characteristics and the choice depends upon the individual application.
Pic1: Showing contacts between the rolling elements with inner and outer raceways.
Pic2: Through stress life fatigue analysis, it shows that the high precision bearing has longer fatigue life and higher safety factor.
TECHNICAL SPECS
Model: MR74ZZ Inner (d): 4 mm Outer (D): 7 mm Width (B): 2.5 mm Grade: ABEC-1 Material: 52100 Chrome Steel Seal: Shield Qty: 1 Lot = 10 PCS
DIMENSIONS LIST
Purposes of Lubrication
The main purpose of lubrication is to reduce friction and wear inside bearings that may cause premature failure. The effects of lubrication can be briefly explained as follows: (1) Reduction of friction and wear Direct metallic contact between the bearing rings, rolling elements and cage is prevented by a lubricant film. (2) Extension of fatigue life The rolling fatigue life of bearings depends greatly upon the viscosity and film thickness between the rolling contact surfaces. Sufficient film thickness prolongs the fatigue life while film thickness shortens it. (3) Dissipation of frictional heat and cooling Circulating lubrication may be used to carry away frictional heat or heat transferred from outside the bearing. (4) Others Adequate lubrication also helps to prevent foreign matter from entering bearings and guards against corrosion and rust.
Application
F A Q
1. Why do the bearings I receive have shaking?
The clearance of the bearing is related to the play. The default is the standard C0 clearance, which is usually 3-18um. The corresponding principle is shown in the figure below. If you don't need to shake, please choose C2 small clearance bearing, If you have any questions, please contact us before purchasing.
2. What is the accuracy of ABEC-1?
ABEC is the American ANSI standard. The corresponding German DIN standard and international ISO standard are as follows:
3. Do you provide logistics tracking information?
Yes, all our products provide full logistics tracking. And the products you buy are all new. We will buy transportation insurance for you. If the product is damaged or lost during transportation, you can get paid.
On Dec-04-19 at 23:47:40 PST, seller added the following information: