Ball Screw SFNU & SFU
Internal Circulation, Flange Type.
SFNU & SFU series features high smoothness, high rigidity, high durability and strong dust-proof, with internal circulation design, making SFNU & SFU series applicable to small operating environment.
Dust Proof / Prevention
Any foreign matter or water, if entering to the ball screw, may increase friction and cause damage. For example, the entry of chips or cutting oil may be expected with machine tools according to the work environment. Where entry of foreign matter is anticipated, use a bellows or telescopic cover as shown in Fig 1.10.2, to cover the screw shaft completely.
When offset load phenomenon occurs, screw life and noise tend to be directly affected, which would usually be accompanied with hand feel of rough running. As the smoothness of single shaft and assembled ball screw might be different. In addition to single shaft’s accuracy, the offset phenomenon was mostly occurred by failed assemble accuracy which is shown in Fig 1.10.3.
Assembling the Ball Screws
If rolled ball nut is shipped un-assembled please follow the procedure as below.
Table 1.10.2 Procedure
(1) For the Ball Screws with internal or end cap type circulation ball nut, it is required to have at least one end with complete thread to the end of screw, it is also required to have the journal area is with diameter to be smaller than the diameter of thread root as Fig 1.10.4 shown.
Fig 1.10.4 For Internal Circulation
(2) The thread on screw shaft are hardened by induction hardening. It shall cause about 10~20mm at both ends journal purpose. The unhardened area will be labeled.