Note:
Stiff ness values listed above are derived from theoretical formula to the elastic deformation between thread grooves and balls while axial load is 30% dynamic load rating.

Unit:mm
Screw size Ball DIA.

Effeftive turns
circuitxnumber of thread

 BASIC RATE LOAD(kgf) BALLNUT DIMENSION Nut Model No.
O.D. Length Flange Assembly
Hole		 Oil Hole STIFFNESS
O.D. Lead Dynamic
(1×106 REV.)
Ca

Static

Co

 D

L

 A T W H X Q kgf/μm
12 12 2.381 1.8x2 410 850 25 31 40 6 32 21 4.5 M4x0.7P 13 FSKW1212A-3.6P
15 10 3.175 2.8x2 1000 2570 34 44 57 10 45 40 5.5 M6x1P 26 FSKW1510B-5.6P
20 3.175 1.8x1 380 830 34 45 57 10 45 40 5.5 M6x1P 26 FSKW1520B-1.8P
16 16 3.175 1.8x1 330 640 32 38 53 10 42 38 4.5 M6x1P 9 FSKW1616B-1.8P
20 20 3.175 1.8x2 780 2280 39 52 62 10 50 46 5.5 M6x1P 21 FSKW2020B-3.6P
40 3.175 0.8x2 390 1010 38 41 58 10 40 48 5.5 M6x1P 14 FSKW2040B-1.6P
1.8x1 430 1140 81 16 FSKW2040B-1.8P
25 25 3.969 1.8x2 1230 3570 47 62 74 12 60 56 6.6 M6x1P 27 FSKW2525C-3.6P
1.8x4 2230 7140 52 FSKW2525C-7.2P
32 32 4.762 1.8x2 1760 5500 58 78 92 15 74 68 9 M6x1P 33 FSKW3232D-3.6P
1.8x4 3200 11000 65 FSKW3232D-7.2P
40 40 6.350 1.8x2 2870 9170 73 95 114 17 93 84 11 M6x1P 42 FSKW4040F-3.6P
1.8x4 5220 18340 81 FSKW4040F-7.2P
50 50 7.938 1.8x4 7890 26330 90 122 135 20 112 104 14 M6x1P 103 FSKW5050H-7.2P