How MFZ Locks on the 30° Thread Flank
MFZ locks through a brass pad rather than through the set screw itself. Each screw drives the pad onto the shaft's thread flank at a 30° radial angle, spreading the load along the flank instead of denting the thread crest. The shaft keeps its full section, and the nut can be taken off and refitted.
The full explanation is on the 30° Flank Locking Series page.
Same Dimensions as MF
Ground and turned grades interchange
No Thrust Washer or Keyway
Fewer parts, simpler assembly
Precision-Turned Contact Surface and Thread
Maximum axial run-out 0.005 mm
3 or 6 Set Screws Per Nut
M5 to M10. 4.8 to 36 Nm max
Where MFZ Locknuts Are Used
Bearing Retention on General Machinery Where the Drawing Allows 0.005 mm
Gearbox, Pump and Fan Shafts
Couplings and Pulleys on Motor and Drive Shafts
Volume Builds That Cannot Carry the Cost of the Ground Grade
MFZ Specifications
Please enter your specifications below to find the right product for your project.
MFZ12 x 1 is the one size with no d1 dimension listed.
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Products in this 30° Flank Locking Series
Grinding
MF
Grinding
Hook wrench · nut exposed
M12×1 to M260×4 · h 14–36 mm
MF is the original 30° flank locknut, ground to 0.002 mm. Use it where the nut sits clear of the housing and a hook wrench has room to work.
BF
Grinding
Hook wrench · nut recessed
M15×1 to M260×4 · h 14–40 mm
BF has a straight outer profile that stays reachable when the housing covers part of the nut, so a hook wrench still has a square surface to seat against. Same locking as MF.
TMF
Grinding
Pin wrench
M20×1 to M200×3 · h 18–32 mm
TMF is driven through holes in its face with a pin wrench (pin spanner in UK and EU practice). It is ground only, with no precision-turned equivalent.
Precision turning
MFZ
Turning
Hook wrench · nut exposed
M12×1 to M260×4 · h 14–36 mm
MFZ is the precision-turned version of MF, with the same envelope and hook-wrench profile at 0.005 mm run-out instead of 0.002 mm.
BFZ
Turning
Hook wrench · nut recessed
M15×1 to M260×4 · h 14–40 mm
BFZ is the precision-turned version of BF, with the same straight profile and hook-wrench access at 0.005 mm run-out.
SFZ
Turning
Open-end wrench · two flats, to M75
M10×0.75 to M200×3 · h 14–32 mm
SFZ has two parallel flats for an ordinary open-end wrench, up to M75 only. It is the only type down to M10 × 0.75, and the type used most in Japan.
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Questions About the MFZ Locknut
The MFZ is the precision-turned locknut in NIKKI's 30° Flank Locking Series, in metric threads from M12 x 1 to M260 x 4 with 0.005 mm maximum axial run-out. The questions below are the ones buyers ask before a first order.
Contact UsThe maximum axial run-out of an MFZ locknut is 0.005 mm. We finish both the thread and the contact surface by precision turning, which is what sets the run-out at this level and keeps the cost below the ground grade.
MFZ and MF share the same dimensions, the same outer profile and the same SCM440 material at HRC 28-32. The difference is the finishing process. MF is ground to 0.002 mm maximum axial run-out, MFZ is precision turned to 0.005 mm and costs less. A Z in the model code means the turned grade.
Each MFZ size lists a catalog maximum per screw in the dimension table, from 4.8 Nm on the M5 screws of MFZ12 up to 36 Nm on the M10 screws fitted from MFZ140. Sizes to MFZ100 carry three set screws, and MFZ105 and above carry six. Tighten gradually and alternately rather than one screw fully first.
Add L to the order code for a left-hand thread (MFZ30x1.5P-L) or U for an inch thread (MFZ30-U18). Standard right-hand metric versions are ordered by the plain name, for example MFZ30x1.5P.
Choose BFZ where the housing covers part of the nut. BFZ is the same turned grade at 0.005 mm, in a straight outer profile that still gives a hook wrench something square to seat against. MFZ suits the nuts that sit clear of the housing, and it goes one size smaller, to M12 x 1.
No. MFZ locks between the set screws, the brass pads, and the thread flank, all inside the nut, so neither a thrust washer nor a shaft keyway is required. Nothing else goes on the shaft, and the nut is reusable if handled properly.