How MKW Locks From the Front Face
MKW locks with clamping screws driven straight down the axis rather than in through the outside diameter. The hex key approaches the nut head-on, so nothing has to reach the flank, and the nut can be secured after a bearing bore, a housing shoulder or an adjacent component has closed around it. Four screws carry the load on the smaller threads and six from M40 x 1.5 upward.
The full explanation is on the Axial Locking Series page.
Bodies of 28 to 46 mm
Two heights on most threads to M50
Locked From the Front Face
Screws parallel to the shaft axis
Ground Contact Surface
Maximum axial run-out 0.005 mm
4 or 6 Clamping Screws Per Nut
M4 to M5. 5.5 to 9 Nm max
Where MKW Locknuts Are Used
Bearing retention in recessed housings where the front face is the only access left
Arrangements that would otherwise carry a separate spacer between the nut and the bearing
Shafts from M20 x 1.5 to M70 x 1.5, every size on a 1.5 mm pitch
Designs wanting a longer body and a deeper thread engagement without moving to a larger thread
Assemblies opened at service intervals, where the clamping screws come off without tapping the nut
Find Your Size(M20 to M70)
Filter MKW locknuts by shaft thread, pitch, or height.
Products in this Axial Locking Series
All four lock the same way, with screws driven through the front face parallel to the shaft, so the nut can be secured with its outside diameter buried. What differs is the finishing grade, whether the nut takes clamping screws or set screws, how many of them carry the load, and how much body height the type asks of the design.
MA
0.002 mm
Two set screws · four wrench slots
M17×1 to M200×3 · h 15–37 mm
MA is the accuracy type in the series, ground on the thread area as well as the contact surface. It also carries the heaviest screws in the axial range, M12 at 56 Nm from MA135, spread over two positions rather than four or six.
MKR
0.005 mm
Clamping screws · three to eight per nut
M10×0.75 to M200×3 · h 14–40 mm
MKR is the general-purpose axial locknut and by a wide margin the densest range NIKKI makes, at 58 sizes. It reaches M10 x 0.75, the smallest thread in the series, and it is the type to look at whenever the thread falls between the usual steps. MKR10 to MKR15 use a different body form from MKR16 upward.
MKK
0.005 mm
Clamping screws · four to eight per nut
M15×1 to M130×2 · h 18–32 mm
MKK carries the heaviest clamping screws in the series, M10 at 36 Nm from MKK75, in a body no taller than 32 mm. Three threads, M30, M35 and M40, are listed in a second outside diameter, larger on M30 and M40 for a bigger contact face, smaller on M35 to fit a tighter housing bore.
MKW
0.005 mm
Clamping screws · four or six per nut
M20×1.5 to M70×1.5 · h 28–46 mm
MKW is the tall type, 28 to 46 mm of body where the rest of the series runs 14 to 40 mm, which suits designs that would otherwise carry a separate spacer. The height sits in the code: MKW40-28 stands 28 mm high, MKW40-44 stands 44. Most threads to M50 are offered in two heights, and MKW runs a little softer than the others at HRC 25-28.
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Questions About the MKW Locknut
The MKW is the tall-bodied axial locknut in NIKKI's Axial Locking Series, in metric threads from M20 x 1.5 to M70 x 1.5 with bodies 28 to 46 mm high. The questions below are the ones buyers ask before a first order.
Contact UsThe maximum axial run-out of an MKW locknut is 0.005 mm. NIKKI finishes the contact surface by a high-precision grinding process, which is what sets the run-out at this level. Where a drawing calls for 0.002 mm, the MA locknut in the same series has the thread area ground as well.
It is the body height in millimeters. MKW40-28 stands 28 mm high and MKW40-44 stands 44 mm, on the same M40 x 1.5 thread. Most threads up to M50 are listed in two heights, and M55 to M70 are offered at 46 mm only.
Yes, on every thread offered in both heights. At M30 x 1.5 the 28 mm body has a 52 mm outside diameter and the 44 mm body has 68 mm; at M45 x 1.5 the figures are 70 and 90 mm. Check the outside diameter against the housing bore, not the height alone.
The catalog maximum is 5.5 Nm on the M4 screws fitted to MKW20 through MKW50, and 9 Nm on the M5 screws fitted from MKW55 upward. Tighten gradually and alternately rather than driving one screw fully home first.
Choose the MKK locknut where the assembly needs a short body or more clamping force, since MKK stands 18 to 32 mm high and takes screws to M10 at 36 Nm against MKW's M5 at 9 Nm. Choose the MKR locknut where the thread sits outside MKW's range, which covers only M20 to M70 on a 1.5 mm pitch, or where an intermediate thread is needed. MKW is the type to specify when the design wants the length, whether for thread engagement or to fill space a separate ring would otherwise occupy.
No. MKW locks through clamping screws driven into the front face of the nut, so nothing else goes on the shaft. The shaft keeps its full section strength, no slot has to be cut, and the nut is reusable if handled properly.