How It Works

Product features

Raised shoulder to optimise socket purchase

Prevailing torque and locking bezel

Thread has extra length to ensure friction surface of the union is maximised

Prevailing torque flanged nut

External dust cover to protect from external environment

Washer body designed to withstand large clamp pressure and to compress the elastomer against the thread of the bolt

Internal lip to seal the thread to prevent material migration along the bolt

Non-stick elastomer with conical rings to seal against uneven surfaces and compress into the thread and hole simultaneously

1 2 3 4 5 6 7 8

All-steel lock-nut

The Kombo Washer offers double-safety – the locking element works in the radial and the axial direction and produces an even clamping action of the nut from preload to the full range (360°) of the bolt’s threads.

Installation and removal

Fast on and off – seal won’t stick to mill surface
Simple one piece assembly is easy to handle (Conventional cup washers require handling three parts)
Typical installation and removal times are less than 10 seconds on & 10 seconds off each and every time – significantly reducing mill downtime (Conventional cup washers typically take 15-20 seconds to remove – sometimes even up to 6 minutes to remove leftover rubber residue)

The ultimate seal solution

Technical details

Kombo Washer strength – M36 example

Assembly takes full clamp load without deforming

M36 at full installation torque of 2200 Nm will provide 343,000 N clamp force. This holds the liner plates tightly in place.

Material properties
Tensile strength, ultimate	772 Mpa
Tensile strength, yield	580 Mpa
Modulus of elasticity	205 Gpa
Poisson’s ratio	0.29

Legacy product weakness – M36 example

Washer fails at 50% load

The washer bends beyond the yield point of the material at less than 50% of the design required load value of 343,000 N.

At full required load the washer collapses and permanently deforms. Resulting bend creep results in loss of load tension on the bolt and loose wear plates.

Material properties
Tensile strength, ultimate	440 Mpa
Tensile strength, yield	370 Mpa
Modulus of elasticity	200 Gpa
Poisson’s ratio	0.29

Property class according to DIN EN ISO 898-2

04, 05, 8, 10, 12

Mechanical properties

DIN EN ISO 2320 (DIN EN 20898-2 / DIN EN ISO 898-2)

Stainless steels

A2-035, A2-040, A2-70, A2-80,
A4-035, A4-040, A4-70, A4-80

Surface coatings

Galvanic surfaces according to DIN EN ISO 4042 (zinc-iron, zinc-nickel, etc.), zinc flake coating according to DIN EN ISO 10683

Threads

Metric and Imperial: standard thread. All other dimensions, materials and surfaces, per drawing, upon request.

Clamping torques [Nm]
d	1. Screw fastening max.	1. Unscrewing min.	15. Unscrewing min.
M 24	56.0	11.5	8.0
M 36	95.0	21.0	16.0
M 48	130.0	40.0	25.0
M 52	160.0	50.0	30.0

After the 5th time of unscrewing the fastener, the clamping torque will remain constant. Recommended tightening speed is 100-150 rpm for steel and galvanized steel, a maximum of 30 rpm for stainless steel.

Verification calculations are recommended for the locking torques. (VDI 2230-2015). Further locking torques can be found in the separate Kombo Washer data sheet.

Kombo Washer All-Steel Lock-Nuts, made of austenitic steel can be bolted together without additional lubricants. The nuts are covered with a special surface coating, preventing them from pitting onto the bolts.