Wedge-Lock Washers

Bolted connections tend to work themselves loose under certain operating conditions. Vibrations cause particular problems as they can overpower the “self-locking effect” of bolted connections. This can lead to functional failure or even lead to the connection coming apart. As it’s not always possible to know what forces are acting on the structure, and as constructional measures cannot be implemented everywhere, securing elements are often used.

One of the few effective securing technologies available is the HEICO-LOCK® wedge locking system, the effectiveness of which has been demonstrated by the latest experimental standards (including DIN 65151, DIN 25201-4, NASM 1312-7).

Functional Principle

Advantages

• Certified system for securing bolts, works at low and high preload levels.
• Particularly suitable for dynamic loads – including when using lubricants. Can be re-used.
• Very easy to install and remove (wedge lock washers are supplied as a pre-assembled pair)
• Suitable for high-tensile bolts of 8.8, 10.9 and 12.9 and their respective nuts.
• Available in steel or stainless steel with narrow or wide bearing surfaces – other materials are available upon request.
• Available from M3 – M76 and ¼” – 3” – customised sizes upon request

Junkers Vibrations Test

The Junker vibration test meeting DIN 65151 (Dynamic testing of the locking characteristics of fasteners under transverse loading conditions – vibration test) standards is a common and reliable method for testing and comparing the security of bolted joints.

The Junkers test is considered a ‘severe’ test of the loosening characteristics of fasteners, particularly when compared to previously introduced test methods which rely on axial dynamic loading to induce loosening.

Heico-Lock Combi-Washers

HEICO-LOCK combi-washers enable quick and easy assembly, especially in difficult installation situations. Combine the simple to use HEICO-LOCK® combi-washers with all commercially available bolts provided by your suppliers, quickly and easily.

• Easy mounting and permanent connection thanks to the inset tabs
• Can be combined with all commercially available bolts
• Also available in small purchase quantities
• Flexible use for various different types of bolts
• Permanent securing and correct positioning of HEICO-LOCK wedge lock washers
• Can be re-used several times
• Cost savings through increased productivity
• Available in steel or stainless steel with narrower and wider contact areas
• Available from M8 to M16

The above available with standard diameters – HKS and larger outer diameter HKB for soft surfaces and slotted holes.

Usage Recommendations

Through-holes

Through-holes require the use of two pairs of Heico-Lock washers.

One pair for securing the bolt and a second pair for securing the nut. Turn both fasteners in order to close the cams on both washer pairs before tightening to minimize settlements. Keep the bolt secure whilst tightening the nut.

Assembly Instructions

Quick reference guide for assembly

• Inspect bolt parts for soiling and damage.
• Check for correct positioning / orientation of the HEICO-LOCK WLW (not applicable with glued individual washers).
• Check for correct matching of the HEICO-LOCK WLW and the bolt head or the nut, as well as the threaded rod, if applicable.
• Choose the correct material for HEICO-LOCK WLW depending on the ambient conditions (we recommend agreement with the manufacturer).

1. HEICO-LOCK WLW made of heat-treated steel (1.1191) with zinc flake coating for normal ambient conditions from -40°C up to 200°C.

2. HEICO-LOCK WLW made of stainless steel (1.4404) for application in corrosive, non-acidic ambient conditions from -200°C up to 500°C.

3. HEICO-LOCK WLW made of 254 SMO® (1.4547) for application in acidic (chlorides, e.g. sea water) ambient conditions from -200°C up to 500°C.

4. HEICO-LOCK WLW made of INCONEL® / Alloy 718 (2.4668) for temperatures above 500°C to maximum 700°C. Minimum temperature – 200°C.

• The surface hardness of the fastened components must be lower than the hardness value of HEICO-LOCK® WLW. We recommend a maximum surface hardness of 430 HV (approx. 44 HRC). With soft mating material, use HEICO-LOCK® WLW with large contact surfaces (HLB-XX) in combination with flange bolts and/or flange nuts.
• With great coating or paint thicknesses the function must be verified by experiment.
• Select the appropriate model of HEICO-LOCK WLW depending on the geometry of the threaded hole.

1. With round or countersunk holes use wedge-lock with small contact surface (HLS-XX).

2.With slot holes use HEICO-LOCK WLW with large contact surface (HLB-XX). Use in combination with flanged bolts/nuts, if required.

• Positioning and orientation of HEICO-LOCK® WLW depending on the bolt type.

1.HEICO-LOCK below bolt head or nut for bolt joints.

2. HEICO-LOCK below bolt head and nut for bolt-and-nut joints.

3. HEICO-LOCK below the nut for assembly of a threaded rod in a threaded hole.

4. HEICO-LOCK below the nut for assembly of a threaded rod in a through hole.

• The surface of fastened parts, particularly the areas in contact with wedge-lock washers, must be free from coarse soiling and as even and smooth as possible.
• The engaged thread, as well as the bolt head and nut contact faces must be lubricated using a suitable lubricant. This must be ensured in any case for stainless steel materials due to their tendency for “seizure”.
• Tighten the bolted joint applying the assembly torque required for generating the assembly tightening force using a torque wrench with a dial or with “clicking” sound. The torque depends on friction (surface coating, lubrication, etc.). Torque recommendations are merely guiding values. The individually required assembly tightening torque must be established by experiment.