Contact washer

The contact washer gets its name from its ability to create a tight connection between the fastening assembly and the mating surfaces. This is achieved through radially oriented serrations or teeth on the working side of the part. Contact washers are made from steel alloys with spring properties. Protection from moisture and aggressive substances is provided by galvanic zinc plating or yellow chromate treatment. Washers should be selected by inner diameter, which must match the metric thread size of the bolt or stud.

Types of contact washers

Visually, a contact washer is a ring shaped like a truncated cone in cross-section. The FLOK catalog offers contact washers in a wide range. They differ in material and type of corrosion protection, in geometric dimensions along the inner and outer contour, and in the presence or absence of tabs for better fixation. The fastening tabs are located on the side of the washer opposite the serrations, along the outer circumference, and are bent inward.

The fasteners in the FLOK catalog are manufactured in accordance with the requirements of the German standard DIN 9093, as confirmed by manufacturers’ warranty certificates. One of the main distinguishing parameters is the type of working surface of the part.

Serrated contact washer

The serrations provide a tighter fit of the fastener against the material of the joined parts. The serration is made with a slight recess into the metal body, without protruding beyond its working plane. The number of serrations or teeth is directly proportional to the overall dimensions of the specific part model.

The washer is not a self-sufficient working element, but it significantly increases the resistance of bolted fasteners to various types of loads. The spring steel from which the part is made withstands vibration and impact.

Toothed contact washer

Unlike the serrated surface, washers of this type have teeth arranged radially around the entire circumference of the part. This design solution ensures maximum tight contact between the fastener and the base, which is important for operating assemblies in demanding conditions. Assemblies made with contact washers are not vulnerable to vibrational and dynamic effects. Galvanic zinc plating or chrome plating protects the assembled structures from environmental effects.

Where contact washers are used

Fasteners of this category are used for building various mechanical systems, in machine building and instrument making, and in construction. The main field of application for contact washers is the electrical engineering industry. Therefore, this fastener should be selected with particular attention to safety requirements.

It is used to connect electrical busbars, and here no breach of the tightness of the joint between individual elements can be allowed. This is ensured by the serrations or teeth on the contact washer. Its configuration and technical properties provide tight contact of the conductive devices throughout the entire service life.

Installation features of contact lock washers

The contact washer is a component of a fastening assembly that uses threaded fasteners — bolts, nuts, studs, screws. The part is installed under the nut, with the serrated surface facing up. The tabs press into the base material; if there are no tabs, the smooth side of the part rests against the base.

During tightening, the lock washer bites into both the nut or bolt head and the surface of the base material with both of its planes. As a result, the strength and tightness of the connection increases. In addition, the risk of the bolted fastener loosening on its own is reduced. For this reason, contact washers are most often used when forming high-strength assemblies for electrical engineering devices and other equipment designed to operate under heavy vibrational loads.

FLOK supplies contact washers of all types.

d	d1	d2	s
M5	5.1	10	1.0
M6	6.1	12	1.2
M8	8.2	14	1.4
M10	10.2	20	1.6
M12	12.4	24	1.6

d	d1	d2	s	h
M3	3.1	6	0.6	0.95
M4	4.1	8	0.8	1.15
M5	5.1	10	1.0	1.5
M6	6.1	12	1.2	1.8
M8	8.2	16	1.4	2.0
M10	10.2	20	1.6	2.6
M12	12.4	24	1.6	2.6
M16	16.4	32	2.5	3.95