Bend protection sleeves

Plug, housing lead-through or permanently defined cable outlet: The appropriate cable protection sleeve depends on the requirements of the assembly. As a manufacturer of customised cable protection sleeves, we implement diameters, ribs, bending radii, attachment, etc. as customer-specific rubber grommets.

Custom-made cable glands
manufactured for your cable-management

A cable grommet guides a cable at the transition to a plug, housing or device and distributes the bending over a defined shaft. As a result, the movement of the line is not concentrated exclusively at the rigid exit edge. Since cable construction, bending radius, direction of movement and installation space differ for each assembly, we manufacture every cable grommet individually according to drawing and do not sell standard geometries.

A closed conical shaft guides the cable via a continuously changing cross-section from the rigid connection into the flexible area. Length, opening angle and wall thickness profile determine how early the bend starts and over what distance it is distributed

Bend protection sleeve conical shaft

Circumferential ribs divide the shaft into successive bending zones. The contour at the connection can be designed to be stiffer and progressively more flexible towards the cable outlet by means of the rib height, rib spacing and core diameter

Bend protection sleeve rib profile

With a lateral cable outlet, the intended cable routing can already be integrated into the moulded part geometry. As a result, the cable leaves the connection in its installed initial direction without a straight shank having to be permanently bent against its neutral position.

Right-angle grommet

A circumferential groove positively locks the grommet in a sheet metal or housing opening. Groove width, collar diameter and insertion contour are adapted to the material thickness, aperture and installation path. In this version, the component also performs the function of a rubber grommet

Cable gland with housing groove

Flange, collar or undercut form the interface to the connector housing, sensor, handheld device or machine guard. For pre-assembled cables, a check is carried out to see whether the cable grommet must be fitted before the connector, pushed over the existing connection or designed with a splittable profile

Flange bend protection grommet

Oval, rectangular or separate apertures can accommodate flat cables or multiple cables in a rubber grommet

Bend relief for flat cable

Benefits of a custom-made strain relief grommet

A custom rubber cable grommet is used when off-the-shelf products do not adequately accommodate the available installation space, cable or connection geometry. The special geometry combines the required range of movement with a fixture that matches the assembly and the intended installation procedure.

Distribution of the bending movement: shaft length, ribs and wall thickness transitions influence the bending profile, allowing the movement to be distributed over a greater distance instead of concentrating at the transition from the flexible cable to the rigid connection.
Adaptation to limited installation space: The fully customisable design of the bend protection grommet enables integration even into housings with tight clearances or unusual exit directions.
Matching with pre-assembled cables: For cables with fitted connectors, the opening cross-section and assembly sequence can be taken into account and, if required, axial separating or connection concepts can be integrated.
Defined connection at the port: Groove, collar, flange or snap-in contour connect the flexible shaft to the mating contour and are flexibly adapted to the housing.
Combination of several functions: In addition to providing anti-kink protection, the grommet can route a cable, cover a housing opening or carry a sealing contour.

Cable glands -
tailored to your application

The suitable material
for your cable protector

For the material selection, the required flexibility and recovery, the temperature range, the media and weathering influences occurring at the place of use, as well as the compatibility with the cable sheath are particularly relevant.

EPDM bend protection grommet

EPDM is suitable for outdoor applications subject to weathering and, depending on the compound, covers a temperature range from approximately -50 °C to +130 °C.

NBR cable grommet

NBR is used in contact with mineral oils and temperatures up to +110 °C.

HNBR cable protector sleeve

Where additional heat resistance or greater oil resistance is required than with NBR, strain relief boots made from HNBR are used.

Silicone cable grommet

Silicone rubber combines high elasticity with a wide temperature range of approximately -50 °C to +220 °C, making it suitable for flexible cable connections at low or high temperatures.

FKM cable protector sleeve

FKM offers resistance to fuels and mineral oils up to approx. +220 °C. Due to the higher Shore hardness, however, its use is limited in highly flexible anti-kink zones.

TPE cable protector

TPE enables flexible bend protection elements in injection moulding and is therefore particularly relevant for larger volumes without special chemical resistance requirements.

Which factors
are relevant for the design of a cable grommet?

The geometry of a bend protection sleeve determines how the connected cable is routed and how bending stresses are distributed along the outlet. As a bend protection sleeve manufacturer, we support you in the design of your custom-made bend protection sleeve and provide technical advice on production-optimised design and structural engineering.

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Inside diameter

The inner diameter is matched to the cable diameter. A tighter version improves guidance and fixation, while extra play can make assembly easier or accommodate cable tolerances.

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Length of the anti-bend zone

A longer bend protection zone distributes the bend over a larger area. A shorter version requires less installation space, but routes the cable over a more compact path.

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Wall thickness

Larger wall thicknesses increase support, while smaller wall thicknesses allow for more flexible movement.

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External contour and taper

The course of the outer contour influences how evenly the grommet yields. A stepped or continuous taper can purposefully shape the transition from the rigid connection to the flexible cable.

05 / 08

Ribs and bend zones

The number, spacing, depth and width of ribs allow the flexibility of your cable grommet to be adjusted. As a result, individual areas can be made more rigid or more flexible, and preferred bending paths can be created.

06 / 08

Transition radii

Sufficiently large radii at geometric transitions favour a uniform force distribution. Very abrupt changes in cross-section, on the other hand, lead to more localised deformations.

07 / 08

Exit-angle

In addition to a straight version, angled geometries are also possible. The outlet angle can be adapted to the installation position and guide the cable in the intended direction.

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Connection geometry

Flanges, grooves, undercuts or insertion areas determine how the grommet is secured to the housing. Their design also influences the assembly, the fit and the transmission of any tensile and bending forces that occur.

You have questions about
Grommets?
We have answers!

What function does a bend protection sleeve serve at the cable exit?

At the transition from a rigid connector or housing to a movable cable, bending movements can concentrate on a short area. The anti-kink grommet extends this transition and distributes the cable movement over a greater distance. At the same time, it protects the cable sheath against contact with sharp housing edges and, depending on the connection geometry, can help to cover the exit point.

Which factors determine the required length of the grommet?

The decisive factors are the permissible bending radius and outer diameter of the cable, as well as the angle of movement, installation space and exit direction. The length should be chosen such that the bend begins within the flexible zone and is not concentrated immediately behind its end. Material hardness, wall thickness profile and rib geometry also influence the required installation space.

What advantages do conical or stepped contours offer?

With a constant cross-section, a significant difference in bending stiffness occurs at the transition to the freely movable cable. A taper or stepped rib structure makes the grommet more flexible towards the cable end and distributes movement more evenly. Which contour is suitable depends on the installation situation, the movement sequence and the material.

What kind of sealing effect can be created between the grommet and the cable sheath?

An aperture designed smaller than the cable diameter creates a circumferential contact pressure and can provide protection against dust or splashing water. For further sealing requirements, additional sealing lips can be fitted inside the bend protection sleeve. The required sealing performance must be defined for the complete assembly, as cable tolerances, surfaces, movement, medium and pressure direction influence the design.

Can a bend relief be directly connected to the connector housing?

With suitable metal or plastic carriers, the anti-kink sleeve can be vulcanised directly onto the housing, creating a material bond. For this purpose, the surfaces are degreased, roughened and coated with an adhesion promoter before a composite component is formed from metal and rubber in the mould. We manufacture both plastic and metal housings in-house at our location in Bavaria.

How is a cable grommet manufactured?

The inner bore and outer contour are formed by the core and cavity of a mould, which we at GUME design and manufacture in our own in-house toolmaking shop. Depending on the process, the raw rubber is then inserted or injected into the mould cavities and heated to approx. 180°C. Through chemical cross-linking, the rubber/silicone thereby takes on its final shape as a grommet in accordance with the drawing. After demoulding, the grommets are freed from flash by cryogenic or manual deflashing and packaged for dispatch.

Can a split cable grommet be fitted retrospectively?

For retrofitting, designs with a longitudinal slit, an overlapping parting line, interlocking contours or two interconnected half-shells are possible. However, the division affects the sealing performance and the behaviour under repeated bending. Whether a split design is suitable therefore depends on assembly access, movement stress and the requirements for the closed joint.