Rectangular Bellows

Rectangular rubber bellows provide reliable protection for mechanical components subject to both axial motion and angular (polar) movement, such as in articulated joints or robotic arms. Unlike cylindrical bellows, the rectangular design allows for controlled lateral bending, making them ideal for protecting parts that follow complex or non-linear paths. Typical applications include robotic arms, actuators with rectangular geometry, cable carriers, and rotating supports for control panels or operator interfaces. The elastic rubber structure ensures resistance to dust, liquids, oils, and mechanical stress, preserving long-term flexibility and functional integrity. Custom design is available to match specific geometric and performance requirements, ensuring durability, protection, and reliability in demanding industrial environments.

Description

Rectangular Rubber Bellows for Slides, Guides and Non-Circular Components

Barbieri Rubber rectangular rubber bellows are flexible protections with rectangular or square cross-section, designed to cover rods, slides, guides and moving parts that are not cylindrical. The rectangular shape suits prismatic seats, linear guides, flat profiles and couplings where a cylindrical bellows cannot be applied. They are standard catalog rubber components, but are often produced as custom rubber bellows for specific dimensions and geometries.

Code	B1 (mm)	H1 (mm)	L1 (mm)	B2 (mm)	H2 (mm)	L2 (mm)	MAX lenght (mm)	Lenght CLOSED (mm)
SOF RET P	33	55	10	36	57	10	230	105
SOF RET M	35	114	9	35	114	9	240	200
SOF RET G	46	175	0	60	195	10	300	70
SOF RET 300	280	300	20	305	300	15	400	180
SOF RET 370×370	368	368	15	368	368	15	250	170
SOF RET	14	30	14,5	14	30	14,5	180	180
SOF RET 60X120X120	58	118	20	98	118	20	280	125
SOF RET 85X200X100	86	202	19	86	202	19	240	70

What a rectangular rubber bellows is for

The rectangular rubber bellows protects linear guides, slides, square shafts, prismatic seats and moving parts from dust, chips, splashes, oil and external agents. The rectangular cross-section follows the machine geometry without requiring intermediate cylindrical adapters and keeps convolutions compact when the system is in the collapsed position. It is a typical solution for machine tools, slides, control levers, translation components and couplings where the protected element is not circular.

Available compounds and typical hardness

Compounds used for rectangular bellows include NBR, EPDM, VMQ silicone, FKM (Viton®), HNBR and NR/SBR. Typical hardness ranges from 40 to 70 Shore A. Compound selection depends on the working environment (oils, steam, ozone, high temperature, chemicals) and on mechanical stress: long strokes call for more compliant walls, hot or aggressive areas call for VMQ or FKM.

Compound	Temperature range	Chemical resistance	Typical applications
NBR (Nitrile)	-40 / +130 °C	Mineral oils, fuels	Hydraulics, automotive
EPDM	-40 / +100 °C	Water, steam, ozone, UV	Hydraulics, outdoor, photovoltaic
VMQ (Silicone)	-60 / +200 °C	High temperature, biocompatible	Food, medical, high-T
FKM (Viton®)	-10 / +180 °C	Aggressive oils, solvents, fuels	Chemical, automotive, hydraulics
HNBR	-20 / +160 °C	Oil + high temperature	Heavy-duty hydraulics
NR / SBR	-50 / +90 °C	Good mechanical elasticity	Anti-vibration, general

Catalog standard version and custom designs

Some rectangular bellows formats are part of the standard catalog range, with a tool already running at Barbieri Rubber and no tooling cost for the customer. For non-standard sizes, special geometries, dedicated end flanges and special compounds, we produce custom rubber square bellows: the customer provides at least a preliminary drawing and we evaluate technical feasibility. The dedicated mold is manufactured in cooperation with our trusted toolmaking partners.

Industrial applications

Rectangular bellows are used on machine tools and machining centers for slide and guide protection, in hydraulics for non-cylindrical components, in automotive and vehicle service equipment for control levers and translation parts, on agricultural and earth-moving machinery for axis and rod protections, and on automated production lines to cover linear guides and prismatic kinematics.

Frequently asked questions

When should I choose a rectangular bellows instead of a cylindrical one?

A rectangular bellows is chosen when the protected component has a non-circular cross-section: slides, linear guides, square shafts, prismatic seats. A cylindrical bellows would require intermediate adapters and bigger envelopes, while the rectangular one follows the component geometry directly.

Can I order custom rectangular bellows?

Yes. Feasibility requires at least a preliminary drawing showing cross-section dimensions, working length, number of convolutions, end-flange geometry and indication of the application.

Which compounds are available?

Standard compounds are NBR, EPDM, VMQ silicone, FKM (Viton®), HNBR and NR/SBR. Selection depends on the environment: oils, steam, ozone, temperature range, outdoor exposure, chemicals. Special compounds are available on request.

What hardness is recommended for a rectangular bellows?

Typically 40-70 Shore A. Lower hardness increases axial compliance and suits long strokes; higher hardness increases wall stiffness and durability in mechanically demanding environments.

Are rectangular bellows resistant to oil and aggressive environments?

Yes, with the right compound. NBR resists mineral oils and fuels, FKM (Viton®) suits aggressive oils, solvents and fuels, EPDM is ideal for water, steam and ozone, VMQ silicone for extended temperature range. Selection is evaluated case by case based on fluid and service conditions.

Additional information

Materials	For over 50 years our research on all bellows and boots materials has been continually improved and tested onsite and even in customer laboratories in order to improve all aspects of performance. Our bellows can today be produced of special materials, or standard materials such as NBR, EPDM, CR if cost is the primary concern. The new compounds of today are a special mix of standard raw materials. They ensure that the bellows will last a long time, with good aesthetics and tolerance of a wide temperature range. Some materials are excellent for outdoor applications because they are resistant to degradation by exposure to the sun’s UV rays, while others are resistant to prolonged contact with mineral oils and greases. For special applications, new molding technologies now allow for bellows production in more sophisticated materials such as: VMQ, Silicone, FKM, Viton, CR, Neoprene, and Chloroprene.
Availability	For urgent needs see our list of standard RECTANGULAR BELLOWS for which we already have the production mold.

Materials

For over 50 years our research on all bellows and boots materials has been continually improved and tested onsite and even in customer laboratories in order to improve all aspects of performance.

Our bellows can today be produced of special materials, or standard materials such as NBR, EPDM, CR if cost is the primary concern.

The new compounds of today are a special mix of standard raw materials. They ensure that the bellows will last a long time, with good aesthetics and tolerance of a wide temperature range. Some materials are excellent for outdoor applications because they are resistant to degradation by exposure to the sun’s UV rays, while others are resistant to prolonged contact with mineral oils and greases.

For special applications, new molding technologies now allow for bellows production in more sophisticated materials such as: VMQ, Silicone, FKM, Viton, CR, Neoprene, and Chloroprene.

Availability

For urgent needs see our list of standard RECTANGULAR BELLOWS for which we already have the production mold.