Flexible bellow covers: single-layer or multi-layers?

Flexible bellow covers are usually used to protect linear guides of machine tools against scraps and debris, and come in different sizes and shapes. A bellow is a cover made out of coated textile, folded in accordion. Its main function is to fold and to unfold alongside with the moving parts of the machine. Depending on the application, it can be subjected to mechanical stress, chemical aggression, high temperature, abrasion and repetitive impacts. Therefore, making a long-lasting bellow requires technical know-how and quality materials.

Types of fabric bellows:

The bellow has to be designed to fit the size and space of a machine tool. The ratio between compressed state (size of the bellow completely folded) and the extended state (size of the bellow completely unfolded) is a crucial factor. Alongside with the constraints imposed by the working environment, it will determine the type of material to use, it’s thickness but also its manufacturing method.

Multi-layers bellows

Multi-layers bellows are made of several layers of materials laminated together to provide the cover its properties. The outer layer can be made of various type of fabrics (including PVC or PU) for the waterproofing and the chemical resistance. A PET film is laminated in the inside to provide the shape and the structure of the cover. Then additional layers are added depending on the properties required (fireproofing, blackout…).

Single-layer bellows

Single-layer bellows are made with a one-layer fabric usually mounted on PVC plates. These plates will provide the structure of the cover and can be attached by different methods (HF welding, glue, thermal welding or/and stitching).

Specificities of each type of bellows:

Multilayered bellows are usually more compact (lack of PVC plates) and can fit easily in small size machine equipment (precision measuring equipment). Because the structural integrity of the cover is mainly provided by the PET film, multilayered laminated bellows are usually limited in size. Their lightweight makes it suitable for high speed LM guides but less for heavy-duty applications.

Single-layer bellows are more common for large-sized machine tools (CNC machines, laser cutting machines), and are usually made with PVC or PU coated fabrics. Folding memory and tensile strength are important features to look at when choosing the fabric since the structural integrity is only provided by the fabric. The necessity to attach PVC plates using welding also limits the type of befitting materials. If polyurethane coating offers better overall performance compare to PVC, not all PU can be easily welded.  Single layered bellows are usually faster to make which makes them more suitable for first mounts (larger series).

Who are we?

OTEGO provides a large range of PVC and PU fabrics especially designed for flexible bellow covers manufacturing. We work with machine tools makers to select and provide the best materials for each type of working environment. Please feel free to visit our page to discover about our range.