“Flexible cable” is a term that’s often misunderstood. Just because a cable is labeled “flexible” does not mean it is suitable for every situation. True flexibility is not a single property — it is a spectrum of mechanical performance shaped by the specific application, type of motion, cable construction and proven lifecycle testing. Our series of blog posts on flexible cable will help you select an appropriate cable for your application. We begin with a review of the various designations for flexible cables in modern industrial systems, along with their characteristics and features.
Stationary cables are designed to be bent during installation only and remain static thereafter in control panels, cable tray installations and fixed machinery. In many of these applications, installation space is limited, requiring tight bend radii. Selecting a cable with an appropriate bend radius helps ensure reliable signal transmission while preventing overbending, which can compromise the cable’s structural integrity and long-term performance. Look for flexible control cables with small diameters that allow for a reduced bend radius, such as SAB flexible power and control cables, which reduce stresses imposed on conductors when they undergo tight bends in multiple directions. Flexible control cables also have a simple construction that minimizes cost.
Continuous flex cables are designed for systems and equipment that run nonstop with frequent linear motion, often at high speeds. The cables typically have a rated bend radius of five to 10 times their outer diameter, ensuring millions of cycles of flex life. Applications include drag chains, automation systems, robotic arms and packaging equipment. Continuous flex cables should be made from robust materials like polyvinyl chloride (PVC), polyurethane (PUR) or thermoplastic elastomer (TPE) to resist abrasion, chemicals and washdowns. Check with your cable supplier to be sure that your desired cable is designed and tested for multi-axis flexing and alternate bending.
Torsion flex cables transmit power or control signals to high-speed, heavy-duty twisting mechanisms in robotic arms, wind turbines or other rotating equipment. They can be used in cable tracks or in dry, wet or damp conditions and wherever cable tracks are not possible.
Suitable for medium mechanical stress, torsional flex cables have finely stranded conductors that allow them to be twisted along their axis from ±90° to ±360° or more over millions of torsion cycles. Some cables in SAB’s torsion cable family boast torsion angles of ±450° over 0.5m. Look for rugged PUR and PVC jackets and high-quality TPE and PVC insulation that boosts cable life under extreme bending.
Tray cables are a specialized cable category designed for stationary installation in overhead cable tray systems. While many tray cable designs are relatively stiff and difficult to route through bends and turns, SAB Tray Cables are engineered with enhanced flexibility to simplify installation, reduce labor, and save time.
UL TC-ER (Tray Cable – Exposed Run) certification allows the cable to exit the cable tray and connect directly to machinery or equipment without requiring conduit, provided it is properly secured at intervals not exceeding six feet. This installation flexibility helps reduce material costs and speeds installation.
Common applications include industrial automation, manufacturing equipment, control systems, material handling and wind turbine installations. Combining rugged construction with superior flexibility, SAB Tray Cables deliver reliable performance while making installation faster and easier.
Tray cables should carry UL (or CSA, in Canada) approvals and have voltage ratings that match the application and shielding to prevent EMI, if needed. TC-ER cables carry a UL 1277 rating, which indicates they have undergone impact and crush tests for use outside of trays and conduits. While these cables are not designed for movement, their flexibility should match the actual cable tray layout.
A Look Ahead
Future posts in this series will explain why proper cable testing is critical to confirming that a cable is truly ideal for your application, provide a detailed overview of cable construction, and share best practices for selecting the right cable for your intended usage scenario.
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