An Extruded Silicone cable is a collection of wire conductors that has been encased in a silicone jacket by means of a special extrusion process. Extruded Silicone cable is designed specifically for motion control, and automation where flexibility, strength, and space economy carry a design premium. The basic technology of encasing conductors in silicone jackets has been in use for over 50 years and can be found in applications ranging from jet fighters to industrial motion control equipment.
The type of flat cable used in computer peripherals is often called ribbon cable. It is inexpensive and easy to terminate because its geometry is standard. Its conductors are laid out in a standard pitch so insulation a displacement connectors (IDCs) for ribbon cable are a standard item. The jacketing material is usually PVC, though some special-purpose ribbon cables may use other materials to handle thigh or low temperatures or applications that demand plenum-rate cabling.
The problem with ribbon cable is that it is not designed for repetitive flexing. Its PVC jacketing is relatively brittle. There are special-purpose jacketing materials exhibiting more flexibility, but they tend to lack mechanical toughness and resistance to harsh chemicals. In addition, ribbon cables are only available in a single wire gauge for all conductors (28 AWG) which limits their use.
There is another type of flat cable that uses PTFE (also known as Teflon®) as
a jacketing material. This material has a reputation for low friction, and flat cables made with PTFE jackets target applications that demand a long life despite repeated flex cycles. One problem with PTFE flat cables is that their manufacturing process induces potential weaknesses in the cable. PTFE cabling is created by sintering together two half shells of PTFE material that sandwich conductors in between (Fig. 1). The seam formed by the two half shells is a point of weakness that can eventually rupture after repeated flexing. Once ruptured, PTFE cable cannot be repaired; it must be replaced.
Moreover, wires in PTFE jacket are not held in place within the jacketing material. They can creep from their initial position or be pulled out of place by forces from the connections at the ends of the wires. To head off such difficulties, PTFE flat cable employs clamps at regular intervals along the cable, which adds cost and weight to the overall design. In linear motion applications, for example, these drawbacks of PTFE cable result in higher inertias for the motor to overcome, increased system vibration, and longer settling times, all of which reduce the performance of the system.
In contrast to this behavior, Extruded Silicone cable needs no clamping system because the
conductors can’t creep out of the silicone encasing them. The encapsulating silicone also acts as a shock absorber, damping and reducing vibration. This further lengthens the life of the cable in applications characterized by severe shaking and oscillations. Extruded Silicone Cables are more than twice as flexible as PTFE cables (Fig. 2), which allows engineers to design more compact, space saving equipment than is possible with PTFE cable technology. The extreme flexibility of Extruded Silicone Cables also provides millions of cycles of flex life, even in the most demanding applications.
: Design World :
Filed Under: Cables + cable management
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