Any machine application involving constant
repetitive motion will benefit from a cable carrier system. To make the right
cable carrier decision for your design, be sure to consider the key decision
points outlined here.
Gather
data. Before contacting a cable carrier vendor, gather all the necessary
technical data. This includes length of travel, what cables or hoses will be
installed, the size of cables and hoses and how much they weigh, and any
environmental factors such as debris, heat or chemicals, as well as speed and
acceleration. Such data are critical, as the factors such as the largest cable
or hose in your system will ultimately determine the minimum size of the cable
carrier. And be sure to account for proper clearance - add an extra 10 percent
for cables and 20 percent for hoses - to arrive at the minimum inner height of
the carrier.
Access. When
choosing a carrier, make sure it allows for easy access to cables at any point
along the carrier. Ideally, gaining access to interior cables or hoses should
not require the use of tools.
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Bend Radius. All cable carriers have a predetermined radius stopping point on each link. When a number of links are assembled, these stopping points restrict the carrier from fully pivoting and form a curve loop or minimum bend radius. All cable carriers have multiple bend radii to choose from and all manufacturers suggest a minimum bend radius. The larger the bend radius, the less stress is placed on the cable and the longer the service life will be. Bend radius is measured from the center of the curve loop to the center of the pivot pin on the side link. Do not confuse this with the dimension of the overall curve height.
Cable and hose packages. Since the primary function of a cable carrier system is to ensure cables bend properly, it is imperative to install the conduits correctly. To ensure maximum cycle life for your machine, the easiest solution is to use cables designed for use in a cable carrier.
Cable carrier length. To determine how long a cable carrier your application will require, first determine the position of the fixed end. The ideal and most cost-effective position is at the center of travel. This will require the minimum amount of carrier to achieve the necessary movement. Use the following formula to determine the necessary cable carrier length: LK = S/2 + K (S = Maximum machine travel distance; K = Curve length; LK = Carrier length; R = Bending Radius; I"M = Deviation from the center point).
Use this formula if the fixed end is anything other than the center of travel: LK = S/2 + a^+M + K
Acceleration and inertia. It is critical to ensure that the cable carrier is strong enough to support the application. In order to determine if the carrier is strong enough, use the following formula to determine the force required for your application: Acceleration Force + Push Force = Force Required. Acceleration force, which is required to keep the cable carrier moving once it has started, is calculated by: Acceleration Force (lb) = Total Weight lb (carrier and fill) x Acceleration ft/sec 2. Push force, which is required to get the cable carrier moving and overcome inertia, is calculated as such: Push Force (lb) = Total Weight x COF Note: The force required must be less than the maximum force for the selected carrier.
Accessories. A variety of accessories should also be evaluated depending on the application, such as:
- Interior separators or shelves to ensure proper alignment of the cables within the carrier and prevent friction, tangling and corkscrewing;
- Mounting brackets to attach the carrier system to the machine itself;
- Guide troughs for long-travel applications;
- Rollers for even longer-travel applications;
- Extender crossbars for oversized conduits; and
- Strain relief to keep cables in position at both ends of the carrier.
Joseph Ciringione is national product and sales manager, Energy Chain Systems,igus Inc.