SOFTWARE & NETWORKS
October/November 2016 | industrial automation asia
and hoses and how much they weigh, any environmental factors such as debris, heat or chemicals, and speed and acceleration. 2. The largest cable or hose: The first question any reputable cable carrier manufacturer will ask is, ‘What is the largest cable or hose in your system?’ This will determine the minimum size of the cable carrier. To this number, add proper clearance — 10 percent for cables and 20 percent for hoses — and the resulting dimension is the minimum inner height of the carrier. 3. Style, style, style: Next, choose the style of carrier. Always choose a snap-open version whenever possible. This type of carrier allows access to cables with
D1 D2 d1
D1 + D2 > 1.2 x hi
d2
d1 + d2 ≤ 1.2 x hi
10% min .08” (2 mm) 10% min. 10% min. .04” (1 mm) .04” (1 mm)
d1 + d2 ≤ 1,2 x hi
10% min .08” (2 mm)
10% min. .04” (1 mm)
10% min. .04” (1 mm)
Distribution rules are necessary because cables and hoses must be able to move freely at all times and tensile force must be prevented at the radius of the cable carrier.
crossbars that snap open at any point along the carrier. If debris or other external conditions are an issue, the tube-style cable carrier replaces the crossbars with lids to fully enclose the carrier and provide complete cable protection. This style is especially useful in applications where woodchips, metal filings and other debris are present. With a split crossbar, simply press the conduit into the carrier to install and pull straight up to remove. For zipper-like removal of crossbars, the carrier has interconnected lids that are pulled back like a zipper, removing the top section of the carrier. The hinged crossbars are attached to the side links and are made of non-fibre, reinforced nylon to enable the hinge to flex. These designs minimise assembly and disassembly time. There also are modular cable carriers for heavy-duty, longer-travel applications. They are available with hinged crossbars that are opened on either the inner or outer radius, depending on which is preferable for the application, or with lids to make them into a tube for debris protection. Special cable carriers are available to meet a variety of application requirements. Some are: low-vibration or low-noise carriers, multi-axis carriers for robotic applications, ‘twister’ chains for rotational movements, fully enclosed carriers for protection against metal chips and flying debris, and carriers with integrated wheels for longer travels and less wear. 4. The environment: The environmental conditions of an application typically determine which type or style of carrier to use. If debris such as woodchips or metal shards are present, or if the application is in a dirty or contaminated area, an enclosed tube is ideal. An open crossbar carrier is lightweight and facilitates easy inspection and replacement of cables, whereas tube carriers offer removable lids for cable access. Also consider whether the
application is underwater or comes in contact with liquids. Note: Space restrictions Many applications have a space restriction that will affect the design and selection of the cable carrier system. It is imperative that the performance of the system is not compromised to meet these restrictions. Keep in mind things such as the camber of the carrier when determining how much height is available for the installation. Camber is the curve of the upper portion of the carrier along its unsupported length. Most cable carriers are manufactured with camber, but special, no camber carriers are usually available upon request. Be advised however, that carriers without camber do not have the same load-bearing capacity as those with camber. 5. 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. If this is unknown, the general rule is 8-10 times the outer diameter of the largest cable or hose. 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 centre of the curve loop to the centre of the pivot pin on the side link. Do not confuse this with the dimension of the overall curve height. 6. Cable and hose packages: Since the primary function of a cable carrier system is to ensure c a b l e s b e n d p r o p e r l y, i t i s 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.
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