Design News, May 2013

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® of the automation system. For example, using aluminum or high strength plastic tooling as opposed to steel can be a significant reduction in total weight being carried. Also with pneumatic grippers, the grip force is a function of the pressure applied. Basically, the higher the input pressure, within rated capacity, the greater the grip force developed. Another significant consideration is the length of tooling used. For angular grippers, the amount of grip force developed is usually inversely proportional to the length of the jaw tooling. For many parallel style grippers, the length of tooling will result in a derating value used to calculate the total grip force developed. GRK Group: These grippers, built for heavy part gripping, are available in four sizes with long and short jaw travels per each size, metric or imperial, with spring assist open or close, as well as two-position teachable magnetic switches. The other attribute, total jaw travel is the distance between the two jaws when fully open, minus the distance when both jaws are closed. Consideration for total jaw travel is dependent upon the required distance of encapsulation, the clearance required when approaching the part to be gripped, and the variation of part sizes for the application. Most gripper manufacturers offer one or two series of products where total jaw travel is a premium feature for that series. SOURCE: PHD PAYLOAD, PRESSURE, AND TOOLING LENGTH Eventually, the designer must consider one of the major criteria for selecting and sizing an automation gripper, that being the payload. This includes not only the weight of the item that is being transferred, but also the total weight of all attached tooling. Designing gripper applications using the lightest material possible for tooling is almost always desirable. This not only decreases external moment forces that are reflected back into the gripper and its mechanics, it also increases the amount of ultimate usable payload that can be carried by the rest Problem-free. Available in 1 foot lengths and up. No minimum order. No cutting charges. SIZING SOFTWARE Fortunately for today's machine designer, many gripper manufacturers offer some form of sizing software that greatly simplifies the gripper sizing and selection process for most any automation application. By filling in the blanks and selecting criteria that applies to their application, the user can obtain a list of gripper models and sizes that will successfully accomplish the task required. Some of these sizing tools are available online and offer the user the convenience of inputting their application parameters in either imperial or metric units, or a mix of both. Some sizing tool packages, such as the one offered by PHD Inc., allow the user to select two or three different models side by side and compare the resulting specifications of one to another. This comparison mode allows the designer to tailor the gripper selection to the optimum device for the application. Over the years, the automation industry has come a long way in assisting machine designers, and the ability to successfully apply cost-effective grippers has never been easier. Jon Dent is distributor training & development manager for PHD. For more information, go to 2 0 1 3 FL U I D P O W E R / M O T I O N C O N T R O L / A S UP P LE ME NT TO DE S IGN NE WS F9 magenta cyan yellow black Chainflex Lasts. ® For use in Energy Chain Systems , Chainflex cables withstand the stress of tight bending radii in moving applications and deliver longer extended life at a lower cost. More than 850 types from Servo to Motor cable, from Control to Firewire cable, from Robot to Fiber Optic. Free samples available. All from stock. ® ® ® Plastics for longer life PO Box 14349 East Providence, RI 02914 800-521-2747 ES244623_DN1305_F9_FP.pgs 05.02.2013 07:03 UBM

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