Assembly Planbook - April 2008 - (Page 39) control software and bead materials or pumps for nonpath programming. flowable materials. With Complementing these respect to the daily volume efforts, the design team’s of material dispensed, it material handling engimay be necessary to employ neers will be responsible a dual supply unit with for creating part fixturing automatic crossover for and tooling. As they do so, nonstop dispensing. Other they will also work with the requirements may include robot supplier to select the material level monitoring or correct robot. To perform de-gassing, as well as dehuthese tasks, both the matemidifying capabilities for rial handling engineers and bubble-free and moisture the robot supplier will need sensitive materials. to know the exact size and At the heart of every disnumber of parts involved pensing system is its meterin the process, the number ing equipment. Selecting the of parts per hour that will right metering approach is be processed, and the speed critical to ensuring the robot with which the material will will dispense the material be dispensed on the parts. consistently, thereby ensurAgain, the specification ing a quality assembly. Techis the key document, like an nologies commonly used in architect’s drawings when robotic applications include building a house. If the propositive rod displacement, cess specification changes piston displacement, recipat any time during the build rocating piston and precicycle, all team members sion gear metering—all need to be notified. technologies that have been With regard to systems In this application, a robot articulates the part under a fixed dispense valve to in use in robotic applicaintegration, the manufac- form a gasket with three different bead diameters. A vision system confirms tions since the 1970s. turer should select a turnkey that the beads are in spec. Double-acting piston, provider with experience in progressive-cavity, piston its particular field. Typically, the robot metering. The option of more metering cup, and time and pressure technoloor dispensing system supplier will be principles ensures a manufacturer will gies are typically not used in a robotic able to provide references. Make sure be able to employ the most effective setting. These types of metering are that, in addition to a stable of program- type of dispensing. The wrong technol- adequate for many other types of applimers writing systems code, the integra- ogy may result in imprecise dispensing, cations. However, because they do not tor has the engineering experience and longer downtimes, more frequent main- employ the positive displacement prininstallation know-how to support both tenance and higher spare parts cost. ciple, part quality may suffer do to lack startup and any needs you might have Always remember that higher initial of precision. It is important that the after the system is up an running. capital equipment cost may result in metering system employ a servomotor more efficient product assembly, better to accurately control displacement of Dispensing System Options product quality, more uptime and lower material by volume, not by pressure. When it comes to dispensing, a lifecycle cost in the long run. Popular robotic dispense methods, or number of different equipment suppliWhen it comes to selecting a spe- patterns, include a single bead extruded ers are available. Some suppliers have cific dispensing system, the dispensing according to a specific cross-section equipment that is specifically designed equipment supplier will look at both the and length; a predesigned profile drop, for use with robots, while others have material formulator’s selection and the also known as “kiss”; a wide coating; equipment that has been adapted to the manufacturer’s process specs to ensure multiple short beads in what is called task. Some dispensing system suppli- it selects the correct types of products. a stitch pattern; and potting or filling ers incorporate one or two principles Among other system components, the by volume. Pattern choice combined of metering in their machines, while supplier will size and spec equipment with the properties of the material being others offer as many as eight types of such as pressure tanks for pourable dispensed has a direct bearing on the www.assemblymag.com April 2008 / ASSE M B LY 39 http://www.assemblymag.com
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