Speeding Equipment Changeovers and Setups
December 31, 1969 |Estimated reading time: 6 minutes
By Mats Magnell
New component-feeder design and intelligence functions can save time and eliminate errors in the loading and unloading process.
As high-mix environments become the norm among manufacturers/assemblers, increased importance is placed on hastening machine-changeover and setup processes. With the number of components per board also growing, those tasks are further complicated. Overall, in spite of recent significant progress, loading and unloading of component feeders remains a bottleneck in the manufacturing process.
Currently, in a typical high-mix environment, operators change an average of 200 component reels per day. With most feeder systems, the loading procedure takes at least one minute to perform while unloading almost matches that time. This means that operators spend almost three to five hours a day alone on those two procedures. Further, loading feeders is highly susceptible to error because it mainly is a manual task. Although sophisticated software, bar code scanning and other innovations have reduced the degree of manual interaction, the issue of how to reduce the time required for loading and unloading remains. Hence the current demand for smaller feeders that are both faster and easier to load, together with more intelligent software and hardware functions that prevent error.
Feeder Design DrawbacksSMT machinery manufacturers have been answering the demand for easier and faster changeovers by introducing design improvements for feeders and feeder systems. Yet, some of their customers use large-sized feeders that attach to carts or trolleys, which often are difficult to maneuver and time-consuming to load. Additionally, it is not possible to keep a tape reel attached with most feeders; it must be removed between changeovers to reload.
While using smaller, stand-alone feeders saves considerable time, a secondary hurdle is the feeder mechanism itself. Because traditional systems take several minutes to load and require special take-up reels, it is likely that assemblers will turn to feeders that are both smaller and easier to load. With a hand-size feeder, loading time could be reduced by half and manufacturers could save hours every day (Table 1).
Reduced Size BenefitsToday's large-size feeders generally require considerable storage space. Smaller feeders save space, permitting plants to keep extra feeders and tape reels nearby and ready for use. Preloaded feeders offer similar savings reducing setup time and enhancing plant productivity. For example, feeders small enough to be stored individually on the shelf can be kept preloaded. Then the process of unloading would be necessary only if an assembler is unable to use the rest of the attached component reel, or if only a few feeders are used, necessitating rotation between them. Preloading also makes it unnecessary to reload component tape during the changeover process, which is yet another way that feeder design innovation will help limit hands-on interaction in the setup and changeover process. Preloading, or keeping ready-to-use feeders on-hand to prevent more loading, then could decrease the likelihood of error-filled runs dramatically.
Small Tape Strips. With traditional feeders, it is impossible to load small tape strips because most take-up reels require a minimum of several inches to separate the cover tape from the component reel. In the case of subcontractors who mainly run small batches (and who often receive small tape strips designated for a given board), their operators typically attach components to the boards manually, a time-consuming process that also is highly susceptible to error. All this inconvenience and increased risk of error can be avoided with smaller feeders.
Intelligence. Feeder setup requires manual operation and probably always will. Therefore, there always will be an associated risk for error. One way to minimize the risk, however, is by applying highly intelligent software and hardware to the feeder-loading process. Not only can intelligent feeders reduce error, they also can aid in the documentation process and help machines manage complex boards more efficiently. They can reduce the risk of error by keeping track of components while the software informs on component status.
OptimizationMany intelligence features are becoming standard in the industry. Most feeder-system software, for example, has an optimization "engine" that enables the machine to continue running while feeders are changed. Such software is constantly re-optimizing, advising on where to place the feeders. With a smaller feeder, however, it is easier and faster to remove and reinsert than to unplug and move around a large cart or trolley. With hand-size feeders, this process takes only seconds. Operators need only clip the feeders from one position to the other, or on and off the machine. The optimization engine then checks to ensure that there are enough feeders for the job. A sophisticated version also can optimize many jobs at a time and match them up with the ERP system so that operators can have a list of how the machine will run them, (e.g., if they have enough parts).
Bar code Functionality. Most feeders now have a bar code function that enables them to be traced. In small, hand-sized feeders, however, the tape can be dedicated to the feeder so that it becomes virtually impossible to load incorrect parts.
Plow-shaped Feeder One answer to the demand for faster and more intelligent feeders is a new type of removable feeder about the size of a pen. Here, operators have only to peel aside the cover tape two to three centimeters and insert the tape into the feeder. Its "plow-shaped" design enables the loading step to be completed in less than 10 seconds. In one example, the technology is applied on five pick-and-place lines. Two are equipped with hand-held feeders for assembly of prototypes and run around the clock, performing at least 10 changeovers a day. A magazine loading that typically required about 40 minutes to set up now is reported to take only 10. Thus, assuming that a cell must carry out 200 feeder loadings per day and that it takes the operator about one minute to load each unit, if that time can be reduced to 10 seconds each, almost 60 hours can be saved each month. Taking into account the unloading procedure, which normally takes the same time, almost 100 hours could be saved monthly (Table 2).
Once inserted in the magazine, the automatic feeding system works like a plow to move aside the cover tape and presents the components to be picked by the machine's mount heads. Unloading cover tape in take-up reels is unnecessary because the cover tape remains attached to the carrier tape after the component is picked. The magazine automatically advances the tape and once empty, it is pushed out the back together with the cover tape, which is still attached. This means that no extra take-up reels are needed.
Enhancing the Setup ProcessBar codes typically track part numbers and tie the stockroom to the purchasing department for inventory control. The parts then are issued from the stock room to the factory floor to be placed on the placement machine. Bar coding a feeder ID to a parts reel ID works best when handled off the machine in order to eliminate downtime. This step, in conjunction with a smart individual feeder, provides the machine with pertinent information for parts location and inventory control. Along with the part number, the quantity of parts on the reel can be provided and used for inventory control before, during and after the boards are built. When the reel is removed, the operating system on the machine and the users' internal data system stores the remaining quantity information for use the next time the component is required. Scanning the bar code label for setup will provide part numbers and the remaining quantity for machine setup, again eliminating potential operator error and controlling the inventory required to complete the board build.
ConclusionToday's fast-changing business environment requires new innovations to reduce changeover and cost per component placed. In any manufacturing setting, downtime, whether for product changeover, machine setup or machine failure, means lost revenue. Over the years, software tools have been used to reduce setup, allowing the user to create programs and perform many of the setup tasks off-line. The advent of intelligent individual feeders provides critical shortcuts to machine setup and eliminates many of the human errors of the past, all of which means more throughput at the end of the day.
Mats Magnell may be contacted at MYDATA automation Inc., 320 Newburyport Turnpike, Rowley, MA 01969; (978) 948-6919; Fax: (978) 948-6915; E-mail: mats.magnell@mydata.com.