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LOT TRACKING & WIP CONTROL SYSTEM |
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Summary of Q-Efficient uses in Semiconductor We use iButtons like a process flow traveler in a factory. The entire process flow is saved on an iButton and attached to a product or lot. Process times are stamped using RF Frequency or handheld reader at each step in the factory a product goes through while being manufactured. This time data is essential for proper simulation modeling and cycle time reduction. The Q-Efficient reader accesses information on an iButton attached to a product. In particular, what step in its process flow it is, where it is going, etc. Q-Efficient readers can be used to help operators determine proper priority of a queue. In most semiconductor or electronic factories this saves operator time by not having to go to a hard-wired station to retrieve data. Readers are something the semiconductor operators requested so they can go to shelves (queue) and touch each lot of wafers (products) and determine what it's next step is, to which machine it goes, what the recipe on the machine is called, the estimated time it will take to process and which machine it came from. These are things the operators usually need to query the database via a computer terminal and keyboard before taking an action. The handheld (wireless) reader gives them instant access to the database information. We focus on semiconductor and high tech manufacturing because our system eliminates paper travelers that sometimes cause contamination. It also helps bullet proof the product's process flow by eliminating deviations from its intended path through the factory. The Q-Efficient readers read the iButtons on each product and are at each machine and machine group. The readers buzz if there is an error, helping to reduce scrap caused by human errors. The screen on the reader can display to the operator the corrective action to take to avoid miss processing a lot. The software can also report who made the error to the section manager if the employees use iButton ID prior to processing a product. This information is pulled from the iButton that is attached to a lot. Also modification can be made to a process flow by a Manager using the Q-Efficient Administrator from anywhere on the network. Next time the Product Lot specified is contacted the new process flow information is updated.
The photo depicts a handheld reader used to contact an iButton, connected to a Q-Efficient box. The Q-Efficient box is a small computer that communicates with the product process flow database loaded on each iButton from the factory Database, updating the time at the start and end of each process step on the IButton for each product lot. The small screen communicates to the operator in real time confirmation that the right product, is being processed on the right machine for the right step in it's process flow and displays the correct process that is to take place on that machine. If it is on the wrong process step, the previous step is incomplete, the machine is currently under use, it is at the incorrect machine the operator is signaled and an error message is displayed with a sound alarm informing the operator what to do or signaling the correct machine.
The above figure shows the administrator software GUI for the Q-Efficient reader and iButton. Through this screen the operations manager can assign a flow to an iButton. To assign an iButton, a manager can contact it with the handheld wand connected to serial port on which the administrator software is running. The Administrator software is connected to the client's database allowing the loading of the process flow data onto an iButton. The left column has a list of process flows from the factory database. Each process flow consists of multiple rows of data including the step number in the flow, equipment name, and process step name and estimated processing time for each step in the process flow. The iButtons are contacted at the beginning of each step and at the end of each step at each piece of equipment recording date and time stamping to the second in order to calculate the processes total cycle time. Once this data is collected on a product the software can be used in combination with MIVP® to give manager reports on cycle time, equipment utilization and assist in process scheduling. The cycle time is then broken down into travel time + wait time + load time + process time and unload time. Since we time stamp at the beginning and end of each process step we can accurately calculate cycle time in two parts;
To calculate process time on the equipment (machine utilization) for scheduling the key is knowing actual processing time used on each machine by all products on the floor.
The above is a wireless handheld reader, which an operator can
download and upload information to the iButtons. When an iButton
is connected to the wireless handheld, information is then sent
by radio frequency to the database from the iButton or to the iButton
allowing further flexibility to the operators when storing, stocking
or doing queries on products during their process flow. There is
also a display on the handheld similar to the display described
in the Photo of the Q-Efficient Reader (see Figure 1).
Click here to fill out a service service request form Lot tracking and WIP control system - Q-Efficient: Q-Efficient WIP Tracking.PDF* Brochure is in Adobe Acrobat Reader (.PDF format). |
