Key Production Indicators

Forget what the machine's max. placement cycle rate is spec'd for. For each board you assemble time the actual placement rate. To do this start the stop watch the instant the camera is positioned over the first fiducial on the first board, then stop the watch the instant the camera is positioned over the first fiducial on the second board. That's the "actual tact time" for that given board and factors in board load/unload time. Be sure that the placement cycle had no "pick recovery"- meaning it was a continuous placement cycle with no stopping and no "miss-picks". If you have multiple placement machines in the line, your slowest tact time machine is the actual for the line. Then you'll have to burden the actual tact time for machine stoppage. Stoppage for feeder changeovers, operator issues, machine malfunctions,..... List all the reasons you are seeing stoppage on the machine(s). You're goal is to achieve the best against the measured tact time. Record machine stoppages during the job and break them down by categories and work to stop the stoppage! Correct stoppage issues that are within your control. Account for stoppage issues that are not in your control, such as defective components being rejected by the vision system. Record this down time and report issues to the supplier and get relief ($$) on your next purchase. The same goes for PWBs. The percentage of the actual tact time is what you want to be concerned about. This is your measure of efficiency. If you follow the continuous flow mfg. principle- which is that you do not start a job unless you have all the components to complete the job and once you start the job you do not stop until its complete- running out of material is not a factor. If you follow the machine OEM's preventative maintenance schedules to keep your machines in "tip top condition", then unscheduled machine down time should be minimal. If your machine stops for feeders empty and your method is to re-load the same feeder, this is the greatest time consumer and it is difficult to establish a standard. Having extra feeders loaded and in close proximity to the machine makes a time standard possible. Loading a feeder onto the machine is a standard time vs. loading a component onto a feeder then loading a feeder onto the machine is a variable time. The investment for extra feeders may be justified if you can show how much more product you can build (generate revenue) in a given time period. FYI: Some machines are smart enough not to stop the placement cycle for empty feeders and can have feeders removed and installed while the machine is cycling. Set up time is another measure of efficiency. 15 - 20 minutes is standard for efficient companies. Look to create procedures and configure your line to achieve a standard time for setup. My instructions to the SMT line super. was to maintain 75-85% of actual tact time and to be placing boards for job "B" by the time job "A"'s last board came out of the oven. This was with 2 lines of Fuji, each w/ GSP2, CP3, CP3, IP2, and Vitronics SMR1100. But then again, I've been called a ball buster.

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