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September 2017 • SMT Magazine 85 Lines can be pre-set up prior to the operators arriving for their shift, 5S programs can be im- plemented to reduce hunting time looking for tools or breaking down materials prior to start- ing work. Break times can be overlapping, etc. Now that you have your available labor hours identified for each work center and they have been properly discounted, then enter this time into your CP model. Whoever is in charge of up- dating this available labor will have to be con- scious of the changing labor by week. Vacation and sick time for instance will fluctuate. Holi- days will occur during certain weeks and there may be planned or unplanned shutdowns that will affect the stated available capacity. You may also be adding resources to a work cell or expe - riencing attrition. For these and many other nu- merous reasons the review of these available re- sources will have to be continually updated. Machine hours are somewhat easier to es- timate. You obviously do not have to concern yourself with sick time or vacation time. Ma- chines (ideally) don't have fatigue throughout the day so long as maintenance has been kept up to date and they are manned properly you can anticipate the same available output from the machine throughout the day. All things be- ing equal, if the machine is placing 10,000 parts per hour at 9:00 a.m., then it should be capable of placing 10,000 parts per hour at 2:00 p.m. as well. What you do have to consider is planned or unplanned preventative maintenance (PM) time, operator clean up and set-up. Programming time and machine warm up periods after sitting idle. For the data in your model to be realistic you must note all the min- utes or hours that the machines are available. If they are sitting in your factory at night and on the weekends and you choose not to run them or man those machines that is your choice. It doesn't reduce the available machine hours. Your model will simply reflect some incremen- tal hours that are available and could be pro- ducing product. This is opportunity cost and should be dis- cussed in another article. When planning ma- chine hours for your CP model also keep in mind that whether standing three operators in front of your machine or ten, the machine typ- ically will not run any faster. Most machines have a fixed placement rate that may be aug- mented somewhat but not significantly through the addition of incremental operators. You may improve efficiency by reducing some stop and start times but that is all. It should be noted in the high-mix, low-vol- ume (HMLV) market, the ability to have a flex- ible work force is essential in meeting custom- er demands while controlling the labor costs. As such, we train our associates in multiple disci- plines so they can be utilized at various points in our process as opposed to being single skilled. This means that in developing the CP model, you must incorporate the understanding that you have a certain amount of resour ce "float" that can be applied up and down the process line to meet the specific constraint. Although an over- simplified object of a CP model is to line balance, in the HMLV world, this is simply not economi- cally possible. The human "resource" is probably the most difficult to apply in a CP model since a successful HMLV organization must have the flexibility to take into consideration specific skill sets over a broader resource range. 8. Queue times are identified. All wait periods, set-up, transfer times and transport times. The one variable that is often overlooked when creating or working with a CP model are the queue times or "wait" periods. These include the times it takes to transfer product from one area to another, set-up times, non-automated IMPLEMENTING A CAPACITY PLANNING TOOL Figure 8: In the fast-paced EMS industry, MC Assembly workers strive to stay ahead of the curve.

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