EMS Sourcing
LeAnmATeriAL FLoW And invenTory AccurAcy
Smart software can help procurement specialists add value and contribute to overall success on the factory floor By Bruce Isbell andMichael Ford, Valor Division,Mentor Graphics
Professional buyers constantly look for betterways to contribute to the overall success and profitability of themanufacturing operation. In this article,Mentor Graphics introduces the concept of intelligent lean as it relates tomaterialsmanagement in today’s fast paced and often chaotic electronicsmanufacturing.
One of themost crucial factors in the efficientmanagement of the
supply ofmaterial into the stockroomis having a clear and accurate viewof inventory.Many ERP systems provide a clear view, but in many cases it is far fromaccurate. Periodic, expensive and labour intensive effort is put into place to boost the accuracy of inventory, such as cycle counts, stock-checks and everyone’s favorite, the weekend killing physical inventory. The sad result of these efforts is repeated discovery that there are huge gaps between the theoretical inventory and the actual counts. Theremust be a betterway.
Attrition and spoilage is a common contributor to poor inventory accuracy
Feeders create spoilage; SMTmachines create spoilage byway of dropped parts; loading, splitting, and splicing reels creates spoilage as parts in the leader tape are discarded. Alsomany production runs may only require a small fraction ofwhat is contained on a reel of any given component, creating a dilemma of splitting the reel (without the right tools and software support this can be awasteful exercise) or issuing thewhole reel to stock and hoping that the residualwill someday be returned to stock.Quite often these residual or partial reels simplywind up as part of an uncontrolled shop floor inventory called “WIP”, the bane of everymaterialmanager. Figure 1 shows a Ven diagramof this process.
Sowhat are the consequence of inaccurate inventory andwhat can
intelligent lean do to help? Let’s take these one at a time. Production environments are a study in creative persistence. Deadlines and customer expectations create a culturewhere engineers and operators alike find creativeways to ‘damn the torpedoes…full speed ahead!’ This is allwell and good except for the havocwrecked on the careful accounting ofmaterials and spoilage on the factory floor. Most ERP systems have no idea ofwhichmaterials and how many are inWIP, howmany reels of each PN, orwhether thematerial is loaded on amachine ormounted on a PCB. Sowhen push comes to shove, parts are taken fromwherever they can be found to avoid lines
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fromstopping, compounding the problemall themore. Nowto prevent catastrophe, prudent buyers, fully aware that there are attrition factors at play, always ordermore parts to compensate and insure that the entirework order can be completedwithout delay. But somehowparts disappear, get squirreled away, get ‘borrowed’ for another hot shot job, placed into thewrong bins, all thewhile attrition and spoilage continue unabated and uncounted. The net result is over time, inventories get bloated, factory agility is severely compromised, ESD and RoHS compliance becomes a nightmare, and every quartermanagement can’t believe themagnitude ofmaterial write-offs and the sluggish turn time on thematerial investment.
There is a constant loss ofmaterial on the shop f loor that remains blind tomaterial buyers and managers until inventories are reconciled by cycle counts or physical inventory accounting
What does ‘lean’mean to you, the buyer?
When you boil down all the books on the subject it comes down to simply this: waste elimination (time,materials, energy, resources, etc.) And it’s not just the direct cost of the waste, but also the lost opportunity for profit. Lean operation formaterialsmanagement requires a systemto reduce waste (and account for it explicitly), commit only what is really needed at the precise time and location that it is needed, extend true visibility ofmaterial usage after parts leave the stock room, and systematically, with asmuch automation as possible, feedbackmaterial consumption and spoilage into ERP so that the accuracy of inventory is preserved at all times.When the buyer can track inventory levels accurately and in real time, as can the planning personnel, including not only the aggregate PN quantities and locations, but also the individual reels and theMSD and RoHS status of every reel (and tray), only then can progress bemade tominimize inventory and create a lean agilemanufacturing flow.When this information is available, more value can be created by introducing JIT (just in time) material flow fromthe stock to the SMT lines.
The heartbeat of success is the pull signal
The intelligence of this solution is the availability and interpretation of the ‘pull signal.’ Pull signals are really simple, such as when your body gets thirsty, you drink something. The pull signal is the thirst
www.electronics-sourcing.eu
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