Page 38 - MetalForming March 2014

Ready; Set; Lean
that the next operation is ready to receive material. This kind of pull- through process contrasts with push- production formats, in which a pur- chase order or shop order authorizes suppliers (external or internal) to deliv- er raw materials or work in process to the shop floor location on a predeter- mined date—ready or not.
In general, good management will limit the number of kanbans to provide an acceptable amount of inventory in the system. Then, by using trial and error to gradually reduce the number of kanbans, managers can fine-tune JIT throughput by identifying manufac- turing constraints and prioritizing logistics. This process will optimize production and minimize the amount of raw material and WIP in the system.
Case Study: PM-Luft
Swedish manufacturer PM-Luft (grain coolers and rice conditioners) has slashed lead times in product assembly by 20 to 40 percent, while
reducing WIP proportionately. How? By using kanban practices in concert with a newly installed Salvagnini order- processing system (OPS) and two new flexible manufacturing systems (FMS). Each FMS features two storage towers, a robot unloader and conveyors. And, while the new systems were reducing manufacturing time and costs, product quality improved.
For years the company had strug- gled with high WIP costs and long setup times related to batch production. Now it has begun the transition toward worldclass manufacturing.
PM-Luft employs a simple form of kanban based on barcodes. Each empty container entering the assembly line carries a barcode label containing all of the program information for processing a specific part. An inline barcode read- er automatically reads the code on the tote, signaling the automatic produc- tion of a predetermined number of parts by its punching/shearing machines and panel benders. When
the program is opened, the following sequence occurs:
1) Previously specified material enters the sheetmetal-processing line from one of the two material-storage towers.
2) The individual sheets are deliv- ered to the line in a single piece-part flow and in a mixed-model fashion.
3) Once the appropriate material is introduced into the punch-shear com- bination machine, it automatically is centered, punched and sheared before it moves on to the next operation.
4) Depending on the production information in the program, the part is assigned to the automatic stacker, sort- ed into bins (if small parts) or sent on to the panel bender.
When the punch-shear machine sends a part number directly to the panel bender, the tooling setup in the bending machine will be ready for all required bending operations. This brings setup time to exactly the level desired—0 sec.
36 MetalForming/March 2014
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