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Operations Planning - Ch15.docx

5 Pages

Global Management Studies
Course Code
GMS 401
Sam Lampropoulos

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GMS 401 -Chapter 15- Operations Planning Introduction Just-in-time (or little JIT): Production system in which processing and movement of parts/modules/work- in-process occur just as they are needed, usually in small batches  In a broader sense, JIT also called big JIT, is a philosophy of “waste” reduction, be it inventory or resources (such as workers, equipment, or floor space), and continuous improvement. In this sense JIT is identical to  lean production: JIT in a broad sense, is a philosophy of waste reduction and continuous improvement  JIT, in the narrower sense, is sometimes contrasted with material requirements planning (MRP). MRP relies on computer-based component scheduling system to trigger and push production through the process, whereas JIT relies on visual signals to trigger and “pull” production and deliveries through the process  JIT controls the inventory through kanbans Overview JIT/ Lean Goals & Building Blocks Ultimate Goal: A balance rapid flow Eliminate disruptions: Make the system flexible Kaizen (CI): Eliminate waste Product Design Process Design Personal Elements Planning and Control The Goals 1. A Balance Rapid Flow: A balanced rapid flow of a family of products is a smooth, even, swift flow of materials, information, or work through the steps of the production process 2. Eliminate of disruptions: Disruptions upset smooth flow of products through the production system and cause variability 3. System Flexibility: A flexible system is one that is robust enough to handle a mix of products and changes in the level output, while still maintaining balance and throughput speed 4. Elimination of Waste: Waste represents unproductive resources. Examples: Overproduction, unnecessary inventory, waiting, overprocessing, inefficient work methods/excess motions 5. Continuous Improvement: kaizen is continual work to improve the system. Kaizen is based on the following: a. Improvement should be done gradually and continuously b. Everyone should be involved c. It does not require spending great sums of money on technology or consultants d. It can be applied anywhere e. It involves learning by doing, using scientific thinking f. Relies on direct observation and data collection Sources of Waste  Overproduction  Over processing  Product details  Unnecessary transportation  Unnecessary inventory  Inefficient work methods  Waiting time  Employee underutilization Building Blocks Product Design Build in Quality  QFD (Quality Function Deploytions) should be used to capture the voice of customers and deploy it in the product design  Products should be designed for easy manufacturing and assembly (DFM and DFA) This speeds up the operations  Concurrent engineering Process Design 1. A Balanced System  In a balanced system, workload is distributed evenly among workstations  Takt time: The maximum time allowed at each workstation to complete its set of task on a unit. Also called cycle time GMS 401 -Chapter 15- Operations Planning  The procedure for obtaining the takt time is:  Determine the net time available per shift by substracting any non-productive time from total shift time  If there is more than one shift per day, multiply the net time per shift by the number of shifts to obtain the net available time per day  Calculate takt time by dividing the net available time by demand during the day  See example on page 552 2. Flexible System  Techniques:  Reduce changeover (=setup) time  Cross-train workers  Use many small machines rather than few large machines  Use safety stocks  Keep some idle capacity 3. Small Lot Sizes  Benefits of Small Lot Sizes  Optimal Lot Size =1  Less WIP inventory – less cost, space needed clutter  Less rework and inspection  More system flexibility – quicker response to changes 4. Setup Time Reduction  Small lots and changing product mixes require frequent machine setuos – requires quick inexpensive setups  In JIT/lean systems, workers are often trained to do their own setups  Group technology may be used to reduce setup cost and time  Multipurpose equipment or attachments  Group technology  Streamline setup  Standardize setup procedure  Train operators  Single-minute exchange of die (SMED): A system for reducing changeover time  Separate changeover activities  Internal – activities that can only be done while machine is stopped  External – activities that do not require stopping the machine  make setup activities external where possible 5. Cellular Layout  Many JIT/lean systems have one or more cells. A cell contains the machines and tools needed to process a family of parts that have similar processing requirements  Conversion to a cell layout requires:  Grouping similar products together  Mapping the current process for major products  Determining the operations required  Determining the capacity requirements  Rearranging the layout (usually U-shaped)  Determining the capacity of the cell  Upgrading the machines if the capacity is inadequate  Balancing the cell ad determining labour requirements  Determining minimum WIO required between the machines in the cell Advantages Disadvantages  Faster throughput  The machines may not be fully utilized and  Less material handling bringing various machines close together  Reduced space requirement may arise safety/ergonomic issues  Flexibility to increase/decrease the capacity by adding/subtracting workers 6. Process Quality  Prevent defects:  SPC to control the process GMS 401 -Chapter 15- Operations Planning  Six sigma to reduce variability  Poka-yoke for fool proof  Poka-yoke: any mechanism that helps an equipment operator avoid mistakes. Its purpose is to eliminate product defects by preventing,
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