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The Revolution of Just-In-Time (JIT) and Lean Manufacturing

The Revolution of Just-In-Time (JIT) and Lean Manufacturing. The essence of the JIT revolution and Lean Manufacturing.

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The Revolution of Just-In-Time (JIT) and Lean Manufacturing

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  1. The Revolution of Just-In-Time (JIT) andLean Manufacturing

  2. The essence of the JIT revolution and Lean Manufacturing • Try to reduce the system operational inefficiencies and the resulting waste by identifying the sources of these inefficiencies and working proactively to eliminate them as much as possible. • In the emerging philosophy, inventories should be carefully controlled and they should not function as the mechanism for accommodating the system inefficiencies => Just-In-Time (JIT) • The aforementioned effort should be an ongoing process towards continuous improvement rather than one-time/shot effort.

  3. Targeting the sources of inefficiency • input • unreliable quality of raw material • unreliable delivery times • operation • unreliable processes in terms of • required processing times • process outcome • complex interacting process flows • long set-up times • unreliable (irresponsive and irresponsible) personnel • output • Highly variable production requirements in terms of • production volume, and • production scope

  4. JIT enabling factors and practices • Emphasis on quality at both the process and the supply side by promoting • Statistical Process Control (SPC) theory and practice • Quality certification programs • Deployment of stable automated processes and foolproof practices (like checklists and machines gauges) to guarantee the desired performance • Employee empowerment and knowledge management (quality circles) • “Tightening” of the supply chain by promoting • Long-lasting and trustful relationships between the different parties in the supply chain • Timely and reliable information flow across these parties that takes advantage of modern IT technologies, like • Electronic Data Interchange (EDI), and e-commerce practices • Real-time communications and global positioning systems • Promotion of vendor owned and managed inventory practices that • Establish economies of scale and protection to variability through pooling • Enhance the demand visibility across the entire supply chain.

  5. JIT enabling factors and practices (cont.) • Simplification of the process flows by promoting cellular manufacturing practices • Dedication of separate production cells to product families with similar processing requirements • U-shaped layouts for facilitating employee sharing • Employee cross-training for more flexible and higher utilization • Set-up time reduction through • The adoption of cellular manufacturing • Externalization of set-up times • Employment of flexible processes and pertinent auxiliary equipment like pertinent fixtures • Part standardization • Focus on repetitive manufacturing and promote the establishment of stable production rates through • Smoothing of the aggregate production requirements by appropriate quota setting • Pertinent sequencing of the final assembly to support a desired product mix • Use of buffer capacity (planned overtime) to protect against slippages from the target production rates • Component standardization

  6. Station 1 Station 2 Station 3 Institutionalizing the JIT practice through the KANBAN-based Production Authorization Mechanism • Remarks: • The KANBANS at each station cap the WIP at that station and they offer a natural • mechanism for reacting to various disruptions taking place in the system operation. • In particular, production at each station is “pulled” as a result of the downstream • activity rather than “pushed” by an MPS-generated schedule. • The KANBANS at each station should be set at a level that enables production • at the target rate • A safe approach to set the KANBAN level at each station is by setting it initially to • the “historical” WIP level, and subsequently decrease it incrementally while • observing its impact on the production rate • Frequent KANBAN changes are ineffective, since the production rate of the line is • rather insensitive to these changes, and they should be avoided

  7. FGI Station 1 Station 2 Station 3 From KANBAN to CONWIP • Why? • It maintains the WIP cap but at the same time it offers more operational flexibility than • KANBAN. • The unrestricted flow of WIP within the line enables better utilization of the (shifting) • bottleneck, and therefore, higher throughput. • Less stress for the line operators since it enables them to work at the “natural pace” of the line. • It enables more flexible scheduling of the line, since in the CONWIP operational context, • WIP is interpreted more generally as some aggregate amount of workload loaded into • the line (even measured in time-units, rather than number of parts) – new parts are pulled from • an available “work backlog” according to a pertinent set of dispatching rules. • Easier to analyze and parameterize through the theory of closed-queueing networks. • Remark: While the above features of CONWIP mitigate the rigidity of the KANBAN-based • shop-floor control, its “pull” nature still implies that it requires stable target production rates • in order to function well, and therefore, it is appropriate for repetitive manufacturing contexts.

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