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

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

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


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 gt 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
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
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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