1. The Revolution of Just-In-Time (JIT) and Lean 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. Institutionalizing the JIT practice through the KANBAN-based Production Authorization Mechanism
Station 1
Station 2
Station 3
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?
Station 1
Station 2
Station 3
FGI
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.