Analysis and Improvement of Flow - Delays in the Processes - Part of Flow Process Chart Analysis

Lesson 156 of  Industrial Engineering ONLINE Course.

Sub-Module - Analysis of Flow - Delays in Processes

Flow is one of the five principles of lean systems.  The other four are specify value, lineup value-creating actions in the best sequence,, conduct the actions without interruption, pull (do actions only when someone requests them), and improve the actions or perform them more and more effectively and efficiently.

Lean thinking provides a way to do more and more with less and less - less human effort, less equipment, less time and less space-while coming closer and closer to providing customer with exactly what they want.

Lesson

156 - Analysis of Flow -  Delays in the Processes - Part of Flow Process Chart Analysis

157 - The SMED System: Shigeo Shingo's Detailed Explanation

158 - Zero Defect Movement and Six Sigma Method (Elimination of inventory and delays)

159 - Total Productive Maintenance - Japan Management Association ( Zero Breakdowns - Elimination of inventory and delays)

160 - Quality Management and Total Quality Management ( Zero Defects - Elimination of inventory, rework and delays)

161 - Learning to See: Inventories (Delays) Between Processes - Value Stream Mapping

162 - News - Information for Analysis of Delays in Processes

Industrial engineer analyzes each process into its ultimate, simple elements, and compares each of these simplest steps or processes with an ideal or perfect condition and modifies the element appropriately. - F.W. Taylor - Hugo Diemer.

Prof. Hugo Diemer  - Taylor's Industrial Engineering

https://nraoiekc.blogspot.com/2020/05/prof-hugo-diemer-taylors-industrial.html

For process improvement, process chart method was explained by F.W. Gilbreth in 1921. The process chart method was included in motion study text books Industrial engineering authors and it was not made an independent subject. It is a weakness of industrial engineering even today. Even though AIIE, started by the active involvement of Georgia Tech. faculty defined IE as Design, Installation and Improvement of Systems, it did not develop proper curriculum for IE in any of these three areas. Process improvement could have been made an independent area. That would have developed the process chart method into a detailed procedure that would have resulted in improvement of material processing operations, inspection operations, transport operations, storage operations and production planning operations.

In this online course, in process industrial engineering module, lessons 78 to 118 discuss analysis and productivity engineering of material processing activities. Lessons 126 to 132 explain inspection operations analysis. Lessons 136 to 141 focus on analysis of transport operations. In lessons 146 to 149, storage and warehousing operations are covered. Lesson 156, the current lesson starts discussion of analysis of delays.

Value stream mapping, a chart explained in detail by Rother and Shook highlights inventory between processes, which is basically delay in material flow.

Value Stream Mapping activity done with stick-notes

1. Identify the steps of  the process using stick-notes. For  the steps that are Non-Value Add use pink sticky-notes, For Business-Value-Add steps use light blue.  For Value-Added steps use light green-and also show a tick.

2.      Determine the step process time and write it on a dark green note below the step. 

3.      Find the wait or delay time between steps and note it on red sticky-notes. 

Paul Deane

https://www.linkedin.com/posts/paul-deane-85844789_value-stream-mapping-activity-done-with-stick-notes-activity-6984396670855774209-7Svk 

I now feel production planning and control is a component of process chart analysis as far as process improvement is concerned. Industrial engineers have to improve production planning routines as part of process chart analysis. Such an emphasis is not there in IE curriculum, as process chart is method is taught in work study or time and motion study courses.

Shigeo Shingo provided the description of elimination of delays in Toyota Production System (TPS) with generalized principles.

Eliminating - Storage Operations (Delay)

Process Delay – Permanent storage – Whole lot is waiting
Lot Delays – Temporary storage – One item is being processed. Other items in the lot waiting.

Another classification is storage on the factory floor and storage in a controlled store.

Eliminating - Storage Operations (Delay)

There are three types of accumulations between processes:

E storage - Storage due to Expected Difference between supply capacity and demand resulting from unbalanced flow between processes  (engineering)

C storage - Cushion Stock - buffer or cushion stock to avoid delay in subsequent processes due to machine breakdowns or rejects (control)
S storage - Safety Stock; overproduction beyond what is required for current control purposes

Eliminating E-Storage

E-storage is due to engineering/planning/design of the production-distribution  system
This can be eliminated through leveling quantities, which refers to balancing flow between high and low capacity processes and synchronization.

Leveling would mean running high-capacity machines at less than 100% capacity, in order to match flow with lower capacity machines that are already running at 100% on short interval basis.
At Toyota, the quantity to be produced is determined solely by order requirements (Takt time).

Principle
Presence of high capacity machines should not be used to justify large lot processing and resulting inventory.
Process capacity should serve customer requirements/production requirements and should not determine them

synchronization.
The lots especially one piece lot is processed without delay in a flow.
It is efficient production scheduling that ensures that once quantities are leveled (output is matched), inventories do not pile at any stage due to scheduling conflicts.
Synchronize the entire process flow.

Eliminating C storage - Cushion Stocks 

Cushion stocks compensate for:
machine breakdowns,
defective products,
downtime for tool and die changes and
sudden changes in production scheduling.


Eliminate Cushion stocks

Prevent machine breakdowns:
Determining the cause of machine failure at the time it occurs, even if it means shutting down the line temporarily.
Total Productive Maintenance movement.
Total Productive Maintenance - Japan Management Association

Zero Defect Movement.  (Zero Defect Movement and Six Sigma Method)
Total quality management. (Quality Management and Total Quality Management)

Use better inspection processes:
Self Inspection.
Successive Inspection.

Enhancement to inspection through Poka Yoke

Poka-Yoke - Shigeo Shingo

Eliminate Lengthy setups and tool changes
Implement SMED to eliminate long set-up times and tool changes
Running smaller batch sizes to allow for quick changes in production plans

The SMED System: Shigeo Shingo's Explanation


Absorb Change in Production Plan
Running smaller batch sizes allows for quick changes in production plans without disturbing flow production to significant extent.

Eliminating Safety (S) storage

Safety stock is kept not to take care of any predicted problem but to provide additional security
It may guard against delivery delays, scheduling errors, indefinite production schedules, etc.
Ex. 10 Delivery to stores
In example 2.10 Shingo mentions a company wherein vendors supply to store and from store components are supplied to assembly line.
Shingo suggested that vendors should directly supply the day’s requirements to assembly floor and in case of any problem, components in the store can be used.
Less Need for Safety Stock Observed
That practice led to the observation that very less safety stock is needed in the store.

Shingo recommends keeping a small controlled stock that is only used when the daily or hourly scheduled delivery fails or falls behind.
In case of unexpected defects also it can be used.


The safety stock can then be replenished when the scheduled materials arrive, but the supply of materials due for the process go directly to the line, rather than normally going into storage first.
This is the essence of the just-in-time supply method.


Eliminating lot delays
While lots are processed, the entire lot, except for the one piece being processed, is in storage (is idle).
The greatest reduction in production time can be achieved when transport lot sizes are reduced to just one; the piece that was just worked on.

SMED
Using SMED (single-minute exchange of dies), set up time is decreased so large lot sizes are no longer necessary to achieve machine operating efficiencies.
SMED facilitates one item lot sizes.

The SMED System: Shigeo Shingo's Explanation

Layout Improvement - Flow
Transportation changes can be accomplished through flow  layout and using gravity feed Chutes which result in shorter production cycles and decreases in transport man-hours.

Reducing Cycle Time
Generally, semi-processed parts are held between processes 80% of the time in a production cycle time.
It quantity leveling is used and synchronization of flow is created, the cycle time can be reduced by 80%.
By shifting to small lot sizes will further reduce cycle time.

Bibliography - Analysis of Delays

ANALYSIS OF PROJECT CONSTRUCTION DELAY

https://core.ac.uk/download/pdf/304293989.pdf

II : Time Waste And Delays In Construction Projects

https://www.nicmar.ac.in/pdf/2012/Oct-Dec%202012/07%20Communication%20II%20-%20Time%20Waste%20And%20Delays%20In%20Construction%20Projects.pdf

What Is a Bottleneck and How to Deal With It?

Bottlenecks are the reason why your projects are costly and slow. Learn how to find and resolve process bottlenecks to establish a smooth, predictable flow.

https://kanbanize.com/lean-management/pull/what-is-bottleneck

Identifying the Root Causes to the Delays and Exceptions in Your Processes

https://info.aiim.org/aiim-blog/identifying-the-root-causes-to-the-delays-and-exceptions-in-your-processes

Predicting and Diagnosing Delays in a Workflow Environment

http://eia.udg.es/~apla/workflow.pdf

Investigating the impact of lean philosophy for identification causes of  delays in the processes in the entire system. 

https://www.diva-portal.org/smash/get/diva2:1442318/FULLTEXT01.pdf

Analysis of time delays - scheduled and unscheduled.

https://www.tandfonline.com/doi/full/10.1080/00051144.2019.1687194

Review of Delay Analysis Methods

https://openconstructionbuildingtechnologyjournal.com/VOLUME/3/PAGE/81/PDF/

Study of Flight Departure Delay and Causal Factors

https://www.hindawi.com/journals/jat/2019/3525912/

DD Form 1723, Flow Process Chart, September 1976  

DIFFERENCE. TIME. NO. NO. 11. ORGANIZATION. OPERATIONS. TRANSPORTATIONS. INSPECTIONS. DELAYS. STORAGES. DISTANCE TRAVELED.

https://www.esd.whs.mil/Portals/54/Documents/DD/forms/dd/dd1723.pdf

developing computer-based schedule delay analysis methods

https://journals.vgtu.lt/index.php/JCEM/article/download/3925/3333

Work Simplification - Navy Training Course

https://books.google.co.in/books?id=4W7tq_D6lRgC&pg=PA43#v=onepage&q&f=false

Flow Process Charting - Air Force Management Engineering Training

https://books.google.co.in/books?id=IrME8HT-v8kC&pg=PA91#v=onepage&q&f=false

A Robust Aggregation Approach To Simplification Of Manufacturing Flow Line Models

Paul Savory, University of Nebraska at LincolnFollow

11-1993

Presentation: presentation slides for doctoral defense presentation

https://digitalcommons.unl.edu/imsepresentations/1/

Ud. 24.6.2023,  26.5.203, 27.6.2022

Pub 8.10.2021