Discover Improvement Potential
Step 2: Analyze Current Methods
5.2 Basic Analysis Methods
5.2.6 Material Flow Analysis
The sixth and final analysis technique we introduce is known as material-and-information-flow analysis inside Toyota. A popular version of this topic widely practiced outside Toyota recently is called value stream mapping. For all intents and
purposes, the terms can be used interchangeably and relate to the same concept. Early forms of the technique exist in industrial engineering as well, as we mention. As with standardized work, full justice cannot be done to the topic of material flow analysis in this limited space. However, we highlight its basic concept and suggest its most effective uses.
The concept of lead time and reducing the time it takes from receipt of customer order until delivery of product and ultimately receipt of payment is an extremely important concept in the Toyota Production System (Figure 5.25). For this reason, the topic of lead time is frequently studied and considered an appropriate topic for Kaizen.
Industrial engineers for many years expressed production flow as existing in one of the following areas: operation, transportation, inspection, and either delay or storage.
Simple process flow charts have been used in operations for decades. Allan Mogenson, who is known as the father of work simplification, stated the following in 1932 regarding process flow charts: “In order to achieve measurement, tools are needed and the most important of these is the process chart. Once a process chart has been drawn up, common sense is all that is needed to improve efficiency and better the process being examined. The process chart then, is the lifeblood of work simplification. It is an irreplaceable tool. It is a guide and stimulant. It takes time to properly utilize but there is absolutely no doubt that it works.”8
Figure 5.25 Lead-time reduction emphasis in the Toyota Production System.
Frank Gilbreth of motion analysis fame also is also credited with introducing flow charts as a structured way for documenting process flow in a presentation to the American Society for Mechanical Engineers in 1921.9The basic process flow chart symbols referenced in Figure 5.26 were used in conjunction with the Flow Process Chart in Industrial Engineering. Figure 5.27 is an example of a generic order flow process in a 1944 Production Handbook.10
This document was used to track the flow of a mail order in a structured fashion and highlight the different problems that might occur in production along the way. The symbols were mapped to represent the flow of the part or process under observation, and to the right side of the form observations were noted. In total, 12 operational steps were recorded, with 4 transportation moves, 3 inspections, and 5 delays. In the legend in the upper left hand corner the 5W 1H (Who, What, Where, When, Why, & How) was listed for questioning
purposes. On the right side of the form under “possibilities”
and earlier alternative form of the ECRS (Eliminate, Combine, Rearrange, Simplify) framework was used to identify potential areas for improvement. This version uses eliminate, combine, sequence, place, person, and improvement.
Figure 5.26 Traditional process analysis symbols.
Figure 5.27 Sample work flow process chart.
This form is not widely used anymore; however, it still represents an effective way to map a series of steps, classify the items into categories, and specify the details. Each step can then become the focus of further analysis for improvement potential. Production-related work as well as office-related tasks and the like can make use of this fundamental analysis technique.
In Toyota, this type of format gave way to an internally developed document used for what is known as material-and-information-flow analysis. The previous form was highly useful in many instances, but it lacked any linkage to the element of time required to complete the tasks from start to finish (e.g., lead time). As an adaptation, the Toyota version of flow analysis instead looked more closely at the time it took for a product to move from raw materials to finished goods (Figure 5.28). In addition to highlighting the process flow of the product, equal attention was given to the flow of information and time required. Different symbols were also developed and added to represent inventory, types of information flow, and scheduling systems.
The bottom of the material-and-information-flow analysis form highlighted the time component of the equation.
Processing time was compared to nonprocessing time for eye-opening purposes. Typically, it might take days or weeks for items to flow from raw material to finished goods, yet the actual processing time was measured in minutes. Key points to consider in a diagram of this type include: Where is there too much inventory? Why are delays occurring? Where are we pushing product instead of pulling production? What type of signals are used for scheduling and conveyance? How and where can production be leveled more effectively? What are
the chief system inhibitors? The items can then become the focus of improvement activities to aid the flow of the overall system (Figure 5.29).
Figure 5.28 Toyota material and information flow analysis before.
The goal and chief strength of the Toyota style of flow analysis is the focus on reducing the lead time of the production system measured. In particular, this style of analysis strongly highlights the wastes of overproduction, unnecessary conveyance, and inventory in the Toyota Production System. Hence, this technique is an important tool since it covers what many have called the most sinful of all wastes: overproduction.
In terms of weakness, it can be argued that the material flow analysis tool is high level and does not provide adequately detailed information. It lacks drill down into types of problems such as quality, downtime, labor, or machine productivity. However, in fairness, that was never the design intent of the tool, and there is no reason that these analyses cannot be done in conjunction as needed.
Figure 5.29 Toyota material and information flow analysis after.
As a general point of view, we suggest using this type of flow analysis as the 10,000-foot level framing mechanism for a product family or series of operation. The material and
information flow can highlight the breadth and scope of high-level problems. Other analysis techniques discussed can then be used for drilling down into the details of work elements, time, motion, or machines as needed.
5.3 Summary
In this chapter, we covered some of the most basic techniques available for studying the current methods of any process.
Almost all of these techniques have their roots in industrial engineering or related fields. Some of the items have been adapted by Toyota or other various practitioners over the years in creative ways. There is no single analysis technique that will work all of the time. Selection of the right tool for the right situation is part of the Kaizen skills development process.
Other methods exist for specifically analyzing quality or cost, for example, and we encourage you to utilize other analysis techniques familiar to you as well. In the appendix section of this workbook, we reproduce the main forms used in analysis and outline the sample steps for completion of each. Time and practice are the only ways to get better at each, so please begin as soon as you see an opportunity to practice the various techniques.
5.4 Homework Assignment
This chapter represents the most critical step in terms of developing your Kaizen skills. There are six main steps of
Kaizen; however, this chapter on Step 2, which analyzes current methods, is arguably the most important. We suggest practicing each of the techniques outlined here to develop better understanding of each tool and to develop skill in application. Work elements, motion analysis, time study, standardized work, machine losses, and material flow analysis represent fundamental ways to begin studying a process and identifying improvement ideas. Learn to use each, as well as its strengths and weaknesses, and you will be well on your way to becoming proficient in Kaizen.
Notes
1. David Ferfuson, (The Gilbreth Foundation).
http://gilbrethnetwork.tripod.com/bio.html.
2. “Bricklaying Yields to Science for the First Time,” New York Times, April 2, 1911.
3. http://gilbrethnetwork.tripod.com/bio.html
4. Fredrick W. Taylor, The Principles of Scientific Management (Mineola, NY: Dover Publications, Inc., 1998).
This Dover edition, first published in 1998, is an unabridged republication of the volume published by Harper & Brothers, New York and London, in 1911.
5. Frank B. Gilbreth, Primer of Scientific Management (Adamant Media Corporation, 2005). This Elibron Classics Replica Edition is an unabridged facsimile of the edition published in 1914 by D. Van Nostrand Company, New York.
6.Frank B. Gilbreth, Primer of Scientific Management (New York: Van Nostrand, 1912), 7.
7. Hiroaki Satake, Toyota Seisan Houshiki no Seisei, Hatten, Henyou [The Birth, Development, and Transformation of the Toyota Production System] (Toyo Keizai Shinbunshinhousya, Tokyo, Japan, 1998), 18–19.
8. Shigeo Shingo, Koujyou Kaizen No Taikeiteki shikou [Systematic Thinking for Plant Kaizen] (Nikan Kogyo Shinbunsha, Tokyo, Japan, 1979), 12.
9. Interview notes with Katsuya Jibiki, former assistant general manager of Toyota Stamping Department, September 2006, Toyota City, Japan.
10. Flowchart, New World Encyclopedia, http://www.newworldencyclopedia.org/entry/Flowchart.
11. Allan H. Mogensen, Common Sense Applied to Motion and Time Study (New York: McGraw-Hill, 1932).
12. Gordon B. Carson (Editor), Production Handbook (Ronald Press, 1944, revised 1958), Sect. 11, p. 14.