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What is Lean?

The main core of Lean Manufacturing is

about eliminating wastes in the business

process. The eight non-value adding

wastes are

1. Overproduction

2. Waiting

3. Unnecessary Transport

4. Over processing

5. Excess Inventory

6. Unnecessary Movement

7. Defects

8. Unused Employee Creativity.

The journey of Lean Production System

which is an offshoot of Toyota Produc-

tion System has two key aspects to it.

One aspect deals with the technical side

of Manufacturing and the other aspect

deals with the softer, People manage-

ment side of it. While the latter is the

most important aspect of Lean, this arti-

cle deals with only the technical aspects

of Lean with few examples

Inventory Reduction

Lean Manufacturing proposes a signal

system to ensure that inventories are

maintained low in the company. Ideally,

Zero Inventory is the best, but is not

possible given the lead times for manu-

facturing products and minimum batch

quantities required for certain proc-

Examples of Lean Manufacturing Systems in Job Shops

Read this article online at http://www.ezinemart.com/ibm

Indo-MIM, world leader in supply of Metal Injection Moulded Components produces close to 1000 varieties

of parts in a quarter. The sales quantities of each of these parts vary from 1000 pieces a month to close to

20 lakh pieces a month. This article discusses the basic principles of Lean and examples of how few con-

cepts of Lean have been implemented in Indo-MIM factory.

Dr. T S Shivashankar Ph D Vice President OperationsIndo-US MIM Tec Pvt Limited

28 industrial business MART July 2012

esses. The signal system is referred to as

“Kanban”. Kanban can be a signboard,

a card, a token or an empty bin. kanban

system of signaling production of a

product is similar to the Fuel Indicators

in the car. Once the fuel levels comes

down, the yellow light in the car blinks

indicating that fuel will last only few

more kilometers and one has to fill the

tank. Today, we have automatic water

regulators in our water tanks which

kick in the motor when the level goes

below the last mark in the tank. Kanban

system is all about replenishing or

producing goods “Just in Time” and not

“way ahead of time”. Given below is a

pictorial representation of what happens

when the inventory levels at Finished

Goods Store goes down.

Kanban systems should be implemented

Figure 1: The shaded zone represents acceptable levels of inventory and is divided into three segments.

As soon as the levels of inventory reaches the segment 1, a Green token is issued to the starting step of

the process (in this case Moulding) indicating that inventory had depleted by one segment. When the

level comes to segment 2, a yellow token is issued. The Molding department either starts production

as soon as they receive Green Token or yellow token or can wait depending on how occupied they are

at the time of receiving the token. But moment the red token is issued, it’s clear that production has

to start immediately. The minimum level of inventory is chosen depending on the consumption and

lead time to manufacture the product.

July 2012 industrial business MART 29

for orders that are routine, where design

changes do not happen along the year.

Before implanting Kanban, it’s important

that customer knows that you are imple-

menting Kanban system and customer

will buy any inventory that’s available

within the kanban limits when product

become obsolete.

Avoiding Overproduction

Over Production or Producing ahead of

time is the other waste that happens in

all factories. One common mistake is to

allow the plant to follow the “Forecasts”

published by Sales department. . Three

things can happen when one builds

based on forecasts and at the same

time the customer is not involved in

that decision. 1) The design can change

anytime 2) Customer may close the

model on which your part was used and

parts become obsolete. 3) Customer

might find another supplier for the same

part. At the end of the month, soon one

would realize that many “forecasts”

didn’t have orders to ship and sales

people were promised by the customer

that orders would arrive just as they fin-

ish the product. Another mistake usually

performed by manufacturing head in

times of slow down is to produce parts

for inventory without any commitment

from customer. Building to a forecast as

Figure 2: Pictorial Representation of differences between Batch Processing and Con-

tinuous Single Piece Flow Processing inside a Cell.

Pneumatic Press Department

Secondary Cells (20 cells), each cell consisting of Pneumatic Presses, Drilling machine,

Toggle Press and Inspection table facilitating Single Piece Flow.

Figure3: Picture of Secondary Operations Department at Indo MIM before and after the implementa-

tion of Cells. Similar machines that were grouped earlier (top three pictures) were made flexible and

combined to form a single Secondary cell – placed next to each other (bottom two pictures). The

Press being heavier cannot be moved, while drilling machines, toggle presses and inspection tables are

on wheels that can be moved at will to create a Cell around the heavier press. Pictures Courtesy Ujwal

and P Barghi

Drilling Department Toggle Press Department

against an order gives the management

a false sense of continued activity in

the plant, while the customer’s demand

is not there.The good intentions of

keeping “machines” and “people” oc-

cupied doesn’t help since goods are not

sold. Taiichi Ohno, the Chief Architect

at Toyota believed that if one has more

inventory at the plant, it is likely that it’s

a wrong inventory. How many times we

have seen that happen in our factories?

In Lean manufacturing, machines can

be idle, but it’s a crime to keep people

and material idle and waiting. In times

of slowdown, the best way to keep-

ing people busy is to use their creative

minds and run more kaizens/continuous

improvement projects rather than make

them run the machines for the sake of

running.


Single Piece Flow – the core to Lean Manufacturing

Next common tool that has the greatest benefit in

making companies lean is the Single Piece Flow. It’s

probably the tool that’s requires lot of thinking and

willpower to implement in shop floor. Single Piece

Flow is nothing but manufacturing single piece at a

time- the entire chain from start to finish. Imagine

a part involving CNC milling, followed by a surface

grinding, followed by an assembly with a mating part

and then inspection and then final packaging.

In Traditional mass production thinking, similar

machines and similarly skilled people are grouped

together. Mass Production thinking sets up depart-

ments of CNC milling machines, Grinding sections,

Pressing and Inspection – all separate. The perceived

benefits of grouping skilled people and equipment

together are 1) Economies of Scale and 2) Apparent

Flexibility in Scheduling (since CNC Milling manager

can schedule his work well when all machines are in

one place). Once the similar machines are grouped,

material handling department moves material once

a certain batch is completed in one department and

then moves to another department.

Lean Thinking looks at the above methodology as

producing “Lots of Inventory or WIP”. As said earlier,

material sitting in one department is a fundamental

waste in Lean. The solution is to un-group similar

machines and mixing all departments into one and

physically having all machines in a serial fashion- one

by one. As shown in the figure, single part moves

from process A to Process B and then to C and ma-

chines that are used to do processes A, B and C are

just placed next to each other.

Advantages of Single Piece Flow

Single piece flow helps in 1) Improving quality, 2) Re-

ducing inventory 3) Reducing lead times 4) Reducing

floor space and 5) Reducing unnecessary transporta-

tion or Movement

The transition from traditional batch processing to

Single Piece Flow is usually dealt with lot of skepti-

cism and resistance. However, the benefits are usu-

ally huge. One important effect is that one can have

better control on quality and a sense of order prevails

when parts are produced via a single piece flow than

July 2012 industrial business MART 31

Figure 4: A manual 100% inspection line for a turbocharger vane. At the end of the Inspection line is the locked box fitted with a carbide gauge that

doesn’t allow an un-machined parts to reach customer. Single piece flow while doing 100% inspection is essential to ensure zero defects. Transparent

“scrap boxes” placed in�

Locked Drop

Box, or a Hundi

Gauge

Figure 5: Feedstock Inventory in Tons in Compounding Department. Data courtesy Laxminarayana, Indo MIM, HSK Plant

as a batch. Source Inspection and Poke

Yoke which are important to get to zero

defects are easily implementable in a sin-

gle piece flow method than on a batch

processing method. Since the operators

or persons doing the job almost stand or

sit next to each other in a “single piece

flow”, the inspection and reworks are

part of the cell.

Visual Factory

Similar to one in the Kanban, visual

charts and tables are important tools

that small job shops can use to display

key metrics. The visual factory helps

operators, supervisors and the managers

see the same data in one place as one

walks in the shop floor.

This is lot different than what one sees in

a power point presentation during Man-

agement Review Meetings that are held

once in three months. Daily display with

actual status and the target makes peo-

ple think of ways of achieving the target.

Discipline in entering the data periodi-

cally is important and top management

has to drive this.


Figure 6: Top Table showing the 6S scores of Various Departments in the first Quarter of 2012.

Below picture shows Secondary Processing Department personnel exulting after winning the 6S

trophy for the month of March 2012. Data and Picture, courtesy Arun Balan, Indo- MIM

Two such Visual Boards are explained

below. One is the Inventory Board at

Compounding Department and the

other is the 6S (6th S stands for Safety)

scores of various departments. The good

thing about the Inventory Chart is that

one can see daily values in the graph

plus the average monthly, yearly values

in the table next to the sheet. The trends

are important and the trends have to be

seen in perspective when one looks at

the graph as well. The inventory target

line of 3 tons is far away from the actual,

but the compounding department has

over the years reduced the inventory

slowly by 4 tons in the last two years.

Conclusion

The journey of Lean Manufacturing is a

continuous one and more importantly a

joyful one. The principles are broad, but

the actions can be quite unique to a par-

ticular organization. The small success

that the team or a group or a company

experiences during the Lean Journey

motivates them to do more next time.

The concept of Lean is today more

important to Small and Medium Enter-

prises (SME) than Large Enterprises.

Importantly, Lean as a philosophy makes

a company a Learning Organization.

Fuji Cho, Former President, Toyota Mo-

tor Corporation says this very nicely

“We Place the highest value on action

implementation and taking action.

There are many things one doesn’t

understand and therefore, we ask them

why don’t you just go ahead and take

action; try to do something? You realize

how little you know and you face own

failures and you simply can correct those

failures and redo it again and at the

second trial you realize another mistake

or another thing you didn’t like so you

can redo it once again. So by constant

improvement or should I say, the im-

provement based upon action, one can

rise to the higher level of practice and

knowledge”

The author Dr. T S Shivashankar Ph.D is

the Vice President Operation of Indo US

MIM Tec Pvt Limited, Hoskote,Bangalore

- 562114. He can be contacted at

[email protected]


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