LEAN system & Six Sigma

Lecture 6.

Value

That customer is willing to pay

That changes products color, function, shape, other attributes so that the product is getting closer to the customers requirements

That we do right at first time

Wastes

Those processes which directly do not create value for customers (muda, mura, muri) : that are not necessary, and must be eliminated That are necessary, because these are

supporting value-add processes, cannot be eliminated (like transporting)

Muda – 7 wastes of lean Mura – not leveled workflow Muri – overloading of workers and assets

Lean thinking

Operation

Traditional improvement

Lean improvement

Non value-add process

Value-add process

Supporting goals

A balanced system, smooth, rapid flow of materials and/or work

Supporting goals: Eliminate disruption Make the system flexible eliminate waste,

especially exess inventory

There are 7 wastes in LEAN (TIMWOOD): Inventory Overproduction Waiting Unnecessary

transportation Processing waste Inefficient work methods Defects

Tools of LEAN relating to quality

Quality improvement - Jidoka

Autonomation – automatic detection of defects during production.

It consist two activities: One for detecting defects when they occure Another for stopping production to correct the cuase of defects.

Fail- Safe methods – Poka Yoke Methods:

The contact method identifies product defects by testing the product's shape, size, color, or other physical attributes.

The fixed-value (or constant number) method alerts the operator if a certain number of movements are not made.

The motion-step (or sequence) method determines whether the prescribed steps of the process have been followed.

Kanban Production Control System Kanban is the Japanese

word meaning “signal” or “visible record” Sign to produce

Sign to transport

Paperless production control system

Preventive maintenance and housekeeping 5S

Sort –decide which item is needed

Straighten – needed items can be assessed quickly

Sweep – clean workplace Standardize – use

standard intructions Self discipline – make

sure that employees understand the need for uncluttered workplace

Six Sigma

mean

3σ3σ

LSL USL

3 sigma process 1 sigma process

LSL USL

6σ6σ

mean

5% is out of limits!

1 σ – 691 462 ppm

2 σ – 308 538 ppm

3 σ – 66 807 ppm

4 σ – 6 210 ppm

5 σ – 233 ppm

6 σ – 3,4 ppm

DMAIC Define Measure Analyze Improve Control

Plan Do Check Act

PDCA

Six Sigma Project Risk Worksheet

Six Sigma Project Return

Project Risk and Return matrix

0 10 20 30 40 50 60 70 80 90 100 Risk factor

100

90

80

70

60

50

40

30

20

10

0

STARS

LOW-HANGING FRIUTS DOGS

?

Rw

turn factor

XY matrix

Inputs and outputs Determine which input is the most important

to focus on

TAGUCHI DESIGN EXPERIMENT (DOE) Robust Design – select technology Parameter Design – set parameters which

affect quality Tolerance Design – improve the quality if

parameter design doesn’t work

Definition of quality – loss to society

QLF (Qualtiy Loss Function)

L=K*V2

K – constant, and V2- mean squared dviation from target value

K=C/T2

C - unit repair cost T – tolerance interval

Target valueLSL USL

Exercise - QLF

Suppose the cost to repair a radiator on an automobile is $200. Compute the QLF for losses incurred as a result of a deviation from target setting where a tolerance of 6±0,5 mm is required and the mean squared deviation from target is (1/6)2.

Solution: K=200/0,52=800 L=K*V2=800*(1/6)2=$22,22/unit

TAGUCHI PROCESS 1. Problem identification 2. Brainstorming session

identify factors, its settings, interactions, Control factor Noise factor

Identify objectives The less is better Nominal is best The more is the better

Experimental design Offline experimentation (number of replications)

Experimentation Orthogonal array (determined by the number of factors and levels) Record the result Compute average performance for each factor Showing the best outcomes

Analysis (which level of each factor is the proper one) Confirming experiment (validate results)

Thank you for your attention!