LEAN ENGINEERING

BY

J T. BLACK

DON PHILLIPS

LEAN ENGINEERING

• Mixed Model Final Assembly (Flexibility)

• Lean to Green

• Sub Assembly Cell (Flexibility)

• Cellular Mfg./ Standard work

• Setup Reduction/ SMED

• Integrated Quality/ 6 / 7 tools

• Integrated PM / TPM

• Value Stream Mapping

• Kanban (Inventory & Production control)

• Continuous Improvement (KAIZEN)

• Elimination of Waste

THE LEAN ENGINEER

Lean Tools

Mfg.Cells

VSM

5S

SMED

TPM

MMFA

Zero Defects

Six Sigma Tools

DOE/ Taguchi

Gage R&R

Reliability

QFD

Green Engineering Tools

Environmental

Design

Risk Analysis

Energy Efficient

Design

Social Design

Remanufacturing

Industrial Engineering Tools

Probability & Statistics Production Control TQM Ergonomics

Operations Research Supply Chain Management TPM Human Factors

System Simulation System of Systems Time & Motion Study

“Lean Engineers make things

cheaper, better, faster, in a

green, flexible way”

LEAN ENGINEERING

The Lean Engineer (LE), has an IE foundation, enhanced with lean tools, six sigma capability and a lean to green outlook to take the plant to zero waste going to the landfill. In his (or her) drive to remove waste from the system, the lean engineer’s tool box is filled as follows:

– The design of a mixed model final assembly line to level demand on the supply chain.

– The design of subassembly cells using rabbit chase, sub-cells or TSS to eliminate conveyer lines and line balancing.

– The design of manufacturing cells using existing equipment to eliminate the job shop’s functional design.

– The design of quick change work holder and cutting tool holders for the manufacturing cells.

– The integration of quality tools and defect prevention devices, in-line inspection devices, including poka-yokes and decouplers.

LEAN ENGINEERING CONT…

– The integration of safety devices, walk away switches, automatic unload mechanisms and ergonomic improvements.

– The development of one piece flow processes for operations like painting and heat treatment and inspection.

– The development of machine tools for true lean manufacturing cells, design and built for the manufacturing cells.

– The last step requires lots of creativity and innovation to design and build and implement machine tools for the cells with narrow footprints, rapid tool and work holder exchanges , in-process inspection, rapid unload and load for one-piece flow, good ergo and safety features and one-piece flow operation built around standard work.

LEAN ENGINEERING IN ACADEMICS

• While many IE programs have neglected the lean engineering material and stuck with efforts to optimize the mass production system or parts thereof, over 60% of the manufacturing industries have implemented lean manufacturing.

DESIGN OF THE FACTORY WITH A FUTURE

By designing and implementing this new manufacturing system (factory) design Toyota Motor Company has become the world leader in the automotive industry. The final assembly line in the mass production system is changed into a mixed model final assembly lines, with conveyers, are redesigned into manufacturing cells. Final assembly operates with a Takt Time, and the cells are redesigned into manufacturing cells. Final assembly operates with a Takt Time and to operate on a “Make One –Check one – Move One On (MO – CO – MOO) basis”. Single cycle machine tools are used with built-in devices to check parts (poka-yokes). Between the machines are devices (decouplers) designed to assist standing, walking workers producing the parts in the manufacturing cells.

THE NEW INDUSTRIAL ENGINEER

When the Toyota Motor Company and Taiichi Ohno invented the Toyota Production System, they also redefined the profession of industrial engineering which grew up and flourished with the mass production system. This new engineer, a lean engineer, must be able to design a mixed model final assembly lines for zero defects, design of manufacturing and subassembly cells for one-piece flow, design of tooling (work holding and cutting tools) for rapid changeovers, and implement (pull) production/inventory control system called kanban), all part of the design of the lean manufacturing system.

DESIGN RULES FOR L-CMS

• TT=Hr’s Available in Day/ DD ; where DD is the daily demand

• DD = (No. of cars/month)/(No. of days in Month)

Note PR = Production Rate for final assembly = 1/TT

• MO – C0 – MOO (one piece flow with defect prevention)

• SMED Rules: A methodology for rapid tool and die change

• MTij < NCT, where NCT TT (1- allowance)

• K = (DD × L + SS) / s (Little’s Law, operational Form)

MASS PRODUCTION VS LEAN PRODUCTION

A BRIEF HISTORY OF FACTORY DESIGNS

EARLY FACTORIES

GOING LEANIndustry Segment ‘08 ‘09

Industrial equipment 61% 65%

Food and beverage 45% 52%

Metal Fabrication 68% 68%

Transportation Equipment 42% 70%

Building materials 51% 55%

Plastics 65% 64%

Electronics 61% 67%

Chemicals 55% 59%

Printing, publishing 55% 51%

Medical devices 61% 87%

Total 56% 61%

LEAN ENGINEER – CORE COMPETENCY

LEAN TOOLS

Value stream mapping

Cellular manufacturing

JIT/Total quality control

Teams

Kanban (pull) and supply chain organization

Environmentally sound

Leveling, Balancing, Sequencing

5S and 5 why methods

Autonomation (jidoka)

Pokayokes and defect prevention

Waste Elimination (7 wastes)

Total Productive Maintenance (TPM)

One-piece flow (Single-piece flow)

Standard work

Zero waste to landfill

Visual management

Self and serial inspection

Leveling final assembly

Takt time (cycle time for final assembly)

Line side storage (POUS)

Kaizen events for continuous improvement

SIX SIGMA TOOLS

Green belt requirements

Performance measurements/metrics

Problem solving

Process capability analysis

Hypothesis testing

Design of Experiments

Gage R&R

Reliability

ISO 9000 & MBNQA

Quality Function Deployment

Regression analysis

Root cause analysis

Variation reduction

7 Quality tools

- Process mapping

- Check sheets

- Pareto analysis

- Cause and effect diagram analysis

- Scatter diagrams

- Histograms and frequency diagrams

- Variables and attributes control charts

with Process capability analysis

IE Foundation

Process mapping; Production and Inventory control; Quality control; Engineering Economics;

Operations Research; Simulation Methods; Human Factors; Ergonomics; Probability and Statistics;

Manufacturing Processes.

“The Lean Engineer is an IE who knows Lean

Manufacturing, has six sigma capabilities with

a green (zero waste) mentality”

DESIGN OF A MODERN JOB SHOP

LINKED – CELL MANUFACTURING SYSTEM

LAYOUT OF A RACK MANUFACTURING CELL

STANDARD WORK SHEET FOR RACK MANUFACTURING CELL

MACHINE TOOL DESIGN FOR JOB SHOP & LEAN MANUFACTURING CELL

ERGONOMICS – LEAN PRODUCTION MANUFACTURING CELL ERGONOMIC ADAVANTAGES

• Less Muscular Fatigue

- CMS standing, walking worker

- Venous pooling

- Better circulation

- Lower heart rates

• Less CTD Hazards

- Non-repetitive movements

- Forces exerted

- Better posture

ERGONOMICS – LEAN PRODUCTION MANUFACTURING CELL ERGONOMIC ADAVANTAGES CONT…

• Better Man/Machine Interface- Adjustable height workstation- Controls/Displays compatibility- Scientific designed tools- Self aligning- EZ access- Self inspection

• Better Interface With System- Streamlined parts flow- More frequent moves- Minimal twisting- Minimal lot size

ADVANTAGES OF HOME-BUILT EQUIPMENT

• Only company with this unique process technology.

• Process technology built to overall system specifications

• Competitors cannot get access to the technology from machine tool vendors

• Only need to build the necessary features into the machines to make the family of parts

• Processes and cell designed and built with flexibility in mind so that it can adapt to changes in product design (both existing product and new products) and customer demand.

ADVANTAGES OF HOME-BUILT EQUIPMENT CONT…

• Equipment is designed for (all of these) standing, walking workers (right height, narrow footprint) – ergonomical

considerations

Easy load/unload – ergonomically designed

Easy maintenance, easy to clean, easy to repair – preventive maintenance considerations

Easy to use (operate) – ergonomically correct

Easy to rearrange (wheels, quick-connect utilities) – L - CMS flexibility

Easy to change tools (automatic tool changers)

Easy to change work holders (rapid setup) modular fixturing leading to rapid changeover of existing products

Reliability and durability

• The equipment (and methods) are designed to prevent accidents (a fail-safe design) and not to produce defective parts (pokayoke).

MANUFACTURING CELL DESIGN

PART DRAWING – SEQUENCE OF OPERATIONS

SHOP LAYOUT - PATH

CELL LAYOUT

MANNED INTERIM MANUFACTURING CELL WITH TWO WORKERS

EXAMPLE – SINGLE CYCLE AUTOMATICS

DECOUPLER

EXAMPLE – PROCESS DELAY DECOUPLER

SINGLE MINUTE EXCHANGE OF DIES

EXAMPLE – ONE TOUCH EXCHANGE OF DIES

THE AUTOMATION STEPS FOR MACHINE TOOLSLIST DEVELOPED BY M.BAUDIN AND J T. BLACK

Early on, Toyota engineers devised a list of steps to follow in sequence to successfully automate a machining process. Today machine tools (CNCs) are so automated that this list is no longer applicable but in many machine shops are still far away from Toyota’s level. This list developed empirically by Toyota engineers as a result of carrying out many projects. The progression has to do with the tasks carried out by operators in the manufacturing cells

1. Add power drives to manual operations (A1). Except for occasional hand tapping, very few operations in today's machine shops utilize cuts actually powered by the human hand.

THE AUTOMATION STEPS FOR MACHINE TOOLSLIST DEVELOPED BY M.BAUDIN AND J T. BLACK

2. Add power feed to manual feed (A2). Conventional machines with automatic feed mechanisms did not have any stopping mechanism, required an operator to prevent cutting from farther than it should

3. Add on automatic stop and return to start position (A3). The third step is the enabler for cell operations in which an operator concurrently serves several machines. The operator can press a walk-away switch to start the cycle. The machine may make several cuts, for each of which the operator needs to press “Start”, or it can automatically sequence cuts, so that the operator only presses “Start” once. Either way, the operator does not need to stay and watch the machine during cuts. This is the MO-CO-MOO level using single cycle automatics.

THE AUTOMATION STEPS FOR MACHINE TOOLSLIST DEVELOPED BY M.BAUDIN AND J T. BLACK

4. Add automatic unloading. Automatic unloading is easier than automatic loading because it does not require precise positioning of the part with respect to the tool. The simultaneous automation of unloading and loading results in using more expensive methods than necessary for unloading. This step is the enabler for chaku-chaku lines also called decouplers. As part of routing operation in the cell, the operator loads the next part and checks for the one just unloaded, unless it is checked in the decoupler.

5. Add automatic loading. While automatic loading, the role of the operator in the manufacturing cell is further augmented to checking parts and conveying them between machines. The machine continually loads the next part and starts cutting without human intervention. The operator, however, still plays an additional role in excepting handling, including responding to stoppages, replacing broken or worn tools, or calling maintenance in case of major failures.

THE AUTOMATION STEPS FOR MACHINE TOOLSLIST DEVELOPED BY M.BAUDIN AND J T. BLACK

6. Add automatic problem detection. The next stage is to eliminate the operator’s exception handling role. As long as the operator relies on noise, smell, the sight of smoke, or the feeling of vibrations to detect when something is wrong, he or she must stay close enough to the machine and pay attention at all times. If the machine is equipped with sensors and an alarm system that alerts the operator to the problem clearly, then the operators role is reduced to transportation.

7. Add automatic transportation. The final steps has machines in a cell linked with chutes, decouplers, small conveyors or, in some cases, robots; and parts of the cell or line work unattended. Lines of stamping presses, machine transfer lines, or what the CIM literature calls Flexible Manufacturing Cells (FMCO are at this level)

MANUFACTURING CELL WITH TRANSFER LINE

STANDARD WORK IS COMPRISED OF THREE ELEMENTS

• Cycle Time (based on Takt time)

• Sequence of operations

• Stock on Hand (inventory in the cell)

THESE ELEMENTS ARE DETERMINED BY CONSTRUCTING THE FOLLOWING DOCUMENTS IN THE FOLLOWING ORDER:

• Table of Production capacity by process

• Standard Operations Routine Sheet

• Cell Design

CONSTRUCTING A MANUFACTURING CELLEXAMPLE – MASTER CYLINDER MACHINING PROCESS

D130

L210 M110

RM

FG

Inspection T420

OTHER INFORMATION:• Tools on machine L110 are changed in 60 seconds every 100 pieces.• Tools on machine L210 are changed in 50 seconds every 200 pieces.• Tools on machine D310 are changed in 100 seconds every 300 pieces.• Tools on machine L110 are changed in 30 seconds every 400 pieces.• 2 seconds walk time between all operations .• 2 Seconds manual time to pick up raw material and store finished goods.

Manufacturing Cell Design

CONSTRUCTING A MANUFACTURING CELLEXAMPLE – MASTER CYLINDER MACHINING PROCESSPART NUMBER: 1234M56G78 REGULAR WORKDAY: 460 MINUTES

NAME: MASTER CYLINDER REQUIRED DAILY OUTPUT: 690

OPERATIONNUMBER

OPERATION NAME MACHINE NUMBER

MANUAL TIME

MTMACHININGTIME

WALKTIME

-010020030040050

Pick up Raw MaterialCut mounting surfaceSurfaceCut O.D.Drill HoleThreadCheck ThreadDiameterPut down finished product

-M110L210D310T420

INSP

2

4543

6

2

-

28292712

6

2

2222

2

26 sec 14 sec

Cycle time CT = 26 + 14 = 40 sec. All machining times less than cycle time

OPERATION O30Drilling – 2 inch diameter hole

Machining Time = Length of cut/ Feed Rate (in/min)

Feed Rate = Drill RPM × Drill feed per revolution

Drill RPM = (12 × Cutting Speed)/( × Drill Diameter)

For Operation O30, Tool Material Indexable Insert

Work Material Cast Iron

Select Cutting Speed = 200 sfpm

Feed Rate = 0.010 ipr

Drill RPM = (12 × 200)/ ( × 2) = 382 rpm

Feed Rate = 382 × 0.10 = 3.82 ipm

MT = (L + All)/(Feed Rate) = (1.52 + 0.20)/3.82 = 0.45 min = 27 sec

EXAMPLE – STANDARD OPERATIONS ROUTINE SHEET

OPERATION 2 CD-300 CENTER DRILLDrilling Hole in Part – 3 inch diameter hole

Machining Time = (Length of cut + Allowance)/ Feed Rate (in/min)

Feed Rate (ipm) = Drill RPM × Drill Feed (ipr)

Drill RPM = (12 × cutting speed) / ( × Drill Diameter)

For Operation 2, Tool Material Spade Drill HSS

Work Material – Steel, Annealed

Select Cutting Speed = 60 sfpm

Feed Rate = 0.020 ipr

Drill RPM = (12 × 200) /( × 2) = 114.6 rpm

Feed Rate = 114.6 × 0.020 = 2.29 ipm

MT = (L + All)/Feed Rate = (3.0 + 0.05)/2.29 = 1”20’ = 80 sec

SUB-ASSEMBLY CELLS

LEAN PRODUCTION REQUIRES• Redesign of final assembly into mixed model to level the demand on the

supply chain

• Redesign of the subassembly cell into flexible U-shaped cells

• Redesign of the job shop into manufacturing cells

• Significant reduction in defect rates, setup times and equipment failures (7 tools; 6 ; SMED; TPM)

• Focus on labor driven systems and not capacity driven systems

• Minimum WIP systems to support maximum flexibility, minimum throughput time, minimum labor, and maximum output rates

• Pull versus push production strategies (Kanban Systems)

• A relentless and never ending drive to eliminate all forms if waste and variance in the system (5S)

FIVE DESIGN RULES FOR LEAN PRODUCTION

TAKT TIME RULE

ONE PIECE FLOW RULE

CELL DESIGN RULE

SMED RULES

KANBAN RULES

IN THE L-CMS UNDERSTANDING THESE DESIGN RULES IS TO UNDERSTAND HOW THE SYSTEM IS DESIGNED AND WORKS

• RULE 1 TT =HR’s Available in a Day/ DD,

where DD = (No. of. Cars/Month)/(No. of Days in Month)

Note: PR = Production Rate = 1/TT

• RULE 2 MO-CO-MOO (OPF with defect prevention)

• RULE 3 MTij < NCT where NCT TT (1 –allowance)

NCT = Necessary Cycle Time

• RULE 4 SMED Rules and Methodology

• RULE 5 K = (DD × L + SS)/ a (Little’s Law – Operational version)

RULE 1 TAKT TIME RULELevel & Balance the manufacturing system – make final assembly mixed model –cells produce the daily demand. Sequence and Synchronize.

The lean production system depends upon smoothing the manufacturing system (Toyota’s terminology). In order to eliminate variation or fluctuation in quantities in the supply chain, it is necessary to eliminate fluctuation in the final assembly by MMFA.

DD =average daily demand for parts = Monthly demand (forecast plus customer orders)

Number of days in each month

PR =Average daily demand (parts)/shift

Available hours/shift=

DD

Hrs/day=

parts

minute

TT = 1/production rate for final assembly (FA) = 1/PR

TT =Available hours/shift

Available DD/shift= TAKT TIME for final assembly

RULE 2 ONE PIECE FLOW RULE

Make the subassembly lines into U-shaped manufacturing cells that operate like final assembly with OPF.

MO-CO-MOO = Make One – Check One – Move One On

with output a linear function of the Number of Operators in a cell.

0

50

100

150

200

250

300

350

400

450

0 1 2 3 4 5

OUTPUT PERHOUR

NO. OF WORKERS

NO DEFECTSALLOWEDTO ADVANCE

RULE 3 LEAN SHOP RULE

MTij < NCT (Necessary Cycle Time)

where NCT = TT (1 – allowance)

and MTij = machining time

i = no. of products in family

j = no. of SCA’s in cell

THE MACHINE TOOLS ARE SINGLE CYCLE AUTOMATICS (SCA’S)

RULE 4 SMED (SHINGO)

1. Determine what us happening now – video the setup

2. Separate the Internal from External elements

3. Shift Internal to External

4. Eliminate Adjustments

LITTLE’S LAWLittle’s Law states a mathematical relationship between throughput rate, throughput time, and the amount of work-in-process inventory. Little’s Law is useful for estimating the time that an item will spend in work-in-process inventory, time for a process. Using the terminology defined in this section, Little’s Law is defined as follows:

Throughput time =Work – in - process

Throughput rateTPT =

WIP

PR Parts/Day

Kanban Design Rule - K=L × DD +S

a Ka = WIP

;

;

L × DD = TPT × PR (parts/min)

For A Cell CT = 1/PR = MIN/PART

TPT = CT × SOH

SO SOH controls TPT

RULE 5 KANBAN RULEK=

L × DD +S

a

K = No. of carts ; a = cart size , L = Lead time , SS = Safety stock DD = Daily Demand = Cars/dayKa = DD × L + SS = inventory in a link

Little’s Law = TPT = WIP/PR (for any manufacturing system)

Or WIP = TPT × PR (units in the system)

= TPT/TT (units in inventory)

Ka = L × DD = WIP = TPT × PR (ignoring SS)

So L for a series of LINKS = TPT for system

Note: DD = Cars/Day = PR = Cars/Day

For A Link For A System

LEAN MANUFACTURING• Flexibility:

- Mixed Model Final Assembly

- Rapid tooling changeover in cells

- Rapid modification for new products

- LTFC Design to scale up or down

- MO – CO – MOO operation in Sub Assembly

• Design Manufacturing Cells for One – Piece Flow, Maintainability, Reliability, Durability

• Quick Tooling Exchange

• Single Cycle Automatics

• Integrated Quality – 7 Tools, Poka – yokes and Decouplers

• Design Machine for Lean Cells

Bio Sketch – Dr. PHILLIPS

Dr. Don T. Phillips is currently a Professor of Industrial and Systems Engineering at Texas A&M University, where he also holds the Chevron Distinguished Professor in Engineering. He received his Ph.D from the University of Arkansas in 1969, and has taught Industrial Engineering courses at The University of Texas at Austin, Purdue University and Texas A&M University. He is Author or Co-author of 6 other college textbooks and over 100 publications in technical journals or conference proceedings. He is a Fellow of the Institute of Industrial Engineers, and recently received a Lifetime Achievement Award from Lamar University where he earned a Bachelor of Science degree in Industrial Engineering. His current research interests are in Lean Manufacturing Systems, Systems Simulation, and Applied Operations Research.

Bio Sketch – Dr. BLACKDr. J T. Black is professor emeritus of Industrial and Systems Engineering at Auburn University. He officially retired in 1998 and has flunked retirement every year since by teaching one class a year on Lean production. He is a fellow of the Institute of Industrial Engineering, the American Society of Mechanical Engineering and the Society of Manufacturing Engineers. Dr. Black received his Ph.D from the University of Illinois, Champaign, Urbana in 1969, his Masters from West Virginia University in 1963 and his Bachelors degree in Industrial Engineering from Lehigh University in 1960. He has taught at West Virginia University, University of Illinois – Urbana, University of Vermont, University of Rhode Island, The Ohio state university, University of Alabama – Huntsville and Auburn University. Since retiring in 1998 he has received the 2004 SME Education Award – developing manufacturing engineering curricula, and the Lean Teacher of the year award from IIE. He writes textbooks, poetry and songs. Textbooks he gets published, poetry has been published by SME and is still waiting for one of his “country” songs to make it big. He plays tennis with a passion and as often as his 72+ year old body will let him and he is able to find other “senior citizens” to play with. His latest adventure is taking his pug Vbo into the show ring. He is having fun.