Lean Manufacturing Automation: It’s Not Just for High Volumes Anymore

Kurt Greissinger

Holistic View of Process Improvement Tools

Ergonomics

Lean Automation

Manual Ass’y

MTM

Hazardous / Heavy Jobs

Productivity

Efficiency

Job Satisfaction

Solve Problems

Improve Quality

Short / Long

Cycle Times

Bosch Rexroth Solution Space

The State of Manufacturing Today

• Cost effective manufacturing in High Cost countries is difficult • Development efforts remain in the U.S.

• Power and utilities in Emerging Markets can be uncertain

• Increasing efficiency enables enterprises to remain competitive • Limited availability of qualified personnel

Goals of Flexible / Lean Production Reduction of: human effort (but increase in productivity) inventory errors and scrap development time for new products shop floor space job related injuries Rapid response and adjustments to customer demand

• Changes in quantity • Changes in variety

Assure delivery of quality products in the most efficient and economical manner

Human Advantages (Human): Flexible Adaptable Human Hand has 26 degrees of freedom Vision built in 10,000 sensors (i.e. temperature, pressure) Easily Scalable (+/- operators)

Disadvantages (Human): Sickness Vacation Needs food/heat/sleep etc Not repeatable (acc/time) Struggles with multi-steps >20 movement Performance: 4 kW briefly, 0.7 kW for a few seconds, approx. 100-150 W over the long term, but with breaks! Approx. lifetime performance: 80,000 km

vs.

Automation

Workstation Design Considerations

Inflexible, Unergonomic Workstations

Workstation Design

Design considerations for workstations: Width of the workstation

Size of the product to be assembled Necessary equipment Work envelope width = 800mm (min) Footrest width = 800mm (min)

- Getting up from chair must be possible by swiveling!

Prevent Overproduction Reach Zone

Right Sizing

Right Sizing

Lean, ergonomic work surface sizes Width = 1000mm (39”), 1200mm (47”), 1400mm (55”) Depth = 555mm (22”), 705mm (28”)

Reach Zone

Right Sizing

Design considerations for workstations: Depth of the workstation

Reach zones Part Presentation Material supply philosophy

- Number of grab containers - Logistics run frequency

Reduce inventory Part Presentation

Part Presentation

Reach to front (grab axis) Dimension no. 1.1 Body depth, standing, dimension no.1.2

Male Female Male Female

Percentile Percentile Percentile Percentile

5th 50th 95th 5th 50th 95th 5th 50th 95th 5th 50th 95th ________________________

M (16 to 60) 662 722 787 616 690 762 233 276 318 238 285 357

= 378 mm

Max. reach depth: e < 325 mm

e

Table top

∆

Derived dimension: reach Distance to work area, reach depth, parameter “e”

Part Presentation

3-D grab area planning

Small grab area for fine motor movements, large grab area for gross motor movements

Correct planning of working methods right from the start (with MTM, …) Check the option for two-handed work

Small grab area Large grab area Two-handed work

Part Presentation

Example: Redesign of a workplace

Grab-area1) after redesign Grab-area1) present 1) Grab area for “little women“ (1540 mm)

Part Presentation

Influence of Length of Movement

[M] move

[cm] Lenth in cm

[B] art of control

M 40 B M 30 B M 20 B

1 movement 15.6 13.3 10.5 [TMU]

2x4000 124.800 106.400 84.000 movement/shift [TMU]

Every shift ~ 75 ~ 64 ~ 50 [min.]

Per Year 275h 235h 183h (220 AT)

Ratio 40h 92h ≅5.3 days ≅12.3 days

1 AT ≅ 7,5 h

Minimize lengths !

Part Presentation

Grasping from grab containers

10 parts in 19 s => 1.9s/ part 10 parts in 14 s => 1.4s/ part 26 % time savings

Part Presentation

20 parts in 16 s => 0.8s/part

Simultaneous positioning with both hands possible in normal angle of vision with P1SE

Simultaneous, two-handed moving motion possible

Savings e.g. with two-handed O-ring positioning: 30% compared to one-handed positioning

Fixture design/two-handed work

58 % time savings

Part Presentation

Design considerations for workstations: Height of the workstation

Operational philosophy Task / application Size of the product to be assembled

Working Height Work Area

Work Area

Derived dimension: working height Standing and sitting/standing workstations, parameter H2)

Physiological work criteria

Stand Sit Change between stand/sit

Hydrostatic blood pressure in legs

Energy required to maintain good posture

Static posture, strain on supporting and musculoskeletal systems

Impairment of breathing and digestion

High stress Medium stress Low stress

Work Area

Anthropometrics International Body Heights

Nationality ♀ Women [cm] ♂ Men [cm] Age Year

5F 50F 95F 5M 50M 95M

Poland 1501 1587 1667 1627 1730 1821 18-60 1984

France 1510 1590 1700 1590 1700 1810

Spain 1430 1590 1710 1530 1650 1770 1878

USA 1511 1615 1720 1636 1748 1853 18-65 1973

UK 1478 1608 1737 1580 1709 1839 1973

Japan 1438 1537 1636 1575 1669 1763 1973

Canada 1455 1577 1699 1608 1727 1847 1973

Former Yugoslavia 1473 1582 1683 1632 1741 1849 18-40 1986

Pygmy 1360 1410 18-30 1950

China (Yangste Fluss) 1560 1670

China (Si Chuan) 1530 1630

Russia 1508 1595 1680 1614 1723 1832 18-21 1977

Lithuania 1570 1651 1731 1672 1768 1864 18-21 1977

Germany 1535 1625 1720 1650 1750 1855 16-60 1986

The “average” person doesn’t exist!

Body sizes

90 % To recognize: 5%- 95%- range

Men:

Women:

4 size- ranges (acc. to DIN 33 402)

1% 5% 50% 95% 99%

1650 mm 1750 mm 1855 mm

1535 mm 1625 mm 1720 mm

Freq

uenc

y

Anthropometrics

Working height with visual distance and development of strength

Compromise between arm position and visual distance

1125 mm

Work Area

O= 1125 mm

Work Area

Optimum average working height:

1125 mm

(Ø from m/f, average requirements for body/arm position, see figure)

For sitting/standing or standing/walking workstations

Working height H2

Only applies to US / Germany. The appropriate dimensions must be taken into account for other countries!

Work Area

Correctly planning the working height

Right Wrong No workplace higher than

heart level! Workplaces above heart level strain the circulatory system, reduce blood flow, and quickly lead to a drop in performance Aim for dynamic activities.

Static holding work restricts the flow of blood to muscles and quickly leads to a drop in performance

Work Area

Comparison of static and dynamic physical work

There is a sufficient supply of oxygen with dynamic work!

Work Area

Procedure for calculating the workstation dimensions

Results In which position must the work be done (sitting/standing)?

Who should work at this workstation (group of people, heights)?

What work requirements result from the particular work task?

How high is the work area over the work space (dimension C)?

What is the thickness of the table top and any cross profiles (dimension K)?

Planning aids

(DIN 33406, templates, checklist or software, e.g.:, layout planner)

Workspace dimensions: W,

D, H

Seat height/area

Legroom clearence

Footrest height/area

Question

Work Area

Practice values for designing a workstation

Workstations that only permit sitting are only suitable for office work, etc. Define the optimum working height (sitting/standing/moving principle) “Flatten” working heights above the assembly line Tendency to design working heights a bit lower rather than too high Standard value for dimensions C+K: max: 160 mm Length of movement > 800 mm (acc. to MTM)-> aids/steps required! Minimize reach depth in fixture (max.”e”: 325 mm) Minimize fixture width (max.: workpiece width +100 mm) Minimize workpiece pallet/ height “C”

Example of a standing workstation Table height A (top edge) = working height H2-

working area height C

Work Area

Exercise

Calculate the height of a work table at a packaging station where men and women work while standing. Boxes (with a weight of 5 kg and dimensions of 250x250x250 mm) must be pushed to the work area, closed with tape, and then have a self-adhesive label attached to the top of the box.

Table height: ?

Working area height?

Supply/removal?

Sitting/standing workstation?

Tape

Work Area

> 350 > 550 > 150

> 80

> 12

0 < 35

0 c

Bodypostures of Standard DIN 33406

Minimum dimensions (in mm) for leg- and foot room on standing workstations

Z

Minimum dimensions (in mm) for leg- and foot room on Sitting / (standing) workstations

Work Area

Thigh height “Z” is not sufficient ( Zmin=200mm)

Z Z

Legroom Clearance Issues Work Area

Getting up from chair must be possible by swiveling the chair

Work Area Legroom Clearance Issues

B- M10C- P2SSD- 2xM10B- RL2- AB = 107.7 TMU= 3.9s + Pain!

Example

Rotate : G5- M20A-RL2, Positioning Etikett: M10C- P2SSD-2xM10B- RL2 Rotate back: G5-M20A-RL2= 66 TMU= 2.4s without pain!!

Work Area

Examples

Work Area

Examples

Work Area

Examples

Work Area

Workstation Design Design considerations for workstations: Adjustability of equipment

Workstations Chairs Material shuttles

Adjustment of Equipment

Adjustable Equipment

Workstations for different employees (shift operation) and jobs

Workstations for changing product sizes and jobs (varying models or products)

Requirement for

Visual inspection Very high High Normal Low

Arm movement Low Normal High Very high

1125 ±100

Adjustable Equipment

Adjustable Equipment

Visual Distance: Almost independent from body height, adjusted via seating height

Visual Distance: Heavily dependent on body height when standing, influenced via working height

Adjustable Equipment

Workstation Design Design considerations for workstations: Required process steps or equipment

Ergonomic positioning of tools Economic positioning of tools Tool selection criteria

Reach Zone Work Area

Tools

Positioning of Tools

** TMU: Time Measurement Unit (1 TMU = 0.036 sec)

Tool at varifiing place Tool at a specific place in a toolholder

Reaching Grabbing

TMU*

12.8 7.3 20.1

R30A G1A

TMU*

9.5 2.0 11.5

43% time savings

R30B G4A

Tools

Center of Gravity Should be near center of fist Avoid nose-heavy tools Consider air hoses, extensions, sockets, etc.

Center of Gravity

Tools

Horizontal Work Surface Vertical Work Surface Horizontal or Vertical Work Surface

Handle Considerations

Handle Configuration Maintain neutral wrist position

Handle Diameter Between 1.25” – 1.75” (25mm – 30mm)

Handle Length Full width of palm (4” – 5”)

Handle Material Avoid grooves and contours that cause pressure points; non-conductive to temp; textured to improve grip

Handle Shape Allows power grip; “D” shape more stable than “O”

Tools

Optimum positioning of tools

Force dev. Move Position Tighten Move

SC4 M30C4 P1SD PT M30B4

TMU** 2.8 16.2 11.2 .... 14.2 44.4

M30C P1SD PT M20B

TMU** 15.1 11.2 ... 10.5 36.8

17% time savings

Nutrunner (weight: 40 N) in a specific location, without weight reduction

Weight reduction to 10 N via a spring pull

* MTM : Method Time Measurement ** TMU: Time Measurement Unit (1 TMU = 0.036 sec)

Move Position Tighten Move

Tools

Workstation Design

Design considerations for workstations: Visual elements

Illumination - Intensity of light (unit: lx = “lux”, reflection, density)

Vision - Visual distances and areas - visual acuity, normal and diffuse field of vision

Contrast Glare

- Backlight or reflection Coloring (green, gray, yellow, red, …)

Lighting Range of Vision

Visual Elements

What do you see ? Visual Elements

Why are visual conditions important?

Reaching, grasping, and positioning require a high level of control Optimum visual conditions for visual, assembly, and inspection activities Joined areas must be clearly visible A poor design will lead to premature fatigue and errors

Visual Elements

Vision is 90% mental and 10% physiological

Adaptation of light-sensitive receiver cells (macula) to different brightnesses by changing the pupil size (iris)

Objects at different visual distances are shown in focus through different curvatures of the ocular lens (ciliary muscle) on the retina

Change to lens aperture and selection of film sensivity

Zoom or variable focal distance

Adaptation

Accommodation

Conjunctiva

Ciliary muscle

Cornea

Pupil

Iris

Macula (retina)

Optic nerve (nervus opticus) Lens

Vitreous body

Aperture

Lens aperture

Lens

Film

Object

Film object

α

Similar to photography

Visual Elements

Degree of reflection

Intensity of light

Light density

The degree of reflection is influenced by the workpiece, fixture and table top

Luminous flux

Illumination: strength and density Visual Elements

Increased Productivity with More Lighting

Decreased Errors with More Lighting

Eliminate errors and defects

Visual Elements

Field of vision and range of vision

• As little change in vision as possible during the work process

• Maintain a uniform visual distance

• Avoid awkward positions

• The neck muscles and cervical spine are greatly stressed if you frequently change the direction you are looking in.

30°

90°

Field of vision - Optimum (no eye or head movement) Range of vision - Maximum (with eye movement, without head

movement)

Head angle: 15° when standing, 25°-30° when sitting

60°

30°

Up to 3s to recover / refocus from head / eye movements!

Visual Elements

Field of vision

40° - 45°

Angle of view Field of vision

40° - 45°

Visual Elements

What is contrast?

Contrast is the difference in light density for two adjacent surfaces

The contrast may appear as a brightness contrast, color contrast, or a combined contrast.

A contrast that is too great results in glare

Visual Elements

Provide proper contrast between part and background

Example of

good contrast

Example of

bad contrast

Low contrast, lower than 3:1 = bad!

Increase contrast by changing background, about 3:1 = better!

Good contrast, higher than 3:1 = good!

Visual Elements

Contrast

Bright background Dark Background

Visual Elements

Glare – rules for limiting contrast

Edge zone (background)

In zone (object)

1:

3

10:1

1:3

In a normal field of vision, aim for only little difference in light density for all of the larger surfaces!

Visual Elements

Direct glare

Reflection glare

Glare

Visual Elements

Visual Elements

Example: Redesign of a workplace Field of vision

Field of vision before Field of vision after redesign

Visual Elements

Display

Assembling area

Examples

Visual Elements

Well designed workstation

Visual Elements

Material Supply

Up to 30% reduced inventory!

Reduce inventory

Plastic VarioGrab

Part Presentation

Material Supply

68% time savings

TBC1 B R10C AB TBC1 M10C

TMU

18.6 29.0 8.4 31.9 18.6 7.9 114.4

R30C M30B

TMU

14.1 13.3

27.4

Benefit when Part Height = Working Height

Minimize Excess Motion

Material Supply

Supermarket rack: "Shopping possibility" for logisticians

Customers define their own standard

Modular and flexible designs

Defined supply systems according to the FIFO principle Free-up captial and space by reducing inventories

Reduce inventory

Material Supply

Recommended Ergonomic Work Height

1400 mm

1100 mm

750 mm

400 mm

Average work height

B: light parts A: heavy parts C: infrequent use

A B

B C

C

Material Supply

Cell Design

Layout Options

Selection according to:

Type of work organization (Division according to work, quantity, components, variants)

Integration of in-house material flow (Delivery of individual parts, components/removal of assembled products)

Flow principle (Main flow, secondary flow, circuit, return flow, combinations)

Availability of parts at the workstation (From rear, from front, from side)

Basic form Without pallet With pallet

Square

U-Shape

Line

Other Forms

Cell Design

Cell Design

Two-handed production: rooted to location, as a result filling work is not possible, unproductive waiting times, moving the finger!

Interfering edge in the grab area for the container

Grab container is outside the diffuse angle of vision, is also too high

Depth e in index table < 325 mm?

e

Workplace- design

Cell Design

Assembly / measuring station with Pick to Light Cell Design

Two-handed assembly and Feeding Processes

Left: Process with pressing and assembly Right: Preassembly 2 parts with O- Rings

Cell Design

Assembly of Power Tools

Cell Design

Sitting/Standing Workplaces with Manual Conveyor Cell Design

Assembly of electronic parts Cell Design

Cell Design

productdesign Industrial engineering production

cost

Design with ergonomics

Redesign with ergonomics

Comparison of Cost vs. Effort

Economics

Role of Automation in Flexible Manufacturing

Automation should be applied to solve problems • Dangerous / hazardous tasks • Unergonomic conditions • Must consider the full process

Must be flexible

• 70% solution in order to implement and begin • Allows for continuous improvement

Reduction of errors and defects

• Prevention • Containment • Poke-Yoke

Common Myths of Automation Automation will take over the world

Common Myths of Automation

Automation and Flexible Manufacturing are opposing Automation replaces people Avoid excessive conveyance (not avoid completely) Automation (such as conveyors) is expensive Automation is complex

Life cycle of an assembly line

Average lifetime of an assembly line:

8 years = 45,900 operational

hours

If our assembly line was a car running at 50km/hour, it would go 2.3M km within 45,900 operation hours.

This is 3 times to the moon and back.

Transfer Systems – Benefits – Eliminate Waiting & Over Processing

Reduces non-productive time, the workpiece does not need to be repositioned

Waiting Overprocessing

Transfer Systems – Benefits – Improve Transportation

Reduces non-productive time through machine workpiece conveying – Single Piece Flow

Excess Transportation

Overprocessing

Transfer Systems – Benefits – Reduce Inventory

Low capital tie-up due to short passage times

Excess Inventory

Transfer Systems –Benefits – Eliminate Unnecessary Motion

Relieves workers from carrying heavy weights

Excess Motion and Movement

Transfer Systems – Benefits – Improve Quality

Protects the workpiece surface

Well-ordered flow of material

Errors and Defects

Transfer Systems - Benefits

Reduces non-productive time No manual transport,

assembly part pick-up during workpiece exchange

Workpiece does not need to be repositioned

Costs Low capital tie-up Ergonomics Relieves workers from carrying

heavy weights Quality Precise assembly and

jointing position Protects the workpiece surface,

well-ordered material flow

Lean production and automation: A contradiction in terms?

Transferring parts manually can cause: drop in quality loss of valuable time

Economically efficient transport solution depends on:

Lot sizes and variety of models Product lifetime Part weight and size Cycle time

Lean manufacturing does not eliminate automated transport

Examples of Flexible Integrated Lines

Workpiece Pallet-Based Transfer System

Alternatives for Transferring Parts from Process to Process

Manual transport Transport of lightweight parts by hand, medium weight parts on

passive roller conveyor, heavy and bulky parts using a trolley Required time for transport: 1..3 sec (dependent on distance)

Pick & place unit

Handling unit picks workpiece at input port, moves it to process and disposes it off at output port after process has finished

Assumption: 30% of the cost for transferring parts, 70 % for process

Transfer system with pallets Processing of parts as much as possible on the pallet Transfer system is used at 100% for transfer of parts cost for returning empty pallets is included

Cost per Transfer Cycle

Assumptions: 5-year, straight line depreciation 2 shifts, 3500 operating hours / year 10kg product weight

Cycle Time

optimal manual cycle times between 20s and 120s! < 20s = lower flexibility >120s = high expense in education of work content or training

Cycle Time in Seconds

Acce

ptab

ility

Source: Mike Rother

0 0 30 20 10 60 50 40 80 70 110 100 90 130 120

Recommended cycle times for manual production systems

How to choose?

recommended not recommended

manual semi- automatic

fully- automatic Process Risks

Flexibility ? Traceability Forces und Ergonomy Partcharactaristics

Torque Turning angle Method of process

Forces Pressing length

Systematic mistakes Pure mistakes

Value added work? Costs ? Damaging Traceability Ergonomy, cycle time

Transport

Assembly

Tightening

Pressing

Inspection

Method of process

Its a balancing act

Automation

Good for High Volume, High Repetition (Manual Expensive)

Manual

Good for intricate assembly Built in Vision and flexibility

(Automation Expensive)

Next Steps Share what you learned today! Learn more Receive buy-in from the top Develop a vision Set improvement goals Select a test area Work with your local Bosch Rexroth distributor Work with a Bosch Rexroth Certified lean consultant Begin with the end in mind Stick with it!

You’re invited to create a lean organization…