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…