Transcript Work Optimization Ch. 13

Dr. Ron Lembke
SCM 462
How accurately can you measure?
1 mm = 1/25”
1/16”
1/32”
Calipers
0.05mm
1/64”
Micrometer = 0.01mm
Calipers
“Lord Chancellor” Micrometer
Accurate to
1/10,000”
Created when?
1805
Henry Maudslay
1771-1831
 “Powder monkey” at age 12, cabinet shop
 Joseph Brama’s (hydraulic press) lock shop
 Invented (or pioneered) slide rest lathe
 Standardized screws
Block making
 Machines for Marc Brunel, Used for 100 years
 Waited for “American System”
Beginning of Standards
 Before standardized parts, need Screws
 1860s Machine Tool industry: Silicon Valley of its day
 All screws custom made by tool & die shops according
to what they thought best
 William Sellers: 1864 “On a Uniform System of Screw
Threads”
Sellers vs. Whitworth
 3 cutters & 2 lathes vs. 1 cutter & 1 lathe
 Simple geometry vs. difficult
 Rounded top vs. straight: ease of manufacturing, ease of assembly
Not Just What you Know
 Machine tool makers didn’t want to be
commoditized like gun makers
 The standard people expect to win usually does.
 Navy Board found it superior, asked Singer
Sewing Machine, Baldwin Locomotive which
would win (already adopted).
 Pennsylvania RR adopted (Sellers on the Board)
 British tanks & trucks couldn’t be repaired in
WWII because Britain adopted Whitworth
Eiji Toyoda’s Ambitious Plans
 Post-WWII Japanese industry in ruins
 Early 1950s – toured Rouge plant
 2,500 cars in 13 years. Ford: 8,000 per day
 “Catch up to Americans in 4 years!”
 Toyoda made delivery trucks and motorcycles, and not
many of either
, the early years
 First two Toyotas imported to U.S. 1957
Elimination of Waste
 Knew they wouldn’t beat U.S. with product
innovation, concentrated on licensing
patents, and producing more efficiently
 Costs prevented mass-production, volume
strategy of American firms.
 Find ways to reduce waste, cost
 Shigeo Shingo & Taiichi Ohno, pioneers
Ohno & Shingo
Couldn’t Emulate GM
 GM huge batches in huge factories
 Japan’s area is 10% less than California and 70%
agricultural.
 Put entire population of CA into 30% of state, then
add 6 times as many people. (and you thought LA was
crowded).
 Land extremely expensive
 Sprawling factories not an option
Small Batches
 GM’s large batches require large amounts of storage




space.
GM produces in large batches because of significant
setup costs.
If Toyota had the same large setup costs, it could
never afford small batches.
Reduce setup cost to reduce batch size.
GM didn’t think of doing this.
Two Pillars of Toyota System
 Just-in-Time: produce the right parts, at the right
time, in the right quantity
 Autonomation: ‘Automation with a human touch’
(make machine mistake-proof)
Just-in-Time
 Downstream processes take parts from upstream as
they need.
 Like an American Supermarket:
 Get what you want
 when you want it
 in the quantity you want.
Kanban
 Japanese for ‘signboard’
 Method for implementing JIT
 In order to produce, you need both material to work
on, and an available kanban.
 Each work station has a fixed # kanbans.
Kanban
2
Flow of work
3
 Worker 2 finishes a part, outbound moves over
 2 has a blue tag avaliable, so 2 gets another part to
work on:
 2 takes off 1’s green tag giving it back to 1, and
 puts on her blue tag and moves it into position.
Kanban
2
Flow of work
3
 When 3 finishes a part,
 Finished parts move over one spot
 He has to have a red tag available to put on,
 He gets a part from 2’s outbound pile,
 And gives the blue back to 2
Kanban
2
Flow of work
3
 When 3 finishes a part,
 Finished parts move over one spot
 He has to have a red tag available to put on,
 He gets a part from 2’s outbound pile,
 And gives the blue back to 2
 3’s production will be taken by 4, offstage right.
 Tag goes back into 3’s bin
Kanban
2
3
 Red finishes his part next.
2
3
 But 4 hasn’t freed up any of the red kanbans, so there is
nothing for 3 to work on now.
 3 could maintain his machine, or see if 4 needs help
How is this Different?
 Processes can become idled (blocked) or starved
 This makes you painfully aware of problems in your
system.
 Material moves through the system so quickly no inprocess recordkeeping is needed.
Total Quality Management
 Not a lot of parts to sift through to find a good one
 Can’t afford high defect rates
 Since low WIP, get quick feedback on errors
WIP Level
 Less WIP means products go through system faster
 reducing the WIP makes you more sensitive to
problems, helps you find problems faster
 Stream and Rocks analogy:
 Inventory (WIP) is like water in a stream
 It hides the rocks
 Rocks force you to keep a lot of water (WIP) in the
stream
Lowering Inventory Reduces Waste
WIP hides problems
Lowering Inventory Reduces Waste
WIP hides problems
Lowering Inventory Reduces Waste
Reducing WIP makes
problem very visible
STOP
Lowering Inventory Reduces Waste
Remove problem, run
With less WIP
Lowering Inventory Reduces Waste
Reduce WIP again to find
new problems
Importance of Flow
 Ohno was very clear about this:
“Kanban is a tool for realizing just-in-time. For this tool
to work fairly well, the process must be managed to flow
as much as possible. This is really the basic condition.
Other important conditions are leveling the product as
much as possible, and always working in accordance with
standard work methods.
-- Ohno, 1988, p. 3
Setup Reduction
 Can’t afford to do huge runs
 Have to produce in small batches
 Toyota Die Change: 3 hours down to 3 SMED:
under ten minutes
 Techniques
 Make internal setups into External
 Eliminate Adjustments
 Eliminate the Setup
 Continuous Process Improvement, anyone?
Lot Sizing
Q
2 DS
H
 Takt time = available time (day) / Customer demand
rate per day
Uniform Plant Loading (heijunka)
 Any changes to final assembly are magnified
throughout production process
 Smoothing
 Master production schedule: 10,000 /mo.
 500 day, 250 a shift
 480 minutes means 1 every 1.92 minutes
 Sequencing:
 If mix is 50% A, 25% B, 25% C, produce
A-B-A-C-A-B-A-C…