1. Just-In-Time Philosophy
The philosophy of JIT can be traced back to Henry Ford, but formalized JIT originated in Japan as the Toyota Production System. W. Edwards Deming’s lesson of variability reduction was a huge influence.
JIT is a long-term approach to process improvement. It uses timeliness as a lever to lower costs, improve quality and improve responsiveness. However, JIT requires enormous commitment. It took Toyota more than 25 years to get right!
The focus of JIT is to improve the system of production by eliminating all forms of WASTE.

2. Just-in-Time
Downstream processes take parts from upstream as they need.
Get what you want
when you want it
in the quantity you want.

3. 4. Just In Time-- What is It?
Just-in-Time: produce the right parts, at the right time, in the right quantity
Requires repetitive, not big volume
Batch size of one
Short transit times, keep 0.1 days of supply

4. Characteristics of Just-in-Time
Pull method of materials flow
Consistently high quality
Small lot sizes
Uniform workstation loads
Standardized components and work methods
Close supplier ties
Flexible workforce
Line flows
Automated production
Preventive maintenance
This slide builds the key characteristics of JIT as described in the text.

5. Push versus Pull
Push system: material is pushed into downstream workstations regardless of whether resources are available
Firms with processes that involve long lead times, a variety of products, customers who will not wait long for product use Push method.

6. Push versus Pull
Pull system: material is pulled to a workstation just as it is needed (customer demand activates the production of goods and services)
Firms that tend to have highly repetitive manufacturing processes and well-defined material flows use the pull method because it allows closer control of inventory and production at the workstations

7. From a a « push » to a « pull » System
Work is pushed to the next station as it is completed S U P L I E R C U S T O M E R

8. From a « push » to a « pull » System
A Workstation pulls output as needed S U P L I E R C U S T O M E R

9. JIT Demand-Pull Logic Vendor Fab Sub Customers
Here the customer starts the process, pulling an inventory item from Final Assembly…
JIT Demand-Pull Logic
Customers
Sub
Fab
Vendor
Final
Assembly
Then sub-assembly work is pulled forward by that demand…
The process continues throughout the entire production process and supply chain 4

10. Pull Versus Push Systems
A pull system uses signals to request production and delivery from upstream stations
Upstream stations only produce when signaled
System is used within the immediate production process and with suppliers

11. Pull Versus Push Systems
By pulling material in small lots, inventory cushions are removed, exposing problems and emphasizing continual improvement
Manufacturing cycle time is reduced
Push systems dump orders on the downstream stations regardless of the need

12. Consistently high quality
Consistently meeting customer’s expectations.
Just-in-time systems seek to eliminate scrap and rework in order to achieve a uniform flow of materials
Use quality at the source which is having employees act as their quality inspectors such that never passing on defective units to the next process.
Poka-yoke (mistake proofing method) designing fail-safe systems to minimize human errors. Ex: design parts to be assembled in only one way- the correct way.

13. Small lot sizes
JIT systems maintain inventory with lot sizes that are as small as possible.
Small lot sizes have three benefits:
small lot sizes reduce cycle inventory which reduces the time and space involved in manufacturing and holding inventory.
small lot sizes help cut lead times then cutting pipeline and (WIP) inventory. (longer processing, longer inspection, defects delays)

14. Small lot sizes Benefits of small lot sizes:
3) small lots help achieve a uniform operating system workload.
setup times must be reduced to realize the benefits of small-lot production.

15. Uniform Workstation Loads
Uniform loads can be achieved by assembling the same type and number of units each day, thus creating a uniform daily demand at all workstations
Two models of production
Line production: all daily requirements of a model are produced in one batch before another model is started
Mixed model assembly: mix of models in smaller lots in a sequence (set up times should be low)

16. Standardized Components and Work Methods
The standardization of components, called part commonality or modularity, increases repeatability.
each worker performs a standardized task , Productivity tends to increase.

17. Close Supplier Ties
JIT systems operate with very low levels of inventory, close relationships with suppliers are necessary.
Stock shipments must be frequent, have short lead times, arrive on schedule, and be of high quality
Purchasing managers focus on three areas: reducing the number of suppliers, using local suppliers, and improving supplier relations

18. Flexible Work Force
Workers in flexible work forces can be trained to perform more than one job.
Workers can be shifted among workstations to help relieve bottlenecks as they arise without resorting to inventory buffers--an important aspect of the uniform flow of JIT systems.
they can step in and do the job for those on vacation or out sick.

19. Line Flow Strategy
A line flow strategy can reduce the frequency of setups.
If volumes of specific products are large enough, groups of machines and workers can be organized into a product layout (line) to eliminate setups entirely.
If volume is insufficient to keep a line of similar products busy, group technology can be used to design small production lines that manufacture, in volume, families of components with common attributes

20. Preventive Maintenance
Because JIT emphasizes low inventory between workstations, unplanned machine downtime can be disruptive.
Preventive maintenance can reduce the frequency and duration of machine downtime.
One tactic is to make workers responsible for routinely maintaining their own equipment and develop employee pride in keeping their machines in top condition

21. Basic Elements of JIT

22. Waste in Operations
Waste from overproduction (manufacturing an item before it is needed and with more quantities) this increase both inventory and lead time
Waste of waiting time (product is not moved and processed, poor materials flow, poor processes linkages this waiting may be 90 percent of LT)
Transportation waste (excessive movement and materials handling, risk of being damaged, lost, delayed, a cost for no added value
Inventory waste (a capital outlay that has not yet produced an income, excessive Inv hides shop floor problems, Increased inv is a result of overproduction and waiting) 6

23. Waste in Operations
Processing waste (more work is done on a piece than what is required by the customer, high precision equipment when simple machine is sufficient, overutilization of expensive assets)
Waste of motion (unnecessary efforts related to ergonomics like bending, stretching, reaching, lifting and walking) jobs with excessive motion should be redesigned
Waste from product defects (quality defect results in scrap and rework and wasteful costs lost capacity, scheduling efforts, increased inspection, and loss of customer good will)
Underutilization of people

25. Streamlined Production
Flow with JIT
Traditional Flow
Customers
Suppliers
Production Process (stream of water)
Inventory (stagnant ponds)
Material (water in stream)

26. 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

27. Lowering Inventory Reduces Waste
WIP hides problems

28. Lowering Inventory Reduces Waste
WIP hides problems

29. Lowering Inventory Reduces Waste
Reducing WIP makes
problem very visible
STOP

30. Lowering Inventory Reduces Waste
Reduce WIP again to find
new problems

31. Reduce Variability Inventory level Process downtime Scrap Setup time
Late deliveries
Quality problems

32. Reduce Variability Inventory level Process downtime Scrap Setup time
Quality problems
Late deliveries

33. Causes of Variability
Employees, machines, and suppliers produce units that do not conform to standards, are late, or are not the proper quantity
Engineering drawings or specifications are inaccurate
Production personnel try to produce before drawings or specifications are complete
Customer demands are unknown

34. Variability Reduction
JIT systems require managers to reduce variability caused by both internal and external factors
Variability is any deviation from the optimum process
Inventory hides variability
Less variability results in less waste

35. Reduce Lot Sizes Q1 When average order size = 200
200 –
100 –
Inventory
Time
Q1 When average order size = 200
average inventory is 100
Q2 When average order size = 100
average inventory is 50

36. Reducing Lot Sizes Increases the Number of Lots
Customer orders 10
Lot size = 5
Lot 1
Lot 2
Lot size = 2
Lot 1
Lot 2
Lot 3
Lot 4
Lot 5

37. Reduce Lot Sizes
Ideal situation is to have lot sizes of one pulled from one process to the next
Often not feasible
Can use EOQ analysis to calculate desired setup time
Two key changes
Improve material handling
Reduce setup time

38. Reduce Setup Times Initial Setup Time
90 min —
60 min —
45 min —
25 min —
15 min —
13 min — —
Step 1
Separate setup into preparation and actual setup, doing as much as possible while the machine/process is operating
(save 30 minutes)
Step 2
Move material closer and improve material handling (save 20 minutes)
Step 3
Standardize and improve tooling (save 15 minutes)
Use one-touch system to eliminate adjustments (save 10 minutes)
Step 4
Step 5
Training operators and standardizing work procedures (save 2 minutes)
Repeat cycle until subminute setup is achieved

39. Quick Setups SMED Principles: (Single Minute Exchange of Dies)
Separate internal setup from External setup
Convert internal setup to external setup
Streamline all aspects of setup
Perform setup activities in parallel or eliminate them entirely

40. SMED Some examples included:
Bringing the dies to the press ahead of time
Assuring that the dies were complete including all fasteners
Modifying all dies to the same physical size, eliminating setup adjustments
Specialized handling equipment
Quick acting fasteners

41. Common Techniques for Reducing Setup Time
1. Maintenance, Organization and Housekeeping It often happens that setup problems are related to poor maintenance such as worn parts, worn tooling, dirt, or damaged threads. Disorganization and poor housekeeping are also contributors to setup problems. These are easy to fix and should be a first step. 2. Internal Elements to External Internal elements occur when the machine is down. Examine each internal element and see if it cannot be done externally. For example, the pre-heating of an injection molding die could be done before it goes into the machine.

42. Common Techniques for Reducing Setup Time
3. Improve Elements 
Here we examine every element to see how we can eliminate it, simplify it, reduce the time required or improve it in some other way.
4. Eliminate Adjustments 
Adjustments are often the most time consuming, frustrating and error prone parts of a setup. There are many ways to eliminate them entirely and this is the ultimate goal.

43. 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.

46. Kanban Workstation 2 finishes a part, outbound moves over
Flow of work 2 3
Workstation 2 finishes a part, outbound moves over
WS2 has a blue tag available, so it gets another part to work on:
2 takes off 1’s green tag giving it back to 1, and
puts on it blue tag and moves it into position.

47. Kanban When 3 finishes a part, Finished parts move over one spot
Flow of work 2 3
When 3 finishes a part,
Finished parts move over one spot
It has to have a red tag available to put on,
It gets a part from 2’s outbound pile,
And gives the blue back to 2

48. Kanban When 3 finishes a part,
Flow of work 2 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

49. Kanban Red finishes his part next.2 3
Red finishes his part next.
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 2 3

50. The Number of Cards or Containers
Need to know the lead time needed to produce a container of parts
Need to know the amount of safety stock needed
Number of kanbans =
Demand during Safety lead time + stock
Size of container

51. Number of Kanbans Example
Daily demand = 500 cakes
Production lead time = 2 days
(wait time +
material handling time +
processing time)
Safety stock = 1/2 day
Container size = 250 cakes
Demand during lead time = 2 days x 500 cakes = 1,000
Number of kanbans = = 5 1,
250

52. Example dL (1+S) 5(2)(1.1) = = = 2.75 or 3 C 4
A switch is assembled in batches of 4 units at an “upstream” work area.
delivered in a bin to a “downstream” control-panel assembly area that requires 5 switch assemblies/hour.
The switch assembly area can produce a bin of switch assemblies in 2 hours.
Safety stock = 10% of needed inventory. k
size of container
Expected demand during lead time + safety stock =
dL (1+S)
5(2)(1.1) = = =
2.75 or 3 C 4 18

53. Scheduling Small Lots A B C A C B Time JIT Level Material-Use Approach
Large-Lot Approach
Time

54. Minimizing Waste: Uniform Plant Loading
Suppose we operate a production plant that produces a single product. The schedule of production for this product could be accomplished using either of the two plant loading schedules below.
Not uniform Jan. Units Feb. Units Mar. Units Total
1,200 3,500 4,300 9,000 or
Uniform Jan. Units Feb. Units Mar. Units Total
3,000 3,000 3,000 9,000
How does the uniform loading help save labor costs? 12

55. Mixed Batch Example
Company produces three products with a mixed model assembly line.
Operates 16 hours per day for 250 days/yr.
Determine the mixed model MPS for a daily batch.
Determine minimum batch MPS and the mix schedule for a day.
Products
Forecasts (year) A
20,000 B
10,000 C
5,000

56. Calculations A B C Year Forecast 20000 10000 5000 Daily BatchA B C
Year Forecast
20000
10000
5000
Daily Batch
divide by 250 80 40 20
Hourly Batch
divide by 16 5
2.5
1.25
Minimum Batch MPS 4 2 1
For every unit of #3 (minimum batch), we need twice as many #2 and 4 times
As many #1 so for minimum batch:
Produce during each day produce AAAA-BB-C repeated 20 times

57. Characteristics of JIT Partnershps
Few, nearby suppliers
Supplier just like in-house upstream process
Long-term contract agreements
Steady supply rate
Frequent deliveries in small lots
Buyer helps suppliers meet quality
Suppliers use process control charts
Buyer schedules inbound freight

58. Typical Benefits of JIT
Cost savings: inventory reductions, reduced scrap, fewer defects, fewer changes due to both customers and engineering, less space, decreased labor hours, less rework.
Revenue increases: better service and quality to the customer.
Investment savings: less space, reduced inventory, increased the volume of work produced in the same facility.
Workforce improvements: more satisfied, better trained employees.
Uncovering problems: greater visibility to problems that JIT allows, if management is willing to capitalize on the opportunity to fix these problems.