8/8/2019 Lean Manufacturing & JIT
1/42
Lean Manufacturing &JIT Production
8/8/2019 Lean Manufacturing & JIT
2/42
Just-in-time- A philosophy for optimizing performance of amanufacturing system.
- Originated from work of Taiichi Ohno at Toyota.
- After WWII, U.S needed large mass production tosatisfy demand for products.
- Japanese market was much smaller, so moreflexible systems were needed to produce smaller quantities of different items in the same equipment.
8/8/2019 Lean Manufacturing & JIT
3/42
Just-in-time After many years, Toyota established the followingstrategy:
1. Kanban based pull production.
2. Waste elimination is guide philosophy.3. Faith in importance and value of quality.4. Kaizen or continuous improvement as a daily
strategy.
5. Emphasis on setup reduction on all machines.6. Integrate suppliers and material acquisition intothe planning process.
7. Cellular layouts with balanced flow.
8/8/2019 Lean Manufacturing & JIT
4/42
Comments about Kanban - JIT
Note that Kanban systems are not the same as JIT.
The pull approach is only one aspect of the JITphilosophy.
The combination of the above factors transforms theshop into a lean facility.
They factors depend on one another.
A Kanban system without high quality or low setups
will not achieve expected benefits.
8/8/2019 Lean Manufacturing & JIT
5/42
B asic Tenets of Lean, JIT Production
CategoriesImp roving Production Environ ment
Quality Engineering
Imp roving Material Flow
8/8/2019 Lean Manufacturing & JIT
6/42
I. Improving Production Environment
1. Eliminate Waste
2. Employee Cross-Training and Job Rotation
3. Employee Empowerment and Involvement
4. JIT Purchasing
5. Reduction of Variability
6. Mistake-Proof Processes
7. Reduce Setup Times
8/8/2019 Lean Manufacturing & JIT
7/42
Some Terminology
Muda: Japanese term for any human activity which
abosrbs resources but creates no real value.
K aizen: process of continuous incremental improvementthrough the identification /elimination of m uda.
K aizen blitz: an event where a team of managers,
engineers and line workers coordinated by a facilitator
come together for three days to focus on improvements
on an area of a plant.
8/8/2019 Lean Manufacturing & JIT
8/42
Some Terminology
Typical strategy in Kaizen Event is asking why five
times until the root cause or motivation for an action is
discovered.
Golden Rule: Use everyones knowledge to identify and
implement improvements quickly and cost effectively.
8/8/2019 Lean Manufacturing & JIT
9/42
1. Eliminate Waste
Original scientific approach was to dissect a large system
into small pieces and make each piece optimal.
Japanese approach: develop a system that connects the
pieces.
Ex. Instead of tracking production statistics and
inspecting out defective products, eliminate any
production of defective items.
8/8/2019 Lean Manufacturing & JIT
10/42
Seven Types of Wastecommonly found in industry.
A . Waste fro m Overproduction
Why make products that wont be sold?
Before, supervisors were evaluated through quotas.
Machine utilization needed to be maximized.
New idea: machines and humans should only be busy
when they have useful tasks to accomplish.
8/8/2019 Lean Manufacturing & JIT
11/42
Seven Types of Wastecommonly found in industry.
B. Waste of Motion
Eliminate motions that do not add value.
Look at workplace design, process planning,
detailed job procedures, material handling.
8/8/2019 Lean Manufacturing & JIT
12/42
Seven Types of Wastecommonly found in industry.
C . Transportation Waste
Position work and storage areas such that
material moves are short.
Keep tooling near its point-of use.
8/8/2019 Lean Manufacturing & JIT
13/42
Seven Types of Wastecommonly found in industry.
D . Processing Waste
Eliminate non-value added operations.
May need to go back to product design and
revise features and tolerances.
8/8/2019 Lean Manufacturing & JIT
14/42
Seven Types of Wastecommonly found in industry.
E . Wasted Ti m e (queuing)
Plan for:
Small lot sizes
Ordered production and release of dependent Items
Good coordination will achieve small WIP and
throughput time.
8/8/2019 Lean Manufacturing & JIT
15/42
8/8/2019 Lean Manufacturing & JIT
16/42
Seven Types of Wastecommonly found in industry.
G . Ex cess Inventory yields added costs due to
Space, obsolescence, opportunity costs, handling, among
others.
Avoid excess inventory.
Can achieve via modular components.
Negotiate long term contracts with suppliers to ensure a
steady stream of high-quality parts.
8/8/2019 Lean Manufacturing & JIT
17/42
2. Employee Cross-Training and Job Rotation
Can train over time to do variety of tasks in their work
area.
Can then rotate through different positions.B enefits:
Enhances worker flexibility and enthusiasm.
Prevents boredom, fresh perspectives and ideas for improvements.
Gives context of communication between workers on
same team.
8/8/2019 Lean Manufacturing & JIT
18/42
2. Employee Cross-Training and Job Rotation
B enefits (continued):
Minimizes fatigue and repetitive stress injuries.
Can move workers around to eliminate temporary
bottlenecks.
In U-shaped cells, workers can operate more than onemachine at a time.
8/8/2019 Lean Manufacturing & JIT
19/42
3. Employee Empowerment andInvolvement
Why hire a body when it comes with a brain?
Employees are a great source of ideas for
improvement.
Employees must be allowed and encouraged to
do so.
This includes authority to stop production andcorrect a problem in production.
The goal is to identify problems early.
8/8/2019 Lean Manufacturing & JIT
20/42
3. Employee Empowerment andInvolvement
A usual approach to empower is via a switch to stop
production.
This warning system is called J ikoda .
The warning light system is called andon .
Usually a bank of three lights is used: green , yellow and
red .
8/8/2019 Lean Manufacturing & JIT
21/42
3. Employee Empowerment andInvolvement
One light is always on, indicating station status.
Red light signals a line stoppage and location of
problem to other workers. Nearby workers assist with the problem, get
additional help if necessary.
Identifier and solver of problemare rewarded.
8/8/2019 Lean Manufacturing & JIT
22/42
3. Employee Empowerment andInvolvement
Employees should be involved in developing
procedures.
Workers take pride in job if they know they arehelping meet customer expectations.
8/8/2019 Lean Manufacturing & JIT
23/42
3. Employee Empowerment andInvolvement
Worker area should also be kept clean and organized.
This helps in pride and dedication.
5Ss:
Sort, Straighten, Sanitize, Sweep and Sustain.
Organized workplace reduces:
Misplacing
Contamination
Brightens up atmosphere
Gives feeling system is under control.
Conveys that sloppiness is not tolerated.
8/8/2019 Lean Manufacturing & JIT
24/42
4. JIT Purchasing
Changes that can be implemented
1. Sole source vs. multiple supply sources.
- Idea: better negotiate long-term contracts with single
supplier.
- This encourages cooperation instead of competing over
terms.
- Suppliers long term interest is now to provide high
quality on time at a fair price to ensure customers
success.
8/8/2019 Lean Manufacturing & JIT
25/42
4. JIT Purchasing
Changes that can be implemented
2. Frequent delivery of small lots vs quantity discounts.
- Traditional approach: occasional deliveries of large
quantities of parts.
- Parts were inspected via sampling.
-Now, no inspection is needed since vendor product
quality has been certified and meets requirements. (If
not, get a new supplier).
8/8/2019 Lean Manufacturing & JIT
26/42
4. JIT Purchasing
Changes that can be implemented
3. Flexible ordering vs. paperwork.
- Contracts usually call for steady flow of product +/-
10%
- Customer can change order quantity on short notice
with little hassle.
- Requires some reserve capacity by vendor.
8/8/2019 Lean Manufacturing & JIT
27/42
4. JIT Purchasing
Changes that can be implemented
4. Vendor owns and manages inventories.
-Vendor can hold inventory on customers site.
- Customer gets billed only when extracting parts.
- Supplier has responsibility to keep enough inventory
level.
8/8/2019 Lean Manufacturing & JIT
28/42
5. Reduction of Variability
Variability reduces efficiency.
If supplies, yields or machine availability are
unpredictable, the tendency is to have large safety stocks
of inventory.
Idea:
Eliminate variability from production processes.
8/8/2019 Lean Manufacturing & JIT
29/42
6. Mistake-Proof Processes
This involves eliminating opportunities for errors.
Idea:
Design processes to avoid producing defective items.
Be able to detect defects before more production steps
are done.
Poka-Yoke: mistake proofing a process.
8/8/2019 Lean Manufacturing & JIT
30/42
6. Mistake-Proof Processes
Basic ideas:
100% of units should be inspected.
Identify defects as close to the source as possible.
Stop production immediately and take corrective action
right after a defect is detected.
Design processes to avoid producing defects.
8/8/2019 Lean Manufacturing & JIT
31/42
6. Mistake-Proof Processes
Some Poka-Yoke Techniques
Checklists and worker source inspection.
Worker checks his own work.
Problem: humans tend to approve their own work.
Checklists help ensure all steps have been completed
in station.
8/8/2019 Lean Manufacturing & JIT
32/42
6. Mistake-Proof Processes
Some Poka-Yoke Techniques
Successive check systems
Worker checks incoming parts from previous station
before starting his own operation.
Worker must approve work by previous worker or
defects must be communicated to previous worker
right away.
8/8/2019 Lean Manufacturing & JIT
33/42
6. Mistake-Proof Processes
Some Poka-Yoke Techniques
Mistake-proof part and fixture design.
Design parts so that they can only fit in a tooling
fixture in proper orientation.
Reshape symmetrical parts to exaggerate
asymmetries easier to detect misalignments.
8/8/2019 Lean Manufacturing & JIT
34/42
7. Reduce Setup Times
Usually the MOST productive investment that can be made toimprove production system performance.
Techniques (*):
- Design parts for manufacturability
- Design parts for standard tools.
- Develop standard methods for setups.
- Divide setup activities into external/internal tasks.
- Design procedures to perform setup tasks in parallel.
- Modular fixturing
- Eliminate adjustments.
- Use power clamps.
8/8/2019 Lean Manufacturing & JIT
35/42
Transitioning from Traditional to Lean
1900s Philosophy
Worker was immigrant, uneducated, spoke little English.
Worker is like a machine designed to perform a limited set of
tasks well.
Product customization was not an issue for customers (all model
Ts were the same).
2000 Lean Philosophy
Worker: most flexible machine.
If properly educated, worker can solve problems and adapt to
new situation.
The customer expects customization.
8/8/2019 Lean Manufacturing & JIT
36/42
Transitioning from Traditional to Lean
Old Production Mentality:
Process-Based Organization
Economic Order Quantities
Large Unit Handling Loads
Receiving Inspection
Maximize Equipment Use
8/8/2019 Lean Manufacturing & JIT
37/42
Transitioning from Traditional to Lean
New Lean Thinking
Product Cell Layouts
Single-Unit mixed model production
Continuous material flow
Mistake proofing
Balanced production line
8/8/2019 Lean Manufacturing & JIT
38/42
Problems in Implementing Lean
Cannot make it happen without the support of floor operators.
Culture change needs to happen.
Old philosophy: run large batches to amortize setup costs of the
largest number of parts and products.
New philosophy: demand based production.
Management not fully involved.
Loss of interest by top management and workers.
After initial implementation, no hard benefits seen in bottom
line.
Might have implemented Lean in wrong areas.
8/8/2019 Lean Manufacturing & JIT
39/42
Pros & Cons of Cell Manufacturing
ProsShorter Lead times
Reduced WIP
Space Savings
Higher Quality End Product
B etter team
communications
Employee ownership and
can do attitude
Supports pull operation
ConsLower equipment utilization of non-bottleneck cells.One piece of the cell breaksdown, the whole cell is out (noredundancy of equipmentwithin a cell)Loss of employee dedicatedexpertiseIf demand falls and cell outputis below cell capacity, per unitcosts are higher.Multi-product cells may not besuitable for higher volumeorders, becoming thebottleneck.
8/8/2019 Lean Manufacturing & JIT
40/42
Transition Stages in Lean Thinking(Ford Motor Company)
Phase 1: Process Stabilization
Improve production environment; predictable/reliable processes; total
productive maintenance, total quality, poka-yoke, setup time reduction,
standard procedures, clean & organize the workplace. Train employees
in lean thinking.
Phase 2: Continuous FlowReduce WIP and batch sizes. No need to run machines at full capacity.
Unit parts can plow in small or single quantities between workstations.
8/8/2019 Lean Manufacturing & JIT
41/42
Transition Stages in Lean Thinking(Ford Motor Company)
Phase 3: Synchronous production.Follow weekly production schedules.
Phase 4: Pull authorizationTo authorize production, parts must be pulled by successive
workstations. Kanbans dictate production.
Phase 5: Balanced productionAll process produce at a constant level and continuous rate.
Every part type is made daily; parts flow continuously.
8/8/2019 Lean Manufacturing & JIT
42/42
Short Articles on Lean Implementations
www.sme.org
Manufacturing Engineering Magazine
September 2003 Issue
Lean by Design and by Necessity
http://www.sme.org/cgi-bin/get-
mag.pl?&&03sem002&000007&2003/03sem002&ARTME&SME&
Lean pays Off at Ariens
http://www.sme.org/cgi-bin/get-
mag.pl?&&03sem005&000007&2003/03sem005&ARTME&SME&