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Just-in-time. Prof. Jiang Zhibin Dept. of IE, SJTU. Tools of Lean Manufacturing Pull Systems / Kanban A Tool for Implementing Pull Systems. Lean Production Through Waste Elimination. Quality at the Source. JIT. People. Operational Stability. JIT Goals. Zero defects

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Just in time

Just-in-time

Prof. Jiang Zhibin

Dept. of IE, SJTU


Just in time

Tools of Lean Manufacturing

Pull Systems / Kanban

A Tool for Implementing Pull Systems

Lean Production

Through Waste Elimination

Quality

at the

Source

JIT

People

Operational Stability


Jit goals

JIT Goals

  • Zero defects

  • Zero excess lot size or lot size of one

  • Zero setups

  • Zero breakdowns

  • Zero handling

  • Zero lead time

  • Zero Surging

    • Level production plan and uniform product mix


Need to reduce cost

Cost

+

Need to Reduce Cost

Traditional Method

(Push)

Seller Driven

Selling

Price

Profit =

(SELLER)

PROFIT

(MARKET)

Modern Method

(Pull)

Customer Driven

=

Selling

Price

-

Cost


Just in time1

Just in Time

  • History - Japan

  • 1980s conclusion

    • Japanese industry worked “smart” - JIT

  • Think of JIT as minimum stock production

  • Type of relationship: close & intimate? JIT

    • internal JIT - in client-server stream

    • external JIT


Japanese experience

Japanese Experience

Waste in operations from

  • overproduction

  • waiting time

  • transportation

  • inventory waste

  • processing

  • motion/movement

  • product defects

  • concentrate effort on shop floor

  • CQI focus

  • staff ownership of problems


Minimizing waste inventory hides problems

Minimizing Waste: Inventory Hides Problems

identify defects from a supplier early in the process saves the downstream work

Machine

downtime

Scrap

Vendor

Change

delinquencies

Work in

orders

process

queues

Engineering design

Design

(banks)

redundancies

backlogs

identify defective work from upstream stations, saves the downstream work

Decision

Paperwork

Inspection

backlogs

backlog

backlogs


From aggregate to mps to mrp1

8

From Aggregate to MPS to MRP1

Aggregate

Plan (product groups)

MRP2

Firm

orders

Forecast

random

orders

Master

production

schedule

(MPS)

Design

changes

Time-phased plan

how many + when we will build each end item.

JIT

Bill of

material

Inventory

record

MRP1

Stock

movements

Reports


Just in time jit

  • participation

  • industrial engineering/basics

  • continuing improvement

  • TQM

  • reducing set up times

  • smaller lot/order sizes sizes

  • stable environment

  • supply partnership

Requires

Just-In-Time (JIT)

  • a system for high-volume production with minimal inventory (raw materials, WIP, finished goods).

  • involves

    • timed arrivals @ workstation JIT

    • reduced ‘buffer’ stocks

    • no waste in production system

    • a “Pull” system thru the plant

  • a management philosophy

  • expose problems & bottlenecks

  • Take away ‘security blanket”

  • streamlined production

  • factory & warehouse networks


Jit requirements 1

JIT Requirements 1

Kanban Pull

  • Demand pull

  • Back flush

  • Reduce batch/lot sizes

Work with suppliers

  • Reduce lead times

  • Frequent deliveries

  • Project usage requirements

  • Quality expectations

Reduce inventory in

  • Stores

  • Transit

  • Conveyors

  • calculation from MRP & EOQs


Jit requirements 2

JIT Requirements 2

Quality

  • Worker responsibility

  • SQC

  • Enforce compliance

  • Error proffing

  • Automatic inspection

Stabilise Schedule

  • Level schedule

  • Under utilize capacity

People Focus

  • pay harmonisation

  • supportive unions

  • subcontractor networks

  • hands-on manager style

  • quality commitment & group involvement

Operations Design

  • Link operations

  • Balance workstation capacities

  • Review layout for flow

  • Stress preventive maintenance

  • Reduce lot sizes

  • Reduce setup/changeover time


Jit requirements 3

JIT Requirements 3

Problem-solving

  • Root problem

  • Long-term solution

  • Team contribution

  • Line-specialist cooperation

  • Learning

  • Measure performance

  • CQI

  • Monitor & report

Product Design Improvement

  • DFM & process design

  • Modules & fewer parts

  • Quality standards

  • upgrade housekeeping

  • clarify process flows

  • revise equipment & process technologies


Jit and demand pull

Call (Kanban) & Pull

Call (Kanban) & Pull

Fabric

Fabric

Fabric

Fabric

JIT and Demand-Pull

Supplier

Call (Kanban) & Pull

Subass

Supplier

Final

Assembly

Customer

Subass

Supplier

Supplier


Client server streaming

Bin

Bin

Bin

Bin

Client Server Streaming

Avoid too much material stocks & WIP

Increase materials coordination & movement

Supplier's

local

warehouse

Call for

more

Saw

Materials

warehouse

Call for

more

Finished Goods

Warehouse

JIT

deliveries

Lathe

Grinder

Bin

Bin

Customer


What is kanban

What is Kanban?

  • developed at Toyota 1950s to manage line material flows.

  • Kanban ( Kan=card, Ban= signal )

  • simple movement system

    • “cards” to signal & communicate reorder information

    • boxes/containers to take “lots” of parts from one work station to another (client-server).

  • Server only delivers components to client work station as & when needed (called/pulled).

  • minimise storage in the production area.

  • Workstations only produce/deliver components when called (they receive card + empty container).

  • The work-station produces enough to fill the container

  • Kanban = an authorization to produce more inventory

  • We thus limit the amount of inventory in process.


Benefits of kanban

Benefits of Kanban

  • An information network used to control production quantities

  • A communication process that controls the movement of material

  • A cost reduction (waste elimination) tool that prevents over production

  • A quality control enforcer because it limits lot quantities to small amounts, thereby allowing defects to be identified early in the manufacturing process


Benefits of kanban cont

Benefits of Kanban (cont.)

  • Manages just-in-time production

  • Gives specific part number, quantity, location, and time demands to lower work centers

  • Identify excess in plant inventory levels

  • Identify potential inventory shortages (low stock indicators)

  • Limits quality rejects byreducing lot size produced


Kanban pre conditions

Kanban Pre-conditions

  • Point of use inclusion (all parts on the assembly line)

  • Level production

There are four pre-conditions for the successful implementation of Kanban

  • Quick Changeover procedures

  • Stabilized processes


Kanban

Kanban

Market Address

Kanban Number

Line-Side Address

<<KAN>>

<<Market_Address>>

<<Line_Side_Address>>

Part Number

Route

<<Part Number>>

<<Route>>

Bar Code Area

Part Description

Dock Code

<<Dock Code>>

<<Part Number>>

Supplier Code

Quantity

Serial Number

<<Supplier Code >>

<<Quantity>>

Comment:

<<Comment>>


What does a kanban card look like

What Does a Kanban Card Look Like?

  • accurate data: correct part nos, quantities & measure'ts

  • visible - chart if material ordered & when

  • fool proof for no stockouts

  • minimum inventory

  • clear & complete info. to suppliers

  • link inventory directly to demand

  • Tie in with POP: issuing orders, receiving & authorising accounts payable

Kanban No.5678990

part No: 66789X

description 16ga. Copper Wire

units Ft.

reorder/lot qty 20

store location Row 12, Bin 6

supplier BICC

supplier tel 0208-891-0121

supplier part RT45502

routing process

Name/location of next proces

Name/location of preceding process

container type & capacity

number of containers released


Function of kanban

Function of Kanban

  • Helps to reduce passage of defects from one area to another by identifying preceding processes.

  • Provides pick-up and/or transportation information, which includes “where from” and “where to” locations. It can also, in some cases, indicate schedule times for pick-up.

  • Communicates production information. It tells what to produce and how many are required. Function No. 3 also states Kanban must be produced in the order received.

  • Prevents overproduction and excessive transportation by restricting in-bound raw material and the production quantity of a process to specific pre-determined lot quantity indicated on the Kanban. It allows ordering of multiple lot quantities only to the extent of Kanban available to be replenished

  • Serves as a work order indicating what has been produced and identifies the physical product

  • Reveals existing production problems and maintains inventory control


Rules of kanban

Rules of Kanban

  • Never send defective products to downstream processes

  • The downstream process draws only what is required by the Kanban from upstream processes.

  • The upstream process produces items in the quantity and the sequence indicated by the Kanban.

  • Parts are never to be produced or conveyed without a Kanban

  • Kanban must be attached to the actual containers of parts

  • Kanban is a tool to fine tune production


Inter process kanban flow

Market Place

2

3

4

Assembly Withdraw

Kanban Mailbox

Post Office

Inter-Process

1

Kanban Post Office

A

V1

5

X

B

B

B

V2

A

A

C

C

E

E

V3

C

Y

D

D

V4

D

D

V5

E

Z

A

A

C

C

E

E

f

f

F

F

V6

Inter-process Kanban Flow


Minimizing waste kanban control system

Minimizing Waste: Kanban Control System

withdrawal kanban

Bin Part A

Bin Part A

Machine Center

Assembly Line

production kanban

Material Flow

Card (signal) Flow


How many kanbans

Expected demand during lead time + safety stock

=

k

capacity of container

+

dL

(1

S

)

=

C

How many Kanbans?

  • Each container = minimum replenishment lot size.

  • Calculate lead time required to produce a "container"

k = No. of kanbans in card set

d = Average No. of units demanded over the period

L = lead time to replenish order (same units of time as demand)

S = Safety stock as % of demand during lead time

C = Container size


Example

Expected demand during lead time + safety stock

=

k

size of container

Example

  • 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.

dL (1+S)

5(2)(1.1)

=

=

=

2.75 or 3

C

4


Re engineering kanban

"Re-engineering" & Kanban

Modern production methods

  • 1. Modular/cell production 9 group technology).

  • 2. Reduce set up, lead and waiting times between procedures.

  • 3. Flow-of-products-oriented layout of processes & machines layout. Products flow smoothly from start to finish, parts do not sit waiting to be worked on, forklift trucks do not travel kilometres to move parts from one area of the plant to another.

  • 4. Flexible manufacturing of mixed models

  • 5. Theory of Constraints - drum-rope-buffer (Goldratt). Building in extra redundancy.

  • 6. Total Preventive Maintenance, prevent machines from breaking down or malfunctioning during production time

  • 7. Team-Work & Autonomation (decision by worker to stop line)

  • 8. Kaizen: Continuous improvement

  • 9. Housekeeping


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