Chapter 9

Inventory Kanbans

Automating the Replenishment Cycle

IT-465 Lean Manufacturing 2

Kanban

• A Japanese word that means signboard or signal.

• Are signals developed to automate the inventory replenishment cycle for items used repetitively in a facility

• Communicate the need for additional material to be pulled from the supplier

• Integral in a “pull” manufacturing system.

IT-465 Lean Manufacturing 3

Typical Kanban Signal

• An empty container designed to hold a standard quantity of material or parts.

• The container is sent back to the supplier from the customer when empty.

• If returnable containers are not used, a kanban can be as simple as a laminated card.

IT-465 Lean Manufacturing 4

Kanbans

• Are:– Communication devices from the point of use

to the previous operation.– Purchase orders for your suppliers.– Work orders for your manufacturing area.– Visual communication tools.– Paperwork eliminators.

IT-465 Lean Manufacturing 5

Kanbans

• Are not appropriate for:– Single piece or lot production– Safety stock– Systems which push inventory carrying

requirements and the associated carrying costs back to the supplier.

– Long range planning tools.

IT-465 Lean Manufacturing 6

Kanbans Reduce Waste

• Eliminate – Over-production– The need for a stockroom– The need to reissue purchase orders

• Reduce:– The data management task for prod plng, work orders– Inventory– Parts expediting– Parts shortages– Material handling

IT-465 Lean Manufacturing 7

Types of Kanbans (Pull Signals)

• Cards attached to portable containers such as tote pans

• Supplier replaceable cards on cardboard boxes designed to hold a standard quantity

• A painted spot or border on the floor around the standardized container

• Color coded striped golf balls• E-mails• Bar code labels• Variations of above

IT-465 Lean Manufacturing 8

Summary

• Kanbans tie related processes together as if they were connected by an invisible conveyor. Kanbans:– Improve communication– Improve customer satisfaction– Reduce inventories– Reduce waste

IT-465 Lean Manufacturing 9

Pull Systems

Outcomes

• Define Pull system

• Define supermarket

• Define kanban

IT-465 Lean Manufacturing 10

Production Scheduling

• Constantly change

• Production never produces to a schedule

• Utilize MRP (Material Resource Planning)

IT-465 Lean Manufacturing 11

Supermarket Pull

IT-465 Lean Manufacturing 12

Scheduling

IT-465 Lean Manufacturing 13

Small-Lot Production + Leveling

IT-465 Lean Manufacturing 14

Leveling Work Volume

IT-465 Lean Manufacturing 15

Leveling Work Volume

IT-465 Lean Manufacturing 16

Flow

IT-465 Lean Manufacturing 17

The Problem with Inventory

IT-465 Lean Manufacturing 18

Kanban TypesProduction Kanban• “One-per-customer” kanban• Supplying process can produce

as little as one containerSignal (Triangle) kanban• “One-per-batch” kanban• Signals when a reorder point is

reached and another batch needs to be produced

• Used in supplying process where changeovers are required

Withdrawal kanban• “Shopping list” kanban• Instructs the material handler

to get and transfer parts

IT-465 Lean Manufacturing 19

The Six Steps of Kanban

1. Consumption process withdraws only what is needed2. Produce to replenish only what is withdrawn by the next

process3. Do not send defective products to the next process4. Parts must not produced and conveyed when there is

no kanban5. Kanban must be attached to the actual parts or

container6. The actual number of parts in the container must match

the number on the kanban

IT-465 Lean Manufacturing 20

One Piece Flow

Goal• Represents a special case of kanban• Lot size/quantity is oneBenefits• Minimizes waste in the process• Defects affect only one component thus creating highest

possible quality• Minimizes inventory and space requirements• Keeps pace with customer demand• Efficiently utilizes labor in a balanced process• Best possible throughput in a balanced process

IT-465 Lean Manufacturing 21

Signal Kanban System

IT-465 Lean Manufacturing 22

Summary

• Pull Systems– Single scheduling point– Produce to replenish use– Customer demand creates production

• Level loading

• Kanban