Lean Supply Chains

notes from the textbook readings

Lean Production

integrated activities designed to achieve high volume, high quality production using minimal inventories of raw materials, work in progress, and finished goods

What does lean production focus on?

eliminating as much waste as possible

• if a step doesn’t create value, it should be removed from the process

Customer Value

in the context of lean production, something for which the customer is willing to pay

Waste

anything that doesn’t add value from the customer’s perspective

• defective products, overproduction, inventories

Where is waste elimination more controllable?

in manufacturing operations compared to service operations

Why are service operations not controllable?

because services operate in a sea of uncertainty and variability that are much harder to control

• aka uncertainty in task time: the variability leads to a negative exponential distribution of task times

• ex: airline boarding

Uncertainty in demand

no service demand forecast is 100% perfect

Customer’s production roles

variability is introduced based on how well service providers perform their role

What do lean production and Six Sigma have in common?

they work best in repeatable, standardized operations

Lean is also based on the logic that

nothing will be produced until it is needed

Lean production demands

high levels of quality at each stage of the process, strong vendor relations, and a fairly predictable demand for the end product

What are the 7 types of waste that need to be eliminated from the supply chain?

1.) waste from overproduction

2.) waste of waiting time

3.) transportation waste

4.) inventory waste

5.) processing waste

6.) waste of motion

7.) waste from product defects

Value Stream

these are the value-adding and non-value-adding activities required to design, order, and provide a product from concept to launch, from order to delivery, and raw materials to customers

Waste Reduction

the optimization of value-adding activities and elimination of non-value-adding activities that are part of the value stream

Value Stream Mapping

a graphical way to analyze where value is or is not being added as material flows through a process

• with this map, identification of wasteful processes and flows can be made so they can be modified or eliminated

• thus making the manufacturing system more productive

What is the two-step process for value stream mapping?

1.) depicting the current state of the process

2.) a possible “future state” with suggested improvements

Lean requires the plant layout to be designed in what way?

to ensure a balanced workflow with a minimum of work in progress inventory

What is also emphasized in the plant layout?

preventive maintenance to ensure flows are not interrupted by downtime or malfunctioning equipment

Quality at the source

means do it right the first time, and when something goes wrong, stop the process or assembly line immediately

• factory workers become their own inspectors, personally responsible for the quality of their output

Anything over the minimum amount necessary is viewed as

waste because effort and material expended for something not needed now cannot be utilized now

The goal is to drive all inventory queues to zero because

It minimizes inventory investment and shortens lead times

Lead Schedule

a schedule that pulls material into final assembly at a constant rate

Freeze window

the period of time during which the schedule is fixed and no further changes are possible

Uniform Plant Loading

smoothing the production flow to dampen schedule variation

Kanban

a signaling device used to control production

Kanban Pull System

an inventory or production control system that uses a signaling device to regulate flows

Value stream mapping is not designed to what?

show the bottlenecks