9 Lean Operations
Chapter Table of Contents
Wastes
The word “lean” means skinny or having no fat. Lean operations have no waste. The types of wastes, also called muda, that lean operations can be referred to as TIM WOODS:
- T – Transport – Moving people, products & information
- I – Inventory – Storing parts, pieces, documentation ahead of requirements
- M – Motion – Bending, turning, reaching, lifting
- W – Waiting – For parts, information, instructions, equipment
- O – Over production – Making more than is IMMEDIATELY required
- O – Over processing – Tighter tolerances or higher grade materials than are necessary
- D – Defects – Rework, scrap, incorrect documentation
- S – Skills – Under utilizing capabilities, delegating tasks with inadequate training
The framework of lean operations focuses on the concepts of value, value stream, flow, pull, and perfection in order to reduce all of these types of waste.
Value is defined by the customer. An organization must have a clear definition of value as perceived by the customer. Time and money spent on features of a product or a service that the customer does not perceive have value are wasted time and money. Knowing what the customer values requires becoming close to the customer and constantly soliciting feedback.
In lean operations, a process flow diagram is called a value stream map. The diagram is similar, but the reason for creating the diagram is to identify all the activities in a process and place them into one of the following categories.
- Value Added (VA) – activities that create value as perceived by the customer
- Non-Value Added (NVA)– activities which don’t create value as perceived by the customer and so should be eliminated immediately
- Essential Non-Value Added (ENVA) – activities that create no value but are company or regulatory policies and so can’t be eliminated just yet
The value stream mapping also identifies the time actually spent in adding value and the time the product spends in storage or transport. Time in storage or transport is waste and should be eliminated.
Continuous flow
Picture-Perfect Manufacturing, from MMS Online, describes how Stremel Manufacturing, in Minneapolis, Minnesota, used current state maps and future state maps to make sure that waste-reduction initiatives “improve the overall flow rather than merely optimize individual steps.”
In continuous flow, a product never waits but flows continuously through the manufacturing system, thus eliminating time in storage and in transport. Batches and queues should be eliminated. If products move through the production systems in batches, then the first item in a batch must wait until the last item in a batch is completed before it moves to the next processing time; batches mean product spends time waiting, and that time is waste. The presence of queues mean that a product was completed at a previous processing step before the next step was ready for more input. Since the final step of the production process is shi