I'm a Swedish-based Lean consultant, and the owner of the free World-Class-Manufacturing.com web site.
In short, I teach key descision makers how to get a cost-effective and robust production.
Contact Oskar Olofsson
Download Lean Cartoons
View all products
 |
Lean Manufacturing Pages |
Lean Manufacturing
Welcome to my Lean Manufacturing pages.
As you may know, “Lean” is a huge concept, with many different tools to use. Even worse, implementing the tools is not enough; you need to implement “Lean thinking” in your organization to achieve sustainable results.
I have developed these pages to help you. If you are new to this, start by taking the Lean assessment. Not only will you measure your current status, but you will also have an action plan proposed for you.
Then you may want learn more from our articles. More than 20 articles covering many different aspects of Lean are waiting for you.
Soon it will be time to implement the tools and concepts; I have made different calculators to help you. The most popular are the OEE calculator, the Kanban calculator, and the Takt time calculator.
Do you need to calculate the costs and benefits for your Lean Program? Try the ROI – calculator.
Everything on the Lean pages is free. If you want to support the site and have a website, please link to me.
Oskar Olofsson, 2010
Introduction to Lean Manufacturing
This article introduces many of the concepts of “Lean Manufacturing”:
- Definitions
- Types of Waste
- Batch Size
- Value Stream Mapping
Definitions
"The Toyota Way can be briefly summarized through the two pillars that support it: Continuous improvement and Respect for people" (1)
Lean Manufacturing (also called Toyota Production System, TPS) is a production system inspired by the Japanese concept of kaizen (the strategy of continuous improvement).
Unlike Kaizen, Lean has a focus not only on quality control but also on quantity control to eliminate waste and reduce costs.
There are many definitions and viewpoints for “Lean Manufacturing”, but the main goal of “Lean Manufacturing” is to eliminate waste.
“Waste” refers especially to excess input materials and useless processing steps. The goal of “eliminating waste” may also be stated as providing exactly what the customer values for the lowest cost of production. This will maximize profit per unit.
The word “Lean” implies “cutting the fat” or “trimming waste”, where “fat” or “waste” refer to whatever is not valued by the customer. So another way of expressing the “Lean Manufacturing” goal is to only use materials and processes that add value for the customer.
What is “value for the customer”?
Here is a simple example of what is “valued by the customer”. Let’s say that you need a supply of nuts and bolts for an assembly operation, so you are the customer for the bolts. You need the size to be correct, but these bolts do not need to be plated or rust-proof or special in any other ways. Therefore nickel plating does not add value to you as a customer, even though it makes a better bolt in other applications.
Further, let’s say you need a supply this afternoon or your factory will shut down. Therefore availability and quick delivery are very valuable to you. You might even pay a premium for express delivery of a one-day supply of already-expensive nickel-plated bolts, while negotiating a discount for a larger supply of standard bolts that your supplier can ship for delivery tomorrow.
In the above example, you, as the customer, place value on having the right size of bolt and timely delivery, but not on nickel plating.
Types of Waste
Three Japanese words defined “waste”:
- Muda means “work that does not add value”. The goal is to eliminate processes (and materials) that do not add value from the customer’s view.
- Muri means “overburden”. The goal is to eliminate inefficient work, whether by better work flow or by working at a pace that the machine or operator is able to sustain.
- Mura means “unevenness”. The goal is to do work at a steady pace; “production leveling” and “pull production” are examples of this approach.
The original development of “Lean Manufacturing” listed seven types of muda waste. More have been added since then:
- Over-production of well-made goods is wasteful, because the overstocked products will either be sold at a discount or warehoused at some expense. These products may rust or become damaged over time. The goods may be overtaken by technological change and thereby become outdated.
- Excess inventory of raw materials, work-in-process or finished goods is wasteful, because it ties up cash and storage space, whether in a warehouse, on shelves or on the factory floor.
- Unnecessary transportation, whether from one area in a factory to another, between warehouse and factory, or across borders. This especially refers to the transportation of goods when they are not being processed. Transportation costs labour and fuel, and has the potential for damaging goods in transit.
- Re-work to correct errors or damaged goods costs labour, at the very least. Extra material, energy, transportation and wear and tear on machinery may be included. This category should be extended to include duplication of paperwork or data entry steps.
- Wasted motion, particularly through poor human engineering. The minimum cost is time. When personnel have to go through extra motions to accomplish a routine task, the result can be an increase in injuries, or in errors caused by extra fatigue. On the other hand, the tasks must allow enough variety and motion so people do not move so little that they are cramped or bored.
- Extra processing to clarify customer requirements and change the manufacturing orders causes different costs. If caught too late, this leads to re-work or even the rejection of shipped goods. This includes processing beyond customer values or taking extra steps that are not required.
- Idle time, especially if the machine operator must wait for the machine to finish and there is nothing else for that person to do. Some advise using a machine’s idle time for minor maintenance, such as adding a drop of lubricant.
- Defective products returned by the customer have obviously wasted materials and labour.
Batch Size in “Lean Manufacturing”
“Lean Manufacturing” tries to reduce batch size to “one” as a way of reducing waste:.
- The smaller the size of a batch, the more responsive the factory can be to customer demand, and so it reduces over-production.
- Minimum batch size minimizes inventory requirements.
- Minimum batch size minimizes transportation between warehouses and factories.
- Minimum batch size minimizes re-work if the inspection process is in-stream with production activity. If a defect is found, only that one batch and ideally, only one piece, needs re-work.
- Minimum batch size reduces idle time if an item can move from one process to the next without waiting for a batch to finish ahead of it.
Value Stream Mapping
Value Stream Mapping is a Lean process that follows the manufacturing process to determine which process adds what type of value to the product. In the above example where you need a supply of bolts today, value was added by the milling operations (to cut and thread the bolt) and also by the expedited shipping process. The nickel-plating step added no value. If you had placed your order with enough lead time for regular delivery, then the expedited delivery service would have added no value.
Value Stream Mapping entails following the manufacturing process, including the handling and storage stages, to determine where value is added. For example, storing goods-in-process so that a coating can dry properly is a value-adding step (if the customer wants the coating). Storing finished goods in a warehouse in order to expedite shipping might add value, depending on the time to manufacture and the urgency of a customer’s order. (In the airline industry, for example, “Plane on Ground” is the highest priority for manufacturing a replacement part). Storing goods-in-process in a warehouse (because the next machine is busy working on previous batches) does not add value.
References
1. Jeffrey Liker, The Toyota Way
2. Lonnie Wilson, How To Implement Lean Manufacturing