When we talk about lean manufacturing, imagine it like a building:
The pieces on the bottom build the foundation for the next level, which create a platform to support the "roof." This is the kind of graphic that most companies use to visualize the lean methodology. Sometimes there are more bits involved, sometimes less.
The seed of lean manufacturing was planted by the Toyota Production System (TPS), and has been refined throughout the years as manufacturing evolves. However, the basic ideas remain.
Lean manufacturing starts with stable operations.
The most important component of stable operations is motivated, flexible employees. Employees who are exhausted, frustrated, or otherwise not performing at their best create an unstable base for the entire company.
Next comes the work performed by the employees. The work should be standardized - done one way and optimized for efficiency. The load should be level every day, meaning the manufacturer produces product even during lulls in business (but does not over produce). TPM stands for total productive maintenance, meaning constantly maintaining machinery, processes, and people to prevent breakdowns before they happen.
Lean manufacturing leads to optimized production.
Optimized production involves a lot of different pieces working together:
ON THE LEFT
Just in time production means providing the customer with the right amount of the right part at the right time. This ties into the biggest philosophy of lean manufacturing: waste elimination.
Flow is the rate at which a product moves through each step in the manufacturing process.
Takt time is the rate at which a company must complete orders, based on customer needs and available working time.
Pull is a method of lean manufacturing where components are only replaced once they are used up. This is based on actual demand, unlike a push system which uses forecast demand to order and use components ahead of time.
Quick changeover refers to shortening the amount of time it takes to prep a machine for production of one product to another (e.g. changing out tools and dies). SMED, or single minute exchange of dies, is a specific technique used to minimize changeover time.
ON THE RIGHT
Jidoka refers to quality at the source, or built-in quality. Specifically, quality is built into the process rather than only checking for it at the end.
Jidoka is also known as line stop, which means any employee has the ability to pull the plug on an operation if they detect an abnormality. This immediate line stop means less chance of complete system failure.
The line stop, although it may halt processes in their tracks, is an important aspect of overall efficiency and waste elimination. Ensuring product quality at multiple steps of the operation means less rejected product at the end, and fewer machine issues in general.
IN THE MIDDLE
The middle pillar houses three things: the seven wastes, continuous improvement, and maintenance of standards.
Continuous improvement and standards maintenance are passive components. As long as the manufacturing company adheres to the other ideals, these two things should happen naturally.
So, what are the seven wastes? The easiest way to remember them is the acronym TIM WOOD:
T: Transport - time and distance a product is moved in the manufacturing process. Transport wastes time and value every second a product isn't being transformed.
I: Inventory or Storage - A product in storage isn't adding value to anyone. The less time a product sits on a shelf, the more value it has
M: Movement - of the machinery and operator. If an operator is away from his or her machine, or the machine is being moved, no value is being added.
W: Waiting and delays - products waiting for the next process.
O: Overproduction - incorporates all other wastes. Overproduction happens when processes aren't working efficiently - so, components or products sit in storage, sit in delays, get moved around, have a higher chance of being damaged, etc.
O: Overprocessing - basically, trying too hard. One writer at EBA worked for a company that produced keypads. The customer requested blemish-free quality to the naked eye. The company examined each keypad with a 14x magnifying glass and any imperfect products were rejected. That's the definition of overprocessing.
D: Defects - every defective product costs money and time in materials, staff costs, and pushing other jobs back to complete that project.
All seven of these wastes are incredibly common in the manufacturing industry. Lean manufacturing aims to reduce these wastes as much as possible to create a streamlined process from start to finish.
Stable operations & optimized production enable lean manufacturing.
All of these things hold up the roof of our lean manufacturing building: lean performance.
Lean performance results in highest quality products, lowest cost for the customer AND manufacturer, shortest lead time, best safety for machines and people, and high morale for all employees (leading directly back to employee motivation at the bottom!).
Why should you care?
The customer is the ultimate beneficiary of lean manufacturing. You receive the highest quality product possible, the lowest cost achievable, and the shortest lead time between placing the order and receiving the product.
If you value high quality, low costs, and process efficiency, then you should value lean manufacturing.
Ask about it next time you need a manufacturer.