Lean Production Methods – The eight basic pillars of lean production systems
In the early days, there was little acceptance of lean production from employees. Rather, there was the misconception that this was a matter of rationalization measures. At the time, however, everyone quickly realized that lean production can only be successful if the entire system is based on just one central point. And this central point was called customer benefit. This way of thinking ultimately made lean production a success. In Germany, this production system quickly became known as “holistic production systems”, using the methods of lean production. A distinction is made between eight basic pillars.
- Avoiding waste: Waste (Muda) represents the counterpart to value. It is therefore important to avoid waste and increase value. All production factors must be minimized if they do not add value. In addition, the organization of processes must be resource-efficient and, on the one hand, reduce waste and improve throughput times. Lean Production is a way of ensuring that production is sustainable.
- Continuous improvement process (Kaizen): The pursuit of perfection is the goal of a holistic production system. In order to be able to achieve this, it is necessary to continuously drive the improvements of existing systems and processes. In order to be able to achieve this, it is imperative to involve the employees in this continuous improvement process. But this also means that every single employee has to question all processes, all methods and all tools. This is the only way to achieve an improvement. Many companies solve this with an in-house improvement suggestion model.
- Standardization: Standardization replaces constant flexibility. The goal here is a small variance between production and process results that cannot be foreseen.
- Zero-error principle: The zero-error principle prevents errors from being passed on to the next process unit. Quality controls are integrated into the standardized process.
- Flow principle: The ideal lean production runs according to the flow principle. This means that production, marketing and sales are all in a flow. From start to finish, everything is linked by a sub-process. These sub-processes build on one another.
- Pull principle: The pull principle describes a production that is geared purely to customer needs. The production here reacts to the demand in the market. There is no flooding of the market with products here.
- Lean Leadership: This is about employee orientation and goal-oriented leadership . The focus is on the transfer of information in flat hierarchies. The divisional managers have to show flexibility here and ensure good integration.
- Visual management: The visual management ensures visual clarification. The procedure can therefore be compared with marketing strategies. Visual marketing means with overview photos, with instructions and workflow plans at the workplace. This ensures the necessary attention and compliance with the processes and procedures.
TIMWOOD – The 7 types of waste
According to gradphysics, the classic Lean Production teaching according to Talichi Ohno distinguishes between 7 types of waste.
|Type of waste||Description|
|T||T stands for transport|
|I.||I stands for inventory|
|M.||M stands for motion|
|W.||W stands for Waiting|
|O||O stands for over-production|
|O||O stands for over-engineering (wrong processes / technologies)|
|D.||D stands for defects (scrap / rework)|
Transport is counted as necessary waste. The reason for this is that in every manufacturing process it is necessary to transport materials through production. The aim, however, is to keep waste in this area as minimal as possible.
With high inventories, the problems that exist in a value chain are hidden. They hide some weaknesses that may arise in other places or that already exist. With high inventories, capital tie-up costs are incurred for every company. This increases the risk of impairment, for example due to obsolescence.
Unnecessary movement lowers productivity. Unnecessary movement includes both small-scale and large-scale execution. Smaller movements are caused, for example, by poor ergometry at the workplace. Larger movements can be caused by employees who are either constantly on the move in their work area or even have to leave the area for procurement.
There is no activity during the waiting period. In this phase, the employee cannot add anything to the added value of the product. Waiting times are caused, for example, by the lack of supplies of material or by waiting for the end of a processing operation on a machine. The previous step has not been completed and the next step cannot therefore be started.
The state of over-production is always given when the production is higher than the acceptance by customers. Stocks are generated from overproduction, which incur costs because there are no buyers. At first glance, there is added value through the manufacture of the products. However, there is always the risk that sales will be generated from customers’ purchases or that it will remain with the inventory.
If processes or manufacturing processes are more extensive than they should and are not required for the product, this is referred to as over-engineering. This mainly happens if there has been no adaptation of the technology or the processes for production over the course of time.
Defects concern rejects or the reworking of products due to poor quality. In this case, part of the added value has already taken place. In the worst case, even completely. This very often happens during the final inspection of the product. In the event of rework, the added value is partially wasted, in the case of rejects it is even completely wasted and must be repeated.
Important key figures in lean production
Success is only possible if there is measurement and control. A measurement of certain key figures can often bring initial success. The following key figures are particularly important for lean production.
|Lead time||The lead time (DLZ) describes the period of time that is required for the manufacture of products in production. The shorter it is, the better it is for the company.|
|Flow rate||The degree of flow is a percentage. This indicates the relationship between the processing time for a product (or service) and the lead time for the product (service). The flow rate is calculated using the following formula:Degree of fluidity = processing time x 100: processing time|
|Flow number||One of the most important indicators is the flow rate. It provides information about the proportion of transport times or waiting times in relation to the actual processing time. The smaller this metric, the better it is. The ideal value is a 1, but this is almost impossible to achieve.|
|Flow factor||The flow factor can be used to determine the mean length of a queue for a workstation. The formula for the flow factor is:Flow factor = number of jobs: number of all jobs started|
|Degree of added value||The degree of added value is a rate that is defined from the factors added value and overall performance. The result is always given in%. The formula for determining this key figure is:Degree of added value (%) = added value x 100 / total output|
|OEE||OEE (Overall Equipment Effectiveness) is a key figure that shows the percentage in which time a system produces products of high quality in a prescribed time.|