Lean methods: Designing an efficient value chain using the example of battery production in the electric car industry

Lean describes a corporate philosophy that aims to design processes efficiently by avoiding waste. The roots of the lean concept lie in production and were developed in the Toyota production system in Japan in the 1950s.

Lean production was created to reduce costs while ensuring quality and customer benefit. Lean management extends this optimization principle by avoiding waste to all areas of the company, including administration and product development, and aims to optimize the entire value chain.

Lean methods are a practical set of tools that anchor the principles of lean production and lean management in operational and strategic implementation.

The overarching goal of all lean methods is to create a waste-free, customer-oriented value chain. What they have in common is a focus on continuous improvement (Kaizen), resource efficiency and a consistent orientation towards customer needs.

The large number of different lean methods results from the need to tackle specific challenges in a targeted manner, for example depending on the industry or manufacturing product. Lean methods such as 5S create structured and clean working environments, while Kanban improves the control of production and logistics processes and ensures flow.

It makes no sense to categorize or even strictly assign individual methods to lean production or lean management. All methods are universally applicable and support both physical production processes and strategic-administrative processes.

Lean methods describe the operational procedure for creating lean production. The strategic planning of lean production manifests itself through lean management.

The individual lean stages for implementing lean production can be described as lean principles and include:

• Challenges
• Waste
• Stabilization
• Flow
• Cycle
• Pull
• Value stream
• Perfection
• Standardization
• Continuous improvement

The principle of challenges refers to the ability to systematically identify and address existing problems and inefficiencies in processes. The aim is to create an awareness of potential for improvement and to take targeted measures to optimize the entire value creation process. Challenges are the starting point for all further lean activities and require a precise analysis of the current situation.

Associated lean methods:

• Process analysis
  Process analysis is used to examine workflows in detail in order to identify weak points, bottlenecks and inefficient steps. It forms the basis for targeted process optimization.
  
  
• Spaghetti diagram
  This method visualizes the movement sequences of people or materials in a work process. The aim is to eliminate unnecessary paths or redundant processes and improve the efficiency of the work layout.
  
  
• Snapshot
  A snapshot describes the status of a process at a specific point in time. It is used to document deviations from standard processes or planned procedures and to identify potential for improvement.
  
  
• Problem-solving methods (e.g. 5W method)
  The 5W method helps to identify the root cause of a problem by asking five questions about why a particular deviation has occurred. This enables sustainable solutions.

The principle of waste (Japanese: muda) in lean management refers to all activities that consume resources but do not create added value for the customer. Waste is one of the main causes of inefficiency in processes and must be systematically identified and eliminated. The seven classic types of waste, supplemented by an eighth, are differentiated:

1. Overproduction:
   Manufacturing more products than needed, leading to storage costs and potential losses
   
   
2. Inventories:
   Storage of raw materials or unfinished products that tie up capital and occupy space
   
   
3. Transportation:
   Unnecessary movement of materials or products without adding value
   
   
4. Waiting times:
   Downtime of machines or people due to lack of materials, information or capacity
   
   
5. Unnecessary movement:
   Non-ergonomic or inefficient movement of employees
   
   
6. Process overfulfillment:
   Performing work steps that are not required or requested by the customer
   
   
7. Errors and rework:
   Correcting faulty products or processes
   
   
8. Unused employee potential:
   Lack of involvement of employees and their ideas in improvement processes

Associated lean methods:

• Value stream mapping:
  A visual representation of the flow of materials and information in a process to identify waste and reduce cycle time​
  
  
• Muda safari:
  A targeted observation of processes on site to systematically identify waste. This method emphasizes the importance of direct analysis at the point of value creation (Gemba)​​
  
  
• Chalk circle:
  Managers or process analysts are placed in an area to observe processes over longer periods of time and identify opportunities for improvement​
  
  
• 5S:
  This method helps to organize workplaces in such a way that unnecessary movements and search times are eliminated
  
  
• Spaghetti diagram:
  Visualizes the movement paths of employees or materials to identify and optimize inefficient paths

The principle of stabilization aims to create the conditions for error-free and efficient production by standardizing processes and minimizing fluctuations. Unlike specific lean methods, stabilization is a continuous process that serves as the basis for all other lean principles such as flow, cycle and perfection.

Central elements of stabilization such as the reduction of loss factors, the 3 Mu (Muda, Mura, Muri), the control of inventories, the shortening of throughput times and the levelling and smoothing of production are not stand-alone methods. Rather, they are closely interlinked tasks that together help to create stable process conditions. These tasks are geared towards avoiding fluctuations and overloads, using resources efficiently and ensuring flexibility in order to be able to react to changing requirements.

The principle of flow in lean management describes the continuous movement of products, information and employees through the production process without interruptions or delays. The focus is on avoiding bottlenecks, excessive inventories and waiting times in order to ensure short throughput times and efficient value creation.

A central component of the flow principle is the one-piece flow, in which products are forwarded individually and directly from one processing step to the next. This is in contrast to traditional batch production, which is often characterized by high inventories, quality problems and long throughput times.

Associated lean methods:

• Batch size reduction:
  The aim is to design production quantities in such a way that materials can be processed in a continuous flow. This significantly reduces inventories and throughput times.
  
  
• Process coupling:
  Processes are arranged so that materials move directly to the next work step without intermediate storage or transportation. This increases transparency and reduces production costs.
  
  
• Layout optimization:
  The physical arrangement of machines and workstations is designed to create short distances and clear material flows. Examples include U-shaped or linear layouts that minimize waste caused by transport and increase clarity​​.
  
  
• Visualization of material flows:
  Flow visualizations such as value stream maps or material flow diagrams help to identify bottlenecks and adapt processes accordingly.
  
  
• SMED:
  SMED (Single Minute Exchange of Dies) is a lean method that aims to minimize set-up times and thus make processes more stable and flexible. The aim is to implement changeover processes in less than ten minutes by clearly defining and optimizing internal and external setup processes.

The principle of cycle in lean management describes the synchronization of production processes with customer demand. It is the “heartbeat” of production that determines how quickly a product must be manufactured to meet customer demand. The customer cycle is calculated by dividing the available production time by the required quantity of products.

Associated lean methods:

• Cycle time calculation:
  Determines the required speed of each process step based on the customer requirement. Example: A customer cycle of 80 seconds means that a product must be completed every 80 seconds.
  
  
• Visualization:
  Tools such as andon boards or cycle displays make production progress visible and help to identify deviations immediately.
  
  
• Process harmonization:
  Adaptation of work content to the customer cycle to ensure even utilization of all process stations. This can be achieved through standardization or work redistribution.

The pull principle in lean management means that products or components are only manufactured or delivered when there is an actual demand. In contrast to the push principle, where production is based on forecasts, the pull system only produces what is actually consumed. The aim is to minimize inventories and closely synchronize production with demand.

Associated lean methods:

• Kanban:
  Kanban is a visual control system that regulates the flow of information within the pull system. It works with cards or bins that serve as signals for re-production or material requests. Examples are visual Kanban, container Kanban or E-Kanban.
  
  
• Just-in-Time (JIT):
  JIT ensures that materials are available in the right quantity and quality exactly when they are needed. It reduces inventories and increases responsiveness to customer requirements.
  
  
• FIFO (First-In-First-Out):
  This method ensures that the parts manufactured or delivered first are processed first. It minimizes the risk of outdated materials and ensures that resources are used evenly.

The value stream principle in lean management focuses on optimizing the entire material and information flow through systematic analysis and design. The aim is to maximize value creation from raw material to delivery to the customer while minimizing waste, variability and inflexibility. The value stream makes it possible to visualize the connection between all processes and identify opportunities for improvement along the entire value chain.

Associated lean methods:

• Value Stream Mapping (VSM):
  A visual method to analyze the process chain holistically. Symbols illustrate the flow of materials and information as well as weak points that can be optimized.
  
  
• Kaizen flashes:
  Markers in the value stream that highlight potential for improvement. These flashes are used to quickly address specific problem areas​​.
  
  
• Definition of key figures in the value stream:
  Customer cycle, process time and lead time are key performance indicators. They quantify the value stream performance and highlight optimization opportunities. A flow rate of less than 1 % in conventional processes can be increased to up to 50 % by optimizing the value stream.

The principle of perfection in lean management pursues the goal of ensuring error-free production and generating quality directly in the process rather than through inspections. Perfection is the long-term pursuit of continuous improvement in which processes are designed to be stable, robust and efficient in order to achieve the goal of zero defects. This goal is particularly crucial in sectors such as the electronics industry, as minimal error rates are necessary to meet quality requirements.

Associated lean methods:

• Poka Yoke:
  Poka Yoke (Japanese for “avoid mistakes”) prevents unintentional errors in the process. The concept comprises three principles:
  
  
  • Contact principle: errors are detected by physical properties of components (e.g. USB plugs that only fit in one direction).
  • Fixed value principle: Deviations in parameters such as weight or quantity are detected (e.g. when picking parts).
  • Process step principle: The process flow is monitored so that deviations in the sequence or missing steps trigger errors and prevent the process from continuing​​.
    
    
• Jidoka:
  Also known as “automation with a human mind”, this method ensures that production is stopped immediately if an error is detected. Andon boards or acoustic signals inform the team of the source of the error, and the error is rectified immediately. This increases productivity and ensures quality.
  
  
• Determination of quality indicators:
  Key performance indicators such as First Time Through (FTT), First Time Right (FTR) and First Pass Yield (FPY) quantify how error-free production is. The aim is to achieve error-free production without rework​​.

The principle of standardization in lean management forms the basis for stable and predictable processes. Standards describe the safest and most efficient way to carry out an activity at any given time. They ensure uniformity and repeatability and provide a basis for systematic improvements. In contrast to rigid norms, standards are dynamic and are continuously developed to ensure optimization.

Associated lean methods:

• Standard worksheet (SAB):
  The SAB describes each work step and the resources required for it in detail. It serves as a reference document for training and audits and supports compliance with the standards​​.
  
  
• Visualization:
  Tools such as shadow boards or workplace layouts facilitate compliance with the standards. Visual signals minimize the need for verbal communication and promote employee autonomy​.
  
  
• 5S method:
  This method supports the introduction of and adherence to standards by ensuring order and cleanliness. 5S comprises the steps of sorting out, tidying up, keeping the workplace clean, arranging as a rule and repeating all steps.

The principle of continuous improvement (Kaizen) is a central component of lean management and describes the systematic, step-by-step optimization of processes. The aim is to reduce waste and increase efficiency through regular adjustments. In contrast to radical redesigns (kaikaku), kaizen is based on small, incremental steps that are integrated into daily work.

Associated lean methods:

• PDCA cycle (Plan, Do, Check, Act):
  The PDCA cycle is the standard method for implementing improvements.
  
  
  • Plan: Problem analysis, goal setting and hypothesis formation.
  • Do: Implementation of measures and collection of results.
  • Check: Comparison of target and actual status and review of results.
  • Act: Implementation of successful solutions as a new standard and renewed iteration.
    
    
• Kata improvement routine:
  A method that encourages employees to solve problems and experiment independently by asking specific questions. This promotes a learning organization and strengthens personal responsibility.
  
  
• Kaizen workshops:
  This form of collaborative working brings teams together to analyze specific problems and implement improvements in a short period of time.
  
  
• Suggestion scheme:
  A structured system that enables employees to contribute ideas for improvement and encourage their implementation. This boosts innovation and increases motivation​​.
  
  
• Problem-solving techniques:
  Techniques such as the 5W method or Ishikawa diagrams help to systematically identify the causes of problems and develop effective solutions​​.

Industrial production is facing increasing demands worldwide, including the optimization of resource use, cost reduction and sustainability. These challenges are particularly pronounced in battery production, which plays a key role in electromobility. According to the “Fact Check Batteries for Electric Cars” published by the Öko-Institut in 2020, global demand for lithium-ion batteries will increase to up to 4,000 GWh by 2030 - a tripling of current demand.

At the same time, legal and regulatory requirements are becoming stricter. For example, the revised EU Battery Directive (EU Directive 2006/66/EC) requires battery manufacturers to implement measures to increase efficiency and recycling in order to reduce their ecological footprint. In addition, there are national climate laws, such as the German Federal Climate Protection Act, which stipulates a 65% reduction in CO₂ emissions by 2030 compared to 1990.

Customer requirements supplement these regulatory requirements: They require batteries with an energy density of at least 350 Wh/kg to enable longer ranges and a reduction in cell costs to below USD 100/kWh to make electric vehicles more competitive. Lean methods such as SMED to reduce set-up times, Poka Yoke to avoid errors and Kanban for production control offer effective approaches to meet these complex requirements.

In the following section, we show how GREIF-VELOX is improving efficiency and sustainability along the entire value chain in battery production for electromobility by developing the Velovac system and focusing on lean principles and lean methods.

GREIF-VELOX has taken on the challenge of optimizing the complex processing of carbon black - an essential raw material for the production of lithium-ion batteries - using innovative filling and bagging technology. The application of lean methods played a central role in ensuring efficiency, sustainability and occupational safety in this process.

Carbon black is an ultra-fine powder with a grain diameter of 60 to 110 nm, which is difficult to pack and transport due to its material properties.

Conventional bagging methods regularly resulted in dust, high cleaning costs and health risks for employees. In addition, bulky bags with air pockets caused inefficient logistics and quality losses due to product contamination.