Perspective Chapter: The Lean Approach in Waste Management – A Case Study

Abstract

This work presents a manufacturing case study focused on reducing waste in a corrugated paperboard packaging company located in Italy. Corrugated paperboard is the primary material used in transporting, distributing, and storing many products, particularly food productions. The project started in September 2020 with the aim of identifying the causes of some waste along the production process and the consequent planning of actions to reduce them. This project was implemented following the logic of lean manufacturing through the use of the PDCA (Plan-Do-Check-Act) methodology. The quality control tools for continuous improvement of the manufacturing process are used. The results achieved by the plant are significant in terms of economic and environmental sustainability. From an economic point of view, the measures implemented have allowed the plant to achieve, in the period between September 2020 and March 2021, a decrease from 10% to 9% of the percentage of the waste with a cost reduction approximately of € 17,000 for each of the first three months of 2021. From an environmental point of view, waste reduction is one of the objectives underlying the sustainability strategy adopted by the company, which has long been committed to the responsible management of its production processes to reduce its environmental impact.

1. Introduction

Four years after the adoption of the 2030 Agenda by the 193 member countries of the United Nations, including Italy, there is a growing awareness worldwide of the need for an integrated approach to address complex economic, social, and environmental challenges in order to shift to a sustainable development model. The sustainability approach, a set of principles, tools, and practices oriented toward sustainable development, is progressively establishing as a new paradigm in the activities and processes management of all organizations [1]. In particular, among the factors that more than others have given a strong impetus in the direction of a profound change in the management models and tools adopted, the joint search for efficiency, effectiveness, and sustainability represents the most significant. In fact, organizations that develop sustainable strategies may have a competitive advantage in terms of higher productivity, better products, and considerable cost savings [2]. In literature, there is a consensus that sustainable development involves improvements in different aspects, such as energy consumption, reduction of emissions to air, water, and soil, environmental impacts of the products, reduction of waste and better efficiency in the use of rawmaterial, health and worker safety [3, 4, 5], and the implementation of lean or Six Sigma approach in the business organizations can improve productivity and environmental sustainability.

In the manufacturing sector, as well as in the cardboard packaging production sector, the management of waste and the efficiency in the use of raw materials represent one of the most critical situations that companies have to manage. The corrugated cardboard production sector, with almost 7 billion m² of produced area, 150 thousand employees, and almost 500 plants in Europe, has become over the last decades the most requested material in the production of eco-friendly and robust packaging to contain, protect and transport. Thanks to its recyclability and biodegradability, it has fostered the birth of green packaging industry, whose main prerogative is the reduction of environmental impact. In Italy, the sector is worth about 4 billion euros and counts on a supply chain that employs 15 thousand people for an annual production that in 2018 exceeded 7 billion m² (an increase of 3.62% compared to 2017). According to the Italian Corrugated Cardboard Manufacturers Group (GIFCO), this is a sector that records continuous growth thanks also to the push of e-commerce. Italy is the second European producer of corrugated cardboard used in packaging after Germany, followed by France and Great Britain. In the last decade, corrugated paperboard companies are under pressure in order to improve productivity and quality while reducing costs. In addition, the need to promote the long-term sustainability of the natural resource, such as wood fiber, which is the single largest input to the manufacturing of paper products, become strategic the efficient use of renewable natural resources, thus reducing waste and improving the circularity of the manufacturing processes. Today, corrugated boxes are made from a high percentage of recycled paper, such as corrugated boxes, cartons, or newspapers. The re-use of such items means corrugated offers a number of environmental benefits. In other words, the adoption of a sustainable strategy allows more efficient use of resources, better cost results, and reduces adverse impacts on people and the environment. There are several methods that facilitate sustainable practices, one of these is lean production [6, 7, 8, 9, 10]. It is a methodology that aims at maximum efficiency through eliminating all those activities with no added value and that are a source of waste and costs.

The objective of the present study carried out in a corrugated cardboard industrial company, was to implement a lean production system based on the PDCA (Plan-Do-Check-Act) method to identify and reduce wastes in the production process of the firm. The orientation toward sustainability has become one of the cardinal principles of company policy, for this, it is important to become more efficient in the use of resources through a reduction of the waste in the production process; thus, enabling the increase of economic benefits. This has led the company to make a strong commitment to improve the environmental impact of all its plants and promote the sustainability of the company for the benefit of future generations. For this reason, since 2020 the management of the company has implemented a lean production approach, with the aim to reduce waste by 0.75% in 2021. To achieve the proposed objectives, a methodology based on the PDCA cycle was implemented.

2. Lean production and waste management in manufacturing

The term Lean production was coined by researchers in the International Motor Vehicle Program at the Massachusetts Institute of Technology to describe the way in which production operations were organized at the Toyota Motor Company in Japan during the 1980s. The goal of lean production is doing the same number of outputs by reducing the number of inputs, through the elimination of waste in order to give customers what they want and satisfying their expectations. In other words, this management approach allows for improving the operational efficiency, quality, and flexibility through the elimination of waste [7, 10]. The elimination of waste is the primary goal of any lean system. The term waste or muda is anything that consumes resources without creating value for the customer. Studies conducted in the manufacturing sector [11, 12, 13] have confirmed the existence of seven types of waste (Table 1) and how they negatively impact time, cost, and product quality. In particular, with specific reference to defects, some research [14, 15] has shown that these represent the main cause of damage or bad quality of products. In this case, bad quality or defects do not only result in customer dissatisfaction, but also in waste due to additional costs and time to repair the defect, resulting in a slowdown in production and increasing lead time. In the manufacturing sector, as well as in the cardboard packaging manufacturing sector, the presence of defects in raw materials are one of the most critical situations that companies in this sector must manage. Waiting time is another particularly important type of waste. For example, employees are not doing their work, as they are unproductively waiting for the elimination of the defect and restarting the machine.

Waste	Definition	Some causes
Overproduction	Producing more than what is needed or producing faster than what is needed.	volume incentives (sales, pay, purchasing) high-capacity equipment line imbalance; poor scheduling/shifting poor production planning
Process wastes	Non-value-added man/machine processing.	Organizational inefficiencies Low machine performance; Inadequate equipment or tools
Transport	Unnecessary material/tools movement.	Poor route planning; complex material flows poor layout disorganized workplace
Waiting	All waiting times that are “not strictly necessary” to the product manufacturing cycle.	Unsynchronized processes; inflexible workforce unscheduled machine downtime long set-up material shortage or delay
Inventory	Excessive process inventories; excessive raw material inventories	Over-production; long lead times local optimization large minimum order quantities high rework rate lack of material requisition and issuance standards
Motion	Unnecessary movement and motions of worker.	poor layout and housekeeping; disorganized workplace and storage locations unclear, non-standardized work instructions unclear process and materials flow
Defects	Processing due to the production of defects; processing due to rework or repair of defects materials used due to defect and rework	unclear customer specifications incapable processes lack of process control unskilled personnel departmental rather than total quality incapable suppliers

Table 1.

Seven types of waste.

Over the years the lean production model has been refined, taking on other designations as well, such as lean organization, lean manufacturing, lean service, lean office, lean enterprise, and even lean thinking, indicating its nature as an industrial “philosophy” that inspires essentially all methods and techniques. Numerous studies [16, 17, 18, 19, 20] have demonstrated the effectiveness of this approach in terms of cost reduction, improved quality, and flexibility through the elimination of all non-value-added activities and waste.

2.1 Continuous improvement and PDCA cycle

Implementation of lean production may be facilitated by the use of quality tools, among which the Plan-Do-Check-Act (PDCA) method can be applied to the implementation of waste reduction programs and sustainable management strategies. This methodology initially was developed in 1930 by Walter A. Shewhart. However, it was William Edward Deming who developed this method with the purpose of providing a tool for product quality control [2, 21]. It quickly became an industry, a useful tool that can support the development of process improvements at the organizational level [22]. This cycle is a sequence of actions necessary not only for pursuing the goal of continuous improvement but also for solving quality-related problems and implementing new solutions. Some authors [23] show that continuous improvement tools, such as PDCA, are often used in change management processes, in the implementation phases of new solutions, or when a new process has to be designed. Thanks to its versatility, this tool can be used successfully in any company and in any sector of activity, such as health and education sectors. The Deming cycle is divided into four phases:

• PLAN: The purpose of this phase is the analysis of the current situation in order to understand the nature of the problem and the development of actions for solving the problem.

• DO: In this phase, the action plan was implemented.

• CHECK: After the application of the action plan, the results of the actions are analyzed. In this phase, it is important to compare the new situation to the old, verifying if there were improvements.

• ACT: At this phase, the new actions will be standardized, and identify other opportunities for improvement.

Numerous studies conducted in different industrial contexts [24, 25, 26, 27] show that different applications of PDCA methodology have been implemented with positive results in terms of reduction of waste and costs, as well as improving the quality of processes and products. Some authors [28] investigated how to reduce defects that minimize the rework rate through the PDCA methodology. In another work [29] the PDCA cycle was used for continuous quality improvement in a dairy laboratory. The results showed a significant reduction from the initial 368 to 85 samples of contaminated UHT milk. This reduction resulted in an increase in efficiency from 68.02% to 74.06% and ineffectiveness from 88.95% to 96.85%. So, the PDCA methodology allowed a reduction in the incidence of errors, making the processes more efficient. The effective implementation of PDCA requires the use of appropriate techniques and tools that can support each of the phases of the cycle, especially in the problem analysis and in the definition of the actions that must be implemented. The seven basic tools are flowcharts, control charts, histograms, Pareto analysis, Fishbone diagram, check sheet, and scatter diagram. Through the synergistic use of these tools and techniques, it is possible to identify the problems that are at the origin of the waste, select the main one, show the relationships between different variables, search for all potential causes, and then get to select the real ones. Numerous researches [30, 31, 32, 33, 34, 35] have confirmed the effectiveness of quality tools in continuous improvement projects. In addition to the seven basic quality tools, some authors [2, 15, 36] also mention the following main ones: Six sigma, the 5S method, A3, failure mode analysis and effects (FMEA), quality function deployment (QFD), single-minute exchange of die (SMED).

3. The case study

This study was conducted in a large multinational company producers of fiber-based packaging and pulp. In Italy, this organization has four plants responsible for the production of corrugated boxes, offering customized packaging solutions for fruit and vegetables, poultry, and industrial segments. The research was carried out in an Italian plant responsible for the production of corrugated packaging solutions for agricultural, consumer goods, and industrial applications. This plant occupies an area of 30,000 m² and employs about 170 people, with an annual production capacity of 150 million m² of cardboard. The flow of materials goes through the following unit:

1. Raw materials warehouse where the paper reels, after quality control, are stored in two separate warehouses.

2. Corrugator unit: the first step is to create sheets of corrugated cardboard; this takes place in the corrugator department. With an area of about 2500 m², it employs a line equipped with machines that perform different functions during the process, such as preheating the paper, corrugating it, gluing the various layers of the final sheet of cardboard, dehumidifying it, cutting the continuous strips of cardboard, etc. In this department is also considered the pulping department in which there is a machine that macerates the waste paper to be then sold in order to make a minimum profit from the production waste.

3. Wip unit: it represents the intermediate unit between the corrugator and the cardboard box machine. In this unit with the sheets of cardboard are sorted in the seven lines of the box factory unit.

4. Box factory unit: it is an area of about 6500 m² with seven production lines, dedicated to the production of cardboard boxes.

3.1 Methodology

Since 2020 the management of the company has implemented a lean production approach, with the aim to reduce waste by 0.75% in 2021. To achieve the proposed objectives, a methodology based on the PDCA cycle was implemented. In the first phase, data collections were carried out weekly in order to quantify the forms of waste. At the same time, the flow diagrams of the various processes under analysis were created with the aim of highlighting those that have occurred in a higher amount [37]. Based on these data, through Pareto chart and Fishbone diagram, it was possible to identify the main causes of waste. In this way, opportunities for improvement were identified [15, 28]. In the second phase, based on the analysis carried out in the previous step, improvement opportunities were implemented. Subsequently, during the third phase, the results of each action implemented were evaluated. Finally, in the fourth phase, on the basis of the evaluation carried out previously, the new measures were standardized.

3.2 Results and discussions

3.2.1 Results of phase PLAN

In this phase, the current situation of the waste in the different production unit was identified through the manageable waste KPI (MW KPI). In order to identify all forms of waste, it was necessary to analyze the overall production process, from the paper reels arrived at the plant, until they were shipped to the final customer. To do this, a flowchart of each department was developed. At this stage, it was important to engage the employees in order to understand exactly where, when and under what conditions the problem occurred. In addition, direct observation of the tools and machinery used in the production process it was important in order to identify problems and defects. During the various meetings with improvement groups, it was decided to focus on the corrugator cardboard manufacturing line where the largest amount of waste was generated. A corrugator cardboard machine is a set of machines designed to bring together three, five, or seven sheets of paper to form single, double, or triple wall board in a continuous process. In order to identify the most frequent causes of waste, the Pareto diagram was used (Figure 1).

Figure 1.

Pareto diagram—causes of waste.

Pareto diagram highlighted that the most important causes of waste in the corrugator cardboard manufacturing line were the downtime, peel, and paper residual around the core of the roll. The analysis of MW KPI pointed out that the high number of defective cardboard boxes was due to the frequent downtime of the corrugator, which had suffered a productivity decrease in recent years. This important type of waste was caused by defects and blocks recurring in the corrugator machine. The results in Figure 2 show that the main causes of downtime of the machine were paper breaking and blocks.

Figure 2.

Pareto diagram—causes of downtime.

To analyze the causes of this phenomenon, the Ishikawa diagram was used. This tool is a result of brainstorming of the working team of the corrugator department, consisting of employees of the Ondulator Department, manufacturing manager, and process improvement manager. As a result, of brainstorming, it emerged that breaking paper was mainly due to mistakes made by employees during the creation of the couplings. Indeed, the breaking paper was caused by wrong operations, wrongs in paper reel peels, paper reel wrong, uncontrolled paper reel, and damaged paper reel.

The same analysis has been made for the block machine. The team identified three main groups of causes: method, machine, and people (see Figure 3). In the “machine” group, the main cause was the incorrect adjustment of belts, causing their premature wear.

Figure 3.

Ishikawa diagram.

The next group of causes “Method” and “People” specified causes, such as lack of right scheduling interventions, failure reporting, incorrect frequency of lubrication activities, and wrong procedure

After identifying the causes which might have affected the problems, the improvement continuous team, through continuous interaction with the employees of the corrugator unit, identified potential solutions, based on the cost-effectiveness of the solution, its effectiveness, reliability, and technical complexity. With reference to each solution, the person responsible for the action itself, the deadline, and goals were then identified.

3.2.2 Results of phase DO

The aim of this phase is to implement the action plan in order to make changes and eliminate the causes of problems in the production process. Among the implemented improvements were the following:

• Root cause analysis, with the aim to obtain a large amount of data in order to understand what happened, how, and why. In this way, it has been possible to show which section of the machine deteriorated most frequently, and how often were these problems occurring.

• Implementation of new breakdown reporting.

• Improvement of maintenance activity end and its planning.

• Employees empowerment through sharing of key indicators related to the number of wrong couplings and downtime of the line.

• Training meetings.

3.2.3 Results of phase check

At this phase, the results of the implementation of actions for each type of problem are analyzed. It is necessary to ask whether the problems identified in phase 1 have disappeared, or at least diminished. This activity, with a view to continuous improvement, was very important because it is possible to highlight any deviations from the planned objective, and it is possible to identify other opportunities for improvement.

Regarding the breaking paper, Figure 4 shows a decrease in downtime after the implementation of the actions planned.

Figure 4.

Downtime for breaking paper after the implementation of the action plan.

3.2.4 Results of phase act

Based on the findings of the check analysis and verified the sustainability and effectiveness of the implemented actions, it was necessary to proceed with standardization of improvement. Standardization is a key element in the lean approach, as standards define best practices for process implementation. What was tried within a single team, what was tried in a single process, the change that was made in a single machine, all of this must be extended to become the new standard to be followed and becomes the basis for subsequent further improvements. Since the purpose of the standard is to enable activities to be carried out without error and waste, it must contain a precise description of the sequence of activities and how these activities should be carried out correctly in order not to generate waste.

4. Conclusion

Lean management is nowadays one of the most dominating management approach, both in industrial and service environments. One of the reasons for such success is its simplicity. The whole concept is based on a common-sense idea of so-called “waste.” Removing it is the very essence of Lean Management. The measures implemented in the Italian plant in the period between September 2020 and March 2021 have allowed sto significantly reduce waste and costs. The waste associated with breaking paper and blocks were reduced from 10% to 9%, with a cost reduction of 17.000 euros. This is an important achievement considering that the company’s competitive position depends on many factors, including price, cost, product, and service quality. In addition, the implementation of the lean methodology has enabled the company to make the overall corrugated cardboard production process more efficient through better organization of the work. This means that in order to improve the process and reduce waste, it is necessary to encourage employees to analyze the problems and identify the opportunities for improvement. The plant’s achievements are also particularly important in terms of sustainability. In fact, waste reduction is one of the goals underlying the sustainability strategy adopted by the company, which has long been committed to the responsible management of its production processes in order to reduce their environmental impact. Environmental protection and responsible production practices are two fundamental aspects of the company’s way of operating. For this reason, the efficient use of paper in the corrugated board production process and the consequent reduction of wastes represent important goals for the company and which are, therefore, continuously monitored.