1. Introduction
The economic development of all countries, both developed and emerging, was impacted by the global economic and financial crisis in 2011. This crisis disrupted market competitiveness and presented new challenges [
1]. Consequently, economic recovery has occurred at varying speeds, as evidenced by the growth of gross domestic product (GDP) worldwide [
2]. However, as noted in [
3], growth in emerging markets is projected to increase modestly in the medium term. Angola finds itself within this context of economic challenges.
During the colonial period, Angola’s economic activity was primarily driven by exports, with 65% consisting of rubber, supplemented by coffee, sisal, cotton, and fishery products. Subsequently, there was notable progress in extractive industries, particularly in diamonds, iron, and oil.
The manufacturing sector, encompassing food, textiles, beverages, and tobacco, contributed 64% to the total industry [
3]. However, following the war, Angola’s productive infrastructure deteriorated significantly, leading to near paralysis in many traditional sectors. By 2014, 95% of exports were reliant on oil [
4], and the international decline in oil prices resulted in reduced revenues for the country.
Presently, the Angolan government has implemented measures to counteract the impact of falling oil prices, focusing on two main strategies: increasing non-oil revenues (through taxes and equity) and diversifying the economy [
4]. In this context, Decree-Law no. 5/04 of 7 September 2004, was enacted to promote industrial diversification [
5]. This initiative involved state support for national and foreign investments linked to scientific development, emphasising training and the application of new technologies. The process of economic diversification had the following main objectives:
Increase the national production;
Reduce the national dependence on imports;
Strengthen the Angolan enterprise;
Promote job creation;
Diversify sources of revenue and foreign exchange.
Therefore, several agreements have been reached with the International Monetary Fund (IMF). The latest report of the Angolan Ministry of Finance [
6], bounded with the National Development Plan 2018–2022, reported, as main initiatives, the implementation of alternative management and exploitation modalities provided by article nº 6 of Public Business Sector Basic Law, as well as the restructuring of companies and the professionalisation of management teams [
7].
This report indicated that, until 2018, the real business cycle of the economy showed a recessive behaviour, having registered a negative growth rate of around 1.1%, due to the low levels of oil production and the lower economic activity of the non-oil sector (spillover effect). However, it also pointed to an economic growth of 3.2% for 2021 [
8].
Meanwhile, [
1] indicated that inflation, which has been declining in recent quarters, may, until 2021, reach 7.9%. The current account will remain in deficit, resulting mainly from the increase in imports in the trade balance and growth in the payment of foreign interest, anticipates the government.
Specifically, the Angolan Ministry of Finance [
8] states that the economic relevance of the public business sector is undeniable, because more than 80 companies in the main sectors of the economy, employing more than 50 thousand workers and holding a total of assets representing about 45% of the GDP. However, they were only in surplus due to the cross-subsidy system they received, and such a subsidy system is no longer viable [
8].
Thus, after this initial diagnosis of the sector, strategic levers were identified for companies to survive without subsidies, one being to seek maturity in the industrial network. The word “Maturity” means that it can be extended to reflect the degree of improvement of things and to describe and measure the degree of comprehensive development of a thing or person [
9,
10].
Industrial maturity is a defined level of process evolution, and this level establishes a rational way to improve a process’s capability [
11]. Therefore, the maturity levels assess and measure the development of an industry from its beginning to maturity and they are quantitative standards [
10].
Seeking this maturity, seven priority clusters were defined in 2004 and rectified by [
8], as shown in
Figure 1. The seven clusters for diversifying the economy are Agriculture, Fisheries, Food, and Agro-Industry; Energy and Water; Extractive Activity; Housing; Leisure, Tourism, and Other Services; Oil and Natural Gas; and Transportation and Logistics. The clusters divided themselves into targeted programs (including the adoption of philosophy and the full range of Lean tools), integrating projects of investment and, for their part, speeding up economic diversification [
12].
Therefore, the objective of this work was to analyse the maturity level of industries in Luanda regarding the Lean philosophy practices and tools; analysing whether the industries knew the 5S, Just-In-Time (JIT), Kanban, Bottleneck Analysis, Jidoka, Kaizen, Poka-Yoke, KPI, SMED, Gemba, Heijunka, Value Stream Mapping (VSM), Hoshin Kanri and Andon; whether such tools were used. In addition, an analysis was conducted of the implementation of the five Lean principles established by [
13]: (a) Value; (b) Value Chain; (c) Continuous Flow; (d) Pull system; and (e) Pursuit of perfection [
13]. This work also aims to propose practical implementation actions to contribute to the continuous improvement in companies’ productivity. The hypothesis raised states that the production practices implemented by the companies operating in the Angolan industrial fabric show an adequate level of maturity in accordance with the requirements of the Lean philosophy (LP) in view of the current challenges of this market.
2. Materials and Methods
The methodology was based on the criterion of accessibility, choosing 87 circumscribed industries in Luanda, on the Industrial Development Pole of Economic Special Zone (ESZ) in Viana, Luanda region, Angola, within the clusters (i) Agriculture, Fishing, Food, and AgroIndustry and (ii) Extractive Activity.
The directors of those industries were interviewed through a questionnaire validated through Cronbach’s Alpha and the Kaiser–Meyer–Olkin (KMO) values, which had questions that characterised the main branch of activity, legal classification, and size (according to Law No. 1/04 of 13 February 2011, where (a) small industries have up to 100 employees but with revenues of less than USD 3 million, (b) medium-sized industries, between 100 and 200 workers but with revenues between USD 3 and 10 million, and (c) large industries with more than 200 workers and more than 10 million USD in revenue).
Seven statistical analyses were performed: Analysis of knowledge of Lean practices and tools and whether they were used; customer value analysis (CV); value chain (VC) analysis; analysis of the use of the pulled production system (PPS); analysis of the use of the continuous production flow (CPF); analysis of continuous improvement (CI), and the maturity model of investigation chosen was that of Milan [
1], which is a “simplified and tested model” of the Lean Enterprise Self-Assessment Tool (LESAT) [
14].
This research followed a hypothetical deductive approach, showing that there are indeed gaps in the scientific knowledge about Lean practices applied in the Luanda region, Angola. This study emphasises the quantitative and qualitative approach based on applying a questionnaire to test the raised hypothesis and make a symbiosis with the LESAT model. To verify the hypothesis, the procedure adopted is exploratory, which is justified through the application of the questionnaire and statistical data analysis. The data processing method is inductive, consisting of analysing the data of each company to generalise conclusions [
15,
16].
The preparation of the questionnaire (
Appendix A) was performed as described in
Table 1.
The questions included in the questionnaire aim for answers related to the application of the LP principles. They were carefully chosen according to the most addressed, using a Likert scale, appropriate for the type of variables and the ease of the answer that is intended to be obtained. The LP tools were also carefully chosen according to the most prominent in the sources researched.
The questionnaire was validated to verify its quality as an instrument for data collection. The validity of the questionnaire obeys the use of several sources that make it possible to find evident and convergent contents, linked to the objectives of the study. For this purpose, the factor analysis method was used, the result of which is shown in
Table 2.
The result of the statistical method of factor analysis confirms the dimensions to be measured and the factor load of the items, and only the dimensions that have a factor load above 0.50 are accepted.
To evaluate the reliability of the questionnaire, Cronbach’s alpha method was chosen, suitable for measuring internal consistency with the Likert scale and interpreted according to the results of the Kaiser–Meyer–Olkin (KMO) test [
17], being from 1 to 0.90 very good; 0.80 to 0.90 good; 0.70 to 0.80 average; 0.60 to 0.70 reasonable; 0.50 to 0.60 bad; and less than 0.50 unacceptable [
18]. The test results are mirrored in
Table 3.
Table 3 shows that Cronbach’s alpha is 0.921, a higher value than Cronbach’s alpha of 0.70 which is allowed for the acceptance of the consistency of the data collection instrument [
19]. In this case, it was not necessary to exclude any dimension due to the fact that they are all correlated and contribute to good consistency.
It should be noted that, for this study, it was possible to estimate the size of the population surveyed through on-site findings in the field research: 98 factories in operation. Companies that are closed are not considered, and the sample for this study is 87 companies that represent 89% of the population.
For data collection, the plan presented in
Table 4 was performed, depending on the geographic location of the companies, the date, and the hours of operation. According to [
20], data collection is the phase of the investigation whose objective is to obtain real information. Initially, a visit was made to request and schedule the date, and the objective was to identify the total population of the companies, the number of workers, and the volume of business. The data collection plan is presented in
Table 4.
The objective was to cover all companies because it is a population with few companies; at the time of application of the questionnaire, 11 companies were unavailable and some still did not operate. All companies in the industrial sector of Viana, ESZ, are presented in
Table 5.
The companies are located in the ESZ, in the municipality of Viana, as shown in
Figure 7.
Figure 8 shows the exact area occupied by the companies in the ESZ.
The location of the ESZ is close to national roads and urban areas, such as the city of Viana at kilometre 28 and the new centralities of Zango, Kilamba Kiaxi, and Cacuaco (
Figure 8) and the future facilities of the international airport and railways. These infrastructures constitute competitive advantages in terms of production strategies with ease of logistics operations.
Table 6 shows the classification of the companies by size and legal classification.
Thus, it can be stated that this study is characterised mostly by medium-sized companies, and from the private sector, which is better illustrated in
Figure 9.
It should be noted that cluster analysis was performed to verify the homogeneity of the answers given regarding the dimensions of the LP that guide the recommended objective. The obtained result is presented in
Table 7,
Table 8,
Table 9,
Table 10 and
Table 11.
The results show a certain association between the evaluated dimensions.
3. Importance of Implementing Lean Philosophy in Industries
There is a significant amount of evidence regarding the advantages of the application of LP in the industrial sector in general. Only the year 2024 can be considered as a reference. According to the research on the scientific database B-on, analysed by peers, in the sources of academic journals, several publications are found, such as the study conducted by [
21] that states that LP practices are a solution to improve business performance in industries. This result was verified in Mexico. Other studies that show the importance of Lean practices in the industries, such as [
22], present advantages in their application in the red ceramics industry and state that this tool is the solution that can contribute to visualise the current state of the production process and help eliminate layoffs. They applied the VSM tool.
The study on the production process applying the VSM tool in the plastics industry also shows the advantages of this tool in the identification of waste, as shown by [
23].
We can also highlight studies conducted on the subject related to the assessment of Lean maturity levels in industries performed by [
24]. This study was applied to the manufacturing sector of Pakistan. The applied model provides the ease of integrating two main paradigms of Lean manufacturing and Industry 4.0 and allows companies to make their assessment. The study on the Lean circular maturity model (LCMM) for companies’ self-assessment in terms of process, product, and life cycle thinking proposed by [
25] focuses on the self-assessment of companies in terms of Lean thinking applied in the production process and in the product life cycle. The study on the maturity model for assessing Digital Green Lean leadership and culture implementation in manufacturing companies developed by [
26] contributes to providing tools that help compare and develop action plans in the context of Industry 4.0, circular economy, culture, and Lean leadership as part of the new Digital Green Lean [
27,
28].
These types of studies were not found in the B-on database in Angola; thus, this research is innovative and relevant for companies that are in this region and sector, as it shows the advantages of the application of LP in productivity, the current state of maturity as well as its gaps, and presents a simple model that will help in the assessment of the state of maturity of the LP in this business sector or another with similar characteristics.
4. Brief Contextualisation of Lean and Maturity Philosophy
The development of industries in any country is a signal and a mechanism for leveraging the growth of economies. The Angolan economy faces great challenges due to the fall in the price of oil on which it depends. Therefore, companies can no longer be subsidised, and so they are committed to becoming competitive and one of the possible ways to achieve this is to adopt and apply Lean practices and tools.
In the 90s, Lean was seen as a set of productive practices, which worked by establishing a rapid cost reduction in production processes. At the beginning of the 21st century, the system started to be seen as a Lean management model [
16]. These authors claim that Lean manufacturing (LM) is implemented by a sequence of steps, usually starting with tools and practices, after a period of diagnosis. LM is recognised, in this way, as a philosophy that helps the management of an organisation, and this philosophy is guided by some principles that seek total customer satisfaction. It is the customer who receives the products indicating the corresponding value, and according to [
13], there are five principles, as follows:
Value: Generally, when referring to a product that you buy, you risk using the designation value when evaluating. When there is satisfaction, we affirm that it has reached the expected value.
Value Chain: The next step is to identify the value chain. This is a process or a set of process steps that each product must go through to be completed.
Continuous Flow: The flow is conducted throughout the value chain, and must be continuous, which means that no problems should exist to stop or reduce an operation.
Pull System: The principle of the pull system follows the creation’s flow and production start only if the customer requests it.
Pursuit the perfection: It comes by continuous improvement.
In this sense, a Lean culture or philosophy is created, which adopts Lean tools with practices in a system aimed at eliminating everything that does not add value, reducing inventories, adopting principles of participative management, and focusing on the constant search for problem-solving, standardisation, cost reduction, and innovation, and therefore, continuous improvement.
However, there is a strong differentiation between the different stages of Lean implementation, from the beginning, which is the knowledge and implementation of tools until it becomes a system that flows automatically because it has already become an active, operating system, as shown in
Figure 2. Thus, the evolution of Lean involves three areas covering the overall concepts of Lean culture and philosophy, the focus of Lean systems, and how Lean tools and practices can be accomplished.
The building of a Lean culture is not just an isolated application of a tool or adopting this or that practice (Area I), but it is about organising the practices and tools to create a moving system (Area II). Once this system is incorporated into the minds of employees, causing the analysis of continuous improvement and pursuit of perfection, there is the Lean philosophy (Area III). Thus, we observe that the basic principles proposed by Womack remain the same but are updated according to the context and needs. The main tools or practices of the Lean philosophy identified in
Figure 15 are described in
Table 12.
These tools, among others, when developed and used, provide industries with a competitive advantage. The constant act of using tools and routines transforms individual use into a Lean system and, later, with the more mature industry, a level of culture, or Lean philosophy, is reached. With the increasing use of Lean practices, a high level of transformation is reached, which we call maturity.
Maturity models [
14] are used to measure the degree of Lean maturity in organisations. A company’s maturity level can be understood as the extent to which processes are explicitly defined, managed, measured, controlled, efficient, and effective [
6].
In this sense [
14], we can divide the models into (i) qualitative ones like the Shingo Prize and the Lai Enterprise Self-Assessment Tool (LESAT) and (ii) quantitative ones that, for the most part, are based on fuzzy logic [
34].
The LESAT, according to
Table 13, presents three sections of analysis, and in each section, there are five levels of Lean maturity. Its application has already been tested in more than 20 companies in England and the USA, which have demonstrated the usefulness of the instrument, its effectiveness, and ease of use [
6].
LESAT is more than a measurement model for Lean maturity because, by using every model, industries can see where they can and if they need to make improvements [
6,
9] when evaluating the implementation of Lean concepts in the process of developing new products, using a model extracted, simplified, and tested from LESAT, as shown in
Table 14 [
6].
The maturity level means steps towards improvement in project management. These steps are associated with the application of tools, processes, methodologies, knowledge, and skills applied to projects to achieve organisational objectives. They range from the lowest levels (not able) to the highest levels (solid; in continuous improvement).
Thus, Ref. [
35] states that level 5 of maturity, or full maturity, would be synonymous with perfection, something that is fully developed and has reached its highest level. Therefore, the simple application of Lean tools (considered a good practice that can provide satisfactory results in the identification and elimination of waste) is an initial level of maturity (Area I seen in
Figure 2), having some tools and practices in place (Area II seen in
Figure 2) and having a whole system in place, working with organisational routines and automatic in the employees’ mind, is a much higher level of maturity (Area III seen in
Figure 2), that is, it reached the Lean culture or philosophy.
The maturity scale of the Lean philosophy is resumed in three areas, as shown in
Figure 16, in which the first represents a low maturity, and adopts very simple Lean tools, and the second is medium maturity. In this phase, Lean is put into operation as a system and the third corresponds to high maturity, which requires the application of culture based on philosophy.
This model measures the Lean maturity of industries and can provide the optimisation of time, material resources, human effort, and productivity gains, as well as for proportional improvements in products and services.
5. The Application of Lean Philosophy in the Angolan Industrial Fabric
In view of the evolution challenges of the Angolan economy already presented, it is necessary to increase the competitiveness of the industries to consequently increase the competitiveness of the economy. One of the possible strategies to increase the competitiveness of these companies may be to increase the implementation of the Lean philosophy (LP) at the business level, that is, to add greater value to customers using fewer resources [
36].
Although LP is not a new topic, it is a relevant topic of maturity in many of the emerging countries, such as Angola. The organisational model is a novelty, arousing great interest in the application of LP, which has the potential to minimise risks in the business development process, by presenting solutions in terms of identification and waste reduction, optimisation of resources, and maximisation of productivity [
27]. Thus, LP has established itself as one of the most efficient production strategies in developed countries [
36,
37], in which the results are evidently satisfactory, judging by the wide range of scientific publications in the area.
Specifically, the Angolan industrial fabric (composed of about 7000 factories) faces numerous problems in the industrialisation process that can have several origins, namely financial, energetic, human resources, infrastructure, distribution and product management, basic materials, among others [
38]. In fact, about 14% are paralyzed and 2% semi-paralyzed, due to different constraints, financial problems, supply difficulties, and in some cases, poor management.
Even in this context of difficulties, some projects are being implemented, through strategies adopted by [
38], aimed at the development of industrialisation projects, the most addressed of which are listed in
Table 15.
Therefore, there is an intention to seek competitiveness in the industries of Luanda and, among these current projects and industrial plants, many seek maturity, and for that they use Lean tools to achieve efficiency and survival, but they are seemingly still at the first stage (Area I seen in
Figure 2).
6. Analysis of Lean Maturity in the Industrial Sector of Angola
This analysis will be performed through the search for principles of Lean philosophy via the analysis of the following:
5.1—Analysis of knowledge of tools.
5.2—Analysis of the use of tools.
5.3—Customer value (CV).
5.4—Value chain (VC).
5.5—Use of the pull production system (PPS).
5.6—Use of continuous production flow (CPF).
5.7—Continuous improvement analysis (CI).
6.1. Analysis of Knowledge of Lean Philosophy Tools
Figure 17 shows the results in the percentage of knowledge of the main Lean tools in the industrial sector of Luanda.
The survey results show that, of the 14 tools presented, only the 5S, JIT, Bottleneck Analysis, and Kaizen tools (28.5%) were known by the companies, and the only tool that was known by 60% of the companies was the 5S technique.
6.2. Analysis of the Use of Lean Tools
Considering the set of 87 industries, 14 Lean tools were verified, that is, among the 1218 possibilities of using or not the tools, only the answer “yes, we use this tool” occurred 132 times, at 10.8%. Given this result, a stratification was made among the 87 companies investigated between small (8), medium (51), and large (28) companies to know whether the size influenced the use of the tools. It was found that, among the large industries, 50% of them used 5S, with 46% using another tool, but 39% did not use any Lean tool; medium-sized industries: 53% used 5S, with 40% using at least one other tool, but 60% did not use any Lean tools; and small industries: 50% used 5S and just another tool and 50% did not use any Lean tools.
Figure 18 shows the results of the frequency of using Lean tools in Luanda’s industries, according to their size.
As can be seen, the pattern of use followed only by the 5S tool is better known and used; even so it reaches an use average of 52%.
6.3. Search for the Lean Principle via Analysis of “Customer Value (CV)”
The results of the analysis of the responses regarding the value given to the customer are presented in means and standard deviation in
Table 16.
Dimensions 1.1 (evaluation of customer needs), 1.4 (existence of registration of complaints), 1.6 (produce based on product quality), 1.7 (delivery deadline), and 1.11 (availability of information about the company and the product) are followed to the extent that the mean values are greater than 4, according to the Likert scale, and also the standard deviation values, in the referred dimensions, are those that show less dispersion. The analysis carried out at this point allows us to conclude that 45.4% of the dimensions of the Lean philosophy “customer value” are followed by the surveyed companies.
6.4. Search for the Lean Principle via Analysis of the “Value Chain (VC)”
This value refers to all activities that are carried out to conceive a product, manufactured and delivered to the customer, including activities that do not add value. Thus, the VSM is a Lean tool that helps to understand the material and information needed for production and helps in identifying opportunities for improvement. The results are shown in
Table 17.
The dimensions 2.1—valuations of the activities of the production process that add value, 2.2—records of the existence of the product in stock, and 2.3—calculation of the product’s processing time, are concentrated around 4, constituting the set with greater emphasis on the results. Even so, the correlation of dimensions will be analysed to verify the consistency of the answers. The analysis carried out at this point allows us to conclude that 50% of the dimensions of the Lean philosophy “Value Chain” principle are followed by the surveyed companies.
6.5. Search for the Lean Principle Using the “Pull Production System (PPS)”
The level of application of the Lean principle is analysed regarding the pulled production system (PPS). The results are shown in
Table 18.
The analysis shows that the three dimensions most followed by the company considering the average and the standard deviation are 3.1—producing according to customer demand, 3.4—levelling production according to demand, and 3.5—specific location for stock, which represents that 42.8% of the dimensions are followed by the surveyed companies.
6.6. Search for the Lean Principle Using the “Continuous Production Flow (CPF)”
The behaviour of the Lean principle continuous production flow is shown in
Table 19 through the mean average and standard deviation of its dimensions.
From the analysis of the previous table, the dimensions 4.1—interconnection of the process steps, 4.2—sequencing of operations, 4.4—production according to plan, and 4.5—organisation of the machines according to the process sequence present a high average and low dispersion, as these dimensions represent 57.2% of those followed by the surveyed companies.
6.7. Search for the Lean Principle via Analysis of “Continuous Improvement (CI)”
The behaviour of the Lean CI principle is shown in
Table 20 through the mean average and standard deviation of its dimensions.
From the analysis of the results shown in
Table 20, the dimensions 5.2 and 5.7 present a high average and low dispersion.
8. Conclusions
The research was conducted on 87 industries located in Luanda, and it was evaluated whether these companies used Lean concepts, tools, and practices, that is, whether they applied the Lean manufacturing model to measure maturity [
34].
Thus, Lean philosophy approaches were discussed in organisations with a focus on practices and tools [
34]. A questionnaire survey of factories that are based in the industrial fabric of Luanda was used, specifically in the industrial development pole and in the special economic zone, both located in the municipality of Viana.
It was necessary to outline (in
Figure 2) the limits of what was just the application of Lean tools, which in themselves do not establish the concept of Lean philosophy (and would be the initial level of maturity), to add the concept of Lean practices establishing the concept of a Lean system (intermediate level of maturity), which added to the “analysis of continuous improvement and pursuit of perfection” and may help reach the last stage, a holistic view of the system, called Lean philosophy (higher level of maturity). It was necessary to consider that Lean is a model that has a great number of peculiarities and understandings that allow for variations in the implantation sequence, which determine maturity.
These maturity levels were measured according to the Maturity model designed by Milan [
6,
28], which was already a simplification of LESAT developed by MIT. After a statistical analysis of the questionnaire answers, it was concluded that the level of Lean maturity in such industries is very low. This result cannot be generalised for all industries in Luanda, because the criterion for choosing industrial companies was accessibility, preferably within the industrial pole. However, there is a very strong expectation that, when expanding the research sample (which we recommend as future work), the result should be worse regarding the implementation of Lean practices, since such industries, on average, are most established.
For future research, it is recommended for the state of maturity of the FL in service companies in Angola to be investigated. As it is the most comprehensive sector, it may certainly contribute to their performance in maximising production.
Investigating the state of maturity of FL in the universities of Angola may help find solutions related to the training of individuals with knowledge of Lean philosophy.
Finally, taking into account the high number of companies that do not know the practices of FL, it would be pertinent to delve deeper into the barriers and drivers to the implementation of FL in this sector. This would also complement this research.