The advent of the Internet of Things (IoT) and Industry 4.0 has revolutionized the manufacturing industry, paving the way for the development of smart factories. These advanced manufacturing facilities leverage cutting-edge technologies to optimize production processes, enhance efficiency, and improve overall productivity. In this paper, we will explore the role of IoT and Industry 4.0 in building smart factories of the future [1], [2]. IoT and Industry 4.0 technologies play a crucial role in the transformation of traditional factories into smart factories. By connecting machines, devices, and sensors to the Internet, IoT enables real-time data collection and analysis, leading to improved decision-making and operational efficiency. Industry 4.0, on the other hand, focuses on the integration of cyber-physical systems, cloud computing, and artificial intelligence to create interconnected and intelligent manufacturing systems [3], [4]. IoT and Industry 4.0 are two revolutionary technologies that are shaping the future of manufacturing and paving the way for the development of smart factories. These technologies are driving a paradigm shift in the way factories operate, enabling them to become more efficient, productive, and connected than ever before [5]. The manufacturing industry is undergoing a digital transformation driven by advancements in technology such as IoT and Industry 4.0. These technologies have enabled the creation of smart factories that are characterized by interconnected systems, real-time data analytics, and automation. Smart factories leverage IoT devices, sensors, and data analytics to optimize production processes, improve efficiency, and reduce costs [6]. IoT refers to the network of physical devices, vehicles, appliances, and other objects embedded with sensors, software, and connectivity that enables them to collect and exchange data [7]. IoT allows these devices to communicate and interact with each other, creating a seamless and interconnected system. Industry 4.0, on the other hand, is a term used to describe the fourth industrial revolution, characterized by the integration of digital technologies into manufacturing processes [8]. Industry 4.0 encompasses a range of technologies, including IoT, artificial intelligence, big data analytics, and cloud computing, to create smart factories that are highly automated, connected, and intelligent. IoT and Industry 4.0 are driving the transformation of traditional factories into smart factories by enabling the collection and analysis of vast amounts of data in real time. IoT devices, such as sensors and actuators, are embedded in machines and equipment on the factory floor, allowing them to monitor and control various processes [9]. These devices collect data on machine performance, energy consumption, and production output, which is then analysed using advanced analytics tools to optimize operations and improve efficiency. Industry 4.0 technologies, such as artificial intelligence and machine learning, enable factories to predict maintenance needs, optimize production schedules, and make data-driven decisions to enhance productivity and reduce costs. IoT and Industry 4.0 are key enablers of smart factories, which are characterized by their ability to adapt and respond to changing market demands quickly and efficiently [10]. By connecting machines, processes, and people in real time, smart factories can achieve higher levels of automation, flexibility, and customization. IoT devices enable factories to monitor and control operations remotely, while Industry 4.0 technologies provide the intelligence and analytics needed to optimize processes and improve decision-making. Together, these technologies are revolutionizing the manufacturing industry, enabling companies to build future smart factories that are more agile, competitive, and sustainable [11]. IoT and Industry 4.0 are driving the transformation of traditional factories into smart factories by enabling the collection, analysis, and utilization of data to optimize operations and improve efficiency [12]. These technologies are revolutionizing the manufacturing industry, paving the way for the development of highly automated, connected, and intelligent factories. By embracing IoT and Industry 4.0, companies can build future smart factories that are more agile, competitive, and sustainable, positioning themselves for success in the digital age. This paper aims to explore the role of IoT and Industry 4.0 in building smart factories of the future, focusing on their impact on efficiency, productivity, and sustainability.

The history and evolution of the IoT and Industry 4.0 have played a significant role in shaping the future of smart factories. These technological advancements have revolutionized the way industries operate, leading to increased efficiency, productivity, and competitiveness [13]. The concept of IoT can be traced back to the early 1980s when researchers at Carnegie Mellon University connected a Coke machine to the Internet, allowing them to check the status of the machine and determine whether it was stocked with cold drinks. This early experiment laid the foundation for the development of IoT, which refers to the network of interconnected devices and sensors that collect and exchange data over the Internet. IoT incorporate several features (See Fig. 1) that enable the functions and workability of the equipment to which they are connected

Industry 4.0, on the other hand, is a more recent concept that emerged in Germany in 2011 [15]. It represents the fourth industrial revolution, characterized by the integration of digital technologies into manufacturing processes. Industry 4.0 aims to create smart factories that are highly automated, interconnected, and intelligent, enabling real-time data exchange and decision-making [16]. The convergence of IoT and Industry 4.0 has paved the way for the development of smart factories, which are equipped with advanced technologies such as robotics, artificial intelligence, and big data analytics. These technologies enable factories to optimize production processes, reduce downtime, and improve product quality. The history and evolution of IoT and Industry 4.0 have paved the way for the development of smart factories that are transforming the manufacturing industry. By leveraging advanced technologies and data-driven insights, smart factories can improve efficiency, productivity, and competitiveness [17], [18]. However, manufacturers need to address cybersecurity concerns to ensure the security and integrity of their operations. The future of smart factories looks promising, and manufacturers need to embrace these technologies to stay ahead in the competitive market.

Advancements in IoT and Industry 4.0 have revolutionized the manufacturing industry, paving the way for the development of smart factories. These technologies have enabled manufacturers to improve efficiency, reduce costs, and enhance productivity [19], [20]. The key milestones in the evolution of IoT and Industry 4.0 and how they are shaping the future of smart factories are highlighted as follows:

I. One of the key milestones in the advancement of IoT and Industry 4.0 is the development of interconnected devices and sensors. These devices are able to collect and transmit data in real time, allowing manufacturers to monitor and control their operations remotely [21]. This has enabled the implementation of predictive maintenance strategies, which can help prevent costly equipment failures and downtime.

II. Another milestone in the evolution of IoT and Industry 4.0 is the integration of artificial intelligence and machine learning algorithms [22]. These technologies enable smart factories to analyse large amounts of data and make informed decisions in real time. For example, AI-powered predictive maintenance systems can analyse equipment performance data to predict when maintenance is needed, helping manufacturers avoid costly breakdowns.

III. Furthermore, the adoption of cloud computing and edge computing technologies has enabled manufacturers to store and process data more efficiently. Cloud computing allows manufacturers to access and analyse data from anywhere, while edge computing enables real-time data processing at the source [23]. This has improved the speed and accuracy of decision-making in smart factories.

The advancements in IoT and Industry 4.0 have paved the way for the development of smart factories. By leveraging interconnected devices, artificial intelligence, and cloud computing technologies, manufacturers can improve efficiency, reduce costs, and enhance productivity. As these technologies continue to evolve, we can expect to see even greater advancements in the future of smart factories. Advanced technologies in Industry 4.0 are presented in Fig. 2.

The IoT and Industry 4.0 have been hailed as revolutionary technologies that have the potential to transform the manufacturing industry and pave the way for the development of smart future factories [24]. However, despite the numerous benefits that these technologies offer, several factors can limit their potential and hinder their widespread adoption in the manufacturing sector. These include the following:

I. One of the key factors that can affect the potential of IoT and Industry 4.0 in building smart future factories is the high cost of implementation. The initial investment required to deploy IoT devices and upgrade existing infrastructure to support Industry 4.0 technologies can be prohibitively expensive for many manufacturers, especially Small And Medium-Sized Enterprises (SMEs) [25]. This cost barrier can prevent these companies from fully embracing these technologies and reaping the benefits they offer in terms of increased efficiency, productivity, and competitiveness.

II. Another factor that can limit the potential of IoT and Industry 4.0 in building smart future factories is the lack of interoperability and standardization. The diverse range of IoT devices and platforms available in the market can make it difficult for manufacturers to integrate these technologies seamlessly into their existing systems and processes [26]. This lack of interoperability can lead to compatibility issues, data silos, and inefficiencies, ultimately undermining the effectiveness of IoT and Industry 4.0 solutions in optimizing manufacturing operations.

III. Concerns around data security and privacy can also act as a barrier to the widespread adoption of IoT and Industry 4.0 in the manufacturing industry. The interconnected nature of IoT devices and the vast amount of data they generate can create vulnerabilities that cybercriminals can exploit to gain unauthorized access to sensitive information and disrupt manufacturing operations [27]. Manufacturers must invest in robust cybersecurity measures to protect their data and ensure the integrity and confidentiality of their systems. IV. The skills gap and lack of technical expertise among the manufacturing workforce can also limit the potential of IoT and Industry 4.0 in building smart future factories [28]. The successful implementation and operation of these technologies require a workforce that is proficient in data analytics, programming, and other technical skills. However, many manufacturers struggle to find and retain employees with the necessary expertise, which can hinder their ability to leverage IoT and Industry 4.0 technologies to their full potential [29].

While IoT and Industry 4.0 hold great promise for revolutionizing the manufacturing industry and creating smart future factories, several factors can limit their potential and impede their widespread adoption. Addressing issues such as high implementation costs, interoperability challenges, data security concerns, and skills gaps will be crucial in unlocking the full benefits of these technologies and realizing their transformative impact on the manufacturing sector. Manufacturers must invest in overcoming these barriers to ensure that they can fully harness the power of IoT and Industry 4.0 to drive innovation, efficiency, and competitiveness in the smart factories of the future.

In recent years, the concept of smart factories has gained significant attention in the manufacturing industry. A smart factory is a highly digitized and connected production facility that utilizes advanced technologies such as interconnected machines, autonomous systems, data-driven decision-making to improve efficiency, productivity, and flexibility, artificial intelligence, IoT, robotics to optimize manufacturing processes and improve efficiency [30], [31]. The key components of a smart factory and their importance in revolutionizing the future manufacturing process are as follows:

I. One of the key components of a smart factory is interconnected machines. Interconnected machines are equipped with sensors and communication technologies that enable them to communicate with each other and with other systems in the factory. This connectivity allows for real-time monitoring and control of the production process, leading to improved coordination and synchronization of operations [32], [33]. By enabling machines to communicate and collaborate, interconnected machines help to optimize production flow, reduce downtime, and minimize errors.

II. Another important component of a smart factory is autonomous systems. Autonomous systems are machines and equipment that are capable of performing tasks without human intervention [34]. These systems are equipped with artificial intelligence and machine learning algorithms that enable them to learn from experience, adapt to changing conditions, and make decisions on their own. By automating repetitive and labour-intensive tasks, autonomous systems help to increase efficiency, reduce costs, and improve quality in the manufacturing process.

III. Data-driven decision-making is also a critical component of a smart factory. Data-driven decision-making involves collecting, analysing, and interpreting data from various sources to make informed decisions about production processes, resource allocation, and performance optimization [35]. By leveraging data analytics and predictive modelling, manufacturers can gain valuable insights into their operations, identify areas for improvement, and make data-driven decisions to drive continuous improvement and innovation.

IV. One of the key components of a smart factory is the use of IoT devices. These devices are embedded with sensors that collect real-time data on various aspects of the manufacturing process, such as machine performance, energy consumption, and product quality [36]. This data is then analysed using advanced analytics tools to identify patterns and trends that can help improve production efficiency and quality. By leveraging IoT devices, smart factories can achieve greater visibility and control over their operations, leading to better decision-making and increased productivity.

V. Another important component of a smart factory is the integration of artificial intelligence (AI) technologies.

AI algorithms can analyse large volumes of data and identify opportunities for process optimization and predictive maintenance [37]. For example, AI-powered predictive maintenance systems can detect potential equipment failures before they occur, allowing manufacturers to schedule maintenance activities proactively and avoid costly downtime. Additionally, AI can be used to optimize production schedules, minimize waste, and improve product quality.

VI. Robotics is also a key component of a smart factory. Robots can perform repetitive and dangerous tasks with precision and efficiency, freeing up human workers to focus on more complex and value-added activities [38], [39]. Collaborative robots, or cobots, can work alongside human operators to increase productivity and flexibility on the factory floor. By integrating robotics into their operations, manufacturers can achieve higher levels of automation and improve overall production efficiency [40].

By embracing these technologies and integrating them into their operations, manufacturers can improve efficiency, productivity, and flexibility and stay competitive in today's rapidly changing market. As the manufacturing industry continues to evolve, smart factories will play a crucial role in shaping the future of manufacturing and driving innovation and growth. Moreover, manufacturers can optimize their production processes, improve efficiency, and stay competitive in an increasingly digital and interconnected world. Hence, manufacturers must invest in these key components to stay ahead of the curve and reap the benefits of a smarter, more efficient factory environment. The key components of a smart factory, as illustrated by Phuyal et al. [31], are presented in Fig. 3.

The concept of smart factories has gained significant traction in recent years, driven by the rapid advancements in technology, such as the IoT and Industry 4.0. These technologies have revolutionized the manufacturing industry by enabling the integration of digital systems and physical processes, leading to increased efficiency, productivity, and flexibility in production. The concept of smart factories, as illustrated by Kim et al. [41], is presented in Fig. 4.

IoT, in particular, plays a crucial role in the development of smart factories by connecting machines, sensors, and devices to a centralized network, allowing for real-time monitoring and control of manufacturing processes [42]. This connectivity enables manufacturers to collect and analyse vast amounts of data, leading to improved decision-making and predictive maintenance. Additionally, IoT facilitates the implementation of smart sensors and actuators, which can autonomously adjust production parameters based on real-time data, optimizing performance and reducing downtime.

Industry 4.0, on the other hand, focuses on the digital transformation of manufacturing through the integration of cyber-physical systems, cloud computing, and artificial intelligence. This paradigm shift enables the creation of smart factories that are highly automated, interconnected, and responsive to changing market demands [43]. By leveraging advanced technologies such as machine learning and predictive analytics, manufacturers can optimize production schedules, minimize waste, and enhance product quality.

The combination of IoT and Industry 4.0 is driving the development of smart factories by enabling seamless communication and collaboration between machines, processes, and people. This interconnected ecosystem allows for greater visibility and transparency across the entire production chain, leading to improved efficiency, agility, and competitiveness. Furthermore, smart factories can adapt to changing market conditions and customer preferences in real time, enabling manufacturers to stay ahead of the curve and deliver innovative products and services [2], [44]. The concept of smart factories powered by IoT and Industry 4.0 represents a significant paradigm shift in the manufacturing industry. By embracing these technologies, manufacturers can unlock new opportunities for growth, innovation, and sustainability. As the digital transformation of manufacturing continues to evolve, smart factories will play a crucial role in shaping the future of production and driving economic prosperity.

The adoption of the IoT and Industry 4.0 technologies in manufacturing has revolutionized the way factories operate, leading to the emergence of smart factories. These smart factories are equipped with advanced sensors, data analytics, and automation systems that enable real-time monitoring and control of production processes [45], [46]. The adoption of IoT and Industry 4.0 in building future smart factories has the following advantages:

I. One of the key benefits of IoT and Industry 4.0 in smart factories is the optimization of production processes. By connecting machines, devices, and systems through IoT networks, manufacturers can gather real-time data on production activities, identify bottlenecks, and make informed decisions to streamline operations [47]. This real-time monitoring and control of production processes enable factories to reduce downtime, minimize waste, and improve quality, ultimately leading to higher productivity and profitability. II. IoT and Industry 4.0 technologies enable smart factories to improve efficiency by automating repetitive tasks and optimizing resource utilization [48]. For example, predictive maintenance systems powered by IoT sensors can monitor equipment performance and detect potential failures before they occur, allowing manufacturers to schedule maintenance activities proactively and avoid costly downtime. Additionally, smart factories can leverage data analytics to optimize production scheduling, inventory management, and supply chain logistics, leading to reduced lead times, lower costs, and improved customer satisfaction.

III. Moreover, the integration of IoT and Industry 4.0 technologies in smart factories enhances overall productivity by enabling seamless communication and collaboration between machines, workers, and systems [49]. For instance, collaborative robots (cobots) equipped with IoT sensors can work alongside human operators to perform repetitive or dangerous tasks, increasing production output and ensuring worker safety. Additionally, IoT-enabled smart devices such as wearables and augmented reality tools can provide workers with real-time information, instructions, and feedback, empowering them to make better decisions and improve their performance.

IV. Another key advantage of IoT and Industry 4.0 in smart factories, is the ability to collect and analyse vast amounts of data in real-time. By connecting machines, sensors, and other devices to a centralized network, manufacturers can monitor and track every aspect of the production process [50]. This data can be used to identify inefficiencies, predict maintenance issues, and optimize workflows, leading to significant cost savings and improved operational performance.

V. Furthermore, IoT and Industry 4.0 enable seamless communication and collaboration between different components of the manufacturing process. By integrating various systems and devices, smart factories can automate tasks, streamline operations, and reduce human error [51]. This interconnectedness also allows for greater flexibility and adaptability, as production lines can be easily reconfigured to meet changing market demands.

VI. Another advantage of IoT and Industry 4.0 in smart factories is the ability to enhance product quality and customer satisfaction. By leveraging real-time data analytics and predictive maintenance, manufacturers can identify and address potential defects before they occur, ensuring that products meet the highest standards of quality [52]. This not only reduces waste and rework but also improves customer loyalty and brand reputation.

VII. In addition, IoT and Industry 4.0 enable manufacturers to implement sustainable practices and reduce their environmental footprint. By optimizing energy usage, minimizing waste, and improving resource efficiency, smart factories can operate in a more environmentally friendly manner. This not only benefits the planet but also helps companies comply with regulatory requirements and attract environmentally conscious consumers [53].

VIII. Implementation of IoT and Industry 4.0 technologies in manufacturing can reduce downtime. By connecting machines and equipment to the Internet, manufacturers can monitor their performance in real-time and predict potential failures before they occur [54]. This proactive maintenance approach helps to prevent unexpected breakdowns and minimize production disruptions, leading to increased productivity and cost savings.

IX. IoT and Industry 4.0 can enable manufacturers to improve quality control by providing real-time insights into the production process [55]. By collecting and analysing data from sensors and machines, manufacturers can identify defects and deviations from quality standards early on, allowing them to take corrective actions before defective products are produced. This not only helps to ensure product quality but also reduces waste and rework, leading to higher customer satisfaction and lower production costs.

X. IoT and Industry 4.0 in smart factories can also enhance predictive maintenance procedures. By monitoring equipment performance in real time and analysing data patterns, manufacturers can predict potential failures before they occur, reducing downtime and maintenance costs [56]. Additionally, IoT enables remote monitoring and control of production processes, allowing for greater flexibility and agility in responding to changing market demands.

XI. Another important aspect of smart factories is the concept of digital twinning, which involves creating a virtual replica of physical assets and processes [57]. By simulating and analysing different scenarios in the digital twin, manufacturers can optimize production processes, improve product quality, and reduce waste. This digital representation also enables predictive modelling and simulation, leading to more informed decision-making and continuous improvement.

XII. IoT and Industry 4.0 technologies enable the implementation of smart supply chains in smart factories. By connecting suppliers, manufacturers, and customers through a network of interconnected devices and systems, companies can achieve greater visibility and transparency across the entire value chain [58]. This enhanced collaboration and communication facilitate faster response times, better inventory management, and improved customer satisfaction.

IoT and Industry 4.0 technologies offer numerous benefits in building future smart factories, including optimized production processes, improved efficiency, and enhanced overall productivity. By leveraging these technologies, manufacturers can stay competitive in the rapidly evolving global marketplace and meet the demands of the digital age. As smart factories continue to evolve and innovate, the potential for further advancements in manufacturing efficiency and productivity is limitless.

transitioning to Smart Manufacturing

Smart manufacturing, also known as Industry 4.0, is revolutionizing the way businesses operate by incorporating advanced technologies such as artificial intelligence, the IoT, and big data analytics into their production processes. Despite the numerous advantages of smart factories, some challenges need to be addressed. While the benefits of smart manufacturing are undeniable, there are several challenges that business operators should be aware of when transitioning to this new paradigm. These include the following:

I. One of the main challenges that businesses face when transitioning to smart manufacturing is the high initial investment required to implement the necessary technologies [59]. According to a report by McKinsey & Company, the average cost of implementing smart manufacturing technologies can range from hundreds of thousands to millions of dollars, depending on the size and complexity of the operation. This significant financial commitment can be a barrier for many businesses, especially SMEs, who may not have the resources to invest in such technologies.

II. Another challenge that businesses should be aware of is the potential disruption to their existing processes and workflows. Implementing smart manufacturing technologies often requires a complete overhaul of the production system, which can lead to downtime, delays, and inefficiencies during the transition period [60]. This disruption can have a negative impact on productivity and profitability, especially if not managed effectively.

III. Businesses transitioning to smart manufacturing must also consider the cybersecurity risks associated with connected devices and systems, as smart factories are vulnerable to cyber-attacks that can disrupt production processes and compromise sensitive data [61]. Manufacturers need to implement robust security measures to protect their systems and data from potential threats. With the increasing interconnectedness of production processes, there is a greater risk of cyberattacks and data breaches that can compromise sensitive information and disrupt operations. Business operators must invest in robust cybersecurity measures to protect their systems and data from potential threats.

IV. In addition to these challenges, businesses must also address the skills gap that comes with implementing smart manufacturing technologies [62]. Many traditional manufacturing workers may not have the necessary technical skills to operate and maintain advanced technologies, such as robotics and automation. Business operators must invest in training and upskilling programs to ensure that their workforce is equipped to handle the new technologies effectively.

While the transition to smart manufacturing offers numerous benefits, businesses must be aware of the challenges that come with it. From the high initial investment and potential disruption to cybersecurity risks and skills gap, there are several factors that business operators must consider when embarking on this journey. By addressing these challenges proactively and implementing effective strategies, businesses can successfully transition to smart manufacturing and reap the rewards of increased efficiency, productivity, and competitiveness in the digital age.

The findings from this study on the role of IoT and Industry 4.0 in building future smart factories have provided valuable insights into the potential benefits and challenges associated with these technologies. The integration of IoT devices and Industry 4.0 principles in manufacturing processes has the potential to revolutionize the way factories operate, leading to increased efficiency, productivity, and competitiveness. One of the key findings from this study is the importance of data analytics in leveraging the vast amounts of data generated by IoT devices to optimize production processes and make informed decisions. By analyzing real-time data from sensors and machines, manufacturers can identify inefficiencies, predict maintenance needs, and improve overall operational performance. Furthermore, the adoption of Industry 4.0 technologies such as artificial intelligence, machine learning, and robotics has the potential to automate repetitive tasks, enhance precision and accuracy, and enable more flexible and agile production processes. This can lead to reduced lead times, improved quality control, and increased customization capabilities, ultimately resulting in higher customer satisfaction and loyalty. However, it is important to note that the implementation of IoT and Industry 4.0 technologies also presents challenges, such as cybersecurity risks, data privacy concerns, and the need for upskilling and reskilling of the workforce. Manufacturers must invest in robust cybersecurity measures, establish clear data governance policies, and provide training and support to employees to ensure the successful adoption and integration of these technologies. Hence, the findings from this study also highlight the transformative potential of IoT and Industry 4.0 in building future smart factories. By leveraging these technologies effectively, manufacturers can achieve significant improvements in efficiency, productivity, and competitiveness. However, companies must address the challenges associated with implementation and ensure that they have the necessary resources and capabilities to realize the benefits of these technologies fully. Only by embracing the opportunities presented by IoT and Industry 4.0 can manufacturers truly unlock the full potential of smart factories in the digital age. Smart factories are characterized by interconnected systems, real-time data analytics, and automation, resulting in increased efficiency, productivity, and flexibility. In order to fully leverage the potential of IoT and Industry 4.0 in building future smart factories, it is essential to consider the following recommendations:

I. Firstly, companies must invest in the necessary infrastructure and technology to support the implementation of IoT and Industry 4.0 in their manufacturing processes. This includes upgrading existing systems, investing in new technologies, and training employees to utilize these tools effectively. Research has shown that companies that make strategic investments in IoT and Industry 4.0 technologies are able to achieve significant improvements in productivity, quality, and cost savings.

II. Secondly, companies should focus on developing a comprehensive data management strategy to effectively collect, analyse, and utilize the vast amounts of data generated by IoT devices and sensors in smart factories. Studies have shown that companies that are able to harness the power of data analytics effectively are able to make more informed decisions, optimize processes, and identify new opportunities for innovation and growth.

III. Furthermore, companies should prioritize cybersecurity measures to protect sensitive data and ensure the security of IoT devices and systems in smart factories. Research has shown that cyber-attacks on IoT devices are on the rise, posing a significant threat to the integrity and reliability of smart factory operations. By implementing robust cybersecurity measures, companies can mitigate these risks and safeguard their operations from potential threats.

The role of IoT and Industry 4.0 in building future smart factories is undeniable, and companies that embrace these technologies are poised to gain a competitive advantage in the global marketplace. By following the recommendations based on findings from existing studies, companies can effectively leverage the power of IoT and Industry 4.0 to drive innovation, improve efficiency, and achieve sustainable growth in the manufacturing sector.