Blockchain-Enabled Open Quality System for Smart Manufacturing: Applications and Challenges

Abstract

In this technological development era, new trends and approaches related to quality management are emerging. Although many studies have focused on quality management in Industry 4.0, new technologies face difficulties in resolving problems arising from lack of trust, transparency, integrity, track-and-traceability, connectivity, and responsibility in evaluating quality. In this article, we discuss the potential of blockchain to deliver business value with transparent quality by introducing a new quality concept called “open quality”. A systematic literature review presents the increased visibility of open quality across the manufacturing system, based on which a “blockchain-enabled open quality” (OQB) framework in the fourth industrial revolution is proposed. The research contributes by providing a platform to share manufacturing information regarding quality within the entire system, thus ensuring that all members and processes of the system obtain verified information to enhance trust, transparency, and track-and-traceability. By this, manufacturers are able to meet the expectations of the customer and stakeholder with an improved product and system quality. In addition, the potential threats associated with OQB system implementation and their possible solutions are also discussed. Moreover, research gaps that can be explored in future study and the opportunities for new concepts of quality in Industry 4.0 are presented.

1. Introduction

The existing quality management systems in the manufacturing industry are generally centralized systems in which there is lack of trust and transparency among the network parties and stakeholders. The data related to quality are shared and reported through unsecured and non-trusted channels since anyone can enter the wrong data or mutate them just to hide the responsibility. Moreover, traditional databases are not always well suited, and are sometimes even non-compatible with the novel technologies of Industry 4.0. There are great challenges regarding secured data sharing within and outside the factory walls. Therefore, manufacturers have been exploring an emerging technology i.e., blockchain, to obtain solutions for specific problems and quality issues [1]. The decentralized nature of the blockchain technology offers a high level of transparency and has gained attention from various sectors that seek to deploy this technology. It has great potential with respect to enhancing trust, traceability, and transparency within a complex smart manufacturing system and overall supply chain. Improving the information and value chain measurability, traceability, and connectivity throughout the collaborative processes within a supply chain can increase the level of data trust as each information flow is recorded permanently [2]. Smart devices with sensors can be integrated with blockchain to send and share real-time information, thus improving the real-time decision-making process to manage and monitor quality and production efficiencies.

Blockchain technology can be coupled with the Internet of Things (IoT) and smart devices to digitalize and automate processes that collect and share information in real time with all the network members of the value chain, which improves the transparency and increases the efficiency of a manufacturing value chain. Although blockchain technology is still in its nascent stage when it comes to application in business, apart from cryptocurrencies, such as bitcoin, there is a growing interest in transforming and building a more robust data trust in various industries [2]. The role of blockchain in Industry 4.0 and the IoT have been discussed in some industries, and blockchain solutions are being combined with 3D printing to enable new manufacturing processes [3].

Industry 4.0, also labeled as the fourth industrial revolution, has become a highly relevant and frequently discussed topic in companies, universities, and the field of research [4]. The factory of the future or smart factory is characterized by smart, interconnected, integrated, and real time-oriented processes and services [5,6]. Industry 4.0, which was introduced by the German government, together with research institutions and industry associations is leading toward a digital and interconnected future in industrial value creation to ensure future competitiveness of the industry [7]. So far, Industry 4.0 has mainly been regarded from a technological perspective. However, the technological conversions required for establishing Industry 4.0 are expected to lead to managerial and organizational challenges alike [7].

Using cyber-physical systems in individual value creation, logistics, and accompanying processes offers different potentials, such as real-time condition monitoring, prognostics, and remote control [6,8]. Further applications include self-organization, error predictability, and continuous optimization, extending the boundaries of enterprises to include its customers and suppliers, as well as being cross functional within an enterprise [7]. The applications of digital technologies of Industry 4.0 in quality management may have significant implications for factories in the future [9]. The smart factory is rapidly becoming more interconnected, with data sharing occurring across a complex network of machines, parts, products, and value chain participants, including machinery providers and logistics companies [1]. Although the technological advancement in the fourth industrial revolution offers considerable benefits and state-of-the-art developments in the manufacturing sector, current benchmarks in quality, productivity, and innovation are very high. Mass customization, just-in-time maintenance, solutions to engineering intractable problems, disruptive innovations, and perfect quality are among the most relevant challenges posed to the Industry 4.0 revolution [10].

“Open quality” is a new quality strategy that accounts for all the quality characteristics of a product and service in an open and transparent way [11]. Measurability(M), traceability (T), and connectivity (C) are the main aspects of the open quality concept through which it enables the value chain for real time quality measurement, tracing the root cause for improvement, and connecting it to potential internal and external resources for enhancing quality levels [11]. This “open quality” strategy can serve as a potential opportunity to strive for the near-to-perfect solution and real-time responses across the value chain process in technology driven organizations. This technology driven era of Industry 4.0 needs to quickly recognize any risk or opportunity and a timely response for an efficient identification of possible resources. To this end, the open quality strategy is expected to play an important role in industrial applications to make a significant contribution to the widespread use of a new quality management strategy.

Moreover, open quality provides a transparent and open platform for all the stakeholders to enhance trust, transparency, integrity, and responsibility among all the network members across the technology driven organization. Similarly, open quality utilizes smart technologies, i.e., Internet of Things (IoT), big data, artificial intelligence (AI), information and communication technology (ICT), and digital twin to optimize the production process with excellent quality and productivity. In this digital transformation era, open quality also acts as a platform for the digitalization of quality management by providing the quality system with enhanced and real-time transparency, visibility, measurability, traceability, and connectivity across the entire value chain.

Similarly, blockchain has tremendous potential that can change the way information is recorded and shared in real-time across a manufacturing value chain system and distributed among all the stakeholders. The information of each process and step in the manufacturing system is recorded permanently in blockchain and can be shared and distributed to other members of the value chain [4]. Any change is validated and tracked without a centralized third party. Thus, blockchain technology ensures a secured and high level of trust of information sharing between each process or activity and among the parties involved in the manufacturing system across the entire value chain.

There is not enough research on digitalization of quality and specifically on building the trust and transparency in the quality system of a technology-driven smart factory in the era of Industry 4.0. Therefore, we aim to contribute through this paper by discussing the potential of blockchain technology integrated with the open quality system by providing a decentralized platform that is capable of managing quality with increased visibility across the technology-driven manufacturing system to build trust and transparency in quality measurability, traceability, and connectivity. The motivation for this work lies in the fact that, currently, there has been no systematic research done on the applicability of blockchain technology in the area of quality management for smart manufacturing systems, the related challenges, and research potential.

The remainder of this paper is structured as follows. Section 2 presents the relevant literature and research background with respect to blockchain and smart factories. Section 3 describes the development in quality management in Industry 4.0 toward open quality and discusses its definition and applications. Section 4 presents the open quality blockchain framework as a reference model implemented in Industry 4.0, which offers advantages that can benefit the technology-driven smart factories. Finally, the contribution of the study is presented as a conclusion along with the limitations and possible future research directions in Section 5.

2. Research Background

2.1. Quality Management in Smart Manufacturing

Over the years, the concept of quality has emerged and developed into a set of principles and assumed truths that define quality of products, services, and systems to be assessed, managed, delivered, and assured [12]. The significant technology developments in the era of Industry 4.0 have also altered the traditional way of how manufacturing systems work and operate. Smart factory is facing disruptions in all sectors including quality management. Quality 4.0 is one of the modern concepts of quality management in which digital technologies are used to provide customers with high quality products [13].

The fourth industrial revolution, where there are lots of development in many sectors, quality management have also made advances through the use of smart devices that are linked to internal and external networks of data, i.e., Industrial Internet of Things (IIoT) that works automatically without human intervention. The technologies of this modern era are capable of communication both with the products (smart products) and their environment, and, thus, can notice any defect or delay that could impede the manufacturing processes [14,15,16]. Vertical integration in a smart manufacturing environment allows transferring control of quality and data diagnostics from the shop floor straight to each level of decision making and vice versa, which makes the products traceable and the error visible to the next process [17].

Intelligent Quality Control System (IQCS) is another concept that replaced traditioned quality concepts in manufacturing processes. It integrated steps within and outside the manufacturing industry affecting sensors, actuators, and general manufacturing processes, like information and material flow. Moreover, manufacturing partners and customers have to be integrated into the development, as they are all part of the overall value chain [18]. Therefore, to address the challenges at various level of integration in the smart manufacturing environment, systems need to provide adequate compatibility and reward to the existing technology driven organizations.

2.2. Quality Responsibility

The dawn of Industry 4.0 has given rise to rapid developments in research and technology in many aspects. Among all other fields, development in quality is also a focal point for research and quality professionals. Quality responsibility is a key factor in ensuring product and manufacturing system quality. In the conventional quality management system, quality responsibility is not considered; however, with the emergence of new technologies and the real-time interactions of the customers with the organizations and products/systems, quality responsibility has gained importance. Quality responsibility helps the stakeholders and customers to assume responsibility for the system and product transparently on a real-time basis. Furthermore, blockchain technology can be used as a traceable and transparent tool for quality responsibility that can be used as a changing strategy for being responsible for quality.

2.3. Blockchain Technology in Smart Manufacturing

Recent technological developments have created smart factories that are inter-connected with real-time information sharing at every stage of the value chain. Manufacturing organizations are developing innovative methods and solutions based on new technologies to enhance their quality and performance in this competitive manufacturing environment. Among other technologies, manufacturers are also experimenting with blockchain technology to improve the interoperability by integrating the entire value chain through a single transparent platform. The smart factory operates across the entire network of the value chain that is working together and communicating on a real-time, thus addressing the challenge of transparency and secure data sharing within and outside the factory walls.

Data obtained from separate systems affect the efficiency of the smart manufacturing system and the product manufactured by globally operated organizations. Therefore, as the quantity expansion and interaction penetration of the participant are on a social scale, decentralized management is more appropriate for self-organized manufacturing among equals than a centralized model [19]. In nearly every industry today, organizations are challenged with finding efficient and secure methods to manage and share data related to process, quality, transactions, contracts, assets, and more. From finance and real estate to healthcare and retail, information silos and disparate databases create operational inefficiencies and make true collaboration between business parties difficult to achieve. However, a new technology, i.e., blockchain, has emerged that allows companies to break down these data silos and digitally connect multiple systems, partners, and customers. Trust is a strong selling point for customers, and blockchain can help nurture that trust. Blockchain technology can build trust by being transparent about the products and solutions with their activity details in each block. Businesses can build trust and bring value to their customers and stakeholders with an appropriately developed process describing how the data flow.

Manufacturing a product requires collaboration between the manufacturer and the supplier, distributor, service provider, customer, government, and other manufacturers throughout the lifecycle of design, production, product, distribution, and service. Trust is difficult to achieve among the different stakeholders because transparency among them is minimal as they are scattered regionally and unfamiliar to each other. Therefore, additional cost and risks are generated in performing different activities, such as supplier audit, quality control, onsite inspection, and external certifications. Blockchain has its unique features; real-time information sharing, transparency, traceability, visibility, reliability, and cyber security, which can help boost the supply chain practices and ultimately improve the overall operation performance in the manufacturing sector in this new industrial era [20]. The study by L. Huang et al. also claims that the blockchain technology bridges the trust, traceability, and transparency in circular supply chain management [21].

Governments must ensure that frequent inspections are conducted and guarantee that legal regulations are compiled. Manufacturers of most industries establish initial trust with customers after considerable time by developing brand recognition and obtaining certain external certifications. Moreover, obtaining certifications and recognition as a brand is a time-consuming and expensive process. A more transparent, secure, and trustworthy project attracts benefits and supporters. Through such technology, organizations gain confidence and attract clients that contribute to the organizations.

The emergence and applications of blockchain technology in different industrial sectors and their subdomains in Industry 4.0 era are illustrated in Figure 1 [22]. The major sectors that are benefiting from blockchain applications are manufacturing industry, agriculture industry, healthcare service industry, power industry, banking and finance, security and power sector, drone industry for tracking, etc. The subdomains that are further sub-categorized are e-commerce, data security, transparency, repair and maintenance, sustainable industrial ecosystem, agriculture food traceability, drug traceability, patient data management, P2P electricity trading, security and privacy, etc. [23,24]. Some platforms, e.g., eBay, Lazada, and Tmall Global have also employed blockchain technology for quality verification to enhance the customers’ trust and guarantees the products’ quality [25]. Bin Shen et al. also claim that mask production organizations were encouraged to adopt blockchain technology to enhance mask quality, increase profit, and ultimately reducing the social health risks during the coronavirus pandemic (COVID-19) [26].

2.4. Blockchain Technology—Definition and Advantages

Blockchain is a shared, decentralized digital ledger of all the transactions across the network, in which a transaction cannot be altered once it has been recorded and verified. Using this technology, participants of the network can confirm transactions without any third-party intermediary. Blockchain technology is usually considered for financial transactions, but in reality, the transactions on a blockchain represent a change in the state of the data point that the stakeholders of the blockchain want to track. Blockchain acts as a platform that replicates, shares, and synchronizes data and distributes them across the shared network to different locations, such as multiple operators, machines, sites, organizations, and countries [27].

Blockchain ensures that a transaction is approved and validated based on unanimous consent. The main characteristic of the distributive ledger is that it does not have any centralized administration or centralized data storage and functions on the basis of a decentralized distribution system [28]. Whenever a participant of a blockchain network initiates a transaction, the details are shared and broadcasted to the entire network to be accessed by other network members and approved on the basis of the agreement of the network members. In this manner, all the transactions are created and validated individually to create a block of data that is secured and can never be altered or deleted later. Thus, a blockchain carries and stores the records of transactions as a chain of data blocks that is accessible across the shared network. The main features of blockchain can be summarized into four core characteristics [29] as shown in

Table 1. Core characteristics of blockchain.

Industrial Impact Area	Blockchain Advantages
Immutable (permanent and temper proof)	Once a block is added into a network and transaction is recorded, it cannot be altered. This creates trust in the blockchain record.
Decentralized (networked copies)	Transaction validation and record-keeping activities are decentralized and automated by network users, thus eliminating central control. In decentralized systems, autonomous devices can use real-time information and interact directly as a cyber-physical system.
Consensus Driven (trust verification)	Mechanism that determines conditions for validations of blocks independently by network users to be added to the blockchain. Consensus mechanism reduces opportunism.
Transparent (full transaction history)	Because blockchain is an open source for the network, members and transactions can be accessed constantly. With its shared visibility, any transaction can be tracked easily.

, and a simple blockchain network architecture is shown in Figure 2.

2.5. Types of Blockchain

There are different types of blockchains depending on how the data are managed upon availability, what actions can be performed by the network users, and who obtains access to the data shared in the network. Thus, it can be classified as public blockchain, private blockchain, and consortium blockchain (hybrid blockchain) depending upon who can access and have authority to the data on the blockchain network. Each type has its own advantages and disadvantages, depending on the needs and constraints of the various applications. Nevertheless, considering that such distinctions are still debatable, the definitions provided here may differ from those in the literature.

In public blockchains, anybody can join the network without the approval of the third party and can make a transaction. Whereas in private blockchains, access to the network and data shared into it is restricted to only those participants who are permitted or invited to join the network. Private blockchains are usually used by large companies with permissions defined between the various stakeholders of the enterprise blockchain. Private blockchains are mostly permissioned such that they can exercise control over which users or IoT devices can perform transactions or act as a node in the network. Consortium blockchain, where the consensus process is controlled by pre-selected nodes of the network, can be defined as a blockchain that attempts to use the best benefits of both the public and private blockchains. Thus, in a consortium blockchain, some processes are kept private, and others are made public to avail the benefits from both private and public depending on the customized organization and manufacturing environment. Hence, a consortium blockchain simultaneously enjoys controlled access and freedom. It can be considered a separate designation of private blockchain, but the main difference is that consortium blockchain is governed by a group rather than a single entity. The consortium blockchain is considered best for companies and organizations that want to avail the benefits of the blockchain, but do not want to expose their critical, business, and process data to the world.

Table 2. Features of public, private, and consortium blockchains.

Type/Characteristics	Public Blockchain	Private Blockchain	Consortium Blockchain
Access	Read: Open	Read: Open/Permissioned	Read: Open/Permissioned
	Write: Open	Write: Permissioned	Write: Permissioned
	Consensus: Open	Consensus: Permissioned	Consensus: Permissioned
Application Scales	Large	Small	Medium
Privacy	Medium	High	High
Speed	Slower	Faster	Fastest
Cost	High	Medium	Low
Architecture	Fully Decentralized	Partially Decentralized	Partially Decentralized
Transaction Rate	Slower	Faster	Faster
Membership/Identity	Anonymous/Pseudo anonymous	Known Identity	Known Identity
Use Cases	Cryptocurrency Document Validation	Asset Ownership	Banking
		Supply Chain	Supply Chain
		Real Estate	Medical Records

lists the different features of public, private, and consortium blockchains.

3. Developments in Quality Management System in Industry 4.0 Era

The dynamic technological advancements in Industry 4.0 impact social behavior with respect to the products and services manufactured by organizations, resulting in the development of new business models and strategies accordingly. The radical technological changes require the organizations to further transform their production and management systems that are compatible with the new technologies. Industry 4.0 changes the contents regarding how the organizations must run and manage their activities to manufacture products or services, which requires the transformation of traditional views and approaches of the overall manufacturing system, including quality management. The development of quality management systems is the subject of research for academics and practitioners amid the transition to Industry 4.0. New conceptual approaches to the definition of quality have been introduced and conceptualized with the new paradigm of Industry 4.0. The transition in understanding the concept of quality management has been studied by many researchers by introducing different concepts, among which are Quality 4.0 [30] and open quality [11].

3.1. Open Quality as a Tool for Quality Responsibility

Researchers have emphasized the development of quality management to take into account the quality responsibility to create a shared value among all stakeholders. A new social responsibility model has been developed by Park et al. [11], integrating the concepts of management quality, quality responsibility by creating shared values, social value, and open quality management into the existing ISO 26000. Because traditional quality management is mostly focused on the product and system quality issues, it ignores the responsibility of the social impact to overall environment; open quality considers this a quality responsibility. The main purpose of quality responsibility in open quality is to consider all the stakeholders that are related and affected by the manufacturing system.

The new paradigm of Industry 4.0 should be accompanied by developments in the quality management system and innovative quality strategies to make it compatible with the radical technological developments. Industry 4.0 and smart factory require characteristics such as real-time access, responsiveness, and transparency to the factory data and manufacturing activities, allowing them to measure, monitor, trace, and connect each activity of the value chain. This real-time information across the value chain is accessible and available to all the stakeholders of the smart factory through the implementation of the blockchain technology. Even though new approaches in quality management have been emerging to keep pace with the radical technological developments, they are disintegrated and not transparent, which makes it difficult to meet the challenges of the fourth industrial revolution.

3.2. Open Quality—Definition, Characteristics, and Benefits

Open quality is a novel concept and strategy, which accounts for all quality characteristics of any product, service or system during its design, manufacturing, or distribution, developed on the basis of open and transparent approaches [11]. The open quality concept is categorized into three major aspects/processes, i.e., measurability, traceability, and connectivity (MTC) [11]. Measurability (M) is the real-time quality measurement of all the process and activities in smart manufacturing or Industry 4.0 to derive the quality level, which also integrates with the quality improvement activity through data analysis. Measurability of the quality aspects leads to traceability (T), which is an aspect for realizing the quality responsibility to determine the root cause and space of improvement for certain quality aspects. Finally, connectivity (C) is an aspect that is practically involved in quality improvement and represents the function of connecting internal and external resources for enhancing quality levels for obtaining zero-defect quality.

Open quality differs from previous quality management methodologies in the manner that it seeks improvement by connecting to both internal and external resources in real time with the integration and assistance of novel technologies, such as system integration, IoT, big data analytics, digital twin, and artificial intelligence, which are the basis of Industry 4.0. Using open quality, manufacturers can develop a quality improvement strategy in smart manufacturing environment governed by the novel technologies of Industry 4.0. Considering the radical changes in the manufacturing environment owing to the radical technological developments, instant response to the changes and decision is the need of the hour in each step of the manufacturing value chain inside and outside the walls of the smart factory. Open quality tends to achieve the sustainable quality assurance through comprehensive and real-time measurement, clarified tracing of manufacturing or service activities, and improvement of connectivity using open and transparent approaches.

3.3. Comparative Study of Open Quality and Quality 4.0

In line with the evolution of technology in Industry 4.0, research and development in the field of quality is also evolving and changing. Such developments always continuously encourage researchers and quality practitioners to think and develop quality strategies that are more compatible with the respective technology advancements. Quality 4.0 refers to the digitalization of the quality management system with the application of technology in the organization and by improving the organizational strategy, culture, and leadership through the use of technology. The concept of open quality refers to the implementation of a new quality strategy that considers all the quality characteristics of a product or service being produced, manufactured, marketed, delivered, and implemented using open and transparent approaches.

Because our research is more focused on product quality than on management in general, we discuss open quality and further expand it in the research developments described in our study.

Table 3. Comparison of Quality 4.0 and open quality.

Feature	Open Quality	Quality 4.0
Definition	New quality strategy considering all quality characteristics of products and services	Digitalization of the quality management system with the application of technology
Focus on	Product/Service	Overall management system
Goal	Traceability and transparency	Digitalization
Approach	Open and transparent approach	Technological approach
Strategy	Strategy based on the technological development and compatibility	Strategy based on technological advancements only

presents a basic comparison of Quality 4.0 and open quality.

3.4. Strategy Development to Integrate Open Quality with Blockchain—Key Issues

The current manufacturing systems are heavily influenced by large quantities of data and information, called big data. In a conventional system, the data regarding the product quality are recorded and shared in a large database, which results in privacy and transparency concerns for the shareholders and customers. Open quality combined with blockchain technology has the potential as a novel platform to minimize and eliminate these issues. Open quality is a transparent and open-quality platform, which can be further enhanced by integrating with the blockchain technology. Blockchain technology is the ideal solution for manufacturing operations with respect to quality issues and challenges faced by data-driven manufacturing systems. By joining the blockchain-enabled open quality platform, the respective stakeholders can have real-time access to the massive amount of data being shared and exchanged throughout the manufacturing system.

Blockchain is a digital technology used in supply chain quality management that solves the trust issues through the blockchain technology’s indigenous potential of immutable and traceable records system through standardized consensus and agreements. This technology has brought a new mechanism and ideas to supply chain quality management and also enables setting up automatic executions of quality management contracts to develop an auto-run intelligent system, thus improving the qualities of products and services [31]. Blockchain adaptation is on the rise in the manufacturing and supply chains across industries as it avails the potential benefits of integrating blockchain and open quality. However, there is a lack of interoperability of standards among blockchain and other technologies [32]. One important issue in a large-scale multi-chain manufacturing environment is the integration of different systems and technologies with blockchain in order to secure cross-chain real-time information sharing and transparent data exchange between the stakeholders and ecosystem [33].

4. Blockchain-Enabled Open Quality System

4.1. Integrating Open Quality and Blockchain

Even though the quality management system is studied and implemented widely in research and industrial applications, the interconnected smart factory with digital transformation towards Industry 4.0 and factory of the future require more attention in order to develop an efficient and compatible technological tool that is an improvement over the conventional quality management system (QMS). Very little attention has been paid to the incompatibility of the QMS with Industry 4.0 technologies that govern smart factory and the problems that may arise in the future owing to the incompatibility. Thus, the need for the connectivity and compatibility of quality and Industry 4.0 technologies is evident because quality is the core requirement for the development transformation initiatives in Industry 4.0. In this section, we discuss the necessity of the blockchain-enabled open quality system for the smart factory to be compatible with the technologies being used in it. There are many benefits and advantages that blockchain-enabled open quality system (OQB) offers to the technology-driven smart factories over the conventional QMS system. The framework of blockchain-enabled open quality system, termed open quality blockchain (OQB) system, used for actual applications in smart manufacturing is presented in Figure 3.

The OQB system is unique in the manner that it encrypts all the data of the quality activity across the value chain and provides an open channel for the quality level to be shared to the stakeholders. In the presence of all the novel technologies of smart factory, OQB increases the trust, transparency, and traceability of the smart manufacturing system. Open quality attributes, i.e., measurability (M), traceability (T), and connectivity (C), are observed at each step of the manufacturing process as the open quality system with all the smart technologies working at place in the manufacturing system. Data from each step and activity are extracted and shared to the data cloud to be analyzed and shared to the blockchain for permanent encryption. The entire system runs on a real-time basis with the help of smart technologies within the smart factory, including cyber-physical system, Internet of Things, smart sensors and actuators, closed-circuit television (CCTV), big data, information, and communication technology (ICT), and artificial intelligence.

The OQB framework shows two layers, i.e., a physical layer and a cyber layer. The physical layer shows the operating activities during the manufacturing process that includes design, simulation, machining/value addition, monitoring, control, and scheduling. It also includes sensors and actuators for data acquisition, collecting and analyzing the vast amount of data across the entire manufacturing value chain. The cyber layer relies heavily on sensors and actuators. Sensors are used to monitor and analyze the process, equipment, and product/work-in-process, and to provide data on how the systems are functioning. Similarly, actuators are used to perform routine actions on equipment to improve process inefficiencies better than a human operator can and help increase the uptime of the organization’s assets and equipment. The data form these sensors and actuators are processed and analyzed in the cyber layer by connected cloud-based systems to track performance over time and provide detailed reports.

Since blockchain has the potential to access, record, store, and share the real-time process and transaction details, this technology may be useful in measuring, tracing, and connecting all the manufacturing details in real time. Thus, it can provide a better platform for quality management across the manufacturing value chain and properly utilize the concept of open quality. Blockchain improves transparency by providing a permanent, secure record of transactions that are then grouped into “blocks”. The transactions are recorded only after a consensus among the participants is reached, and the blocks cannot be removed or altered in any way once created. This ensures that every touchpoint, including raw material, supplier, manufacturer, batch numbers, factory and processing data, expiration dates, storage and inventory information, and shipping detail are permanently recorded. If an issue, such as an inventory error or a contamination scare arises, it can easily be referred to any given touchpoint and the details to identify the issue can be analyzed such that questions, including what may have gone wrong, and most importantly where, can be answered.

Blockchain technology has potential implications in real-time measurability, traceability, connectivity, transparency, interoperability, virtualization, decentralization, immutability, and more. Using blockchain technology, network members and users can monitor the real-time activities with the internet-connected devices by tracking the origin of the goods and the intermediate transactions of the entire process in a transparent manner [34]. With such exceptional qualities, volume of data can be transformed into real-time transactions that can ultimately transform the quality system across the value chain. Researchers have predicted that the business value addition of the blockchain may reach more than $176B by 2025 and exceed $3.1T by 2030 [35]. The unique and beneficial properties of the blockchain-enabled open quality system compared to those of the conventional QMS system are listed in

Table 4. Comparison of blockchain-enabled open quality system and conventional quality management system.

Feature	Blockchain-Enabled Open Quality System	Conventional QMS/QIS/Certifications
Definition	Blockchain-enabled open quality system is unique in the way that it encrypts all the data of the quality activity into a blockchain and provides an open channel for quality level to be shared with stakeholders, ensuring a transparent quality management system.	QMS is a formalized system that documents processes, procedures, and responsibilities for achieving quality policies and objectives (ASQ).
Focus	Measurability, traceability, and connectivity. Transparent system measuring, tracing, tracking, and connecting the entire manufacturing network across the value chain in real time and recording it in a blockchain that is unchangeable.	QMS coordinates and directs the activities of an organization to meet the customer and regulatory requirements and improve its effectiveness and efficiency on a continuous basis.
Goal	An open quality system through a decentralized platform with real-time data storage and sharing across the value chain, making the quality open and transparent to all the stakeholders.	The purpose of QMS is to ensure that the information, methods, skills, and controls are used and applied in a consistent manner every time a process is performed.

.

Blockchain offers manufacturing organizations the opportunity to support traceability, records management, supply chain automation, payment applications, and other operational transactions. There are significant process-improvement considerations that the blockchain can take into account with respect to quality. It can deliver real-time immutable operational records or transactions that are replicated among a network of business partners/stakeholders. The process obtains information that was previously stored in the central ERP silos of just one company and makes it available in a decentralized distributed network of records within different units of a company as well as across the value chain and disparate companies.

4.2. Stakeholders in Manufacturing Blockchain

Technologies, including blockchain, are the driving force of smart manufacturing; however, one of the biggest and most expensive mistakes manufacturers commit is neglecting the role of the people, i.e., all the stakeholders of the manufacturing ecosystem. Problems escalate when the manufacturers ignore the value of people involved in digital transformation and neglect to define individual roles and responsibilities. Blockchain helps to encourage stakeholders to register their services on the distribution ledger [36] that are beneficial to them in achieving their objectives more efficiently. For instance, all the stakeholders of the manufacturing system must register and input their roles and activities through smart contract on the blockchain. Every stakeholder can trace the work in process, component, or product history using blockchain platform [37]. Because blockchain in manufacturing is still at a very nascent stage, it is difficult to define and identify the stakeholders of the blockchain network when it is implemented in the smart factory.

To avoid this problem, it is important to consider and identify the stakeholders in the manufacturing blockchain, defining their roles, responsibilities, and the authorities that can access the blockchain network. Moreover, it is necessary to mention that in a manufacturing environment, machines and equipment are some of the most important sources of data required to be stored and shared; hence, they must also be considered stakeholders of the manufacturing blockchain network.

Blockchain governance faces a boundary problem. It is very crucial to identify and define the roles of the stakeholders or the boundaries regarding the governing of the blockchain network, that is, the definition of the stakeholders. Governance decision around blockchains in any manufacturing environment depends on the roles and responsibilities of the stakeholders. The stakeholders in this case can be the individuals or group of people who have responsibility and authority at any value-adding step of the manufacturing operation. Even machines can also be considered here, because through IoT and integrated systems, machines interact with each other creating and sharing real-time data with each other and the blockchain network.

4.3. Blockchain-enabled Open Quality Applications and Challenges

Blockchain does not replace the current way of doing things, but rather complements it. Initially, the professionals and practitioners were cautioned with the use and implementation of blockchain during the early stage of this new technology owing its uncertain and unknown advantages and effects. However, in recent years, blockchain has gained immense popularity owing to its potential to revolutionize multiple industries in an innovative way. Among many of the advantages, one such innovative advantage is the opportunity of increasing efficiency through automation by utilizing smart contracts. Other applications of blockchain technology include increased availability, real-time monitoring and tracking, peer-to-peer communication, reliable data origin, short transaction time and costs, and reduced risks for any mutation [38,39,40,41].

Blockchain-enabled open quality system consists of blockchain platform with the smart contracts and IoT smart devices, i.e., sensors and actuators providing secure and accurate information through safe distributed ledger with various quality information, asset information, stakeholders’ information, logistics information and transaction information. Using this information or data, smart contracts are created automatically to execute quality management and improve the efficiency of the overall manufacturing value chain. Digital identity is used to control the access and authority to the data to keep the confidentiality and privacy of the network members.

By adopting blockchain-enabled open quality system, organizations are able to reduce the cost of quality, improve trust and transparency, and increase brand loyalty. It also allows organizations to reduce costs related to the activities of quality management, i.e., inspection, verification, quality checks, certifications of quality system, and information including origin and tracking of items, validation of contracts, and transfer of value. The system need not implement new types of activities as it reduces them and complements the existing operations to scale trust, transparency, real-time measurability, traceability, and connectivity through all the stages of the industrial value chain, from sourcing the raw material to delivering the finished product as well as feedback from the customer. The different applications and challenges of the blockchain-enabled open quality system are listed in

Table 5. Applications and challenges of open quality blockchain system.

OQB Applications	OQB Challenges
A decentralized platform for real-time measurability, traceability, and connectivity of the manufacturing value chain.	The incompatibility with other technologies owing to the instability of the various networks that are evolving.
Provides the possibility of managing quality operations based on global consensus with the blockchain indigenous decentralized nature.	Transaction scalability issues: many public blockchains currently support a quantity of transactions per unit of time that is not compatible with many industrial applications.
The reduction of costs and time for economic and operational transactions.	Integration of this system in a smart factory environment is difficult to achieve and requires more effort with respect to research and development.
The ability to automate verification, validation of operation transactions, and certification processes.	The lack of real and widespread understanding of the phenomenon due to its novelty.
Trace, track, and monitor the entire value chain in real time from raw material to the final delivery of product for the consistency of operations.	Difficulty in identifying and defining the roles and authorities of the stakeholders to govern the blockchain network.
Data acquisition, storage, and certification of remote operations through consensus of the stakeholders to help them in real-time decision making.	This philosophy is not mature yet and needs more time to mature and get standardized globally.

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Moreover, approximately half of the respondents in a recent survey submitted that the quality inspection in their organizations were mostly manual, i.e., less than 10% automated [42]. Manual or visual inspection is often dependent on the ability, attention, and inherent biases of the operator; thus, approximately 80% of such inspections are accurate [43]. Therefore, this creates the hidden-factory effect, where abrupt activities contribute to deterioration of the quality and efficiency [44].

4.4. Possible Threats and Drawbacks for Implementation of OQB System

Blockchain-enabled open quality system offers lots of advantages and benefits, i.e., trust, transparency, visibility, track and traceability, responsibility, connectivity etc., that are already mentioned in the previous sections. The advantages are revolutionary in manufacturing and service sector for sure as they can be used in multiple use-cases and industries. However, there exist some threats and drawbacks associated with the implementation of the OQB system just like any other novel technology or new conceptual platform. In this section, we will discuss some points that show the possible drawbacks for practical implementation of OQB system. The possible difficulties for the OQB implementation could be high cost, high energy consumption, complexity, blockchain interoperability, integration, scalability issues, data immutability, immaturity/lack of adaptation, and storage issues. Each of the drawbacks and their possible explanation are mentioned in

Table 6. Possible drawbacks associated with blockchain-enabled open quality system.

Drawbacks	Explanation
High Cost	Implementation of OQB system is a costly process at the start.
High Energy Consumption	Some solutions consume too much energy; similarly, OQB system implementation and running the overall system consumes high energy.
Complexity	Due to the huge distributed network, complexity could be one of the drawbacks that can be resolved with further research.
Interoperability	Implementing the OQB system, interoperability is difficult due to the huge distributed system, but with more research and experiments, it will become facile.
Immaturity and Lack of Adaptation	Since it is a novel concept, organizations do not have much confidence in it and it needs to be recognized for its complete utilization.
Integration	Since blockchain technology and OQB are new concepts that needs further development, currently it is difficult to integrate with other technologies.
Data Immutability	Data immutability can sometimes be a problem due to uncontrolled errors and mistakes that needs corrections.
Storage issues	Big data in a manufacturing system need lots of storage over time due to increased number of operations and nodes, so storage can be one of the drawbacks that can be resolved over time with its adoption.
Scalability Issues	It is one of the biggest drawbacks due to blockchain’s fixed storage capacity and consensus method.

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No doubt, blockchain technology is a disruptive technology and blockchain-enabled open quality system is a novel concept and framework that is still in a process of constant transformation and adaptation. Therefore, it is important to be aware of and understand the advantages as well as possible drawbacks associated with the OQB system in order to decide its practical implementation accordingly in a better way.

5. Conclusions and Future Studies

The intense interest for Industry 4.0 has propelled a large number of technologies to develop and integrate in a significant way. Moreover, in several manufacturing and service sectors, quality tools and research must be developed to keep pace with the technological advancement. For this, it is important to adopt usable technologies, such as blockchain, in quality sector encompassing transparency issues and secure management, storing, and exchange of big data across the manufacturing value chain. Blockchain offers unique advantages in situations where trust is lacking between parties that need to securely capture, store, and share critical data.

It is evident that the blockchain-enabled open quality system has the potential to cause an industrial and manufacturing revolution in the form of organizational and global decentralization. It can create improved opportunities in business and manufacturing sectors that have never been identified using conventional technology and methodologies, be they technical, economical, or organizational. Owing to the potential benefits of blockchain technology and open quality system, it must be ensured that the blockchain-enabled open quality system is not controlled by a central or private authority, but is built on consensus, resulting in a transparent system that can measure, trace, track, and connect the entire manufacturing network across the value chain.

The main contribution of this research is that blockchain-enabled open quality system can enable nearly all processes or operations to take place in real time and record it permanently with a high degree of accuracy and control. It performs automated and unchangeable recordkeeping of all the quality activities across the manufacturing value chain. It can operate as a stand-alone solution for many industries, but specifically in smart manufacturing environment. Moreover, The value realized increases significantly combined with smart factory indigenous technologies, such as machine learning, IoT, big data, cyber-physical system, cloud computing, and other technologies, thus revolutionizing the entire end-to-end value chain system.

Blockchain is a novel technology that can be used to scale up the transparency in the quality sector by integrating it with the open quality concept. However, owing to it being not yet fully developed, it has many technical shortcomings, such as high cost, high energy consumption, storage and scalability issues, immaturity, complexity, and interoperability with other technologies. Moreover, being a nascent technology, it has not yet been examined and integrated with the other novel technologies. However, more research, adaptation, and experimenting with this novel concept and platform will enable reducing and ultimately eliminating these drawbacks through future research study. The adoption and exploration of the benefits, advantages and challenges of such an integration can be considered a future course of study.