1. Introduction
Research on developing automated processes to enhance productivity and reduce labor costs has become a fundamental focus across various industries. Especially the food industry faces unique challenges as it adapts to rapidly changing market trends and evolving consumer demands. It has utilized various methods to process food materials into products to satisfy consumer needs. It has also focused on improving processes such as raw material management, processing, distribution, and quality [
1]. Home Meal Replacement (HMR) products have emerged as representative solutions that meet these requirements. HMR refers to prepared foods that can quickly and conveniently replace home-cooked meals and are both easy to store and consume [
2]. The increase in single-person households has led to a rise in the consumption of convenience foods, with a focus on ease of use and reduced meal preparation time [
3,
4]. Shelf-stable HMR products are often produced through a retorting process, a critical step in ensuring food safety and quality by achieving commercial sterilization [
5]. In the Korean HMR market, “bibimbap” contained with retorted vegetables was introduced, which has been very portable and easy to prepare [
6]. Stew-type HMR products based on meat (ham, sausages), vegetables, and kimchi have also gained popularity. These products, rich in water and various nutrients, are prone to bacterial contamination, necessitating commercial sterilization for shelf stability [
7]. This process, typically applied to products sealed in pouches made from bonded single-layer plastic films, metal foils, or laminates, not only extends shelf life, but also requires compliance with stringent safety standards, essential in large-scale automated production systems [
8]. Food manufacturing companies are placing more emphasis on sustainability and efficiency in production, while simultaneously maintaining quality and safety standards. Companies are transitioning from traditional manual production processes to the adoption of automated systems, driving digitalization [
9].
Robotics have emerged as a critical solution for improving efficiency, safety, and product quality in food manufacturing. Robotic technology, which reduces costs and improves quality, is gaining significant attention [
10]. The purpose of robotics applications is to automate dangerous, repetitive, and labor-intensive tasks. Robots can be categorized based on their degrees of freedom and the roles of their joints. Cartesian robots move in straight lines, while six-axis articulated robots are more flexible [
11]. Articulated robots are structured like a human arm, providing high flexibility within a confined workspace. This flexibility allows for the design of trajectories suited to specific purposes. This made robots increasingly used alongside existing equipment in various manufacturing industries [
12]. Early applications of robotic automation in the food industry were primarily focused on palletizing tasks, which were well-suited for simple, repetitive transport and stacking processes [
13]. As robotics technology advanced, research was conducted to select appropriate robots based on food types, conditions, and states [
14]. To demonstrate the feasibility of these selected robots performing more precise operations, many studies were conducted in food processing industries [
15]. The application of robotics is being studied in the meat industry, particularly in sectors like beef and poultry [
16,
17,
18]. Additionally, research is being conducted to improve processes in the seafood industry [
19], like improving salmon filet cutting operations using a 3D vision system combined with robotic automation [
20]. Despite such advances, the International Federation of Robotics (IFR) noted that the food and beverage sector showed the lowest application of industrial robots compared to other industries. This is due to the complexity of standardizing robotic applications in the diverse processes of the food sector, compatibility issues among platforms, and limited sharing of integration methods by suppliers. The majority of SMEs remain hesitant due to financial costs and perceived risks, compounded by specific needs for hygiene, worker safety, productivity, and ease of operation.
To solve these problems, simulations have been employed to assess the economic benefits and effectiveness of applying robots before actual implementation [
21,
22]. Considering that the food industry is a complex and dynamic sector that involves various processes, simulation models play an important role. Simulation has been used as a key decision-making tool. Discrete Event Simulation (DES) is one of the most widely used simulation techniques in manufacturing process research and analysis [
23]. It is used to identify bottlenecks in production processes and logistics systems, as well as to compare and analyze results after optimizing production conditions [
24]. Previously, block diagram-based logic and scripts were used to create models similar to flowcharts, which represented production quantities, processing times, and other metrics [
25]. A small-sized pizza manufacturer analyzed the manufacturing time of each process through simulation and suggested improvement measures to report the possibility of increasing production and efficiency [
26]. In addition, a case study in a factory manufacturing frozen French fries and chips emphasized the importance of improving using a simulation. In this factory, it was analyzed that performance was significantly improved compared to the existing production method by optimizing the configuration, including three packaging lines and two cutting process lines [
27].
With advancements in technology, factory simulations now allow process flows to be visualized in a virtual space [
28,
29]. This enables tracking and pre-monitoring of process changes during operations. Simulation models can effectively manage and optimize food production processes by alleviating bottlenecks through simulation analyses of factors such as labor efficiency and material flow [
27]. Moreover, Digital Twin (DT) models are increasingly recognized within Industry 4.0, although those involve complex integration of real-world data into digital representations [
30]. However, in contrast to individual predictions during production or distribution, food manufacturing companies often are subjected to small quantity batch production. This characteristic, combined with the complexity of production planning, inventory management, and uncertainties, presents significant challenges for SMEs in adopting DT technologies [
31]. Despite data limitations and fixed processes that restrict production scheduling in the food industry, some studies have demonstrated the feasibility of DT for efficient operations, such as monitoring and controlling production and supply plans in ice cream factories [
32]. While there has been extensive research on using simulations and robotics, there is still a lack of studies demonstrating their actual effectiveness in real-world food industry applications.
The main purpose of this study is to provide a practical case study solution by applying articulated robots in two different manually operated retort product loading processes within automated production lines. Specifically, this research identified a gap between the simulation and real application of HMR manufacturing systems by analyzing key performance indicators (KPIs). The simulations were used to identify existing production challenges, such as worker overload, and to evaluate the effectiveness of robotic automation as a solution. By implementing simulation-based models, the study aimed to predict potential productivity gains and validate these predictions against real application results. The simulation demonstrated the potential to assess increases in production output and compare them with actual outcomes upon implementing automation. To support this study, Discrete Event Simulation (DES)-based Tecnomatix Process Simulation and Plant Simulation were utilized, focusing on increasing line productivity and addressing digitalization challenges faced by SMEs.
2. Materials and Methods
Two cases with different scales of retort product production processes were chosen for this study. Using simulation software, this study analyzes the workload of workers in the existing manual production environment and assesses the effectiveness of implementing a robotic automation system. The following methods were employed to compare the performance between the manual and automated processes.
2.1. Methodology Description
Plant simulation is an important tool for modeling and optimizing manufacturing processes. Companies use simulation models as a key decision-making tool when determining whether to add a new production line or to improve an existing process. Specific procedures and approaches were followed to achieve the objectives of designing and testing the simulation [
33,
34]. The process improvement began with gathering data from the current site. Based on the initial objectives, data on production output, target products, and the number of workers were collected. This information was then applied to modeling and simulation to identify bottlenecks in the current process. The improvement simulations were subsequently used to evaluate whether the initial objectives were met through an iterative feedback process. Once the objectives were validated, the simulation results were implemented in actual production environments.
Plant simulation processes were used in this article to achieve the research objective of improving existing manual processes by applying a robotic automation system. Since the accurate analysis of simulation results significantly impacts the success of simulation studies, SIEMENS Tecnomatix Process Simulate (V16.0.1, SIEMENS Inc., Munich, Germany) was utilized. This tool was used to configure robot motions and trajectories that can automatically load products, either assisting or replacing human workers. SIEMENS Tecnomatix Plant Simulation (V2201, SIEMENS Inc., Munich, Germany) was additionally employed to compare the outcomes of the current manual process with the improved robotic automation system.
2.2. Designated HMR Process for Case Study
In general, the manufacturing process for retort food products consists of several sequential steps: measuring ingredients, filling, sealing, sterilizing (retorting), cooling, inspecting, and packaging, depending on the type of product [
8]. This study focuses on improving repetitive and commonly required processes within the retort manufacturing workflow by applying a robotic automation system. The selected process involves loading products onto trays for sterilization after they pass through metal detection, as shown in
Figure 1.
The selected process is critical for maintaining the continuity of the workflow, depending on the production speed of the supplied products. Two cases with different scales of retort product production were chosen. For each case, modeling and simulation were utilized to study methods for automating the production line that loads products onto empty trays. A virtual production facility was recreated to replicate the actual work environment, allowing for a comparative analysis between the current manual production method and the robot-automated system. Factors considered include the current facility design, equipment (such as trolleys and trays), and the workspace between the worker and collaborative robots.
Case A represented a large-scale manufacturing site. In this setup, a turntable was used as an intermediate waiting process to control the flow of production. This setup allowed workers to keep up with the production speed. The process was carried out in a harsh environment where multiple workers were involved. They faced hazardous conditions such as a slippery floor and congested work paths, which increased the risk of accidents.
Case B is a production facility using an order-based production system. In this setup, the production quantity was managed by adjusting the number of workers in the process according to the production schedule and required output. Due to the minimal number of workers involved, there was a higher risk of musculoskeletal hazards for the workers. The process required moving heavy trays of products from one space to another, as the loading area and the retort area were in different locations. This created a cumbersome process where products had to be transported using trolleys.
2.3. Application of Robot and End-Effector in Process Simulation
A collaborative robot was selected to improve the process. Commonly known as cobots, collaborative robots are designed to work alongside human operators without posing safety risks [
35]. These robots are typically constructed with a lightweight frame and equipped with collision detection control system, making them suitable for shared workspaces. They also operate at a relatively slow speed, prioritizing safety by minimizing risks to human operators and shared workspace objects. An articulated robot with a payload capacity of 20 kg, a reach of 1700 mm, and repeatability of 0.1 mm (Doosan Robotics, Suwon, Republic of Korea, Model: H2017) was utilized. This robot is capable of handling trays with a maximum length of approximately 960 mm and transporting six products at a time, each weighing approximately 3 to 4 kg. The robot model was integrated into the simulation library, which facilitated accurate replication of its movements within the simulated environment. The end-effector used was equipped with 30 vacuum gripping systems designed to load products onto the tray one row at a time. The vacuum pads were supplied by VMECA (Magic Gripper, VMECA Co., Ltd., Incheon, Republic of Korea) and featured Micro 2-stage cartridge dual vacuum cartridges (MC10D) with 2-fold top bellows and an integrated 200-mesh vacuum filter. The technical specifications of the vacuum system include a maximum vacuum pressure of −83 kPa, a maximum suction flow rate of 23 NL/min, and an air consumption rate of 20.3 NL/min at 2.2 bar. This configuration was chosen to ensure secure handling and efficient placement of products during the loading process.
To attach the end-effector to the robot’s manipulator, the tool and frame were configured accordingly in the process simulation, as shown in
Figure 2. This setup is essential for defining the tool’s position and orientation relative to the robot, allowing the end-effector to be designated as the Tool Center Point (TCP) for accurate trajectory and motion design. Robots determine spatial constraints based on the TCP and the robot’s body. If the TCP is defined using poses, the robot flange position must be expressed as a pose (position and orientation) relative to the robot base or a reference frame. When programmed to move along a specific path, the TCP follows the actual path. This setup facilitates trajectory planning in Tecnomatix Process Simulate, enabling precise placement of objects, as illustrated in
Figure 2.
After completing the initial setup, the robot’s process trajectory and speed were configured. Using Tecnomatix Process Simulate software (V16.0.1), the robot’s initial position, known as the ‘Home Position’, was first selected. This is usually set to an appropriate location for starting the task and the same point to which the robot returns after completing its operations. The robot’s movements were planned by identifying pick-up points for the products and placing positions on the tray, connecting these points using point-to-point (PTP) movement. These generated paths were further refined using various features of the software, including collision detection that allowed the robot’s movements to be tested against the actual layout of the production site. The software detected potential collisions with objects such as conveyors, trays, and other equipment, ensuring safe operation.
In conventional settings, the speed at which workers load products is inconsistent. By adjusting the speed of robots in the simulation-based paths, as shown in
Figure 3, it was possible to minimize process time and establish a consistent production rate. Considering worker safety, the robot speed was set at 70% of its maximum capacity. Safety concerns were prioritized; therefore, the robot was programmed to operate at maximum speed only within a specific, short path segment—specifically when placing the gripper at the designated spot and lifting approximately 3 cm upwards—to reduce operational time. Through robot simulation, the feasibility of product loading was assessed in advance by accounting for on-site conditions and tray size (960 mm), enabling the selection of the most suitable robot for the process. By configuring the robot’s movements and adjusting its speed, automated production rates could be achieved faster than those in existing manual settings. While a single quick movement might save only about 0.2 s, the cumulative effect over weekly and monthly production could result in significant time savings.
2.4. Chosen KPIs
The objective of both cases was to enhance the production process in order to increase throughput per hour or, at the very least, maintain productivity through the implementation of a robot-automated system. Improvement could be achieved in several ways, with the current bottlenecks and product imbalance representing the main obstacles to overcome. To evaluate the impact of the enhanced simulation on these factors, a series of key performance indicators (KPIs) were selected for analysis. Only production-related KPIs were used for evaluation. The selected KPIs were throughput, utilization rate, and human resources. The modeling and logical sequence were developed using the standard library tools of Tecnomatix Plant Simulation from Siemens (V2201). Each of these basic KPIs reflected performance aspects derived from simulation based on monitored and measured data from the actual site. The KPIs could be grouped into similar categories to reduce complexity [
36].
In the existing process, throughput was derived based on manual production records, and the number of workers involved was determined at that time. The maximum production level was selected based on the historical production data from the company, representing the highest recorded output. Throughput was calculated according to Equation (1) [
36]:
where
GQ is good quantity,
RQ is rework quantity, and
AOET is the actual order execution time (hour). The throughput of the robotic automation system was also calculated based on the quantity produced within the same execution time.
Utilization rate is defined as the ratio of each machine, robot, and worker’s actual work time (
AWT) to the planned operation time (
POT). This indicator helps identify worker overload in manual processes. In automated systems, it evaluates whether the robot operates continuously without interruptions caused by bottleneck operations. The utilization rate is determined according to the following equation:
For both the existing process and the robotic automation system, the Plant Simulation program was configured with common settings, including Availability and the Shift calendar. Availability was set at 95%, representing the percentage of time the equipment was capable of performing the assigned tasks. In the food industry, maintaining high reliability was considered crucial due to the need for very low probabilities of operational issues. The mean time to repair (MTTR) for the robot was set at 15 min, which was defined as the minimum time required to restore the equipment to its initial operating state after a shutdown. The Shift calendar was configured based on a 5-day, 40 h workweek, meaning that the simulation results reflected the performance of the process during an 8 h maximum daily operation.
2.5. Model Creation Using Simulation: Robotic Automation System
The movement of the robot and the overall system flow were modeled in Tecnomatix Plant Simulation(V2201), as shown in
Figure 4. Using the SimTalk programming language in the method function, commands were configured to use conveyor sensors. This configuration ensured that the tray supports continued moving along the conveyor, while trays designated for product loading stopped precisely at the specified position. When the trays reached the robot’s position, the robot performed the assigned tasks according to the process simulation settings. Once the products were fully loaded onto the tray, it was discharged, and a new empty tray was automatically supplied according to the predefined conditions.
4. Discussion
This study explored the potential of applying robotic automation systems in food manufacturing processes. While previous studies have primarily focused on general manufacturing settings, this research specifically addressed challenges in the HMR sector. Simulations were used to assess the performance and feasibility of transitioning from manual to automated systems. The primary objective was to identify issues such as worker overload and bottlenecks in existing manual processes, and to evaluate how these could be improved through automation.
The simulations analyzed the utilization rates of workers and identified bottlenecks during process execution. It confirmed that implementing a robotic automation system can effectively address these inefficiencies. These results aligned with previous studies demonstrating that robotics showed significant potential to enhance production efficiency in manufacturing [
16,
17,
18,
19,
20]. The comparison between the worker utilization rates in the manual system and the robot’s performance after automation showed significant improvements in process efficiency. Both Case A and Case B demonstrated the system’s applicability across various production environments by applying a similar robotic automation system under different conditions.
The validation of the simulation results through actual site application is a significant contribution of this study, as it confirms the practical utility of simulation models in predicting production improvements. This validation showed that the simulated outcomes closely matched the actual results, affirming the reliability of the simulation models. The similar results between the simulation and real application show that simulations are useful tools for planning and improving production processes.
To determine the effectiveness of the robotic automation system, KPIs such as throughput and utilization rate were selected. These KPIs are critical in evaluating production-related factors and were used to compare the performance of manual and automated systems. Additionally, the number of workers involved was also analyzed to assess the system’s capability to replace human labor. The findings indicate that robotic automation can reduce the physical strain on workers while maintaining or even increasing production output.
Despite the promising results, several limitations must be acknowledged from this study. The simulations were based on specific case studies and may not fully represent all possible production environments. This study focused exclusively on pouch-type HMR products with specific dimensions of 150 mm (Length) × 256 mm (Width). Therefore, the findings could show different results when applied to different types of HMR products or other manufacturing processes. Case A allows for intermediate control by workers during production. In contrast, Case B operates under the assumption of a fixed production rate of six units per batch, which may not accurately reflect other production cases. Additionally, the study did not address the cost implications of implementing robotic systems, which could affect the feasibility for SMEs. As only unit processes were selected for analysis, future research should consider a broader range of production environments. It is necessary to gradually expand the scope by considering preceding and subsequent processes, allowing for an eventual full-scale factory simulation that supports digital transformation. It should also conduct detailed cost–benefit analyses and explore the integration of robotic systems with human labor to better understand their practical applications.
This research demonstrates the usefulness of simulation models in designing and testing production systems. This study highlights the potential for robotic automation to enhance production efficiency and worker safety in the food industry. For SMEs, this study provides practical insights into overcoming operational challenges associated with manual processes. It suggests that integrating automation can be significantly helpful in productivity while also reducing labor costs. The case studies show that robotic automation systems can be effectively integrated into existing production environments, offering significant productivity gains and operational consistency. Furthermore, the study illustrates that similar automation strategies can be applied across different production settings, making it a versatile solution for the food manufacturing industry.
Further research could focus on exploring more diverse production environments and investigating different types of robotic system configurations, including delta robots commonly used in food packaging, to determine their effectiveness across various stages of food processing. It could also analyze the cost-effectiveness of implementing such systems in SMEs. Additionally, investigating hybrid systems that combine both human and robotic labor could provide further insights into optimizing production efficiency in various contexts.