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The Indonesian roof tile manufacturing industry relies heavily on manual operations, specifically in transportation and inspection processes, which creates multiple issues, such as fatigue, injuries, human error, and reduced productivity. Various industries in the Indonesian industrial landscape have begun embracing a problem-solving approach known as the theory of inventive problem-solving (TRIZ) to mine solutions for industrial issues. Nevertheless, its application in the Indonesian roof tile manufacturing industry remains unaddressed. The study aims to solve manual handling issues in the roof tile manufacturing industry using TRIZ. Three observations were outlined from manual roof tile transportation and inspection, followed by the formulation of engineering contradictions (ECs). The ECs were linked with system parameters, which were used as indicators within the contradiction matrix to extract inventive principles as solution models for conceptual development. The concept included an automated system with a conveyor belt (#15: dynamics) for effective transportation, automated image capture (#28: mechanics substitution) for effective inspection, and a flipping conveyor (#25: self-service) to eliminate manual contact. Although the study addressed several issues stemming from manual operations, mechanical analysis, prototyping, and usability testing still require improvements.

The scheduling of parallel machines with and without a job-splitting property, deterministic demand, and sequence-independent setup time with the goal of minimizing makespan is examined in this work. For simultaneous processing by multiple machines, single-stage splitable jobs are broken into random (job) sections. When a job starts to be processed on a machine, an operator has to setup the machine for an hour. By creating two Mixed Integer Linear Programming models, this work proposes a mathematical programming strategy (MILP). A MILP model takes the job-splitting property into account. Another model, however, does not include the job-splitting property. This study investigates the performance of the proposed models using Gurobi solver. These programs' numerical calculations are based on actual problems in the Indonesian city of Bandung's plastics industry. On four identical parallel injection molding machines, 318 jobs must be finished in 22 periods. The real scheduling method is contrasted with these two MILP models. The maximum workload imbalance, the maximum relative percentage of imbalance, and the makespan of these three scheduling systems are used to evaluate their effectiveness. Without the job-splitting property, MILP can handle the real issue of scheduling identical parallel machines on injection molding machines to reduce makespan, resulting in a 36% average decrease. The MILP model's job-splitting property can reduce makespan by an additional 2.40%. The order of relative ranking is MILP with job-splitting property, MILP without job-splitting property, and actual scheduling based on the makespan minimization, workload imbalance, and relative percentage of imbalance.

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Currently, the use of manual labour in the transportation and inspection systems of leading roof tile manufacturing companies in Indonesia is still prevalent. Manual labour is usually labour-intensive, has higher risks of musculoskeletal disorders, and produces frequent occurrences of errors and losses. Furthermore, the current studies of suitable concepts and test protocols for roof tile transportation at the manufacturing stage as well as their inspection systems are not practicable in Indonesia. There is also no study that has used the theory of inventive problem-solving (TRIZ) in the development of concepts and protocols for roof tile transportation and inspection systems. Using TRIZ as a supporting tool, this study investigated the development of a transportation system to be employed during the manufacturing of the roof tile and a test protocol for their usability in Indonesian companies to overcome this concern. The study included screening and scoring concepts and usability test protocols identified from the existing literature, with the support of TRIZ tools such as the engineering contradiction, contradiction matrix, and inventive principles. Thus, the finalised concept comprised a belt conveyor system (Inventive Principle 20: Continuity of Useful Action) with a flipping mechanism for transportation and a vision-based camera for inspection. Results of the study showed that the concept excelled in cost, durability, reliability, versatility, low risk to the product, efficiency, and safety. The t-test protocol (Inventive Principle 23: Feedback) was selected based on the results due to its versatility in testing efficiency, reliability, and productivity. It was concluded that this concept has the potential to alleviate roof tile workers of physical work and reduce the prevalence of musculoskeletal disorders.