🏭Production and Operations Management Unit 12 – Operations Scheduling and Control

Key Concepts and Definitions

• Operations scheduling involves planning and coordinating resources, tasks, and timelines to optimize production efficiency and meet customer demands
• Production control ensures that the scheduled plans are executed effectively, monitoring progress and making adjustments as needed
• Capacity refers to the maximum output that a production system can achieve given the available resources (labor, equipment, materials)
• Lead time represents the total time required to complete a product or service from start to finish, including processing, waiting, and transportation times
  • Can be broken down into setup time, process time, queue time, and wait time
• Bottlenecks are process steps or resources that limit the overall capacity and throughput of a production system
• Work-in-process (WIP) inventory includes partially completed products or components that are still undergoing production
• Throughput measures the rate at which a production system generates output, typically expressed as units per unit of time (hours, days, weeks)

Importance of Operations Scheduling

• Effective scheduling optimizes resource utilization, reducing idle time and maximizing productivity
• Helps meet customer demand and delivery deadlines by coordinating production activities and prioritizing orders
• Minimizes work-in-process inventory, reducing holding costs and improving cash flow
• Identifies and alleviates bottlenecks, improving overall system throughput and efficiency
• Facilitates better communication and coordination among different departments and stakeholders involved in the production process
• Enables proactive decision-making and problem-solving by providing visibility into future production plans and potential issues
• Contributes to improved product quality by ensuring that processes are performed in the correct sequence and under the right conditions

Types of Scheduling Systems

• Forward scheduling starts with the current date and plans production activities forward in time based on available resources and due dates
  • Suitable for make-to-order or custom production environments
• Backward scheduling begins with the due date and works backward in time to determine the latest possible start date for production
  • Often used in make-to-stock or repetitive manufacturing settings
• Finite capacity scheduling considers the actual availability and capacity constraints of resources when creating production schedules
• Infinite capacity scheduling assumes unlimited resource availability, focusing primarily on meeting due dates without considering capacity limitations
• Job shop scheduling deals with the sequencing of tasks in a production environment where products follow unique paths through various workstations
• Flow shop scheduling applies to production systems where products follow a consistent, linear path through a series of workstations

Scheduling Techniques and Tools

• Gantt charts visually represent the timing and duration of tasks, resources, and milestones in a horizontal bar format
• Critical path method (CPM) identifies the longest sequence of dependent activities in a project, determining the minimum completion time
• Program Evaluation and Review Technique (PERT) uses probabilistic time estimates to calculate the expected project duration and identify critical activities
• Material Requirements Planning (MRP) generates production schedules based on customer orders, bill of materials, and inventory levels
• Capacity Requirements Planning (CRP) compares the capacity needed to execute a production schedule against the available capacity, highlighting potential overloads or underutilization
• Scheduling optimization software uses mathematical algorithms and heuristics to generate optimal or near-optimal schedules based on defined constraints and objectives
• Visual management tools (Kanban boards, production control boards) provide real-time visibility into the status of production activities and facilitate communication among team members

Production Control Methods

• Kanban is a pull-based production control system that uses visual signals (cards, containers) to trigger production and material replenishment based on actual demand
• Theory of Constraints (TOC) focuses on identifying and managing the most limiting constraint (bottleneck) in a production system to improve overall throughput
  • Drum-Buffer-Rope (DBR) is a TOC-based production control method that synchronizes production with the bottleneck's pace
• Just-in-Time (JIT) production aims to minimize inventory and waste by producing goods only when they are needed and in the required quantities
• Statistical Process Control (SPC) uses statistical techniques to monitor process performance, detect deviations, and initiate corrective actions
• Production leveling (Heijunka) smooths out production volume and mix over time to reduce variability and improve efficiency
• Visual control systems (Andon lights, dashboards) provide real-time feedback on production status, quality issues, and abnormalities

Performance Metrics and KPIs

• Throughput measures the rate at which a production system generates output, expressed as units per unit of time (hours, days, weeks)
• Cycle time represents the average time required to complete one unit of product from start to finish
• Capacity utilization compares the actual output to the maximum potential output of a resource or system, expressed as a percentage
• On-time delivery (OTD) measures the percentage of orders delivered to customers on or before the promised due date
• Overall equipment effectiveness (OEE) evaluates the performance of equipment based on availability, performance, and quality factors
• Inventory turnover ratio compares the cost of goods sold to the average inventory value, indicating how efficiently inventory is being managed
• Schedule adherence measures the percentage of time that production activities are completed as planned, without delays or deviations

Challenges and Optimization Strategies

• Variability in demand, processing times, and resource availability can disrupt production schedules and impact performance
  • Implement flexible scheduling techniques and maintain buffer capacity to absorb variability
• Conflicting objectives (cost, quality, delivery) may require trade-offs and prioritization in scheduling decisions
  • Use multi-objective optimization techniques and involve stakeholders in defining priorities
• Complex product mixes and routings can increase scheduling complexity and computational requirements
  • Apply advanced scheduling algorithms and use simulation to evaluate alternative scenarios
• Unexpected disruptions (equipment breakdowns, material shortages) can derail production schedules
  • Develop contingency plans and incorporate real-time monitoring and re-scheduling capabilities
• Lack of accurate and timely data can hinder effective scheduling and control
  • Invest in data collection systems, IoT sensors, and integration with ERP/MES systems
• Resistance to change and organizational silos can impede the implementation of new scheduling practices
  • Foster cross-functional collaboration, provide training, and demonstrate the benefits of improved scheduling

Real-World Applications

• Automotive manufacturing utilizes complex scheduling systems to coordinate the assembly of thousands of components into finished vehicles
• Semiconductor fabrication relies on advanced scheduling techniques to optimize the utilization of expensive clean room equipment and minimize cycle times
• Aerospace and defense industries use project scheduling methods (PERT, CPM) to manage the development and production of complex systems (aircraft, satellites)
• Food and beverage processing plants employ production control methods (Kanban, JIT) to ensure freshness and minimize inventory costs
• Hospitals and healthcare facilities use scheduling systems to manage patient flows, operating room utilization, and staff assignments
• Construction projects heavily rely on scheduling techniques (Gantt charts, CPM) to coordinate multiple trades, resources, and milestones
• Service industries (call centers, logistics) use scheduling optimization to match staffing levels with demand patterns and improve responsiveness