Sum-up #2: Machine performance and Maintenance
Part 1: Introduction to Machine Efficiency
In the world of manufacturing, the performance of machines holds a key role in determining the overall success of operations. In today’s fiercely competitive industry landscape, achieving and maintaining peak machine efficiency is a strategic necessity for any organization. In this article, we’ll explore the significance of machine efficiency, its financial implications, and delve into Lean methodologies for its enhancement.
Machine efficiency has a direct impact on production output, product quality, and operational expenses. When machines run at their optimal capacity, companies can meet customer demand promptly, reduce lead times, and make the most of their resources. Conversely, inefficient machines can lead to production delays, quality issues, and increased operational costs.
Cost Impact of Machine Efficiency
Several key performance indicators (KPIs) shed light on the financial impact of machine efficiency:
- Planned vs. Unplanned Downtime: Planned downtime is essential for maintenance and changeovers, but unexpected downtime due to breakdowns or inefficiencies can be costly. For instance, planned downtime for routine maintenance might occur weekly, allowing operators to inspect and lubricate the machinery. In contrast, unplanned downtime can result from sudden breakdowns, leading to production stoppages and unforeseen repair costs.
- Idle Time: Idle time occurs when machines are not actively producing, often due to material shortages or process bottlenecks. For instance, if a machine has to wait for raw materials to arrive, it experiences idle time, which can be expensive due to its impact on production efficiency.
- Target Speed vs. Actual Speed: The difference between the ideal production speed and the actual speed at which machines operate can affect production efficiency and costs. For example, a machine designed to produce 100 units per hour but running at only 80 units per hour due to mechanical issues affects production targets.
- Manufacturing Lead Time and Bottlenecks: Longer lead times and bottlenecks in the production process can hinder timely order fulfilment and increase operational costs. A bottleneck occurring at a specific machine can cause delays, affecting the overall lead time for product delivery.
- Repair and Spare Part Costs: Frequent repairs and high spare part costs result from inefficient machines and significantly impact the bottom line. Frequent breakdowns lead to increased repair costs, and maintaining an extensive inventory of spare parts for emergency replacements can be expensive.
- Breakdowns: Unexpected breakdowns lead to production halts, revenue loss, and increased maintenance expenses. For instance, a sudden mechanical failure in a critical machine causes unscheduled production stoppage, leading to lost production time and immediate repair needs.
Part 2: Understanding and Analyzing Losses
To address machine efficiency, it’s crucial to accurately understand and quantify losses. Two fundamental tools for this purpose are Overall Equipment Effectiveness (OEE) calculations and Value Stream Mapping (VSM).
OEE Calculation
OEE is a comprehensive metric that combines Availability, Performance, and Quality to assess machine efficiency. It helps identify areas for improvement by pinpointing where losses occur and why. High OEE signifies minimal losses and high efficiency. Implementing OEE should be the first step to drive improvements as it provides a comprehensive tool to set priorities and allocate resources to the most impactful losses.
The simplest way to calculate OEE is: OEE = (Good Count × Ideal Cycle Time) / Planned Production Time
However, to gain insights into what’s happening in the manufacturing process, we need to delve deeper.
The OEE calculation is based on three factors: Availability, Performance, and Quality.
- Availability is calculated as the ratio of Run Time to Planned Production Time, accounting for events that stop planned production such as unplanned or planned stops.
- Performance is the ratio of Net Run Time to Run Time and should not exceed 100%. It is usually at the discretion of the team to decide what duration of downtime falls under availability or performance loss. Simple restarts (<5 minutes downtime) are categorized as performance loss, while interventions fall under availability loss. Ramp-ups, slowdowns, and intentional or unintentional target speed losses impact performance.
- Quality considers manufactured parts that do not meet quality standards, including those needing rework. OEE Quality is similar to First Pass Yield, defining Good Parts as those successfully passing through the manufacturing process without rework. Quality loss can be further categorized into sampling, in-process yield loss (rejects), and non-conforming product rejected at the end of the production process.
Value Stream Mapping (VSM)
Value Stream Mapping is a visual tool used to analyze the entire production process, highlighting inefficiencies, waste, and bottlenecks. It provides a clear roadmap for process optimization, enabling a holistic view of the manufacturing process and helping organizations prioritize improvements.
Part 3: Process Optimization
While our main focus in this article is machine performance, it’s crucial to consider all supporting mechanisms that boost efficiency. Let’s briefly explore the main options for optimizing manufacturing processes.
Lean methodologies offer effective strategies for process optimization to enhance machine efficiency. Three key approaches include:
- Kanban: Implementing a Kanban system enables just-in-time production, minimizes inventory levels, reduces waste, and ensures smoother production flow. For instance, Kanban cards can signal when specific quantities of raw materials need replenishing, preventing overstocking and ensuring a steady production flow.
- Pull System: A pull system, often integrated with Kanban, allows production to be driven by actual customer demand, avoiding overproduction and associated costs. For example, a bakery uses a pull system to make fresh bread based on customer orders throughout the day, ensuring a constant supply without waste.
- JIT (Just-in-Time) Manufacturing: JIT manufacturing focuses on producing goods only as needed, eliminating overproduction, reducing lead times, and enhancing machine utilization. As an example, a car manufacturer receives orders from dealerships and produces vehicles based on actual demand rather than manufacturing cars in advance.
Kaizen and Kaizen Blitz: Kaizen promotes continuous improvement through small, incremental changes, while Kaizen Blitz involves intensive workshops to rapidly implement significant improvements through employee involvement, usually through cross-functional teams. Both methodologies drive efficiency enhancements.
Part 4: Downtime Reduction
SMED (Single-Minute Exchange of Die)
SMED is a Lean manufacturing technique designed to minimize the time required to change over a machine or production process from producing one product or batch to another. While the name suggests “single-minute,” the goal is not necessarily to achieve changes within a minute, but rather to dramatically reduce setup times.
Reducing changeover time is crucial not only to reduce downtime but also to improve supply chain flexibility, enabling manufacturers to respond quickly to changing customer demands and profitably produce smaller batch sizes. In many cases, changeovers require specialized engineering teams, but implementing best practices empowers operational teams to perform changeovers efficiently.
A range of tools and methods can be used to improve changeover time:
- Separate Internal and External Setup: SMED distinguishes between internal (tasks performed only when the machine is stopped) and external (tasks performed while the machine is running) setup tasks. The goal is to convert as many internal tasks into external ones as possible.
- Convert to Quick-Release Fasteners: Replace traditional bolts and screws with quick-release fasteners that can be easily tightened or loosened without tools.
- Standardize Tools and Procedures: Ensure all tools are organized, readily available, and standardized for each changeover to prevent delays due to missing or incorrect tools.
- Use Visual Aids: Employ visual aids like checklists and color-coding to guide operators through the setup process, making it more efficient and less error-prone.
- Create Setup Reduction Teams: Form cross-functional teams, including machine operators, maintenance staff, and engineers, to collectively identify and implement setup time reduction opportunities.
- Implement Parallel Operations: Whenever possible, parallelize setup tasks to perform them simultaneously rather than sequentially.
- Eliminate Adjustments: Design machines and processes to require fewer adjustments or make these adjustments easier to perform.
- Standardize Components: Reduce the number of product-specific components, such as changeover parts or tooling, to minimize the need for different setups.
- Use Quick-Change Tooling: Invest in tooling and fixtures designed for rapid changes, such as quick-change chucks or dies.
Implementing SMED is an ongoing process that requires continuous improvement efforts. Regularly reviewing and refining changeover procedures can lead to further reductions in setup times and increased manufacturing flexibility.
Andon System
The Andon system provides real-time visibility into machine status, enabling swift responses to issues and minimizing downtime. This can be a display with efficiency/yield/downtime data or a simple alarm sound and light when and where the machine stops.
An interesting application in large, highly automated areas is to shut down the light when machine performance drops, allowing operators to observe the machine before an actual failure occurs. The earlier signs we use as triggers, the more efficient the Andon system becomes.
In situations where preventive application is not feasible, significant savings can still be achieved by educating the team about the importance of response time and providing them with the right tools, such as simple alarm sounds or walkie-talkies, to speed up information sharing.
Breakdown Analysis and Root Cause Analysis
Analyzing breakdowns and conducting root cause analysis helps identify and eliminate the underlying causes of downtime. For example, after a machine breakdown, a team may conduct root cause analysis and discover that insufficient lubrication led to the failure. They can then implement a preventive maintenance schedule for regular lubrication, reducing the risk of future breakdowns. This approach can also be extended to check lubrication schedules for other areas where similar parts are used proactively.
Poka-Yoke and Visual Control
Poka-Yoke mechanisms and visual controls are designed to prevent errors and defects, reducing unplanned downtime by improving visibility.
Visual Control:
- Workstation Layout and Organization: Use visual cues such as colored lines, floor markings, and shadow boards to designate specific areas for tools, materials, and equipment, ensuring everything has a designated place. This helps operators quickly identify missing items and maintain order.
- Labelling: Applying simple, easy-to-read labels on machines with setpoints can expedite machine setup and aid ongoing operation when environmental factors or material quality fluctuations require adjustments. Marking lubrication points, inspection points with color-coded dots, displaying belt threading, and marking turning directions with arrows can enhance efficiency.
- Production Status Boards: Implement visual boards or displays near workstations showing real-time production data, including production targets, actual output, and any issues requiring attention. This provides instant feedback to both operators and managers.
- Kanban Boards: Visual boards displaying Kanban cards help control inventory levels. As materials are consumed, operators move Kanban cards to signal the need for replenishment, ensuring a smooth and efficient production flow.
- Quality Inspection Stations: Visual control is crucial in quality control. Implement inspection stations with clear criteria for acceptable and non-acceptable products, along with visual aids to help inspectors identify defects. Reducing inspection time can help further reduce downtime by speeding up the start-up process or investigation of issues.
Poka-Yoke (Error Proofing):
- Product Assembly: Design products and assembly processes to make it physically impossible to assemble components incorrectly. Components with unique shapes or asymmetric features can only fit together in one way.
- Automated Verification: Use sensors, cameras, or other automated systems to verify that each step of a process has been completed correctly. If an error is detected, the system can halt production or provide an alert.
- Checklists and Job Aids: Provide operators with checklists or job aids outlining the correct sequence of steps and key quality criteria. This helps prevent errors by ensuring that no critical steps are missed.
- Color-Coding and Labeling: Employ color-coded components, labels, or warning signs to guide operators in selecting the correct materials or performing tasks in the correct order, especially in complex assembly processes. Many advanced warehouse management systems offer the opportunity to scan materials and check against the Bill of Materials (BOM), further improving efficiency.
- Fixture Design: Design fixtures, jigs, and templates that allow only for the correct positioning of parts or components, preventing misalignment or incorrect placement during assembly.
- Shut-Down Mechanisms: Implement shut-down mechanisms that activate when an error is detected. For example, a machine might stop automatically if a product’s dimensions fall outside the specified range. While this increases initial downtime, it prevents significant yield losses (hidden efficiency loss).
- Counters and Sensors: Use counters or sensors to monitor the number of operations performed. If the required number of operations is not met, it triggers an alert or stops the process.
- Software Validation Checks: In software development, incorporate validation checks that prevent users from entering incorrect or invalid data. These checks can include data formats, range limits, or mandatory fields. For instance, preventing input errors, like entering “12” instead of “1.2,” can prevent extended breakdowns.
Part 5: Maintenance Strategies
Finally, we arrive at my favourite topic: maintenance. Even the most dedicated efforts can lead to chaos without a proper maintenance strategy. I’ve seen numerous cases where countless working hours were spent investigating process problems without major breakthroughs, only to have those problems disappear after yearly maintenance, leaving everyone baffled.
I’ve also led a material investigation when, despite all efforts, I couldn’t pinpoint any material parameter or environmental factor causing process stoppages. Then, using the old-fashioned problem-solving methodology I learned at Procter & Gamble, I went back to basics: standards and base conditions. It turned out that the whole cup dispenser was slightly tilted, and the patterns of rejects and stoppages perfectly matched the misalignment – dropped cups on one end and jams on the other. So, let’s explore how maintenance and machine condition can be improved.
Total Productive Maintenance (TPM)
TPM is a comprehensive approach to equipment maintenance and management, aiming to maximize the efficiency, effectiveness, and overall performance of manufacturing equipment. TPM goes beyond traditional maintenance practices, involving the entire organization and focusing on the holistic management of equipment throughout its lifecycle. It was developed in Japan and is a core component of Lean manufacturing.
Key Principles and Concepts of TPM:
- Equipment Ownership: TPM encourages a sense of ownership and responsibility for equipment among operators and maintenance teams. Operators actively participate in caring for and maintaining the machines they operate. The best practice I’ve seen (and implemented) used Equipment ownership as the core of the operator’s performance management system. Everyone had a personal scorecard, and in addition to team performance metrics, operators were encouraged to look after their primary unit/cell. They were asked to record minor defects, observe the machine to understand losses, collect data, and come up with Kaizen ideas. This enabled us to tailor the onboarding process and also motivated and developed experienced staff.
- Autonomous Maintenance (AM): Operators are trained to perform routine cleaning, inspection, lubrication, and minor maintenance tasks on their machines. The goal is to prevent breakdowns and maintain equipment in optimal condition.
- Planned Maintenance (PM): Planned maintenance activities are scheduled in advance based on equipment conditions and usage patterns. This includes major overhauls, component replacements, and other preventive measures.
- Focused Improvement (Kaizen): Continuous improvement teams work to identify and address root causes of equipment-related issues, aiming to eliminate recurring problems and improve overall equipment effectiveness (OEE). TPM identifies six major sources of productivity loss in manufacturing and aims to eliminate or reduce them. These losses are: Downtime, Speed Loss, Defects and Rework, Idling and Minor Stoppages, Setup and Adjustment Time, Yield Loss.
- Training and Skills Development: TPM emphasizes training and skill development for both operators and maintenance staff. Properly trained personnel are better equipped to handle equipment and maintenance tasks effectively.
- Process and Equipment Design: TPM encourages the integration of equipment reliability considerations into the design and procurement processes. This helps ensure that new equipment is easy to maintain and performs optimally.
- Safety: Safety is a fundamental component of TPM. Safe working conditions and practices are critical to preventing accidents and equipment damage.
Autonomous Maintenance (AM)
Autonomous Maintenance (AM) is a fundamental pillar of Total Productive Maintenance (TPM) and a key concept in Lean manufacturing. It involves empowering operators and frontline workers to take ownership of the equipment they operate by performing routine maintenance, inspections, and minor repairs. The goal of AM is to prevent equipment breakdowns, improve overall equipment effectiveness (OEE), and enhance the reliability and availability of machines.
The AM process typically begins with a thorough initial cleaning of the equipment and its surroundings. This cleaning process serves as more than just tidying up; it reveals hidden issues, such as oil leaks, loose components, or accumulating debris, which could contribute to equipment failures.
Operators are trained to perform daily inspections of their machines, often before each shift. During these inspections, they diligently observe the equipment, looking for signs of abnormalities, wear and tear, loose parts, or any indications of deterioration. The objective is to detect and address potential issues at an early stage, preventing them from evolving into more significant problems.
To maintain consistency and effectiveness, AM emphasizes the development of standardized procedures for cleaning, inspection, and lubrication tasks. These procedures are carefully documented and made readily accessible to all operators, ensuring that everyone follows the same protocols.
Lubrication plays a crucial role in preventing friction-related failures. Operators are responsible for checking and replenishing lubricants according to established schedules. Adequate and timely lubrication helps ensure that moving parts function smoothly and efficiently.
Another essential aspect of AM is enabling operators to tighten loose bolts, nuts, and other fasteners, as well as make minor adjustments when necessary to maintain machine settings within specified tolerances.
As part of their responsibilities, operators are trained to replace consumable parts that wear out over time, such as gaskets, seals, or filters. The timely replacement of these components contributes to the overall reliability of the equipment.
Central to the success of AM is ongoing training and skill development for operators. This training not only enhances their ability to perform maintenance tasks but also equips them with the knowledge to recognize early signs of problems and address them appropriately.
Operators are encouraged to actively report any issues or abnormalities that fall outside the scope of routine AM tasks. This reporting system serves as an essential mechanism for identifying and addressing more complex maintenance needs, ensuring that nothing goes overlooked.
In summary, Autonomous Maintenance (AM) is a systematic approach that empowers operators to become active custodians of the equipment they operate. By conducting routine cleaning, inspections, lubrication, and minor maintenance tasks, operators contribute to reducing breakdowns, enhancing reliability, and ultimately, improving the overall efficiency of the organization’s operations. AM is a continuous process that requires commitment and engagement from both management and frontline employees.
Planned Maintenance (PM)
Planned Maintenance (PM) is designed to ensure the ongoing reliability and performance of machinery and equipment through proactive and systematic maintenance activities and is primarily focused on expert-led engineering tasks.
In PM, maintenance activities are scheduled in advance based on various factors, including the machine’s usage patterns, operational history, manufacturer’s recommendations, and the overall maintenance strategy of the organization. The primary objective of PM is to prevent equipment breakdowns and maintain machines in optimal working condition, ultimately leading to increased equipment reliability and availability.
One of the key principles of PM is to shift from a reactive maintenance approach (waiting for machines to break down before addressing issues) to a proactive one. This involves planning and executing maintenance tasks during scheduled downtime or non-production periods, minimizing disruptions to production processes.
PM encompasses a range of activities, including inspections, component replacements, adjustments, and overhauls. These activities are typically categorized into three main types:
- Time-Based Maintenance: Scheduled maintenance tasks are performed at predefined time intervals, such as daily, weekly, monthly, or annually. These intervals are determined based on equipment manufacturer recommendations and historical data. Time-based maintenance helps ensure that vital components are replaced or inspected regularly, reducing the risk of unexpected failures.
- Condition-Based Maintenance: Instead of relying solely on fixed time intervals, condition-based maintenance takes into account the actual condition of the equipment. Various monitoring techniques, such as vibration analysis, thermal imaging, and oil analysis, are used to assess the health of machines. When specific parameters or conditions deviate from acceptable ranges, maintenance actions are triggered. This approach maximizes the lifespan of components while reducing unnecessary maintenance.
- Run-to-Failure Maintenance: In certain cases, it may be more cost-effective to run equipment until it fails, treating specific parts as consumables. This approach is typically employed for non-critical or readily replaceable components. For example, in some industries, light bulbs or air filters are changed only when they fail.
PM often involves the use of computerized maintenance management systems (CMMS) to schedule, track, and manage maintenance activities efficiently. CMMS software helps organizations plan and prioritize maintenance tasks, track equipment histories, and manage spare parts inventories.
In conclusion, Planned Maintenance (PM) is a systematic and proactive approach to equipment maintenance that plays a pivotal role in TPM and Lean manufacturing. By scheduling and executing maintenance tasks in a planned and organized manner, organizations can achieve higher equipment reliability, lower downtime, and significant cost savings while ensuring the long-term sustainability of their operations.
Summary
Maximizing machine efficiency in manufacturing is an ongoing process that requires a multifaceted approach. By understanding the cost impact of inefficiencies, analyzing losses through tools like OEE and VSM, optimizing processes, reducing downtime, and implementing effective maintenance strategies, organizations can enhance their competitiveness and achieve sustainable growth in today’s dynamic manufacturing landscape. Lean methodologies provide the necessary framework and tools to navigate this journey toward operational excellence.
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