Today, industrial enterprises need to continuously optimize their production processes in order to increase productivity and gain competitive advantage. In this context, Manufacturing Execution Systems , (MES) have a critical importance. MES offers significant advantages such as increasing productivity and reducing costs by providing real-time monitoring and management of production processes. Cycle time analysis, one of the key components of these systems, is an important element that directly affects the performance of production processes.
In manufacturing processes, cycle time is one of the most important data indicating how often a product is completed for a process. However, errors are often made in cycle time calculation, either in terms of methodology or actual values. Cycle time can be calculated as the time from the start of one unit to the start of the next unit and can be divided into machine cycle time and operator cycle time.
1. Cycle Time
Cycle time refers to the time it takes to complete a process or task from start to finish. For businesses, cycle time is critical to improve efficiency, increase customer satisfaction and minimize costs. Cycle time consists of two main components: machine time and operator time. These two times can sometimes be longer than the full cycle time.
Formula for calculating the cycle time:
Cycle Time = Total Time / Number of Products
Cycle time is an important metric in production management to evaluate the efficiency and effectiveness of the production process. A lower cycle time indicates a more efficient and competitive production process. Cycle time can be reduced by using smart factory applications and unmanned factory automation, enabling 24/7 production.
Cycle time calculations for various production processes are as follows:
- Plastic injection molding: Cycle time = Cap closing time + Plastic injection molding time + Cooling time + Cap opening time
- Sheet metal bending machines: Cycle time (s) = (Metal thickness (mm) / Blade thickness (mm) ) * (1 / Blade speed (mm/s) )
- Injection molding: Cycle time (s) = (Preparation time (s) + Melting time (s) + Pressing time (s) + Cooling time (s) )
- Milling machines: Cycle time (s) = (Preparation time (s) + Machining time (s) )
- Assembly lines Cycle time (s) = (Longest assembly time (s) / Number of parts in the line)
1.1 Cycle Time Measurement Methods
The most common method for cycle time analyses is direct measurement with a stopwatch at a specific time period. However, this method is noted to carry risks such as observer effect and limited time window.
Manufacturing Execution Systems , (MES) can automatically monitor equipment data and continuously record cycle time, enabling automated cycle time analysis. This provides more accurate and comprehensive data compared to manual stopwatch measurement.
Basic steps for the calculation of cycle time:
Defining Operations: First, it is necessary to define which operations are included in the cycle time. These operations can include any operations performed during the transformation of a workpiece from raw material to final product.
Time Measurement: The time required for each operation is measured. Time measurement can be done with tools such as stoppers, time recorders or more technological methods, for example, automatic time tracking systems through sensors.
Waiting and Delays: Waiting and delay times that occur when the workpiece moves from one operation to another are also taken into account. These times can be caused by various reasons, such as equipment failure, lack of materials or imbalances in the workflow.
Calculation of Total Cycle Time: Total cycle time is calculated by adding the time of each operation and waiting/delay times.
Total Cycle Time=∑(Time of each operation + Waiting and Delay Times)
Analysis and Improvement: After calculating the total cycle time, opportunities for improvement are sought at each stage of the process. The operations that take the longest or cause the most delays are identified and strategies are developed to increase the efficiency of these operations.
1.2 Cycle Time Analysis
The main objective of cycle time analysis is to optimize the production process by examining its sub-components. These components include effective machine cycle time, machine cycle time and operator cycle time.
Cycle time analysis is critical in the following areas:
Line Balancing: Accurate analysis of cycle times assists in line balancing efforts and enables the production line to be made more efficient.
SMED , (Single Minute Mold Exchange): Cycle time data can be used to improve mold changeover times. This means shorter setup times and increased productivity.
Productivity Increase: MES systems increase productivity and reduce costs through cycle time analysis.
OEE Measurement: Cycle time data is used in Overall Equipment Effectiveness (OEE) measurements.
Quality Control: Helps detect and prevent quality problems.
Time Management: MES systems , improve time management with cycle time analysis.
Inventory Management: Accurate cycle time data allows inventory levels to be optimized.
Process Management: Cycle time analysis contributes to the improvement and standardization of processes.
Improving Setup Times
Improving setup times is critical to increase production efficiency. MES systems use cycle time data to monitor and optimize setup times:
SMED , (Single Minute Mold Exchange): SMED is a systematic approach to reduce mold change times. MES data can be used to support SMED practices:
- Separating internal and external setup activities
- By optimizing external installation activities
- By simplifying internal installation activities
Automated Installation: Some MES systems help automate installation processes. This reduces human errors and ensures consistent setup times.
Standardization of Setup Procedures: MES can standardize setup procedures using cycle time data. This facilitates operator training and reduces variability in setup times.
Monitoring Machine Setup Statuses: MES can monitor machine states and setup steps. This allows for quick detection and troubleshooting of problems.
Preventive Maintenance: Regular maintenance improves setup times by reducing machine failures and unexpected downtime. MES can support preventive maintenance programs.
When setup times are improved, production efficiency and equipment availability increase. Shorter setup times mean more production time and lower costs.
1.3 RELATIONSHIP BETWEEN OEE AND CYCLE TIME
OEE (Overall Equipment Effectiveness) is an important KPI (Key Performance Indicator) that manufacturing units use to measure performance and losses in the production process. OEE depends on the following three main parameters:
- Availability
- Performance
- Quality
OEE = Availability x Performance x Quality
Cycle time is an important factor affecting the Performance component of OEE. Improvements in cycle time can increase the Performance component and therefore the overall OEE value.
Accurately tracking production data is crucial for calculating OEE. This data includes:
- History
- Production order
- Manufactured parts
- Start and end times
- Operators
- Machine codes
- Good parts
- Scrap
- Reprocessing
- Malfunctions
- Setup time
- Waiting time
Analyzing these metrics helps focus improvement (Kaizen) efforts by identifying the biggest losses. High OEE levels (85% and above) are considered "World Class Manufacturing" and are a goal for many companies, but require significant improvements in areas such as setup time, minor downtime and quality.
- Collecting real-time data from the production floor
- Storing and organizing data in a central database
- Providing access to critical data from other systems
- Receiving work orders from ERP and distributing them to production units
