Regardless of the type of production we are discussing, lean thinking is the baseline for factories. Lean is about three core topics: "quality," "cost," and "delivery." Everything revolves around these three core production topics. After decades of development, lean manufacturing has become an operational management system jointly implemented by excellent manufacturers around the world. Because stable and reliable production must be ensured before we can talk about digital transformation and intelligent upgrading, we must let technology return to the essence of manufacturing and discuss production line design on this basis.
Intelligent manufacturing is becoming a hot topic in industry. In terms of its goals, intelligent manufacturing aims to address the ever-increasing demands for "personalized needs" and "cost efficiency." In essence, it focuses on several key issues:
(1) Using software-defined intelligence to enable machines and production lines to adapt to changing needs;
(2) Optimize production efficiency through analysis of global production data;
Whether it's a "standard assembly line" or "mass customization," a company's competitiveness comes from quality, cost, and delivery capabilities. Therefore, for production line investors, stable, high-quality production is the only way for a company to truly gain "added value" from production and thus achieve long-term profits.
The second problem is easy to understand. Today, through industrial internet technology, we can connect existing single-machine production to achieve transparent data transmission. However, the first problem will encounter a bottleneck because the "rigidity" of machinery makes it difficult to achieve the "flexibility" of production. Under the planning of the automation system, the production line has the ability to adapt to changes in production based on process modeling. However, the actuators need to be able to handle such changes. Therefore, the traditional production line becomes a bottleneck.
The key metric for evaluating the efficiency of production line investment is "OEE," which is of great concern to most end users. In addition, time to market and return on investment are also key evaluation metrics.
If we continue with the traditional production model, achieving high-quality production will not be so easy. Figure 1 is a key point about OEE calculation. We can see the factors affecting OEE and analyze the following aspects in conjunction with process control:
(1) Quality: Quality impacts include startup/shutdown waste, as parameter calibration takes time to reach a steady state, and production waste, such as defective products caused by unstable control effects.
(2) Performance: Factors affecting machine performance include mechanical wear that prevents high-speed operation, which is equivalent to operating the machine with a defect and resulting in low efficiency. Pauses may also be caused by electrical instability or interference, which can also affect performance.
(3) Availability: For small batches and multiple varieties, production line changeover does not add value in lean manufacturing. Therefore, this link will reduce availability. Quick changeover can reduce this loss. Downtime is because mechanical and electrical failures will prevent production from proceeding normally.
❖ Figure 1 - OEE is a key indicator for evaluating the overall investment efficiency of a production line.
Understanding the key metric OEE reveals that "personalization" actually presents many challenges for production:
(1) Start-up loss: If the model is changed frequently, the start-up waste cannot be solved. Since the order size is smaller and the start-up waste is a fixed value, this will lead to an increase in the defect rate because the denominator becomes smaller.
(2). Setup and adjustment: Due to frequent model changes, the required adjustment time greatly reduces the availability of the equipment. Originally, the mold was changed and the machinery was adjusted once a week. For personalized products, it may take several hours every day. Therefore, the "value-added" processing time of the equipment will be reduced.
Besides the loss of quality and usability caused by model changeover, traditional mechanical production lines also have the following problems:
❖Figure 2 - Traditional mechanical production lines use chains or belts for transmission.
(1) Mechanical wear: Traditional mechanical chains or belts are used for transmission. Wear of gears and other components often leads to insufficient precision and prevents the machine from operating at high performance, resulting in losses due to deceleration and maintenance interruptions.
(2) Inflexible adjustment: This includes the use of induction motors with insufficient low-speed characteristics in traditional conveying, or assembly and processing methods such as indexing plates, which makes it impossible to achieve high-speed and stable adjustment. In particular, the indexing plate is not easy to produce at high speed due to its large mechanical inertia.
(3) Cannot be customized: Mechanical indexing plates are often designed for batch processing, and the spacing between their workstations and the speed of movement cannot be easily adjusted according to changes. This means that for new production, the system often needs to be redesigned and tested, which makes it impossible to guarantee the availability of the overall production line.
(4) Numerous buffer zones: Since mechanical conveying often cannot be optimally matched between production lines, buffer zones need to be established between high-speed sections and downstream sections, and these buffer zones often occupy a large factory area.
(5) Complex maintenance: Due to the complex structure of the mechanical system, a large number of experienced maintenance personnel are often required to ensure the stable and reliable operation of the production line.
For the reasons mentioned above, the manufacturing lines for mechanical conveying systems cannot be flexibly adjusted, resulting in a low overall OEE level. These problems become even more prominent under the demand for personalized production.
To meet increasingly personalized production demands, a new generation of production line design technology, the flexible electric drive conveyor system, has emerged. Figure 3 shows the production line planning diagram of ACOPOStrak. ACOPOStrak uses long stator linear motor technology, with sliders carrying the workpieces running on tracks. These sliders operate in a "non-contact" manner with the tracks, which can be understood as "magnetic levitation" trains. The sliders on these tracks use electromagnetic means, which allows the spacing, running speed, and acceleration of the movers to be adjusted according to software definitions. This solves the "rigidity" of traditional machinery in flexible manufacturing, making the entire production line flexible.
❖Figure 3 - ACOPOStrak Flexible Electric Drive Conveyor System
Furthermore, ACOPOStrak offers diverse track design options, allowing for multiple angles, as shown in Figure 4. This enables highly flexible production lines. Based on high-precision track mechanical coupling design, it can achieve both "convergence" and "diversion," which is particularly suitable for the following scenarios:
(1) Products from multiple production lines are combined and assembled into a main line, such as in the electronics manufacturing industry, or in mixed packaging, such as in the food and beverage industry;
(2) A high-speed production line is divided into multiple downstream units for diversion processing, or into different areas for different product assembly or packaging.
(3) Dedicated repair station/fixture replacement station: Defective products detected by visual or other methods can be sent to a dedicated channel for processing, or this channel can also be used as a work station for tooling and fixture replacement.
❖Figure 4 - Flexible Production Line Organization
Flexible electric conveyor systems, such as B&R's SuperTrak/ACOPOStrak (Figure 5), have brought about some disruptive production line designs, including several aspects that enhance production line capabilities:
❖Figure 5 - Benefits of Flexible Electric Drive Conveyor System
(1) Hot-swap: Quickly change tooling fixtures, and this change can be performed in a fixed area while the current production line is in operation;
(2) Digital Twin: This technology allows new production combinations in operation to be tested and verified in a virtual environment. That is, the current number of sliders, speed, spacing, position, acceleration/jerk characteristics can be simulated in the software to ensure that the production process can enter a steady state after a rapid changeover. As shown in Figure 6, digital twins make production line design faster and reduce investment risks, especially the verification of new production lines, which used to be a very time-consuming process. However, due to the integration of electro-magnetic-software, this work has now become much easier.
Figure 6 - Validating production line process feasibility in advance using digital twins
(3) Track changing technology: This technology enables more flexible adjustments to production. These adjustments only require parameter settings and do not require complex adjustments to the production line. Compared with traditional indexing plates and belt and chain transmission, this technology is designed for "flexible" manufacturing.
(4) Collaborative work: The design of electro-magnetic-soft integration enables the track to work collaboratively with robots and other process equipment such as packaging machines, injection molding machines, and chip attaching machines. Extremely high synchronization can be achieved through the bus.
(5) Flexible adjustment: These quick slider adjustments can be simulated not only in the virtual environment, but also in reality, making the transformation more flexible.
In summary, flexible electric drive conveyor systems can improve OEE in several ways: including faster changeover times, more reliable product quality, and lower production line downtime risk. Overall, it significantly improves production line OEE, which means that the production line can still maintain high quality, low cost, and fast delivery capabilities even with highly customized production lines.
In addition, flexible production lines also have significant room for improvement in shortening time to market:
■ Verification before production line deployment: As mentioned earlier, digital twin technology can perform simulation verification before production line deployment, and can also perform production verification after new product changes on the operating production line. This ensures investment security and also brings investment security to the restructuring of traditional production lines when there are major product changes.
■ High OEE leads to high ROI, which is the essence of lean manufacturing. A high-performance production line can help your factory produce high-quality products in a long-term and stable manner, which is a production line with high return on investment.
Flexible electric drive systems are designed to meet the high return on investment of production lines in the era of "personalized" production. Please pay attention to B&R, where ACOPOStrak will be exhibited at the Shenzhen Machinery Exhibition from March 28-31, 2019—this is the first time this production line has been publicly displayed. Welcome to visit the B&R booth.
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