Solution combining lean production and industrial revolution 4.0 in industrial garment enterprises.

   Researches on Lean production model and traditional Lean model applied to garment enterprises have been interested and researched by many authors around the world. The results of Lean production application in industrial garment enterprises have been proven to help businesses reduce production costs by 15-20% compared to before applying this production technology. Despite such successes, garment enterprises are always looking for ways to reduce production costs more in order to improve their competitiveness by price, and one of the ways to achieve this goal is to apply using a combination of lean production technology and the achievements of industry 4.0 at the same time in garment enterprises. However, once the results of industry 4.0 have been applied in enterprises, is it necessary to use lean anymore and is the simultaneous application of both lean and industry 4.0 more effective than just applying lean technology? Using either of these two components is still unanswered questions. The above questions are also the main issues that this article will aim to solve to help garment enterprises have more effective investment and development directions in the coming period.

1- Achievements of the industrial revolution 4.0 in the garment industry

   The industrial revolution 4.0 with the foundation of digital technology has created a trend to combine real production and virtual production model by digitizing the entire real production process into data for management by computer. The key technologies of this revolution are the Internet of things (IoT), radio identification (RFID), sensors, additive manufacturing, and cloud computing. cloud computing), connected robot technology, interactive software over the network, big data. The above solutions have and will create many innovations and creativity in the garment production process, especially the production organization in the sewing line.

   Internet of Things is a technology that allows remote connection via a global information network between human and machine entities; In order to be able to connect to each other over the Internet, the data to be shared is transferred to storage in shared servers commonly known as "clouds". The sensor is the part responsible for collecting information from the environment, this information is put into the controller to process and output the appropriate commands to decide the behavior of the system. Artificial intelligence and robotics is the application of technologies that allow machines to replace humans in both thinking for themselves and performing many different tasks. RFID radio frequency identification technology is a technology that uses electronic chips attached to products or other necessary devices to track the entire movement process as well as information about products to serve the purposes of customers. management and control of the production process. Additive manufacturing is the use of 3D printing technology to print products in incremental layers to fabricate products. Big data are information sources with common characteristics of large volume, fast speed and formatted data in many different forms. decision making, discovery, and process optimization.

   In industrial garment production, for basic products such as T-shirts, basic shirts, casual pants, jeans, the production process has been replaced by robots to help improve quality and especially is to improve labor productivity, reduce product costs. For fashion products that are made with adhesive materials such as plastics or polyester fibers, etc., the product manufacturing process is carried out on 3D printers, both for high productivity and reductions. product price. However, the application of 4.0 technology to the garment industry also has many limitations. Specifically, to produce products with special properties such as: fashion products are designed in many layers, have complex designs and textures, change frequently according to the market, and are manufactured using materials. If the material is not sticky, the application of 4.0 technology is very difficult or the investment cost is very large, so it is not effective to be able to deploy in the next 10-15 years.

2- Lean production technology in industrial garment enterprises

   The traditional Lean production model has been mentioned in many domestic and foreign studies. This Lean model is described quite fully in "House TPS" and it is also deployed in industrial garment enterprises, including the following main components:

- Three core values ​​of Lean are implemented in garment enterprises: (1) Customer comes first: this concept helps garment enterprises to always provide customers with products of the highest quality, lowest cost and shortest delivery time; (2) Respect for people: this concept helps garment enterprises to make employees always feel satisfied about the workplace; (3) Eliminate waste: this concept helps businesses increase profits by reducing costs and gives businesses more flexibility in the market. In addition to the three core values ​​above, the guiding ideology of the Lean production method is also built on two factors: continuous improvement and respect for employees. These can be considered as the ideas of Lean production; Although these ideas are not visible in a tangible way, they are the key ideas for the successful implementation of Lean production in some garment enterprises.

- Based on the above core ideas, the "House of TPS" was built, including a foundation containing tools such as standardization of work, problem solving and improvement implementation. continuity; In addition, some other studies also mentioned that the implementation of 5S, visual management, overall productivity maintenance, balanced production are also factors that lie in the foundation for implementing Lean production. These fundamental factors help create stability in the process of industrial garment production.

- Following the foundation, garment enterprises also use two pillars to implement Lean production. The first pillar is just-in-time (JIT) production, which means the right type of product, the right quantity, and the right time to ensure productivity. The JIT pillar includes components such as: planning production rhythms, creating continuous product flows, applying a “pull” production system, applying a rapid product changeover system, and price chain mapping. management, line balancing, cell-based space optimization, integration with business logistics including supply chain and customers. The second pillar is the quality factor with the idea that quality is at the source; This pillar includes components such as: quality control with statistical tools, doing it right (Pokayoke) to prevent errors, using quality status signals to control quality in production ( Andon), stop production when errors are detected, solve problems related to errors, standardize work in depth towards customers.

   Field trials have demonstrated that lean manufacturing can be effectively applied to the apparel industry as an important step in identifying and eliminating waste. Specifically: after implementing Lean, BY Garment Industries in the Philippines uses a flow-driven manufacturing process and production cadence, production time standards have helped: activities that do not create added value increase was reduced and reached 100% efficiency, the rate of unqualified goods was reduced to 0.08% and there was no unfinished capital in the line, productivity improved [6].In addition, in India, the application of value chain mapping and re-arrangement of premises has helped reduce product turnaround time by 18%, and the distance to move semi-finished products from the cutting area to the sewing area. 85.3%. The use of value chain tools at the same time as rapid production transformation has reduced the preparation time for new product codes from 28 minutes to 8 minutes and 10 seconds (70.84% ​​reduction), contributing to increased productivity. from 19,600 products/shift to 27,740 products/shift (up 40%) [5]. Lean research also shows that after 3 months of implementation, labor productivity of the lines has increased by 23.6% on average, the defect rate has decreased from 12% before deployment to 8% for jacket products. and 5% for shirt products after deployment [3].

3- Inadequacies exist when applying some tools of traditional lean

   As analyzed above, the study of the traditional Lean model and the study of digital technology have been carried out by many authors. However, the researches on the Lean production model in the garment industry applying both lean and digital technology are still very limited. It can be seen that although the application of lean in garment enterprises has been effective, there are still some shortcomings as follows:

3.1 The adjustment of the machine when entering the line consumes a lot of time 

   The rapid production transformation in the garment enterprise depends a lot on the adjustment of sewing equipment according to the characteristics of the product. This is only done when the semi-finished products are put into the line, so the waiting time for machine calibration greatly affects the average productivity of the line. In fact, a line with a simple product changeover like a shirt can take 1-2 hours, while a complex product like a multi-layer jacket can take 4-8 hours depending on the complexity. of the product.

3.2 The maintenance of equipment under the method of preventive maintenance still creates a lot of waste in production time

   Preventive maintenance requires routine maintenance even though the machine may still be in good condition, which can consume unnecessary maintenance time. In addition, there are some sewing equipment that has not yet reached the period of periodic maintenance, but due to production conditions, it may have technical problems before the scheduled maintenance time, leading to workers having to stop production. affects productivity and creates wasted waiting.

3.3 Is there still time lag in handling deviations in production?

    When implementing lean production, garment enterprises often use tools such as factory layout, semi-finished product path layout, etc. to correct deviations in production, identify problems and solve problems. Ask employees to make the necessary changes to ensure the production plan. One disadvantage of Lean is that the above jobs cannot be done in real time and often there is a delay thus reducing the efficiency of production planning and control.

   On the other hand, in production, the handling of arising situations is mainly based on the statistical results on an hourly or every two hours basis, not to mention that there are garment enterprises that have time to collect production data and transfer it to the customers. to the relevant parts longer, up to 4 hours at a time. Processing based on such statistical results creates a delay corresponding to statistical data processing time, which can lead to unreasonable waste of transportation, unreasonable layout. ..due to the time to detect irregularities is slower than the time when these irregularities take place.

3.4 More defective goods occur due to delay in detecting quality problems

   Although garment enterprises use quality inspectors on the line to detect product quality defects right in the sewing process; However, due to the limitation of human resources, many garment enterprises only arrange this staff to inspect some key parts. The inspection on this line also only checks alternately from one stage to another but cannot simultaneously check many stages at the same time, so it may lead to the failure to detect and promptly handle the problems. Errors arise at omitted or untested stages.

3.5 Occupational safety still occurs because only warning the hazardous area by warning signs

   Industrial garment enterprises often design and install quite specific instructions on hazardous areas in the working process; On the other hand, enterprises also require employees to fully learn occupational safety rules at the enterprise. However, due to the nature of the work performed mainly by hand, on the other hand, due to the changing health factors of workers from time to time, violations of labor principles may still occur due to the Warning signs are mainly passive warnings, have not yet created high attention for workers to safety principles.

4- Solution combining Lean production technology and achievements of Industry 4.0 in industrial garment enterprises

4.1 Applying digital equipment in the sewing line to shorten the time of code change

   In order to create high flexibility when converting product codes, digital applications in industry 4.0 can be applied as follows: the use of sensors and software in industry 4.0 will facilitate the product transformation process. when applying Lean is made more effective. The reason is that using new software and sensors will allow machines to automatically recognize products and load the right programs and tools to make products without human intervention. Therefore, the preparation of equipment and tools for code conversion is automated, the operator only has to focus on the jobs that create added value for customers. In the sewing business, if the semi-finished products are tagged with tags using RFID technology, the digital sewing devices in the line can fully identify the semi-finished products that are about to enter the line in terms of the properties of raw materials, the of thread… to automatically adjust the device according to sewing requirements without the intervention of an electromechanical technician to adjust the machine.

4.2 Automated maintenance application to shorten equipment downtime

   The use of predictive algorithms in Industry 4.0 helps to automate equipment maintenance, reduce equipment repair time, and improve labor productivity. In Lean technology, preventive maintenance is often used to improve equipment performance. This preventive maintenance process will be enhanced when converted into automated maintenance by the application of advanced analytical algorithms and self-learning machines. These technologies will help analyze the large amount of data collected by the sensors, so that potential problems leading to shutdowns can be identified before they occur.. Based on the problem detected, the maintenance technician can prepare in advance to reduce downtime and improve productivity. In addition, the maintenance thanks to big data and total analysis techniques in Industry 4.0 as above has improved the transparency of the maintenance process, actively contributing to improving the performance of tools. in lean as well as promoting the continuous improvement process.

4.3 Application of virtual-reality production system in industry 4.0 to minimize time lag in handling production scenarios

   The speed of production can be increased by real-time situational processing: the application of real-time data will help to accelerate the production management process. For real-time production management, industry 4.0 helps to provide an algorithm known as a centralized "control tower" to solve two main problems: data collection and input material handling, factory to create a horizontally integrated value chain. Real-time data will help enhance and accelerate continuous improvement efforts in the plant. Employees at sewing lines and managers can share real-time data to find the root cause of reduced performance, thereby recommending solutions faster to solve problems. on production in industrial garment factories.

4.4 Application of real-time sensor technology to minimize error goods

   Product quality is better controlled thanks to the application of real-time sensor systems and artificial intelligence: Quality control is driven by the collected data to aid in the self-inspection process. In Lean, many tools have been applied to reduce the error rate and increase the speed of debugging, but it only helps to reduce the number of defective products by 50%-70%. If the defect rate is to be reduced to close to 0%, then aid the self-inspection process by using a data-driven analysis approach to identify the root cause of the defect produced. Industry 4.0 will help with this process by providing real contextual data and detailed product tracking. The surface defect detection camera system connected to the quality management system will help analyze the surface defects in detail, generate automatic reports of defects, greatly reducing the error rate.

4.5 Application of sensor technology to improve occupational safety

   Work safety will be enhanced thanks to the application of environmental sensors. The use of sensors and training applications in virtual reality helps improve the working environment. Instead of passively using warning signs or warning of accident-prone areas, businesses can install sensors into protective tools for operators to warn of dangerous areas. for workers. This creates proactive warnings with lights or whistles when workers approach a hazardous area, greatly reducing the number of occupational accidents caused by human error.