Online testing of nonwoven fabrics leads to perfect products

Reducing the probability of fabric defects, improving product quality and continuity, increasing production, and improving efficiency are the ideal production conditions that non-woven fabric companies dream of. As the market now has more and more demands for high-quality and defect-free products, manufacturers have turned to fully automatic online detection and quality control systems to obtain more perfect products.

The online detection system can not only prevent or reduce the rewinding and repackaging process of non-woven final products after testing and screening of defective products, but also ultimately reduce the economic losses caused to manufacturers by customer returns. After years of development, the online detection system has reliable performance, is easy to use with existing equipment, and is easy to operate. Therefore, manufacturers only need to consider the return on investment after the installation of the instrument.

The crux of the matter

Some critics believe that this system is a luxury for the nonwoven industry. However, Mr. Heil, president of Isra Surface Vision, Germany, said: "Nonwoven sanitary materials must use online detection and quality control systems, just like fresh air is needed in cars to ensure that the final product meets the customer's quality requirements. Otherwise, it is not certain what problems exist in the products delivered to customers. If the target requirements stipulated in the contract are not met, they will face the problem of returns, especially for diaper hygiene products and consumer medical products, where customers have higher quality requirements." Mr. Heil emphasized, "Please consider whether the loss caused by returns is greater or the cost of purchasing an online detection system is higher."

Mr. Guzzardo, the marketing manager for North America of Erhardt-Leimer of Germany, expressed the same view. He believed that the end-users in the end market have more and more stringent requirements for products and put forward higher quality requirements for manufacturers. Nowadays, online detection systems have become a necessity, not just a selective product. He said, "In the past, due to the limitation of technical conditions, high-resolution equipment was difficult to produce, and even if it was available, the price was very expensive. Enterprises would rather compensate for the economic losses caused by returns than invest in expensive detection equipment. Now with the large-scale production of computers and photographic equipment and the improvement of technology, this return on investment is more economical than producing defective products and returning them."

Dr. Tan, CEO and chairman of AccuSentry, pointed out that the overall defective rate in the non-woven fabric industry is 5%. By adopting an online monitoring quality control system, the defective rate can be reduced to 2%. Such a reduction of 3 percentage points means hundreds of thousands of yuan in revenue for enterprises. For example, a 1% reduction in the defective rate of diaper production lines will save $250,000. This investment pays back very quickly. In the current economic situation, improving efficiency on the one hand and reducing the defective rate on the other hand are the only magic weapons for enterprises to win. In addition, the online inspection system can optimize the overall production process and ultimately improve the efficiency of the equipment and reduce the probability of defective products. Dr. Tan said that our goal is to make the overall efficiency of the equipment 85% and the defective rate 2%.

Higher resolution

At present, the non-woven fabric market tends to be lighter and thinner spunbond products, so online inspection system manufacturers have to respond quickly and develop innovative technologies to adapt to high-speed production and improve the probability of defect detection. The focus of research includes the development of high-resolution systems and new lighting technologies.

Germany's Isla company took the lead in developing the Smash System. Mr. Heil said: "The system has a very high photographic resolution and can scan quickly. It is suitable for high-speed production of light and thin spunbond products, even if the production speed reaches 1000 meters/minute." In addition, the company has also developed new lighting technology that can quickly and effectively discover various defects in sanitary products, providing manufacturers with more efficient and safer systems. AccuSentry has found business opportunities in high-speed diaper production lines. Dr. Tan said: "In the past three years, online detection systems have begun to enter the diaper industry. Almost all large equipment manufacturers are very interested in this technology. One of the main reasons is that the production speed of diapers is getting faster and faster. Some time ago, 600 diapers per minute were considered high speed, but now less than 1,000 per minute is nothing."

High-end lighting technology

Another breakthrough in the online detection system is the use of new lighting technology. Mr. Heil said that the Smash System uses LED technology, which will provide a wider field of view during detection, so that the surface defects of lightweight spunbond fabrics can be seen at a glance. At the same time, Germany's Leimer Company has also been involved in online detection lighting technology. The company has developed a unique lighting technology to provide customers with accurate lighting positioning.

Printing more perfect

Printing LOGO and various patterns on sanitary materials and medical supplies has become a popular trend. In recent years, there has been a demand for using online detection systems to check printing effects. Mr. Heil said: "Nowadays, more and more patterns are printed on nonwoven fabrics. The company's PrintStar system is designed for this purpose. It can detect 100% of the patterns and detect pattern printing errors on high-speed production lines. It can also identify and classify defects such as pattern gap size, splash spots, printing errors, and pattern overlap. In addition, the PrintStar system can also track color differences. If the color changes or there is fiber staining, the system will accurately identify it to ensure that the color meets the customer's requirements."

Another company, Germany's Leimer, has also received requirements for monitoring printed logos and patterns. For this reason, the company has developed the NYSCAN system, which is dedicated to checking various printed patterns. [page]

Detecting errors early

The current popular production method in the nonwoven industry is to inspect defective products at an early stage, rather than inspecting the fabric after the product is completed. Dr. Tan believes that this phenomenon is very correct, especially for some special products, such as the elastic threads at the leg bands of diapers. When an elastic thread splits from one bundle into three bundles, from the perspective of use, the product has quality problems. If production continues until the bundle of elastic thread is completely broken, it will take at least 30 minutes for the elastic thread to grow. Whenever this problem occurs, people will complain about why the error is not discovered and corrected early. Therefore, discovering the problem in advance and remedying it in advance is the best option.

Automation is the key

Mr. Guzzardo believes that full automation of online inspection systems will become the mainstream of development. He said: "Future development will make this system with an operating system touch screen, which is more convenient to use. The company's CCD camera equipment has fully automatic calibration and focusing functions, so that the camera can be accurately positioned along the entire fabric surface. This intelligent camera equipment has a built-in multi-directional drive motor, which can accurately position the internal CCD chip without manual operation by workers. In addition, the device can also perform post-calibration corrections on the online inspection system, such as annual ISO audits. It has an automatic calibration template inside and multiple camera heads are configured along the fiber web width to monitor the entire fabric surface. This calibration template can provide a reference for post-calibration and can diagnose and upgrade the entire system through the Internet.

Wide adaptability

The multi-function of the online inspection system provides a good foundation for its wide adaptability. Now the online inspection system with defect detection and monitoring functions has appeared. The fiber web control system (WMS) of Lemmer has this function. Mr. Guzzardo said: "WMS can work closely with production equipment to monitor various defects and provide operators with possible causes of defects for timely correction. "

Information collection function

In addition to quality inspection, the online inspection system can also monitor the overall production situation. Dr. Tan said: "When monitoring the product, a lot of information will be received. Although the purpose of installing this system is for quality inspection, the biggest contribution of the system to production is to collect information, such as statistics and trends on various factors affecting the occurrence of defects. Enterprises can use it to monitor sensitive parts of products or equipment and formulate maintenance plans accordingly." Dr. Tan added: "The emergence of defective products not only wastes production capacity, but also wastes production time. The online inspection system can make a statistical arrangement diagram of the various defect information collected. After analysis, the cause of the defect can be found, so as to improve and optimize the equipment parameters and ultimately reduce the defective rate. Therefore, from this perspective, purchasing this system has a very good return on investment relative to the overall equipment efficiency and the defective rate. "

More observation points

Another trend in the development of online inspection systems is to increase online monitoring points. When a problem is detected in any part of the product, the equipment can be stopped immediately. Dr. Tan pointed out that in the production process of diapers, elastic yarns, belts and all production components can be inspected. Companies will think that only inspecting one point has greatly improved product quality. If we monitor the entire production line, the company will benefit more.

Space is not a problem

. Some companies may question whether the online inspection system can be installed normally on existing equipment. Dr. Tan said: "This system can be installed and used with a slight modification of existing equipment." But the key issue is whether there is enough space. In this regard, AccuSentry is specially equipped with Sentry Line scanning cameras. One of its features is that it occupies a small area, can scan the passing products line by line, and record product information in detail. Its second feature is that it has a high resolution and is suitable for working under high-speed operation conditions.

Future investment hotspots

Where will the investment hotspots for online inspection systems be in the future? Mr. Heil believes that Asia will become a big market, followed by Europe and the United States, because the Asian market has increasingly higher quality requirements for sanitary materials and disposable medical products. "We have installed several sets of equipment in the Czech Republic, and these potential emerging markets have also put forward new requirements for product quality." Dr. Tan believes that "the largest market for online inspection systems is in the United States, followed by Europe and South and Central America, and finally Asia, because the proportion of diapers used in different countries is different. Developed countries use more. In the United States, there can be 10, 12 or even 30 production lines, but in Asia, there may be only three such production lines. Therefore, it is necessary to consider the difference in living standards between developed and developing countries."

Future Development Trends

What is the future development trend of online inspection systems? Dr. Tan believes that detecting the application of hot melt adhesives in the production process of diapers will become a major application area. He said: "In the past, no one was interested in detecting the elastic yarn and the application of hot melt adhesive. However, we found that if the hot melt adhesive did not drip exactly in the middle of the elastic yarn but deviated, the bonding strength would be affected. Therefore, the company's online detection system developed for diaper products has specially added camera equipment. One camera detects the elastic yarn and the glue application, and the other detects the acquisition layer, the front adhesive sticker and monitors the final product before packaging."

Another development trend of the online detection system is to add an early warning system to it. When there is a problem with the product, the equipment will automatically adjust, which provides great convenience for the operator.

In addition, the fiber web defect marking system will also become a hot spot for development. It can mark the defect position online for later removal. Ryeco is one of the companies that produces defect markers. The device can mark defects along the slitting line or the edge of the cloth. After the cloth is rolled, the marking line becomes a ring, which the operator can clearly identify. In addition, the marking point can be sensed by a sensor, and the machine can be shut down or the defect can be removed after the problem is sensed. The mark can be colored or colorless. The colorless mark can be colored under ultraviolet light. In addition, the length of the mark can be adjusted according to the situation.

The latest research result of Ryeco is to use a marker to mark the length of the fiber web. During production, the marker marks the fiber web in the form of binary code according to the preset length, and then interprets it into the accurate code number. Regardless of whether the non-woven fabric shrinks or stretches, the data obtained in this way is quite accurate. At the same time, the defect mark will form another file for storage. In this way, not only the defects are eliminated, but also the accurate code number of the non-woven fabric is recorded.

There is no doubt that the online detection system has gone through a considerable period of time before it is recognized by people. We will wait and see whether companies will buy and use it in the future. Mr. Guzzardo believes: "Factory sales staff will try their best to encourage companies to adopt online detection systems, because they can proudly tell customers that we will provide you with the best products." Mr. Heil believes that the competition in the non-woven fabric market is becoming more and more fierce. Only high-quality products with constant quality can win in the competition. (end)