Battenfeld Groste Engineering Co., Ltd. (Groster, Massachusetts) has successfully developed an O-frame online film thickness detector. Using this thickness detector can quickly and accurately detect the thickness of the blown film and can directly exchange data with a computer control system at a higher level. The testing instrument can detect the thickness of a multilayer coextruded film without being influenced by the composition of the film and the temperature.
The O-frame scanning on-line thin film thickness gauge is installed between the main plastic film pulling mechanism of the blowing machine and the auxiliary plastic film pulling mechanism, and the thickness of the film is detected from both sides of the plastic film using beta rays. The sensor mounted on the right-angle bracket scans both sides of the plastic film. When the main stretching mechanism rotates by the first 90°, the sensor starts transmitting the detection data to the host computer system. Compared with the traditional on-line thickness measurement system of the old plastic film that only started to calculate the thickness of the film after the 360-degree rotation of about 20 minutes, and began to transmit the detection data, the detection speed of the O-frame thickness gauge is much faster. According to Carl Johnson, blow molding equipment engineer at Battenfeld-Groster Engineering, their thin-film thickness detector is not only more accurate than the thickness gauges commonly found on the market, but also has a faster detection speed. When the main plastic film stretching mechanism has not completed one rotation, about 6 minutes, the first test report can be obtained. The thickness gage uses an intelligent algorithm language for data processing. Based on its calculations, with the help of the Extrol process control software, the thickness variation, distribution state, and average film thickness of the plastic film can be obtained with accurate values. Based on these data, the control system of the blow-molding line can adjust the control parameters of the blow-molding production in a timely manner, combined with the use of gravimetric-analysis quantitative control technology and an automatic plastic film form conditioning system, which can keep the thickness tolerance of the plastic film very small In the range.
O-frame online thin film thickness measurement system can obtain test results faster than any other detection system on the market
In the production of multi-layer co-extruded plastic films, it is very important to accurately measure the thickness of the plastic film and keep the thickness of the plastic film unchanged. In many multi-layer co-extrusion blow molding lines, oscillating capacitance thickness measurement systems are used. The disadvantage of this detection system is that at higher temperatures or when materials with different dielectric constants are contained in multilayer films. The thickness of the multilayer film containing EVOH material or nylon material cannot be detected. In addition, gamma ray detection systems that replace this oscillating capacitive detection system are limited by the rotation limit. However, O-frame scanning plastic film thickness gauges are different from them, and their detection results are not limited by the temperature and composition of multi-layer co-extruded plastic films; they have better detection than γ-ray thickness detection methods. Signals, better time constants. Therefore, the O-frame scanning plastic film thickness gauge has high detection accuracy, good stability and long service life.
In general, O-frame scanning thickness gauges are installed for the full detection of blown film thickness. The beta ray sensor can be used in conjunction with other sensors, such as an infrared sensor or a nuclear sensor (Nuklear), to assist in the acquisition of more data and information such as the thickness of each layer of a multilayer coextruded film. Its non-contact thickness detection method enables O-frame thickness gauges to also be used for the detection of very sensitive, mutually-adhesive plastic films.
The price of beta-ray sensors for O-frame thickness gauges is about the same as that of conventional oscillating capacitive sensors. In addition to installing this thickness detection system in the latest plastic film blow-moulding line in Baden- feld, this type of inspection system can also be retrofitted on older blow-moulding lines equipped with Extrol process control software.
Source of information: pack.cn