| 以下是我们历年发表文章一览表。请选择。这些文章是Lorentzen & Wettre共享知识资源的范例。 |
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Recent work lead by Roman Popil at the Institute of Paper Science and Technology at GT (IPST) has investigated the influence of linerboard bending stiffness and interflute buckling on ECT performance.
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Using measuring statistics for fibre properties, the pulp's properties can now be measured in ways that are more practical than before. Among other things it is the length, width, deformation and coarseness of fibres and fines that are measured. In addition, the measurement technology is automated and enables, via a special sampling system, totally automatic and frequent analysis of pulp quality throughout the manufacturing process.
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A glossy paper will reflect light and reproduce a high quality printed image with greater contrast, but it will also reflect light into the observer's eye making the reading difficult. So how do you make sure that the paper has the right gloss for the right purpose?
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The importance of regular calibration of reflectometers cannot be overstated. It is an essential prerequisite for accurate and reproducible measurements of the optical properties of pulp and paper products. FPInnovations produces optical reference standards in an Elrepho master instrument from Lorentzen & Wettre.
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L&W Moisture Tester is a high precision offline bench-top instrument for measuring the moisture content. It can be used for production control and verification of online systems and for back-up of online moisture sensors. It is time saving and easy to use. In just a few seconds the measurement results are displayed, which is very fast compared to the gravimetric method. |
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There is a close relationship between Tensile Stiffness Orientation (TSO), also called the polar angle, and the fibre orientation. However, it is TSO that relates to the different application problems that occur at the end users.
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During April 2010, we have been running a demonstration bus tour in France – called Paper Machine Optimization Program bus (PMOP bus). The demo bus is to give an idea of what a 4 days onsite PMOP visit involves, showing the customer that their paper machine is reactive, and how to optimize the paper machine settings with the help of our instruments.
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A combination of online and inline measurements makes it possible for pulp and paper producers to meet the increasing demands to produce uniform high quality products at minimal cost, something that requires better monitoring of the process. The sooner any deviations from the normal are detected the better the result for the end product.
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Producing the right paper quality at the right cost is essential, but not easy. It is especially difficult with machines that are now producing considerably more than they ever used to. There is a never ending quest for increased production, better paper quality and lower costs. A lack of success can mean large losses for both the customer and the producer. A very common problem is big variations in fibre orientation leading to twist warp, baggy edges and web breaks.
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For Lorentzen & Wettre it is important that all our customers world wide, regardless of their location, receive the same level of high quality service and support. We have our own local service offices in Canada, China, England, Finland, France, Germany, Italy, Japan, Singapore, Sweden and USA. In these countries and their respective territories we have naturally high knowledge about the market and its needs. In the other markets where we operate through a net of Agents/Distributors we need to secure the quality level in a somewhat different way.
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L&W Felt Permeability Meter is a new instrument, which provides you with the best possible knowledge about the condition of the press felts. This enables you to optimize dewatering and reduce costs significantly.
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Instruments that are exactly the same should provide the same results. This is a reasonable requirement so that the characteristic of a product may be compared, in order to classify products that have been manufactured in different places. This in turn requires knowledge of what is a "true" reading. Thereafter it is possible, with the aid of a standard calibrated measuring device, to obtain good reproducibility.
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L&W Autoline 400 is the most advanced automatic paper testing system on the market. It is a complete paper quality measuring system that performs everything you need, from sample preparation to the final reel report with very little operator involvement. L&W Autoline tests more paper than any other automated testing system in the world.
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Analytical chemistry offers various possibilities for identifying the constituents of paper during production. This is a tool for assisting papermakers in product development and quality con-trol. Conventional chemical analyses, however, cannot be used to tackle acute production problems because they take too much time from sample preparation to the availability of re-sults. New methods need to be found.
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In order to optimise dewatering and to avoid extra costs, measures must be taken in the press section, which is something that pays for itself quickly. For this to be possible, the covering in the press section must be measured and analysed. The typical and most important measuring parameters here are the moisture and permeability profiles of the press fabric. With new technology, it is now possible to visualise the variations in moisture and permeability in the form of detailed 2D and 3D graphics, with which any problems in the press fabric can be found. Other characteristics that are measured and displayed at the same time are frequency analysis and fabric length.
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According to our customers, Lorentzen & Wettres products and services are of high quality. This leads to customers trusting our products and concentrating on profiting from the measured results. This high quality that we have does not come naturally, but requires both expertise and care at many stages.
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Reducing measurement uncertainty or test variability is at the heart of what L&W Autoline 400 provides the modern paper mill. In today's competitive market place, costs have been cut to the bone. The largest potential for cost savings now comes from incremental changes in the paper making process. To achieve these cost savings an accurate measurement of the process is required.
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The roughness of a certain surface is often of importance for the user and thus specified. When this is the case there is a good chance that the method used to describe the roughness is a method according to Bekk, Bendtsen, or Sheffield, a PPS method (PPS or PPS-Flex) or the Stylus Roughness method.
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The TSO angle indicates the direction of the maximum dimensional expansion of the sheet during moisture change. This is actually at 90 degrees from the TSO angle. The printer can easily handle a sheet with a TSO angle close to zero degree and the maximum elasticity aligned with machine direction.
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An evaluation of dynamic properties such as wetting and absorption in your paper and board products can usually reveal why a printing, coating or gluing process does not perform as expected. This section of surface science explains some of the mysterious secrets related to missing dots, ghost images, dot gain, mottled print and more.
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TSIMD is an important property for all printing grades as the paper during converting is stressed in the machine direction.
Misregister in four colour printing is caused by a re-wetted paper which will expand more in the direction that has less elasticity, i.e. least TSI, and that is always in the cross direction. A roll change to a roll with another TSI level will need a longer tuning period and consequently lead to more rejects.
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Can we rely on measurement results? How accurate are the measurements? These are some of the questions often raised about both online and offline measurements. For offline measurement, there are a number of guidelines in the various testing standards, which specify measurement apparatus and measurement procedures. At Lorentzen & Wettre, we have made it a matter of principle not only to comply with testing standards, but also to exceed them.
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The actual amount of the paper elasticity is presented by the tensile stiffness index (TSI) and is a basic parameter in papermaking. The distribution of TSI in the paper web is dependent upon the end-use of the product produced and the tuning capacity of the paper machine. For instance, newsprint and sack paper have completely different demands.
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