A direct technique developed for measuring yarn torque is explored for the case of worsted wool yarns. The technique balances the torque in a yarn hank against a wire of known torsional rigidity. It is shown that this technique gives a reliable measure of the torque per strand independent of the size of the hank. The torque per strand was found to be linearly dependent on the applied external tension and a finite torque exists even at zero applied tension. This leads to the concept of resolving the torque into two components, (a) the torque due to the applied tension and (b) the intrinsic torque that exists in the untensioned yarn. The torque due to the applied tension does not depend on the yarn history but only on yarn geometric factors such as the yarn twist and linear density. By comparison the intrinsic torque depends on factors such as the level of yarn set as well as the twist and linear density. These components of torque due to tension and intrinsic torque are shown to be consistent with literature models and lead to estimates of yarn specific volume, yarn packing fraction and relative fiber relaxation moduli after steaming.
Wood products manufacturers require an efficient recovery of product from lumber to remain profitable. A company's ability to obtain the best yield in lumber cut-up operations (i.e., the rough mill) varies according to the raw material, product, processing equipment, processing environment, and knowledge and skill of the rough mill's employees. This book discusses several key principles that can help manufacturers understand and solve yield and production problems. Our publication was inspired by the 1981 publication "Rough Mill Operator's Guide" written by Edward K. Pepke and Michael J. Kroon. Computer-based technologies and new rough mill layouts and equipment are prevalent in today's rough mills, therefore, they are given considerable emphasis in this contemporary version of the Pepke-Kroon guide. The Authors ForewordWood product companies require an effi cient recovery of product from lumber to remain profi table. A company's ability to obtain the best yield in lumber cut-up operations (i.e., the rough mill) varies according to the raw material, product, processing equipment, processing environment, and knowledge and skill of the rough mill's employees. This book discusses several key principles that can help manufacturers contemplate and solve yield and production problems.In 1981, Edward K. Pepke and Michael J. Kroon published Rough Mill Operator's Guide, which has gone out of print. Since that time, the proliferation of computer technology has changed the way many rough mills operate. With advanced technology, there is a need to educate operators and managers. Without education and training, the technology is often ineffective, or worse, it is detrimental to the goal of improving rough mill performance. Clearly, there is a need for a contemporary version of the guide. However, many of the principles presented by Pepke and Kroon are still valid. Both the newer technologies and processing strategies and the long-established methods that still apply are discussed in this publication "Rough Mill Improvement Guide for Managers and Supervisors," and a future companion publication, "The Rough Mill Operator's Guide."Our initial goal was to update the "Operator's Guide." However, in preparing for rough mill improvement workshops, we realized there also was a lack of updated educational materials for managers and supervisors. This book is a compilation of material the authors generated to teach the workshops. The "Operator's Guide" will be published separately, and together with this publication, will provide a pair of useful educational resources for rough mill owners and operators.This book is divided into three sections. The fi rst section covers the importance of product yield as it relates to value, the impact of lumber grade and quality characteristics on yield, and the use of part grades and scheduling in the rough mill. The second section reviews both traditional and modern cut-up operations in the rough mill, focusing on the major processes of ripping and crosscutting lumber. The third section pre...
If given enough time, the moisture content of wood will reach an equilibrium with its surrounding environment. The temperature and relative humidity (RH) of the surrounding air will establish equilibrium moisture content (EMC) conditions, and the moisture content of the wood in that environment will approach a value determined by the RH. This article introduces an Excel spreadsheet that will calculate an estimate of the EMC based on any one of the following three pairs of data: RH and dry-bulb temperature, wet-bulb temperature and dry-bulb temperature, or dewpoint temperature and dry-bulb temperature.
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