Richard L. Lemaster

Fixed abrasive diamond wire machining—part I: process monitoring and wire tension force

The process monitoring and mechanics of fixed abrasive diamond wire saw machining are investigated in this study. New techniques to affix diamond particles to a steel wire core have advanced to make this process feasible for the machining of ceramics, wood, and foam materials. Developments in fixed abrasive diamond wire machining are first reviewed. Advantages of using fixed abrasive diamond wire machining are then introduced. The process monitoring and signal processing techniques for measuring the cutting forces, wire speed, down feed rate, and wire bow angle in diamond wire saw machining are developed. The application of a capacitance sensor to measure the wire bow and a procedure to convert the wire bow to vertical cutting force in a rocking motion wire saw machine are developed. The tension force of the wire during cutting is also derived and discussed.

Fixed abrasive diamond wire machining—part II: experiment design and results

Abstract Experimental results from fixed abrasive diamond wire machining of wood and foam ceramics are presented. Three types of wood—pine, oak, and fir, and three types of foam ceramic—silicon carbide, zirconia, and zirconia toughened alumina, are tested. The research investigates the life of diamond wire and effects of process parameters on the cutting forces, force ratio, and surface roughness. A scanning electron microscope is used to study the worn diamond wire, machined surfaces, and debris. The diamond wire saw is demonstrated to be very effective in machining foam ceramics. The wire life for cutting wood at slow feed rates is low. The short tool life for dry cutting of wood indicates that more research in new fixed abrasive diamond wire and wire saw machining technologies is necessary.

Process Monitoring Evaluation and Implementation for the Wood Abrasive Machining Process

Wood processing industries have continuously developed and improved technologies and processes to transform wood to obtain better final product quality and thus increase profits. Abrasive machining is one of the most important of these processes and therefore merits special attention and study. The objective of this work was to evaluate and demonstrate a process monitoring system for use in the abrasive machining of wood and wood based products. The system developed increases the life of the belt by detecting (using process monitoring sensors) and removing (by cleaning) the abrasive loading during the machining process. This study focused on abrasive belt machining processes and included substantial background work, which provided a solid base for understanding the behavior of the abrasive, and the different ways that the abrasive machining process can be monitored. In addition, the background research showed that abrasive belts can effectively be cleaned by the appropriate cleaning technique. The process monitoring system developed included acoustic emission sensors which tended to be sensitive to belt wear, as well as platen vibration, but not loading, and optical sensors which were sensitive to abrasive loading.

Tool Wear When Cutting Wood Fiber–Plastic Composite Materials

Wood fiber–plastic composite materials, a relatively new material, are finding applications mainly in the US residential and commercial construction markets. Thus, the volume of material produced and used is steadily increasing while the range of applications keeps expanding. So far, attention has been paid mainly to primary production processes of wood fiber–plastic materials, while secondary manufacturing processes have attracted less attention. However, with the broadening applications of such materials and their increasing use, secondary manufacturing processes for wood fiber–plastic materials are gaining importance. This study investigated the performance of five commercially available wood fiber–plastic composite materials and solid wood (eastern white pine) with respect to tool wear and resulting material surface roughness. Large performance differences between different wood fiber–plastic composite materials and between solid wood and wood fiber–plastic composite materials with respect to tool wea...

Evaluation of the energy balance for the production of briquettes from biomass.

Wood densification consists of processing wood by-products such as sawdust and chips into uniformly sized particles that are compressed into wood-based fuel products (pellets and briquettes). The main advantages are related to handling improvements of residual wood and energy generation opportunities when compared with wood chips from other forms of wood residues. The objective of this study was to evaluate the energy balance for production of briquettes from wood residues. This research involved determining the energy consumption required to perform the main manufacturing operations to produce wood briquettes: size reduction, drying, and densification of wood. The amount of energy that can be obtained from the combustion of wood briquettes was also measured. The effects of several factors such as wood species, material dimensions, and raw material moisture content on the energy requirements for manufacturing briquettes were studied. Four densification strategies were evaluated from an energy consumption ...

An investigation of the use of active infrared thermography to detect localized surface anomalies in lumber

Efforts are being pursued to improve and automate processes for grading, trimming, and cutting up softwood and hardwood lumber by automated, non-contact, non-labor-intensive methods. Existing technology for detecting defects in lumber has focused heavily on the use of charged coupled device scanners or cameras, but these devices are limited by inherent color differences of the material. Thermography has been proven to detect knots in lumber, but the use of active thermography has not been investigated in terms of detecting dents, holes, and gouges. This research focused on four heating techniques, i.e. defect side heating, back side heating, forced air heating, and pulsed thermography, to detect dents, holes, gouges, and knots. All four heating methods proved successful for at least two defect types. Implementation of these techniques in an industrial setting will depend on the requirements of the manufacturer and the physical limitations of the industrial line.

The use of acousto-ultrasonics to determine the quality of the brazing of carbide-tipped cutting tools

Abstract The goal of this research was to improve the reliability of brazed cutting tools and saw blades through the development of non-destructive evaluation techniques (NDEs) to ensure tool quality. The objective was to determine the sensitivity of an acousto-ultrasonic-based technique to varying braze conditions of carbide teeth. This preliminary research developed a quick NDE technique to test not only the quality of brazed joints during manufacture, but also to inspect the carbide for micro-cracks that may have been introduced by stresses during the brazing process. The test system used an electric spark against the sawblade teeth or plate to initiate a stress wave in the sawblade which was received by an acoustic emission sensor coupled to the sawblade with a fluid couplant. A reading was taken through the saw tip and adjacent to the saw tip on the saw shoulder. An energy reading of each of the signals was obtained. A ratio was then taken of the two energy values. This gave a “self-calibrating” feature taking into account various slots and holes in the blade which could affect the waveform. This system was able to detect braze joints that had too much or too little heat applied during the brazing process, as well as no flux or twisted teeth. Future work will be conducted on saws of various sizes and designs as well as different grades of carbide tips.

Improving Housing Conditions from the Crawl Space up with a Monitoring and Control System

Abstract Housing issues constitute a growing research area due to changes of building features and the use of technologically advanced material and devices in homes. Thus, housing-related research needs to be conducted in order to improve the living conditions in houses. This research explored the interactions of temperature and relative humidity in three contiguous housing environments (indoor, outdoor, and crawl spaces) to analyze and evaluate common housing issues. To achieve this goal, the design, development, and verification of a Housing Elements Research Chamber (HERC) by means of a monitoring and control system was tested. The monitoring and control system used sensors to continuously monitor temperature and relative humidity under different conditions. This study used the HERC to simulate housing conditions within the crawl space in order to determine the appropriateness of using different moisture-removal methods to improve housing conditions. Results showed that the use of temperature and relative humidity sensors as part of a monitoring and control system provided adequate tools to study the climate interactions between different environments in a house. Furthermore, findings indicated that the use of multiple moisture-removal methods is a desired solution to improve housing conditions.

Determining the Economics of New Moulder Configurations

The moulder is one of the most widely used machines in the wood industry. Its function is to cut stock with rough dimensions to a finished width, thickness, and cross-sectional shape in one pass, making it cost effective to produce mouldings, floors, window and furniture components, etc. Today’s moulders are fast, safe, flexible, versatile, precise, and productive. Many different configurations can be selected when specifying the purchase of a moulder. The Moulder Economic Calculator (MEC) was developed to determine the economic impact of choosing different moulder configurations. The calculator uses input data on machine price and purchase method, machine configuration, production parameters, and production costs. The MEC program gives three types of outputs: surface quality, productivity, and costs. The MEC program is a flexible tool that allows the user to estimate the cost of machining one linear foot of wood. Some capabilities of the MEC program include determining the effect of machine price on mach...