Sharpness Of Blades Research Articles

Wear behavior and CO2 emissions analysis of drum mower blades during Alfalfa harvest

The productivity and efficiency of harvesting forage crops depend on the sharpness and quality of the mower blades. Therefore, studying blade wear during Alfalfa harvesting is crucial to sharpening and maintaining blades. This research aims to create mathematical models to predict the wear of mower blades and assess the wear rate of mower blades, fuel consumption, and CO2 emissions during the harvesting operation. Blade wear was measured by the weight loss method and examined by scanning electron microscopy (SEM) before and after the field experiment. The results showed that the weight of the mower blade decreased from 103.82 to 98.39 g after 37.5 working hours. Over time, fuel consumption and operating costs increased due to the wear of blades. Also, CO2 emissions were 17.7 kg h−1 at the beginning of the experiment and increased to 29.5 kg h−1 after 37.5 working hours. Due to wear in the blades, the increase in fuel consumption, cost, and CO2 emissions reached 67% at the end of the experiment. From the obtained mathematical equations, the sharp part of the blade has worn out after 34 ± 3 working hours.Graphical abstract

Safety and Health Concerns for the Users of a Playground, Built with Reused Rotor Blades from a Dismantled Wind Turbine

This paper analyses the user safety of a playground built out of reused blades from a dismantled wind turbine. Located in Rotterdam and designed by the Netherlands architecture firm Superuse Studios, the playground, called “Wikado”, represents an example of the circular economy applied to the built environment. With reused materials, Wikado represents a saving in resources and energy, when compared to a standard playground built with primary materials. Furthermore, the playground creates a unique design experience for its users, who can still recognise the original rotor blades following their transformation into slides, platforms, and tunnels. However, the safety of the playground could be questioned. This paper will analyse the materials and products used in the playground and their condition some years after opening. The analysis focuses on the risks of human health during the use of the playground. It considers the shape and the sharpness of the rotor blades, its components such as glass fibres and epoxy resin. As a result of the analysis, two risk analysis conceptual models help to assess the health concerns regarding the contact with the materials, and some yellow drops leaching from the rotor blades. This analysis informs the contemporary debate concerning the reuse of materials, and more generically, the circular economy applied to the built environment: whether it is recommended and safe to reuse materials for a different function from that which they were originally designed. This paper will explain that in the analysed case study, it can be safe to reuse materials for a different function, but only with the appropriate precautions.

Effect of coating thickness on the cutting sharpness and durability of Zr-based metallic glass thin film coated surgical blades

The cutting sharpness and durability of commercial blades without and with 200–500nm thicknesses of Zr-Cu-Al-Ag-Si and Zr-Cu-Ni-Al-Si metallic glass thin film (MGTF) coating were systematically characterized and evaluated. The amorphous states of all MGTF coatings were examined by grazing incident X-ray diffraction analysis. The observation of scanning electron microscopy reveals that MGTF coated blades own much smoother surface than the commercial one which indicates smaller friction force during cutting process. Results of sharpness test in the beginning reveal that all MGTF-coated blades possess smaller value of blade sharpness index (BSI) than the commercial one. The cutting durability of the MGTF-coated and commercial blades was evaluated by the variation of BSI values by 25cm cutting test. The commercial blade was blunted (BSI=0.49) after 20cm cutting path. Conversely, the 300nm-thick MGTF-coated blades present the smallest BSI value after 20cm cutting path in comparison with other thicknesses MGTF-coated blades and commercial blade. As a result, the cutting durability of surgical blade can be significant improved by Zr-based MGTF-coating, can keep the BSI value less than 0.45 after 20cm cutting test.

Analysis of the sharpness of blades for food cutting

Although the sharpness of a blade is responsible for cutting performance, there is no single and unambiguous literature definition of sharpness. The blade sharpness index (BSI) proposed by McCarthy et al. (Engineering Fracture Mechanics 74, 2205–2224, 2007) is a dimensionless number, derived from different cutting properties, to classify the sharpness of thin blades such as scalpels. In this study we transfer the BSI concept to blades with geometries typical in food cutting applications. After a series of cutting experiments at two velocities with blades that differed in wedge angle and abrasion state and by using three elastomers as substrate, we identified that the BSI can be regarded as a linear function of blade tip radius and force at cut initiation. The BSI was independent of cutting velocity, cutting substrate and wedge angle. Subsequently, cutting of foods with differently blunted blades revealed a specific impact on cutting performance, which depended on the food properties. Thus the BSI concept itself is helpful to classify the blade state, but it is less sufficient to evaluate the suitability of a knife with respect to a particular cutting application.

The Sharpness of Blades Used in Dermatologic Surgery

There are numerous blades available for use in dermatologic procedures. There are different advantages that are inhere.nt to different blades due to their shape and size. One aspect of the blade that is instrumental to its performance, but is not objectively defined, is sharpness. This information could be useful when choosing a blade for a particular procedure. This study aims to objectively define the sharpness of blades used in dermatologic surgery. The Sharpness Tester (Cutlery and Allied Trades Research Association, Sheffield, UK) was used to test the force in Newtons a blade requires to cut through a silicone cylinder. New blades were used to determine a standard for the sharpness of new blades. Blades used for surgery were tested to determine the sharpness after use. The sharpest blade is the double-edged razor blade (0.395 N) followed by the dermablade (0.46 N), plastic handled #15 (0.541 N), #15c (0.575 N), #10 (0.647 N), and the #15 blade (0.664 N). The sharpness of a blade is an important factor in its ability to perform a task and should be taken into account when choosing a particular blade for a particular procedure.

Commentary on the Sharpness of Blades Used in Dermatologic Surgery

Commentary on the Sharpness of Blades Used in Dermatologic Surgery

Dicing of hard and brittle materials with on-machine laser-dressed metal-bonded diamond blades

Abstract The ultra-precision dicing of hard and brittle materials causes high wear on the abrasive tool which results in the deterioration of blade cross section as well as the decrease of diamond grain exposure. Resin-bonded diamond blades are used due to their in-process self-sharpening capability. Nevertheless, the shape of the blade cross section generated by self-sharpening is random which leads to poor accuracy when precise grooves need to be produced. Metal-bonded diamond blades feature higher tool lifetime and shape accuracy compared to resin-bonded blades, but are not capable of performing self-sharpening. In this study, the laser dressing of metal-bonded diamond blades is investigated to enable their use in the ultra-precision dicing of hard and brittle materials by continuous laser dressing. We investigated laser dressing with and without the presence of cooling water. The sharpness (grain exposure) after dressing is measured by the cutting face surface roughness. The dicing performance is evaluated by observing the dicing results in terms of cutting depth consistency and by monitoring the spindle power during dicing. Dicing blades which have been laser dressed in an environment with coolant feature less grain exposure than dicing blades which have been laser dressed in dry condition. The dicing results show an improvement in the sharpness and durability of laser-dressed dicing blades in comparison with new or conventionally dressed blades. The ability to apply and perform laser dressing on a dicing machine in an environment with coolant shows the feasibility of laser technology for continuous dressing.

On the sharpness of straight edge blades in cutting soft solids: Part II – Analysis of blade geometry

In Part I of this paper a new metric, titled the “blade sharpness index” or “BSI”, for quantifying the sharpness of a straight edge blade when cutting soft solids was derived from first principles and verified experimentally by carrying out indentation type cutting tests with different blade types cutting different target or substrate materials. In this Part II companion paper, a finite element model is constructed to examine the effect of different blade variables including tip radius, wedge angle and blade profile on the BSI developed in Part I. The finite element model is constructed using ABAQUS implicit and experiments are performed to characterise the non-linear material behaviour observed in the elastomeric substrate. The model is validated against the experiments performed in Part I and a suitable failure criterion is determined by carrying out experiments on blades with different tip radii. The paper finds that a simple maximum stress criterion is a good indicator for predicting the onset of cutting. The validated model is then used to examine blade geometry. It is shown that finite element analysis is an important tool in helping to understand the mechanics of indentation. Furthermore, the study finds that all the blade geometric variables have an influence on the sharpness of a blade, with the BSI being most sensitive to tip radius. Increasing the tip radius and wedge angle decreases the sharpness of the blade.

On the sharpness of straight edge blades in cutting soft solids: Part I – indentation experiments

The sharpness of a blade is a key parameter in cutting soft solids, such as biological tissues, foodstuffs or elastomeric materials. It has a first order effect on the effort, and hence energy needed to cut, the quality of the cut surface and the life of the cutting instrument. To date, there is no standard definition, measurement or protocol to quantify blade sharpness. This paper derives a quantitative index of blade sharpness via indentation experiments in which elastomeric materials are cut using both sharp and blunt straight edge blades. It is found that the depth of blade indentation required to initiate a cut or crack in the target material is a function of the condition or sharpness of the blade’s cutting edge, and this property is used to formulate a so-called “blade sharpness index” (BSI). It is shown theoretically that this index is zero for an infinitely sharp blade and increases in a quadratic manner for increasing bluntness. For the blades tested herein, the sharpness index was found to vary between 0.2 for sharp blades and 0.5 for blunt blades, respectively. To examine the suitability of the index in other cutting configurations, experiments are performed using different blade types, target materials and cutting rates and it is found that the index is independent of the target material and cutting rate and thus pertains to the blade only. In the companion Part II to this paper a finite element model is developed to examine the effect of blade geometry on the sharpness index derived herein.

The toughness of secondary cell wall and woody tissue

The ‘across grain’ toughness of 51 woods has been determined on thin wet sections using scissors. The moisture content of sections and the varying sharpness of the scissor blades had little effect on the results. In thin sections (< 0.6 mm), toughness rose linearly with section thickness. The intercept toughness at zero thickness, estimated from regression analysis, was proportional to relative density, consistent with values reported for non–woody plant tissues. Extrapolation of the intercept toughness of these woods and other plant tissues/materials to a relative density of 1.0 predicted a toughness of 3.45kJ m −2 , which we identify with the intrinsic toughness of the cell wall. This quantity appears to predict published results from K IC tests on woods and is related to the propensity for crack deflection. The slope of the relationship between section thickness and toughness, describing the work of plastic buckling of cells, was not proportional to relative density, the lightest (balsa) and heaviest (lignum vitae) woods fracturing with less plastic work than predicted. The size of the plastic zone around the crack tip was estimated to be 0.5 mm in size. From this, the hypothetical overall toughness of a thick (> 1 mm) block of solid cell wall material was calculated as 39.35 kJ m −2 , due to both cell wall resistance (10 %) and the plastic buckling of cells (90 %). This value successfully predicts the toughness of most commercial woods (of relative densities between 0.2 and 0.8) from ‘work area’ tests in tension and bending. Though density was the most important factor, both fibre width/fibre length (in hardwoods) and lignin/cellulose ratios were negatively correlated with the work of plastic buckling, after correcting for density. At low densities the work of plastic buckling in the longitudinal radial (LR) direction exceeded that in longitudinal tangential (LT), but the reverse was true for relative densities above 0.25. This could be attributed to the direction of rays. Density for density, the toughness of temperate hardwoods tested was about 20 % lower than that of tropical hardwoods. This is probably due to the much greater number of vessels in temperate hardwoods. Vessels appear either not to display buckling behaviour during fracture at all or to collapse cheaply. These general results have applications to other plant tissues.

Laser Evaluation of Cutting Angle and Surface Finish in Scalpel Blades

Abstract A simple inexpensive technique to assess the sharpness of scalpel blades by laser diffraction is presented. Two of the factors that contribute to edge sharpness such as cutting angle and grinding finish of the side faces are evaluated by optical transformation techniques. One could therefore arrive at an optimum set of values of the above two factors which would in turn lead to the production of sharper blades.

刃物の切れ味の研究（第5報）剃刀における組織と切れ味の関係について

刃物の切れ味の研究（第5報）剃刀における組織と切れ味の関係について

A ``MAGNETIC SHARPENER''

The claim that the mere placing of a double-edged safety razor blade upon the poles of a specially designed permanent magnet has a sharpening action has been investigated by studying the characteristics of the device and by testing the sharpness of blades so treated in comparison with untreated and with mechanically stropped blades. No definite ``magnetic sharpening'' was observed to occur in these tests.