Attrition Wear Research Articles

ガス通気研削加工法の開発

Grinding has drawbacks where the attrition wear of grain deteriorates the accuracy and the quality of workpiece under the condition of high speed and high pressure. So far it has been made clear that a chemical reaction in manufacturing is the cause of the attrition wear of grain. In other words, the chemical reaction control should make possible to manufacture with the sharp grain. This study pays attention to the chemical reaction caused by grinding into steel materials with aluminum oxide grain. The purpose of this study is to reduce a chemical reaction by removing oxygen that is caused by it in the grinding point and to propose a new grinding method that maintains sharp grain on wheel surface for long time. The method used is a kind of processing method where argon gas passes through a grinding wheel. According to this method, the chemical reaction should be caused between workpiece and grain controlled, and the workpiece surface should be manufactured as good one with the sharp grain. As a result obtained it was clear that the manufacture efficiency of the new processing method was improved better in comparison with a conventional method of it. This paper shows the valuation of grinding phenomena and effect of the new processing method.

In vitro evaluation of the marginal degradation of dental composites under simulated occlusal loading

Objectives: Our objective was to use an in vitro oral wear simulator to compare the susceptibility to marginal breakdown of different classes of dental composites. Methods: Two microfill composites (Silux Plus, 3M and Heliomolar, Vivadent), two minifills (Z100, 3M and Herculite, Kerr) and two midifills (Fulfil, Caulk and Clearfil, Kuraray) were placed in two increments (40 s cure) into class I cavities (5×3.5×2 mm 3 deep) cut into the facial enamel surfaces of bovine incisors treated with an adhesive (Scotchbond MP, 3M). The restored teeth were aged 1 day in water, mounted in the OHSU oral wear simulator, covered with a slurry of poppy seeds/PMMA beads and subjected to 50 K cycles of wear against an enamel stylus [J.R. Condon, J.L. Ferracane, Evaluation of composite wear with a new multi-mode oral wear simulator, Dent. Mater. 12 (1996) 218–226). The specimens ( n=10) were positioned to produce abrasive wear (load=20 N] across one margin and attrition wear (load=70 N) across the second margin. Volume loss of material (mm 3×1000) was estimated from 10 profilometric tracings perpendicular to the attrition margin, and then differentiated into composite and enamel degradation. Fracture toughness of the composites was measured in bending with the single-edge notch technique. Results were compared with ANOVA and Tukey's test at p<0.05. Results: Signficant wear of the composite was produced at the attrition margin. Enamel degradation at the margin paralleled the composite results. The microfills, and to a lesser extent the minifills, showed more marginal breakdown than the midifill composites. Marginal breakdown shows an excellent inverse correlation with fracture toughness for these composites. Significance: These results are in general agreement with clinical studies showing greater marginal degradation for microfill composites and suggest that the OHSU oral wear simulator may be a useful adjunct for the study of the marginal degradation of dental composites.

Tool Life and Surface Integrity When Machining Inconel 718 With PVD- and CVD-Coated Tools

Test results show that when machining nickel-based Inconel 718 alloy under the cutting conditions investigated, the multilayer PVD-coated carbide grades gave the best performance in terms of tool life. This was due to their higher hardness, toughness, abrasion resistance, good heat transmission behavior of the multiple (TiN/TiCN/TiN) coatings as well as thicker coating layer (relative to the single-coated grade). The smaller grain size and higher density of their substrates also enhance the strength and hardness of the multi-coated PVD tools, thus providing higher resistance to attrition wear. Machining with the single-PVD TiN-coated grade generally produced a better surface finish due to the polishing action of the honed cutting edge and the generation of a uniform finishing edge with coating bottom on the trailing edge during machining. The absence of any significant tearing on the machined surfaces after cutting with the PVD- and CVD-coated tools at the cutting conditions investigated can be attributed to the low friction coefficient of the coating materials. Excessive plastic deformation, however, occurred on the machined surfaces. Increased hardness of the machined surface layer (up to 0.6 mm deep) also occurred as a result of high pressure and temperature generated during the machining operation. This tends to increase the hardening rate of Inconel 718. Presented at the 52nd Annual Meeting in Kansas City, Missouri, May 18–22, 1997

Evaluation of a Self-Propelled Rotary Tool in the Machining of Aerospace Materials

The self-propelled rotary tool (SPRT) incorporating round-shaped cemented carbide cutting inserts exhibits superior wear resistance when machining titanium IMI 318 alloy under finishing conditions involving a low depth of cut of 0.25 mm. The rotary cutting action extends tool life by more than 60 times compared with the rhomboid and round inserts used in single-point turning. Excessive chipping was the dominant failure mode when machining IMI 318 with the SPRT due to thermal and mechanical shocks as well as vibration during machining. When machining nickel-based Inconel 718 alloy with the SPRT tipped with CVD-coated carbide inserts, improvement in tool life was not significant as a result of severe attrition and abrasion wear mechanisms. Component forces recorded with the SPRT were lower than those obtained during conventional single-point turning. An increase in feed rate only had a marginal adverse effect on the surface finish due to increased burnishing action between the tool and the workpiece during rotary cutting. Surface finish improved by reducing inclination angle which leads to a corresponding increase in the effective nose radius of the round cutting tool.

Factors effecting dental composite wear in vitro.

The wear of posterior dental composite restorations takes place through a complex combination of wear mechanisms. To isolate and measure the contribution of the different tribological phenomena in a controlled manner, an oral wear simulator was employed. Results previously reported demonstrated the simulator's ability to form strong correlations with clinical results for both abrasion and attrition wear. These results were generated with the device configured to mimic masticatory dynamics, specifically employing a human enamel stylus, physiologic load levels, and a foodlike slurry for a third body. In this study the slurry was replaced with water to examine the role of the third body in producing abrasion. The third body was found to reduce wear for most materials. In a separate test the enamel stylus tip was replaced with steatite, a semiporous ceramic with wear characteristics similar to enamel when opposing dental composite. The use of a steatite antagonist increased abrasion for the larger particle filled materials. The adhesive wear mechanism was found to be a contributing factor in dental composite wear.

Evaluation of composite wear with a new multi-mode oral wear simulator

Objectives. The goals of this study were to develop a machine which simultaneously produces wear through the two main oral wear mechanisms of abrasion and attrition by the action of an enamel antagonist and to compare the results obtained for dental composites using this machine to those obtained from clinical studies and other in vitro studies.Methods. The accuracy of this new wear tester was determined by examining 11 commercial composite filling materials and 1 amalgam. Specimens were subjected to three-body abrasion and attrition wear for 50,000 cycles. Profilometry was used to quantitate wear of the composites. Linear regression analysis was used to correlate the results to those obtained from clinical studies, as well as from other in vitro were testers. The area of enamel wear was also determined by image analysis. The SEM was used to evaluate the wear surfaces.Results. The lowest abrasion wear was recorded for the amalgam and the microfill and smaller-particle composites. Attrition wear was enhanced for the microfill composites and one small-particle hybrid. There was a strong correlation between the results obtained with the new wear tester and those obtained in the clinical trials cited in the literature. Wear of the enamel antagonist was the greatest for the composites with the largest particle sizes. The wear tester showed a reasonable correlation with other wear-producing machines.Significance. A new wear tester developed to evaluate and discriminate abrasion and attrition wear provided results similar to those reported in the literature for a variety of commercial composites. The new machine is capable of characterizing the behavior of a material in multiple wear modes simultaneously with one simple, realistic test.

Wear of Ti-Si-N coated ceramic cutting inserts

Multicomponent Ti-Si-N films with a very high hardness which were reported recently have a possible application for wear resistant coatings, especially for cutting inserts. This study performs the cutting test for a silicon nitride based ceramic insert coated with Ti-Si-N using a radio frequency-plasma enhanced chemical vapour deposition method with TiCI 4, SiH 4, and N 2, as feed stocks. The wear behaviour of coated specimens was evaluated under the selected cutting conditions. The influence of microstructure of the deposited film on wear properties was investigated. Evidence of reduction in crater wear was observed for the Ti-Si-N film deposited at a low SiH 4, to TiCI 4 flow ratio corresponding to the maximum hardness and finest microstructure obtained in this study. Attrition wear of the Ti-Si-N film was observed on the rake face whilst spalling appeared on the flank face. It is suggested that a “solution strengthening” of Si in the fine grain Ti-Si-N film deposited at a lower SiH 4 to TiCl 4 flow ratio promotes the hardness and reduces the friction at the chip-insert interface so that subsequent rake wear improvement can be obtained. However, the adhesion between film and substrate should be improved further.

高マンガン鋼の研削における砥石損耗について ステンレス鋼との比較

This paper describes the grinding characteristics on high manganese steels (Mn steels) which are austenite type. The grinding tests were performed in order to estimate these grindability by measuring the radial grinding wheel wear or the grinding force and observing the working surface of grinding wheels. The results were compared with those of austenitic stainless steel which has much similarities to high Mn steels in the material properties. The main conclusions are summarized as follows : (1) In grinding of high Mn steels by conventional or CBN grinding wheels, glazing of the cutting edges due to attrition wear is clearly recognized in the former wheel but not in the latter wheels. (2) The grinding wheel wears in the CBN grinding wheels are remarkably smaller than in the conventional wheels. (3) Because of the loading of grinding wheel, grinding wheel wear on austenitic stainless steel is remarkably greater than that on the high Mn steels.

Quantitative in vivo wear of human enamel.

In this study, the attrition wear, also called occlusal-contact-area wear, of human enamel was measured quantitatively with a computerized three-dimensional measuring technique over a period of four years. Tooth replicas from a clinical trial were used. A running-in wear period after restorative treatment, followed by steady-state wear, was suggested. The average steady-wear rate on occlusal contact areas was about 29 microns per year for molars and about 15 microns per year for premolars.

超精密切削用ダイヤモンド工具の長寿命化 無電解Ｎｉ‐Ｐの超精密切削加工に関する研究

This research is primarily aimed at the longer tool life of natural single crystal diamond in ultra precision for an electroless nickel phosphorus plating. The following results have been obtained : (1) The profile to increase of the tool life drawn from this work is that back and side rake angle were formed at -5 with nose radius 0.76mm and other tool dimensions has constant values. (2) The groove wear of natural single diamond tool is grown by asperity of tool feed mark on the ultra precision machined surface. (3) The typical tool wear of diamond shows an attrition wear without a chipping failure in the optimum tool profile.

The application of thin cemented carbide hardfacings to elements of card machines — a case history

The formation and behaviour of cemented carbide hardfacings a few micrometres thick deposited by the metallic surface fusion (MSF) process on parts of card machines are described. Rolls treated by the MSF process moving the processed cards are smoothed during service to produce flat featureless surfaces. In another application the overlay protects a steel spring from damage arising from fretting and sliding against a cemented carbide piercing punch. The deposit is worn out in a similar way, whilst the punches are slightly marred by “attrition wear”. In each application elements treated by the MSF process perform satisfactorily with a reduced failure rate.

A Model of Performance and Life of Diamond Drill Bits

The performance and life of diamond drill bits is presented with discussion of the analytical background, single point diamond studies, laboratory drilling performance tests, and field performance comparisons. The analytical basis of the diamond bit performance model is discussed with respect to the diamond-rock cutting mechanism, mathematical modeling of rock properties, factors affecting drilling efficiency, and the attrition wear model. Single point diamond tests are described, and the test results are used to determine a rock wear constant and to determine the velocity dependent exponent of the wear equation. Using the model, laboratory drilling test results are predicted for both petroleum and mining diamond drill bits. The location of wear and the bit life are predicted in both laboratory and field tests. The data presented shows the analytical model satisfactorily describes diamond bit performance and life over a wide range of drilling conditions and formations.

総型研削における砥石摩耗

In form grinding, wheel wear is given rise to public discussion in finished accuracy of workpiece. So, to make clear of the mechanism of wear phenomena at the vicinity of grinding wheel's sharpedge in V-groove grinding, the present paper describes the influence of grinding conditions upon wheel wear. Cylindrical high-speed steel (SKH-9) is traverse ground with the V-shape trued wheel. Groove-width and -edgeangle are little changed through the grinding process, but groove-depth is changed, caused by wheel wear. Then, decreased amount of groove-depth is selected as the parameter of wheel wear. The relation between the grinding conditions and wheel wear is investigated experimentally. The following results are clarified.(1) In V-groove grinding, wheel wear is consisted of initial wear and stationary wear process. The initial wear is caused by great fracture and releasing of abrasive grain, and stationary wear is caused by small fracture and attrition wear.(2) There is a close connection between a grain size and wheel edgeangle concerning with wheel wear. Wheel wear is minimized at the case of which suitable grain size is used at a certain wheel edgeangle.(3) The lower the workspeed and the smaller the cutting depth, the smaller the wheel wear.

The role of prow-deposits in the wear of abrasive grits by superficial fracture

Prevailing concepts of wear of abrasive grits assume a mechanism of slow attritious wear land formation or one of cutting edge destruction by chipping. A second attritious wear mechanism is reported, involving rapid land wear by superficial fracture. Transfer of prow-deposits from the workpiece to wear lands accompanies rapid land wear by fracture. Crack nucleation, in the region of tensile stress generated at asperity junctions, leads to crater generation. Fragment production yields larger individual wear particles than competing attrition processes. The resulting wear rate of an abrasive is 10 to 50 times larger than attrition wear rates generating polished surfaces. Differences in fracture wear rate, among the abrasives studied, result from the varied character of microstructural flaws in the grits. The spacing, size and shape of these flaws affect the fragment size and fracture frequency. Adherent prow-deposits of various sizes form on abrasive grits contacting metal workpieces during sliding, micromilling and grinding. Deposition on the wear lands depends on workpiece properties and environmental conditions. Strong adhesion and ductility of the workpiece favor formation of prow-deposits on grit asperities.

A scanning electron microscope study of attrition wear in tungsten carbide taper pin reamers

The wear of tungsten carbide taper pin reamers used to ream holes in a composite structure of aluminium alloy plate overlaying a plate of ultra-high strength steel was examined under the scanning electron microscope. The predominant process of wear was by attrition, which involved the mechanical detachment of individual or groups of tungsten carbide grains from the reamers by both the swarf and workpiece material. This process of attrition wear was initiated by the removal of the cobalt binder phase, resulting in the undermining and subsequent removal of tungsten carbide grains. A mechanism is described for explaining how the cobalt binder phase is initially removed, and the means by which tungsten carbide grains are then removed are discussed. Consequent on the removal of tungsten carbide grains some cobalt binder phase attached to these grains is also removed, and this subsequently becomes an important mechanism of cobalt binder phase removal.

Metallurgical appraisal of wear mechanisms and processes on high-speed-steel cutting tools

AbstractThe wear mechanisms and processes on high-speed-steel tools used to machine steels, cast iron and a nickel-based alloy under conditions encountered in practice have been investigated. Evidence is presented of five different wear processes: (a) superficial plastic deformation by shear at high temperature; (b) plastic deformation of the cutting edge; (c) wear based on diffusion; (d) attrition wear; (e) abrasion wear. All these wear processes operate under conditions of seizure between tool and work material, and frequently more than one process is taking place at the same time. The first three are dependent on temperature, and temperature distribution in the tool is of major importance. Cratering can be caused by (a) or by (c), the former being rapid and the latter relatively slow. Flank wear may be caused by diffusion (c) or by attrition (d). Evidence of abrasion (e) by Ti(C,N) particles in stabilized austenitic stainless steel is conclusive. In the range of materials tested, however, the contribut...