Wear mechanisms of WC-Co drill bit inserts against alumina counterface under dry friction: Part 2 — Graded WC-Co inserts

The tribological behaviour of innovative graded cemented carbide inserts were studied by using a rotary tribometer and abrasive alumina counterfaces. This work completes the study made on commercial inserts with homogeneous cobalt content. Inserts with three types of graduation processes were considered: inserts with borides WCoB phases, imbibed inserts and inserts combining both processes (i.e. inserts with reactive imbibition). Physicochemical and mechanical measurements show that the WCoB phases increase the hardness towards the active surface and the imbibition increases the insert core fracture toughness. The wear tests indicate that the boride phases lower the friction coefficient. In addition, as for the commercial inserts, cemented carbide volumes with higher cobalt content also reduce the friction coefficient. Concerning the wear results, the boride phases improve the abrasion resistance. By applying a third body approach, the WCoB phases limit the introduction of cobalt binder in the source flow, the cohesion of alumina particles in the internal flow and the formation of an abrasive paste in the contact. The imbibition process, where the cobalt migration is controlled, does not affect the wear resistance by avoiding a cobalt enrichment of the cemented carbide near the active surface

Advanced ceramic material for high temperature turbine tip seals

Forty-one material systems were evaluated for potential use in turbine blade tip seal applications at 1370 C. Both ceramic blade tip inserts and abradable ceramic tip shoes were tested. Hot gas erosion, impact resistance, thermal stability, and dynamic rub performance were the criteria used in rating the various materials. Silicon carbide and silicon nitride were used, both as blade tips and abradables. The blade tip inserts were fabricated by hot pressing while low density and honeycomb abradables were sintered or reaction bonded

Hard Metal Production by ERS: Processing Parameter Roles in Final Properties

Cemented carbide is a hard composite material, used widely in a variety of industries. The value of the global tungsten carbide market is expected to grow by 4.4% (compound annual growth rate) from 2017 to 2022. One of the main markets is in metal cutting and wear parts, where small pieces (or inserts), a few grams in weight, are used. Field-assisted sintering technique (FAST) technologies allow for the production of small blanks in a single step from powder, which are near final dimensions. Production cycles are very short. In this paper, one of the FAST processes, the ERS technology, is applied to obtain WC10Co parts. A review of the process variable effects on the final properties of the parts is accomplished. Final properties of a range of conventionally produced inserts are obtained, using 100 MPa compacting pressure, 80 MA/m2 of current density, and processing times of around 800 ms.This research was funded by EU, grant number FoF.NMP.2013-10 608729 (7th Framework Programme) EFFIPRO

Experimental investigation on flank wear and tool life, cost analysis and mathematical model in turning hardened steel using coated carbide inserts

Turning hardened component with PCBN and ceramic inserts have been extensively used recently and replaces traditional grinding operation. The use of inexpensive multilayer coated carbide insert in hard turning is lacking and hence there is a need to investigate the potential and applicability of such tools in turning hardened steels. An attempt has been made in this paper to have a study on turning hardened AISI 4340 steel (47 ± 1 HRC) using coated carbide inserts (TiN/TiCN/Al2O3/ZrCN) under dry environment. The aim is to assess the tool life of inserts and evolution of flank wear with successive machining time. From experimental investigations, the gradual growth of flank wear for multilayer coated insert indicates steady machining without any premature tool failure by chipping or fracturing. Abrasion is found to be the dominant wear mechanisms in hard turning. Tool life of multilayer coated carbide inserts has been found to be 31 minute and machining cost per part is Rs.3.64 only under parametric conditions chosen i.e. v = 90 m/min, f = 0.05 mm/rev and d = 0.5 mm. The mathematical model shows high determination coefficient, R2 (99%) and fits the actual data well. The predicted flank wear has been found to lie very close to the experimental value at 95% confidence level. This shows the potential and effectiveness of multilayer coated carbide insert used in hard turning applications

Application of CrAlN coatings on carbide substrates in routing of MDF

This study deals with the development of Chromium Aluminium Nitride (CrAlN) hard coatings (by varying the nitrogen content in the plasma, the target bias voltage, the working pressure and the deposition time) and their characterization by physical and mechanical techniques (XRD, nanoindentation, Young’s modulus, stress, scratch-test, composition, etc.) in order to determine the optimal deposition conditions to apply the coatings to carbide substrates. Moreover, in order to improve the adhesion of the same optimal hard coatings and as it was efficient with Diamond Like Carbon (DLC) coatings, we tried to modify the carbide inserts by chemical attacks with Murakami’s agent before machining. The coated tools (with and without Murakami’s attack) were then tested in routing of Medium Density Fibreboard (MDF). A comparison of the abrasion and shock resistance of the conventional tools with the treated ones, was made. The efficiency of Murakami’s agent was also studied. It was obvious that the coated carbide tools had greater tool life than the untreated ones. Besides, Murakami’s attack was not optimized or not a solution to improve the adhesion of nitride coatings on carbide inserts.Regional Council of Burgundy ISOROY Franc

On Measurement and Interpretation of Toughness Behaviour of Carbide Tools

The actual significance of any definition of toughness behaviour of carbide tools depends on the existence of an interrelation between the quality as defined and the occurrence of chipping and premature failure in cutting. While at present there is no adequate analysis available and the existing classifications do not even provide a qualitative indication for tool choice, one first has to evaluate the behaviour of cemented carbides for simplified load conditions. Where fracture and chipping is a mechanical phenomenon, in the case of tools assisted or even dominated by thermo-mechanical effects, a logical first step for the evaluation of carbide grades would seem to determine the property profile of carbide tools in terms of toughness and resistance to thermal shock, but in such a way that a qualitative interpretation of the cutting conditions can be taken into account. This article deals with a tentative approach for the evaluation of toughness performance of throw-away carbide inserts with the aid of a four point bending test and the diagonal compression test, the latter also being used for measuring the relative resistance to thermal shock

The influence of surface treatment of PVD coating on its quality and wear resistant

The article deals with a determination of the influence of a cutting edge preparation on the quality and wear resistance of coated cutting tools. Cutting inserts made from a sintered carbide with a deposited layer of PVD coating were selected for measurement. Non-homogeneity caused by the creation of droplets arises in the application layer during the process of applying the coating by the PVD method. These droplets make the surface roughness of the PVD coating worse, increase the friction and thereby the thermal load of the cutting tool as well. Also, the droplets could be the cause of the creation and propagation of droplets in the coating and they can cause quick cutting tool wear during machining. Cutting edge preparations were suggested for the improvement of the surface integrity of deposited layers of PVD coating, namely the technology of drag finishing and abrasive jet machining. After their application, the areal surface roughness was measured on the surface of coated cutting inserts, the occurrence of droplets was tracked and the surface structure was explored. A tool-life test of cutting inserts was carried out for verification of the influence of surface treatment on the wear resistance of cutting inserts during the milling process. The cutting inserts with a layer of PVD coatings termed as samples A, B, and C were used for the tool-life test. The first sample, A, represented the coating before the application of cutting edge preparations and samples B and C were after the application of the cutting edge preparation. A carbon steel termed C45 was used for the milling process and cutting conditions were suggested. The visual control of surface of cutting inserts, intensity of wear and occurrence of thermal cracks in deposited PVD layers were the criterion for the evaluation of the individual tests.Web of Science97art. no. 43

Ultrasonic Polishing

The ultrasonic polishing process makes use of the high-frequency (ultrasonic) vibrations of an abradable tool which automatically conforms to the work piece and an abrasive slurry to finish surfaces and edges on complex, highly detailed, close tolerance cavities in materials from beryllium copper to carbide. Applications range from critical deburring of guidance system components to removing EDM recast layers from aircraft engine components to polishing molds for forming carbide cutting tool inserts or injection molding plastics. A variety of materials including tool steels, carbides, and even ceramics can be successfully processed. Since the abradable tool automatically conforms to the work piece geometry, the ultrasonic finishing method described offers a number of important benefits in finishing components with complex geometries

Rain water harvesting management system in Zoo Negara, Selangor

Water is a key requirement either to human, animal or plant. Rainwater Harvesting System (RWH) is a technology used to collect and store rainwater from the roof for reuse. The objective of this study was to investigate the factors that influence the effectiveness of the application of RWH and RWH in terms of the quantity of water collected. The scope of the study is to carried out at the National Zoo, Hulu Kelang, Selangor. This study focuses only on the second phase of the application of RWH at the National Zoo. Method of methodology used was through observation and interview. The results shown, factors that affect the application of RWH at the National Zoo is water demand, improve the quality of lake water and rainfall. For the second objective, based on the analysis, the rainwater is channelled to assist in improve the lake water. This is because, as a result of water quality tests conducted NAHRIM every month found that the lake water quality status has changed from Class IV (contaminated) to Class III (moderately polluted). Rainwater is also able to accommodate the needs of the lake water. Respondents also agreed that the application of RWH at the National Zoo for the second phase is effective. The results of this study, it can be beneficial for the government to encourage the installation of Zoo SPAH in other states

Advanced ceramic material for high temperature turbine tip seals

Ceramic material systems are being considered for potential use as turbine blade tip gas path seals at temperatures up to 1370 1/4 C. Silicon carbide and silicon nitride structures were selected for study since an initial analysis of the problem gave these materials the greatest potential for development into a successful materials system. Segments of silicon nitride and silicon carbide materials over a range of densities, processed by various methods, a honeycomb structure of silicon nitride and ceramic blade tip inserts fabricated from both materials by hot pressing were tested singly and in combination. The evaluations included wear under simulated engine blade tip rub conditions, thermal stability, impact resistance, machinability, hot gas erosion and feasibility of fabrication into engine components. The silicon nitride honeycomb and low-density silicon carbide using a selected grain size distribution gave the most promising results as rub-tolerant shroud liners. Ceramic blade tip inserts made from hot-pressed silicon nitride gave excellent test results. Their behavior closely simulated metal tips. Wear was similar to that of metals but reduced by a factor of six