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Thin Films for Cutting Tools
Published in Fredrick Madaraka Mwema, Tien-Chien Jen, Lin Zhu, Thin Film Coatings, 2022
Fredrick Madaraka Mwema, Tien-Chien Jen, Lin Zhu
Other aero-engine materials such as hardened steels and structural ceramic encounter a serious challenge during machining because of their properties such as hardness, strength, wear, and chemical resistance. Therefore, these materials are hard to machine and pose a challenge during manufacturing components because of the high stresses and temperatures developed at the tool–work interface during machining. These materials exhibit poor heat conduction; this leads to the accumulation of high temperatures on the surface of the parts being machined. The high temperatures accelerate the tool wear, consequently lowering the tool life and increasing the cost of the machining process. In general, these materials (for aerospace engine applications) have the following characteristics [8]: They have a low thermal conductivity.They undergo rapid work hardening during machining due to their austenitic matrix.They retain their strength even at elevated temperatures.They tend to cause build-up edges (BUE) and stick (weld) onto the surfaces of the cutting tools.They react with cutting tools under the atmospheric temperature and humidity.
Abrasive Jet Machining
Published in Rupinder Singh, J. Paulo Davim, Non-Conventional Hybrid Machining Processes, 2020
Kamaljit Singh Boparai, Jasgurpreet Singh Chohan
Since the advent of hybrid composites and hard-to-cut materials, a major shift has been experienced in technology adopted for machining of these high-strength materials. Moreover, there is a need of hour to continuously improve manufacturing processes to meet the demand of highly precise and miniature components for biomedical, optical, and micro-electromechanical systems. The challenge faced by manufacturing industry is to fabricate intricate parts at minimum cost with high surface integrity (Nguyen and Wang, 2019). There are certain conditions where excessive tool wear is a major disadvantage while machining extremely hard materials. In many cases, tool wear and excessive heat generation increase cutting forces inducing defects and seriously deteriorate the surface integrity of parts (El-Hofy et al., 2018).
General introduction
Published in Adedeji B. Badiru, Handbook of Industrial and Systems Engineering, 2013
Near-net-shape manufacturing is common in many applications, such as in the production of coins like dimes and nickels. The idea is to complete much of the processing in a single step without requiring significant finishing. Injection molding, used for the fabrication of plastics; investment and impression-die casting; and precision forging are all considered to be near-net fabrication processes. Machining, once considered wasteful and expensive, has once again proven its immense worth in producing very tight tolerances and finishes. Powder processes are currently very important in the fabrication of very hard materials. Powder metallurgy is restricted to metals and involves a sequential application of compaction and sintering or isostatic compaction to shape objects. Other state-of-the-art technologies in rapid prototyping include stereolithography and 3D printing.
Surface hardenability studies of the die steel machined by WEDM
Published in Materials and Manufacturing Processes, 2018
Eswara Krishna Mussada, Choo Chee Hua, Ayyagari Kameswari Prasada Rao
Hard and brittle materials, such as hardened steels, ceramics, super alloys, fiber-reinforced composites, soft elastomers, tissues, and metal matrix ceramic composites, are most demanded functional materials in several industries owing to their exceptional mechanical, thermal, corrosion resistant properties, etc. Unfortunately, conventional machining methods can no longer be employed for such materials, efficiently; hence, they are normally categorized as difficult-to-machine materials. There are several processes that machine materials by evaporation, melting, electrical energy, chemical reaction, and/or hydraulic power conjointly referred to as the unconventional (or nontraditional) machining process. These machining techniques are unaffected by the brittleness and hardness or the softness of the workpiece materials. Some of these processes are useful in near-net-shape machining of the difficult-to-machine materials to the final component, thus discovering applications in automotive, electronics, aerospace, die, and mold industries. Electrical discharge machining (EDM) is one of the nonconventional manufacturing processes that erodes materials with the help of electric discharge pulses generated between the workpiece and electrode. These discharge pulses generate a plasma channel, which in turn rises the temperature up to 20,000°C at the electrode-workpiece gap in a short span [1]. This temperature rise is enough to melt and evaporate materials irrespective of their hardness and melting points.
Experimental investigation and parametric optimization in abrasive jet machining on nickel 233 alloy using WASPAS and MOORA
Published in Cogent Engineering, 2018
S. Rajendra Prasad, K. Ravindranath, M. L. S. Devakumar
In the present manufacturing scenario, there is a large variety of materials like Al, Mg, steel and so on and still increasing day-by-day. To process the component with required properties, it is especially difficult with conventional machining processes. In general, it may be extremely difficult to process the hard materials with conventional machining when compared to soft materials, and also the machining of hard materials is time consuming, high processing cost, less accurate, more chance of tool failure, poor surface finish etc. All these factors lead to development of new machine and techniques to achieve required properties with ease of operations, less time consumption, good surface finish, increasing material removing rate, increased tool life, less power consumption, low cost of production as well as products involving complex designs. Most of the unconventional machining solutions are available to process complex designs, with different material characteristics (physical and mechanical) to suit required applications. They are ultrasonic machining (USM), electrical discharge machining (EDM), electrochemical machining (ECM), laser beam machining (LBM), plasma arc machining (PAM), water jet machining (WJM), abrasive water jet machining (AWJM), abrasive jet machining (AJM), etc.
Tribological characterisation of epoxy–graphene–liquid filler composite coatings on steel under base oil external lubrication
Published in Tribology - Materials, Surfaces & Interfaces, 2018
Vikram Kumar, Sujeet K. Sinha, Avinash K. Agarwal
The tribological performances of machine parts, such as gears, bearings, engine piston rings, etc, can be drastically improved by applying a suitable coating on both or one of the mating surfaces [1]. Several hard and soft tribological coatings have been developed in the past according to the stress and thermal requirements at the interface. Among hard coatings, diamond-like-carbon (DLC), WC, TiC, TiAlN, CrC, etc. [2–6] have been successfully used for tribological applications. Hard coatings are also suitable for machine tools where hardness, wear resistance and thermal resistance are the main requirements. Some of the drawbacks of hard coatings are that they provide high friction (exceptions are DLC, MoS2, etc.), high interfacial stress between the substrate and the coating, poor adhesion to the substrate [7], high wear against itself or a harder material, abrasive to the counterface and non-reactivity to the lubricant molecules [8]. In addition, most of the hard coatings tend to be very brittle, and hence once a defect (crack) initiates, it grows at a fast rate leading to its complete delamination from the substrate. The delaminated wear debris of hard coating material (or, the third body) is very damaging to both the interacting surfaces which quickly increases the wear of both surfaces. In order to mitigate the above, several researchers have experimented with softer polymeric coatings. Polymers can have better adhesion to the substrate, low friction and are not damaging to the counterface [9,10]. Epoxy-based coatings/bulks with various fillers such as carbon materials (graphite, graphene and carbon nano tubes) [11], functionalised reduced graphene oxide [12], carbond fibre [13] and liquid lubricants (PFPE and SN150) (added in situ) [14,15] have shown promising results in dry state (no external lubricant present). Polymer coatings provide low cost and environment-friendly solution to the problem of wear in machines. The liquid lubricant-filled epoxy (in situ lubrication) gives low friction coefficient of 0.07 for a sustained period of more than 2 × 105 number of cycle at contact stress value of 0.025 GPa and sliding speed of 0.63 m s−1 [14,15].