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This paper discusses research on machining and repairing of turbomachinery components which are generally complex geometries and made up of difficult to machine materials (nickel super alloys or titanium alloys).

The approaches, methods and methodologies used for machining and repairing of blades are reviewed as well as the comparisons between them are made.

Particularly, the most recent blade machining and repair techniques using high flexible machine tools and industrial robots, are mentioned.

The limitation of the approaches, methods and methodologies are given and supported by real practical application examples.

This paper presents a state of the art review of research in machining and repairing of turbomachinery components, which have been mainly done in the last decade. The paper act as a reference, gathering the works about turbomachinery components from a manufacturing point of view.

The purpose of this paper is to determine the influence of a toroidal cutter axis orientation and a variable radius of curvature of the machined contour of sculptured surface on the five-axes milling process. Simulation and experimental research performed in this work are aimed to determine the relationship between the parameters of five-axes milling process and the shape and dimensional accuracy of curved outline of Inconel 718 alloy workpiece.

A subject of research are sculptured surfaces of the turbine blade. Simulation research was performed using the method of direct mapping tools in the CAD environment. The machining research was carried out with the use of multi-axis machining center DMU 100 monoBLOCK DMG, equipped with rotating dynamometer to measure the components of the cutting force. To control the shape and dimensional accuracy, the coordinate measuring machine ZEISS ACCURA II was used.

In this paper, the effect of the toroidal cutter axis orientation and the variable radius of curvature of the machined contour on the parameters of five-axes milling process and the accuracy of the sculptured surfaces was determined.

Five-axes milling with the use of a toroidal cutter is found in the aviation industry, where sculptured surfaces of the turbine blades are machined. The results of the research allow more precise planning of five-axes milling and increase of the turbine blades accuracy.

This paper significantly complements the current state of knowledge in the field of five-axes milling of turbine blades in terms of their accuracy.

The objective of CNC machining is to produce mechanical parts with designed quality most efficiently. To generate CNC tool paths for machining a sculptured part using a three‐axis CNC machine, surface geometry, cutter shape and size, as well as tool path interval and direction need to be considered. In this work, the relation between the direction of a tool motion and cutting efficiency is studied. A new measure of cutting efficiency in three‐axis CNC milling – the length of effective cutting edge (ECE) is introduced. The ECE length is mathematically proven to reach its maximum when the tool cuts a sculptured surface along its steepest tangent direction at the cutter contact point. The steepest tangent direction is thus proven to be the most efficient tool feed direction in three‐axis sculptured part machining. The study identifies tool feed direction as a new control parameter in CNC tool path planning, and forms the foundation for further research on three‐axis tool path generation of sculptured parts.

The case for Computer Aided Process Planning in small and medium sized batch manufacturing organisations is described. Current implementation options are detailed together with likely realisable benefits. The procedural methodology being used by the authors in a manufacturing organisation is outlined.

In recent days, rapid machining through digital prototyping has been popular for its applicability in a wide range of complex and useful parts. Rapid construction of prototypes from point cloud data based on section plane method is available, which is an approximate method. Discusses some suitable methodology for conversion of point cloud data to a physical prototype where data acquisition is through a mechanical touch trigger probing process using CNC milling machine. The process is quite useful for reverse engineering of complex sculptured parts. A concept called tangent plane method is adopted for the generation of 3D geometry on point cloud data of sculptured parts with due emphasis on probe radius compensation after data capture and tool radius compensation during tool‐path generation. Computer simulated results are presented, based on real‐world point cloud data.

This paper aims to propose a global adaptive direct slicing technique of Non-Uniform Rational B-Spline (NURBS)-based sculptured surface for rapid prototyping where the NURBS representation is directly extracted from the computer-aided design (CAD) model. The imported NURBS surface is directly sliced to avoid inaccuracies due to tessellation methods used in common practice. The major objective is to globally optimize texture error function based on the available range of layer thicknesses of the utilized rapid prototyping machine. The total texture error is computed with the defined error function to verify slicing efficiency of this global adaptive slicing algorithm and to find the optimum number of slices. A variety of experiments are conducted to study the accuracy of the developed procedure, and the results are compared with previously developed algorithms.

This paper proposes a new adaptive algorithm which globally optimizes a texture error function produced by staircase effect for a user-defined number of layers. The adaptive slicing algorithm dynamically calculates optimized slicing thicknesses based on the rapid prototyping machine’s specifications to minimize the texture error function. This paper also compares the results of implementing the developed methodology with the results of previously developed algorithms and presents cost-effective optimum slicing layer thicknesses.

A new methodology for global adaptive direct slicing algorithm of CAD models, based on a texture error function for the final product and the possible layer thicknesses in rapid prototyping, has been developed and implemented. Comparing the results of implementation with the common practice for several case studies shows that the proposed approach has greater slicing efficiency. Typically, by utilizing this approach, the number of prototyping layers can be reduced by 20-50 per cent compared to the slicing with other algorithms, while maintaining or improving the accuracy of the final manufactured surfaces. Therefore, the developed slicing method provides a better solution to trade-off between the rapid prototyping time and the rapid prototyping accuracy. For the many advantages of global direct slicing, it can be seen as the future solution to the slicing process in rapid prototyping systems.

This paper presents an innovative approach in direct global adaptive slicing of the additive manufacturing parts. The novel definition of an error function which comprehensively addresses the resulting manufactured surface quality of the entire product allows presenting an objective function to solve and to find the optimum selection of all the layer thicknesses during the slicing process.

Complex and exquisite patterns are sculpted on the surface to beautify the parts. Due to the thin-walled nature, the blank of the part is often deformed by the forming and clamping processes, disabling the nominal numerical control (NC) sculpting programs. To address this problem, a fast adaptive sculpting method of the complex surface is proposed.

The geometry of the blank surface is measured using on-machine measurement (OMM). The real blank surface is reconstructed using the non-uniform rational basis spline (NURBS) method. The angle-based flattening (ABF) algorithm is used to flatten the reconstructed blank surface. The dense points are extracted from the pattern on the image using the OpenCV library. Then, the dense points are quickly located on the complex surfaces to generate the tool paths.

By flattening the reconstructed surface and creating the mapping between the contour points and the planar mesh triangular patches, the tool paths can be regenerated to keep the contour of the pattern on the deformed thin-walled surface.

The proposed method can adjust the tool paths according to the deformation of the thin-walled part. The consistency of sculpting patterns is improved.

Near-net-shaped processes of jet engine blade have better performance in both reducing the material waste during production and improving work reliability in service, while the geometric features of blade, both sculptured surface and thin-walled shape, make the precise machining of blade challenging and difficult owing to its dynamics behaviors under complex clamping and machining loads. This paper aims to present a fundamental approach on modeling and performance analysis of the blade–fixture system.

A computerized framework on the complex blade–fixture dynamic behavior has been developed. Theoretical mechanic analysis on blade fixturing and machining is proposed with an especial emphasis on the boundary conditions of the blade–fixture system. Then the finite element analysis (FEA) method is used to simulate the variation trend of preloads, stiffness and blade distortion. The strong influence of parameters of workpiece–fixture configuration on blade distortion and machining error is investigated.

With a case of real jet engine blade machining, the experimental results and theoretical predictions suggest good agreement on their variation tendency. The loaded pressure of clamps has a critical influence on the total stiff performance of the blade–fixture system, and the profile error of the blade contributes much to the inconsistency in geometric dimension and surface integrity of blades’ machining. In the end, the results also validate the effectiveness of this methodology to predict and improve the performance of the blade–fixture configuration design.

The adaptive machining of near-net-shaped jet engine blade is a new high-performance manufacturing technology in aerospace production. This study provides a fundamental methodology for the performance analysis of blade-fixture system, to clear the variation law of blade distortion during preloading and machining, which will contribute to minimize the machining error and improve productivity.

Presents a new adaptive slicing method for layered manufacturing. The CAD model is first sliced uniformly into slabs of thickness equal to the maximum available fabrication thickness. Each slab is then resliced uniformly as needed to maintain the desired surface accuracy. This approach improves on past work by determining the adaptive refinement through interpolation rather than extrapolation, and it is well suited for execution in a parallel processing computer. The method has been implemented successfully and tested with .STL CAD models on a Stratasys FDM 1600 rapid prototyping system, where typical measured build times were reduced by approximately 50 per cent without reducing overall surface accuracy.

This study aims to use nanofluid-based minimum quantity lubrication (NMQL) technique to minimize the use of cutting fluids in machining of Inconel-625 and Stainless Steel 304 (SS-304) (Ni-Cr alloys).

Machining of Ni-Cr-based alloys is very challenging as these exhibit lower thermal conductivity and rapid work hardening. So, these cannot be machined dry, and a suitable cutting fluid has to be used. To improve the thermal conductivity of cutting fluid, multi-walled carbon nanotubes (MWCNTs) were added to the soybean oil and used with MQL. This study attempts to compare tool wear of coated carbide inserts during face milling of Inconel-625 and SS-304 under dry, flooded and NMQL conditions. The machining performance of both materials, i.e. Inconel-625 and SS-304, has been compared on the basis of tool wear behavior evaluated using scanning electron microscopy-energy dispersive spectroscopy.

The results indicate higher tool wear and lower tool life during machining of Inconel-625 as compared to SS-304. Machining of Inconel-625 exhibited non-consistent tool wear behavior. The tool failure modes experienced during dry machining are discrete fracture, cracks, etc., which are completely eliminated with the use of NMQL machining. In addition, less adhesion wear and abrasion marks are noticed as compared to dry and flooded machining, thereby enhancing the tool life.

Inconel-625 and SS-304 have specific applications in aircraft and aerospace industry, where sculptured surfaces of the turbine blades are machined. The results of current investigation will provide a rich data base for effective machining of both materials under variety of machining conditions.

The literature review indicated that majority of research work on MQL machining has been carried out to explore machining of Ni-Cr alloys such as Inconel 718, Inconel 800, AISI4340, AISI316, AISI1040, AISI430, titanium alloys, hardened steel alloys and Al alloys. Few researchers have explored the suitability of nanofluids and vegetable oil-based cutting fluids in metal cutting operation. However, no literature is available on face milling using nanoparticle-based MQL during machining Inconel-625 and SS-304. Therefore, experimental investigation was conducted to examine the machining performance of NMQL during face milling of Inconel-625 and SS-304 by using soybean oil (vegetable oil) with MWCNTs to achieve ecofriendly machining.