Core Machining Research Articles

Influence of feed entrance angle on transverse tearing burr formation in the milling of superalloy honeycomb with ice filling constraint

In the end milling of superalloy honeycomb cores, the contact form between the cutting tool and honeycomb wall and the force state of the honeycomb wall are variable, there will be difficulties in chip removal. The irregular extension of transverse tearing burrs can deteriorate the machining quality of honeycomb core surfaces, thereby adversely affecting the assembly and service performance of sandwich structures. Based on kinematic analysis, modeling of the removal and deflection process of honeycomb walls was conducted. The feed entrance angle in the case of machining thin walls with high feed speeds was characterized, and the force state of the honeycomb wall and the degree of shear or compression it bears were analyzed. Analytical models of damage scale and single-tooth cutting state were established under different feed entrance angles. The impact of feed entrance angle on the minimum burr length and the minimum constraint failure width was analyzed. The milling experiments of GH4099 superalloy honeycomb wall with ice filling constraint were designed and conducted to clarify the influence of different feed entrance angles on cutting force and transverse tearing burr length. The morphology of burrs and the wear form of the cutting tool were analyzed, and the formation mechanism of transverse tearing burr on the honeycomb sidewalls was revealed. The research results indicate that the feed force Fx is 2.1 to 4.7 times greater than the main force Fy or the back force Fz. When the feed entrance angle is <90°, transverse tearing burrs either do not occur, or occur crimped burrs that are gradually removed. Particularly within the range of 0° to 30°, the machining quality is better. The cutting force has a significant shearing effect on the honeycomb wall, making it susceptible to plastic deformation and reaching the fracture strain. The cutting edge can effectively remove material from the honeycomb wall, resulting in normal wear on the minor flank face and tip of the cutting tool. When the feed entrance angle is greater than 90°, it is easy to form large banded burrs, and the burr length is relatively similar to about 1500 μm. The cutting force has a significant extrusion effect on the honeycomb wall, resulting in minimal deflection deformation of the honeycomb wall, and making it difficult to fracture. The cutting tool fails to perform effective cutting, leading to increased friction between the cutting tool and honeycomb wall, which continuously induces irregular extension of the burrs. The research findings are of great significance for achieving damage control in metal honeycomb core machining and guiding process and clamping optimization.

Circular usage of waste cooking oil towards green electrical discharge machining process with lower carbon emissions

A global manufacturing community is dedicatedly striving to implement the concept of NetZero in precision cutting of difficult-to-machine materials, specifically, Inconel 617 (IN617) with due consideration to environmental protocols. The fast strain hardening issue of the said alloy during conventional processing rationalizes the application of electric discharge machining (EDM). However, EDM has been criticized for its high energy consumption and limited cutting efficiency. Moreover, conventional dielectric (kerosene) employed in EDM has drastic environmental and operator health concerns. To address the abovementioned issues, waste cooking oil (WCO) has been employed in this study which enhances the reusability of resources and minimizes the cost of the dielectric. Making the process sustainable is imperative along with continuously escalating scarcity of engineering resources. Therefore, the potential of shallow and deep cryogenically treated electrodes (SCT and DCT) has been comprehensively examined against nanofilled WCO to achieve the aforementioned objective. Three different concentrations of powder (Cp) and surfactant (Cs) to uplift the machining responses are investigated through a detailed parametric experimental design. Core machining factors such as material removal rate (MRR), surface roughness (SR), and specific energy consumption (SEC) are examined through optical and electron microscopy studies and 3D surface profilometry. Hereafter, machining factors are modelled using the artificial neural network (ANN) technique. An exceptional improvement of 80%, 25.3%, and 75.16% has been achieved in MRR, SR, and SEC respectively using nanopowder-mixed WCO against SCT brass compared to the responses’ values obtained against conventionally used kerosene. Furthermore, compared to kerosene, the maximum CO2 reduction of 79.97 ± 11.2% is achieved with WCO.

In-plane compressive responses and failure behaviors of composite sandwich plates with resin reinforced foam core

The paper presented an experimental study on the effect of the resin reinforced core configuration and core thickness on in-plane compressive responses and failure behaviors of composite sandwich specimens. Two resin reinforced core machining configurations were designed with three core thickness along. In-plane compressive load, displacement, strains on both sides, and failure morphology were closely monitored during the loading process. Meanwhile, the theoretical method also was supplementary to forecast the failures of sandwich structures. It was found that the enhancement of grooved, perforated holes and contour cut (GPC) core was better than double-side grooved and perforated hole (DGP) core to improve the in-plane compressive capacity of sandwich specimens for all thick cores. The core fracture or skin/core debonding failure of sandwich specimens resulted in an instant drop of in-plane compressive load, and the global buckling led to a slower reduction. The failure mode changed from global buckling to skin/core debonding at both sides as the core thickness increased for the Plain core sandwich specimen; switched from global buckling to a combined failure of core fracture and skin/core debonding at both sides, and then to skin/core debonding at both sides for the DGP core sandwich specimen; the skin/core debonding at the shallow side occurred for all GPC core specimens. The slight buckling trace of strains before the peak load probably triggered the skin/core debonding of sandwich specimens. The theoretical method could well forecast failure loads and corresponding failure modes of sandwich specimens with the 15 mm thick core, and reasonably predict failure loads for sandwich specimens with 30 mm and 45 mm thick cores.

The Effects of Core Machining Configurations on the Mechanical Properties of Cores and Sandwich Structures.

Composite sandwich structures are widely used in the fields of aviation, marine, and energy due to their high specific stiffness and design flexibility. Improving the mechanical properties of the cores is significant to the strength, modulus, and stability of composite sandwich structures. Two kinds of core machining configurations were designed by combining thin grooves, perforated holes, and thick contour cuts as well as non-machining plain cores. The cores and sandwich structures with these configurations were fabricated using a vacuum-assistant infusion process. Static tensile, compressive, shear, and peeling tests were conducted on the infused cores and sandwich structures. The results showed that the tensile, compressive, and shear moduli, and compressive strength of the infused cores can be greatly improved. The tensile strength changed negligibly due to stress concentration induced by irregular foam cell and the shear-lag phenomenon of the resin column/foam interface. The shear strength of the infused cores increased slightly. The thick contour cuts and perforated holes can greatly improve the face sheet/core peel capacity of the sandwich structures, whereas the thin grooves can moderately improve the peel capacity. Both infused cores with the designed machining configurations exhibited positive effects on the compressive, tensile, and shear moduli, and compressive strength, considering the material costs. The study provides a comprehensive and quantitative insight into the effects of core machining configurations on mechanical properties of infused cores and composite sandwich structures.

Influences of machining parameters on tool performance when high-speed ultrasonic vibration cutting titanium alloys

Tool performance is a key factor in evaluating machining processes. To improve machining productivity and part quality, researchers have conducted numerous studies on improving tool performance, such as tool design, coatings, functional micro textures, cooling/lubrication conditions, cutting parameter optimization, and intermittent cutting. Focusing on materials that are difficult to cut (i.e., Ti alloys), this paper explores a high-speed ultrasonic vibration cutting method that combines intermittent cutting, cooling, and lubrication. Through theoretical analysis and experiments on tool wear, cutting force, temperature, etc., the influence of machining parameters on tool performance is investigated. The results show that a large separation effect coupled with good cooling and lubrication conditions is key to improving tool performance. Among these, the feedrate and phase shift resulting from the rotary (spindle) speed are the core machining parameters. On this basis, the choice of machining parameters is summarized to provide a reference for the high-efficient machining of Ti alloys for scholars and engineers. First, cooling and lubrication conditions, such as dry machining and fluids, are determined. The duty cycle is then set from 0.5 to 0.6 via a relatively small feedrate value (i.e. 0.005 mm/r) and a π phase shift. Finally, the cutting speed and depth of cut are chosen according to the requirements of machining efficiency and cost.

A customizable process planning approach for rotational parts based on multi-level machining features and ontology

Turning is the one of the most commonly available and least expensive machining operations. Confronted with the increased number of part variants and the requirement for fast system responsiveness in dynamic environments, traditional methods for building a computer-aided process planning (CAPP) system for turning are infeasible due to the fixed feature library and hard-coded heuristic rules. In this paper, a customizable approach for automatic process planning of rotational parts is proposed to boost the productivity of enterprises by realizing multi-level machining feature recognition and knowledge-based machining activity/resource selection. First, from the decomposed cells of the turning area, basic turning features are successively recognized based on a novel cell machinability analysis. The high-level custom features are define based on the directed acyclic graph and recognized from the basic feature precedence graph using the subgraph matching algorithm. To facilitate the knowledge-based process planning, a knowledge base is then established utilizing ontology, in which the taxonomies, properties, and causal relationships among the core concepts, namely, machining feature, machining operation, cutting tool, and machine tool, are formally defined. Finally, a five-step procedure is proposed to automatically infer manufacturing activity/resource for multi-level features through rule-based reasoning. The effectiveness and extensibility of the proposed approach are validated through two case studies on complex rotational parts.

Improving four-point bending performance of marine composite sandwich beams by core modification

The aim of this study was to improve four-point bending performance of foam core sandwich composite beams by applying various core machining configurations. Sandwich composites have been manufactured using perforated and grooved foam cores by vacuum-assisted resin transfer moulding method with vinyl-ester resin system. The influence of grooves and perforations on the mechanical performance of marine sandwich composite beams was investigated under four-point bending test considering the weight gain. Bending strength and effective bending stiffness increased up to 34% and 61%, respectively, in comparison to a control beam without core modification. Analytical equations were utilised for calculating the mid-span deflection, equivalent bending stiffness and ultimate bending strength of the sandwich beams. Finite element analysis was also performed to analyse the flexural response of the specimens taking into account the combined effect of orthotropic linear elasticity of the face sheet and the non-linear behaviour of the foam core.

Ontology-based module selection in the design of reconfigurable machine tools

Reconfigurable machine tools (RMTs) are important equipment for enterprises to cope with ever-changing markets because of their flexibility. In design of such equipment, selection of appropriate modules is a very critical decision factor to effectively and efficiently satisfy manufacturing requirements. However, the selection of appropriate modules is a challenging task because it is a multi-domain mapping process relying heavily on experts’ domain knowledge, which is usually unstructured and implicit. To effectively support RMT designers, an ontology-based RMT module selection method is proposed. First, a knowledge base is built by development of an ontology to formally represent the taxonomy, properties, and causal relationships of/among three domain core concepts, namely, machining feature, machining operation, and RMT module involved in RMT design. Second, a four-step sequential procedure is established to facilitate the utilization of encoded knowledge from a knowledge base to aid in the selection of appropriate RMT modules. The procedure takes a given part family as the input, automatically infers the required machining operations as well as the RMT modules through rule-based reasoning, and eventually forms a set of RMT configurations that are capable of machining the part family as the output. Finally, the efficacy of the ontology-based RMT module selection method is demonstrated using a plate family manufacturing example. Results show that the approach is effective to support designers by appropriately and rapidly selecting modules and generating configurations in RMT design.

Investigation of Tool Core Temperature and Mechanical Tool Load in Milling of Ti6Al4V

The special properties of titanium and titanium alloys, such as their high strength-to-weight ratio, their corrosion resistance, and their biocompatibility are of high importance for aerospace, medical and other industrial applications. However, components made of these difficult-to-cut materials entail major challenges for machining processes. High thermo-mechanical tool load results in rapid tool wear, and the already significant machining costs are further increased by premature tool exchange to avoid tool breakage, damaging the valuable workpieces. Both, tool wear progress and risk of tool breakage can be reduced by gaining extensive knowledge about the thermo-mechanical tool load over the tool life time. In this paper, the influence of different machining parameters on the end milling tools’ core temperature and the resulting active force affecting the tool are investigated over tool life time. To measure thermal and mechanical tool loads, an adapted sensory tool holder was used. The results show a strong interdependence between tool load, tool core temperature, machining parameters and tool wear.

Effects of core machining configuration on the debonding toughness of foam core sandwich panels

Core machining is often applied to improve the formativeness of foam core and the manufacturing effectiveness of sandwich panels. This paper investigates the effects of core machining configuration on the interfacial debonding toughness of foam core sandwich panels fabricated by vacuum-assisted resin transfer molding process. Several machining configurations are conducted to foam core, and skin–core debonding toughness of fabricated sandwich panels is evaluated using double-cantilever-beam tests. The sandwich panels with core cuts exhibited higher apparent fracture toughness than the panels without core cut, specifically in the case of perforated core. The relationship between core machining configuration and measured fracture toughness is discussed based on the experimental observations and the numerical analyses of energy release rates.

Application of Cleaning Technology in the Remanufacturing for Loader's Axles and Transmission Box Components

The high-efficiency cleaning is one of the key technologies in the remanufacturing process. It is the premise and guarantee for remanufactured core inspection and machining. It also is an important link to improve quality and reliability of remanufactured products. On the basis of analyzing the structural feature, working conditions and main dirt of worn-out or discarded component of axles and transmission of construction machinery, the remanufacturing cleaning technology is discussed.

Modeling and Numerical Control Machining of the Mould of a Rearview Mirror of a Motorcycle Based on the Reverse Engineering Technology

The Reverse Engineering Technology (RET) is extensively employed in the realm of product designing. In this paper, a Three-coordinate Measuring Machine is utilized first to measure the data points of the rearview mirror of a motorcycle, then under UG modeling environment, surface reconstruction is conducted, and lastly procedures like mold splitting and mold core machining are finished upon exercising the Moldwizard Module of UG software. In short, the application of the RET greatly shortened the period of product designing and manufacturing.

Optical design and manufacturing technology for high resolution laser scanning unit

This paper presents optics and fabrication process of key elements in a laser scanning unit for high quality laser beam printers or multi-function printers with over 600dpi optical resolution which today’s commercial system shows. Considering the light sources with different wavelength, optical characteristics in the laser scanning unit which includes a scanning lens and an athermalization element are explained. Also fabrication technologies to realize high resolution laser system such as mold design, core machining and injection molding processes are described. Finally, the hybrid lens as the athermalization element having refractive and diffractive surface is suggested to compensate thermal defocus. The hybrid lens is fabricated and their performance and effect on laser scanning unit are evaluated.

A high-efficiency rough milling strategy for mould core machining

Increasing the efficiency of rough machining operations can produce significant productivity improvement in mould and die making because most of the metal is removed in the roughing stage. In this paper, a high-efficiency 2.5-dimensional rough milling strategy for mould core machining is presented. The strategy consists of three different tool paths. The first tool path is generated on the basis of the convex hull boundary of a machining region. Owing to the absence of concave tool path segments, the convex hull based tool path can eliminate the chip load fluctuation problem encountered in corner cutting. The second tool path is an enhanced unidirectional straight-line tool path, which has the virtue of maintaining a steady cutting resistance throughout. The large staircases left behind by these two tool paths are refined by using the third tool path which is a contour-parallel tool path that cuts the mould core layer by layer in an upward manner. After applying these three tool paths, the stock material left on the mould core surface can be post-processed by the subsequent finish milling operation. A case study is illustrated to demonstrate the practicality of the presented rough milling strategy.

Virtual reality and hypermedia in learning to use a turning lathe

Abstract A Virtual reality environment with hypermedia was designed to help undergraduates understand the structure and functioning of a turning lathe. Study 1 was carried out with 30 novice students and Study 2 involved 24 students attending a machining course. These studies demonstrated that the virtual lathe can foster the comprehension of some core machining concepts. Further, the studies suggest that novice students benefit most from earlier free navigation of the virtual environment whereas expert students benefit from an analysis of the hypermedia.

Influence of the head core machining upon the fringing field

Theoretical considerations connected with spacing losses in video-tape recording are presented. The Beilby layer on the head and gap surfaces, residual stress of the head core after machine processing cause great losses at very short wavelength. An analysis of the fringing field has been applied to estimate the equivalent non-magnetic layer. Based on determined experimentally actual permeability in the surface layer incorporated into a boundary-value-problem head model, it can be shown that the spacing losses related to the non-magnetic spacing can be effectively determined in quantitative form. Because of the considerable decrease of permeability in the head core at high frequency machining effects should not be neglected in recording performance considerations. The non-magnetic spacing has been estimated to be 0.26 μm at 5 MHz.