The Present State of Surface Conditioning in Cutting and Grinding

All manufacturing processes have an impact on the surface layer state of a component, which in turn significantly determines the properties of parts in service. Although these effects should certainly be exploited, knowledge on the conditioning of the surfaces during the final cutting and abrasive process of metal components is still only extremely limited today. The key challenges in regard comprise the process-oriented acquisition of suitable measurement signals and their use in robust process control with regard to the surface layer conditions. By mastering these challenges, the present demands for sustainability in production on the one hand and the material requirements in terms of lightweight construction strength on the other hand can be successfully met. In this review article completely new surface conditioning approaches are presented, which originate from the Priority Program 2086 of the Deutsche Forschungsgemeinschaft (DFG).

A CNN Prediction Method for Belt Grinding Tool Wear in a Polishing Process Utilizing 3-Axes Force and Vibration Data

This paper presents a tool wear monitoring methodology on the abrasive belt grinding process using vibration and force signatures on a convolutional neural network (CNN). A belt tool typically has a random orientation of abrasive grains and grit size variation for coarse or fine material removal. Degradation of the belt condition is a critical phenomenon that affects the workpiece quality during grinding. This work focuses on the identifation and the study of force and vibrational signals taken from sensors along an axis or combination of axes that carry important information of the contact conditions, i.e., belt wear. Three axes of the two sensors are aligned and labelled as X-axis (parallel to the direction of the tool during the abrasive process), Y-axis (perpendicular to the direction of the tool during the abrasive process) and Z-axis (parallel to the direction of the tool during the retract movement). The grinding process was performed using a customized abrasive belt grinder attached to a multi-axis robot on a mild-steel workpiece. The vibration and force signals along three axes (X, Y and Z) were acquired for four discrete sequential belt wear conditions: brand-new, 5-min cycle time, 15-min cycle time, and worn-out. The raw signals that correspond to the sensor measurement along the different axes were used to supervisedly train a 10-Layer CNN architecture to distinguish the belt wear states. Different possible combinations within the three axes of the sensors (X, Y, Z, XY, XZ, YZ and XYZ) were fed as inputs to the CNN model to sort the axis (or combination of axes) in the order of distinct representation of the belt wear state. The CNN classification results revealed that the combination of the XZ-axes and YZ-axes of the accelerometer sensor provides more accurate predictions than other combinations, indicating that the information from the Z-axis of the accelerometer is significant compared to the other two axes. In addition, the CNN accuracy of the XY-axes combination of dynamometer outperformed that of other combinations.

Calculation and justification of modes of electroabrasive finishing of polyhedral channels

The process of processing various shapes with simultaneous removal of allowances from several mating surfaces using a new patented method is considered. An original tool has been created for the electro-abrasive process of stock removal at the finishing stage. The influence of the anodic component of the combined process, the possibility of its improvement by reducing the electrode wear is shown. The dynamics of electrode wear and technological modes for a new tool with its longitudinal feed with constant pressure, calculated by the proposed method, are considered. The choice of the voltage to the electrodes is substantiated, the value of which does not contradict the results of studies of other domestic scientists. Examples of the use of a new one for finishing treatment of channels with a conjugate profile of cross-sections used in cooling systems of heat engines are given.

Evaluation of Parameters Affecting Magnetic Abrasive Finishing on Concave Freeform Surface of Al Alloy via RSM Method

The attempts of researchers in industries to obtain accurate and high quality surfaces led to the invention of new methods of finishing. Magnetic abrasive finishing (MAF) is a relatively new type of finishing in which the magnetic field is used to control the abrasive tools. Applications such as the surface of molds are ones of the parts which require very high surface smoothness. Usually this type of parts has freeform surface. In this study, the effect of magnetic abrasive process parameters on freeform surfaces of parts made of aluminum is examined. This method is obtained through combination of magnetic abrasive process and Control Numerical Computer (CNC). The use of simple hemisphere for installation on the flat area of the magnets as well as magnets’ spark in curve form is a measure done during testing the experiments. The design of experiments is based on response surface methodology. The gap, the rotational speed of the spindle, and the feed rate are found influential and regression equations governing the process are also determined. The impact of intensity of the magnetic field is obtained using the finite element software of Maxwell. Results show that in concave areas of the surface, generally speaking, the surface roughness decreases to 0.2 μm from its initial 1.3 μm roughness. However, in some points the lowest surface roughness of 0.08 μm was measured.

The Metrology of Ground Concrete Surfaces Morphology With 3D Laser Scanner

This paper is devoted to machining of concrete by grinding and the metrology of its surface morphologies. The surface morphology is still open problem from metrological as well as mathematical morphology points of views. In order to understand better abrasive process the raw morphologic state is compared with the ground concrete surfaces. The most significant results are presented in the form of profiles, 3D isometric views and isotropy analysis. Several 3D surface roughness parameters were calculated.

Feasibility Study of Micro-Hole Wall Grinding by Micro-Elastic Abrasive Particles

This study aims to develop a polishing process improvement technology for deep micro-hole knockout hole wall with high aspect ratio, and discuss the optimal polishing parameter combination of abrasive jet machining method and micro-elastic abrasive particles for deep micro-hole knockout hole wall surface. A micro-elastic abrasive process technology was thus developed. The experimental results showed that the micro-elastic abrasive has better grinding effect on the surface roughness of knockout hole wall in length of 300 mm and in inside diameter of ψ2mm in the machining conditions of jet pressure 0.5MPa, volume mixing ratio 2:1 of abrasive particles to additive and vacuum attraction 70 cmHg. It was improved from 2.39 μm Ra (10.74 μm Rmax) to 0.08 μmRa (1.12 μm Rmax), proving the feasibility of micro-elastic abrasive. The surface was improved well, and the process time was shortened greatly.

A Fundamental Investigation on Ultrasonic Assisted Fixed Abrasive CMP (UF-CMP) of Silicon Wafer

Chemical mechanical polishing (CMP) is often employed to obtain a super smooth work-surface of a silicon wafer. However, as a conventional CMP is a loose abrasive process, it is hard to achieve the high profile accuracy and lots of slurry must be supplied during CMP operations. As an alternate solution, a fixed abrasive CMP process can offer better geometrical accuracy and discharges less waste disposal. In this paper, in order to enhance the polishing efficiency and improve the work-surface quality, a novel ultrasonic assisted fixed abrasive CMP (UF-CMP) is proposed and the fundamental machining characteristics of the UF-CMP of a silicon wafer is investigated experimentally. The results show that with the ultrasonic assistance, the material removal rate (MRR) is increased, and the surface quality is improved.