Papers by Author: Mariusz Deja

Abstract: New tools for flat grinding are the subject of the paper. Electroplated diamond tools with different grains - D64 and D107 - were used in a modified single-disc lapping machine configuration. The results from flat grinding, such as the material removal rate (MMR), surface roughness and plane-parallelism are presented in the paper. Apart from ceramic samples, the additional experiments were carried out on cemented carbide workpieces (H10S) with the use of a diamond electroplated tool (D64). SEM microscopic images of unworn and worn active tool surface are presented with abrasive grains worn by attrition and cavities in the nickel bond after the grains pull out.

Abstract: The focus of this paper is on CAPP for parts manufacture in systems of definite process capabilities, involving the use of multi-axis machining centers for parts shaping and grinding machines for finishing. It presents in particular a decision making scheme for setup determination as a part of generative process planning. The planning procedure consists of two stages. The first stage is associated with generic setup determination applying tool accessibility analysis to machined features and reasoning based on geometrical product specification (GPS). The second stage involves machine specific setup planning considering the availability and capability of machines on a shop floor through setup merging. The impact of dimensional and geometric tolerance as well as the surface roughness of relatively complex mechanical element on the generated process plan with several setups was presented. The relevant reasoning mechanism within a decision making scheme on generated process alternatives is shown based on a numeric case.

Abstract: Two methods for the abrasive properties evaluation, based on the image processing, are presented in the paper. Image processing analysis was developed to evaluate quickly the abrasive properties as the tool wears down. The coefficient based on the image brightness was calculated and additional analysis was based on the number of grains located on the active surface of the tool before and after machining. The second method is slower but gives better results especially for reflecting metallic surfaces. The active surfaces of electroplated CBN and diamond tools were analyzed. The practical time of electroplated tools' usage can be predicted with proposed methods.

Abstract: New tools for flat grinding of ceramics (Al₂O₃) are presented in the paper. Electroplated CBN tools (B64 and B107) were used in a modified single-disc lapping machine configuration. The results from experiments, such as the material removal rate and surface roughness parameters are presented and analyzed. Numerical simulations, based on the model for the shape error and tool wear estimation in machining with flat lapping kinematics, are also presented. The tool life of electroplated tools can be extended by choosing appropriate parameter K related to the process kinematics.

Abstract: The focus of this paper is on computer-aided process planning (CAPP) for parts manufacture in systems of definite processing capabilities, involving multi-axis machining centers. A methodical approach is developed to optimally solve for process planning problems, which consists in the identification of process alternatives and sequencing working steps. The approach involves the use of the branch and bound (B&B) concept from the field of artificial intelligence (AI). A conceptual scheme for generation of alternative process plans in the form of a network is developed, based on part design data modeling in terms of machining features. A relevant algorithm is proposed for creating such a network and searching for the optimal process plan solution from the viewpoint of its operational performance, under formulated process constraints. The use of the approach is studied numerically with regard to a real life case study and diverse machine tools with relevant tooling are considered. Generated process alternatives for complex machining with given systems are studied using models programmed in the Matlab environment.

Abstract: Lapping of plane surfaces is the technology which allows achieving high surface quality. Kinematics of lapping has the main effect on the flatness of active plane of the lapping tools as well as on the quality and flatness of the machined surface. Lapping machines can be used for grinding without the chuck-related problems as encountered in conventional surface grinding. The configuration of a conventional single-disk lapping machine was modified and the rotational velocity of a workpiece holder can be precisely controlled by a stepper motor. Two types of tools were used for experiments on a modified machine. The first tool was equipped with grinding inserts made of resin and synthetic diamond micrograins (grit size 3/2 m). In the second stage of experiments the single-layer electroplated diamond tool (D107 – grit size 106/90 m) was applied. Ceramic workpieces (Al2O3) were machined on the modified single-disc lapping machine with the use of both tools and with additional loose abrasive. Experimental results of removal rates, technological parameters and kinematical analysis are the subject of the presented paper.