Nivaldo Lemos Coppini

Machining optimisation in carbon fibre reinforced composite materials

Abstract By virtue of their characteristics, the applications of composite materials based on carbon fibre reinforced plastic (CFRP) have been increasing considerably. Thus new manufacturing process and production techniques must be developed to ensure high precision and good surface quality of the components. As a result of this manufacturing scenario, it is necessary to study the machining process. This work reports practical experiments in turning, to study the performance of different tool materials such as ceramics, cemented carbide, cubic boron nitride (CBN), and diamond (PCD). The results show that only diamond tools are suitable for use in finish turning. An optimisation methodology was used in rough machining to determine the best cutting conditions. The tests were carried out with cemented carbide tool at various cutting speeds. In the optimisation methodology were used the cutting length as the tool replacement criterion and some parameters were monitored such as the feed and cutting forces that can used be used as a safety system. Finally, it is concluded that the optimisation of the cutting conditions is extremely important in the selection of the tools and cutting conditions to be used in the CFRP manufacturing process.

Characteristics of carbon–carbon composite turning

Abstract This work shows as introduction some properties of the carbon fibre reinforced carbon composite (CFRC) related with its composition, fabrication process, mechanical properties and main applications. After this work presents the experimental results, where turning tests were carried out to study some aspects of the CFRC composite machinability. During the experiments were observed the performance of different tool materials like ceramics, cemented carbide, cubic boron nitride (CBN), and diamond (PCD). For the cemented carbide were carried out various trials in different cutting speeds and feed rates, where can be investigated the influence of the cutting conditions on tool wear. During the tests were measured the tool wear and monitored the machining forces and engine motor current. Experimental results showed that only diamond tools are suitable for use in finishing turning. In rough turning, the carbide tools can be used with some restrictions parameters.

Genetic Algorithm Applied to Investigate Cutting Process Parameters Influence on Workpiece Price Formation

In this work, genetic algorithm (GA) technique was applied to investigate cutting process parameters influence on workpiece price formation using the concepts of contribution margin. The cutting process is one of the most important processes among many others available in manufacturing scenarios. Nevertheless, it is common to find some manufactured item, or at least one part of it, that was made, by cutting process. Because of its importance, many studies related to its optimization were performed, and in the last years, cutting process optimization task has been explored in different approaches from several knowledge areas, such as deterministic methods, operational research and artificial intelligence, and design of experiments. The obtained results from GA application presented in this work are in good agreement with others already reported and could be properly used in cutting process optimization parameters.

Machined part sales price build-up based on the contribution margin concept

One of the main competitive moves observed in the last two decades was the change in product pricing, evolving from a cost plus margin paradigm to a market-driven one. In the present days, the customer defines how much he or she is willing to pay for a given product or service. As a result, traditional cost accounting procedures and their related pricing formulas cannot accommodate that kind of change without significant turnaround in practices and concepts. Taking that into consideration, this paper proposes a procedure tool based on the contribution margin concept as well as on cutting process economic analysis to be applied to small and medium size (SMS) machining service companies. To improve the readers comprehension, a numerical simulation is also presented. All the figures have been calculated taking into account the Brazilian currency (Reais). At this moment (2009), the exchange rate is approximately R

Minimum lubrication in Al-Si drilling

2.40 to US

Value stream mapping simulation using ProModel ® software

1.00. The numerical simulation presented herein was developed mainly to allow the reader to follow the proposed procedure and not to consider the numeric results as actual data.

Experimental Design Applied to the Machining of Windows Cage Ball Joints Homokinetic SAE 8620 Steel with CBN Tool

The high percentage of the refrigeration costs (17%) in the operational production costs, the ecological subjects, the lawlegal demands related to the preservation of the environment and the human health justify the recent researches about the restriction towards the use of abundant cutting fluid in machining processes. However, it is important to point out that the use of a minimal mist lubrication (mixture of air and oil) has been possible in production processes for machining, due to the technological development of tool materials and also machine-tools. The objective of this work is to test the minimum quantity of lubricant (MQL) technique (10 ml/h of oil) mixed in a flow of air in the drilling process of aluminum silicon alloy (SAE 323) with a solid carbide drill (K10). The input variables were drill diameter (and consequentelyconsequently, depth of cut) and cutting speed. The results showed that when high depth of cut and cutting speed are used, the operation using abundant fluid is not possible because the drill breaks after a few holes. Moreover, the quality of the holes obtained using MQL is not worse than that obtained for with smaller cutting speed and depth of cut.

Increasing Production and Minimizing Costs During Machining by Control of Tool’s Wears and or Damages

Value Stream Mapping (VSM) is a tool that has been used in lean manufacturing to redesign production systems in several industrial sectors. As part of lean principles, the VSM is a pictorial technique used to identify several kinds of wastes existing in the manufacturing floor and enables an easy way to visualize possible alternatives to eliminate them. The company considered for the research is a traditional manufacturer of industrial gearboxes and auto parts, who has been using the VSM to locate and eliminate wastes for a family of products. This paper proposes the utilization of ProModel® 7.0 software as a simulation tool to build-up and evaluate several alternatives for the future state value stream map (FSVSM). As a result it was possible to conclude that simulation represents a valuable strategy to obtain an optimized solution for the FSVSM, as it allows the analysis of several alternatives and many manufacturing indicators.

New Operational and Decision Support System for Cutting Process Optimization

In this work a factorial planning had been used to evaluate the CBN tool life during cut-ting SAE 8620 steel. Part U2222 of a TPGW 160408 insert of TX-LS TB650 and 2NU-SHMA6942 S7182BN300 classes from two manufacturers were used in this experiment. A 23 factorial design was used In cutting process to evaluate the behavior of the tool life and reason of the exchange of the part on influences of the chamfer (in S and T+S), the advancing speeds (0.09, 0.10 and 0.11 mm/rpm) at a cutting speed of 91.2 m/min. Model have been fit by variance analysis (ANOVA) and the processing optimization was done by response surface methodology (RSM). Results showed that a hyperbolic model had more adjusting than other models and the optimization showed a high life time for the TX-LS TB650 tool from A manufacturer on 0.09 mm/rpm of advancing speed, where it was observed that the pre-cranking was the reason of the exchange.

Profit Planning and Control in the Machining Industry Based on the Contribution Margin Concept

Industries involved in machining processes need to increase their competitiveness to adequately meet the market demand, i.e. better quality of their final products and a more efficient machining process. There are some industries that prefer to work with the managers of machining tools in order to control the costs of the proceedings. However, the authors of this article have the opinion that it is essential to have professionals hired directly by the company to play the role of improvements introducer to the machining process. So, following this procedure, this paper proposes the use of the Six Sigma methodology to the management and stratification of the consumption and tool breakage during the machining process. Thus, the DMAIC method was used. By providing data collection during research in the areas of factory production, causes of tool breakage were identified. With this information were initiated actions seeking process improvements and also attempting to define new ideal conditions, both of machine tools, as tools. The result showed that it was possible to propose a model for controlling the tool breakage and, undoubtedly, contribute to reducing costs and increasing productivity.