Browsing by Author "Malyer E."

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    The influence of toolpath strategy on geometric accuracy in incremental forming
    (Trans Tech Publications Ltd, 2013) Malyer E.
    Incremental sheet metal forming is a new process to manufacture sheet metal parts and it is becoming a remarkable technology for fast prototyping and small lot production because of the advantages of this technology such as process flexibility, product independent tooling and higher formability. On the other hand, limited maximum drawing angle, relatively coarse surface roughness, low geometrical accuracy and long forming time are common disadvantages of the process. Furthermore, it is affected by process parameters which are tool diameter, forming velocity, spindle speed, forming geometry and depth, etc. Toolpath strategy which is used to form sheet metal by CNC machine has a key role among these parameters. The present study has been undertaken in order to investigate the suitable toolpath strategy which is developed for metal cutting by commercial CAD/CAM software to increase geometrical accuracy and decrease thinning and forming time. For the intended purpose, seven different toolpath strategies which are rough and finish strategies were used to form a truncated frustum by using one millimeter thick S235JR steel alloy. The effect of each strategy on the surface roughness, geometrical accuracy and thinning distribution of formed product was studied by measuring thickness, drawing angle and depth of formed parts. Therefore, formed parts scanned by 3D laser scanner and STL files of parts were generated then STL files were converted into CAD file. CAD data of parts was used for measurements. The measurements showed that not only forming movements but also transition movements along the tool path affected the geometric accuracy and thinning distribution, surface roughness and forming time of formed parts. On the other hand it was observed that rough strategies were given good results as finish strategies and tool paths generated by CAM software need to be editing for better geometric accuracy, thinning, forming time and surface quality. Copyright © 2013 Trans Tech Publications Ltd.
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    Effects of burnishing parameters on the quality and microhardness of flat die surfaces
    (Carl Hanser Verlag, 2015) Müftüoʇlu H.S.; Malyer E.
    In this study, the burnishing process is recommended as finishing operation of flat die surfaces for improving not only surface quality but also mechanical properties of milled die surfaces. This technique can be applied after milling operations in CNC milling centers with a single fastening that increases the accuracy of the die geometry. To determine both the usability of the process on flat die surfaces and the influence of process parameters, a simple burnishing tool with a fixed deformation element was designed and constructed. The CNC milling center was used for burnishing operations. The burnishing process was employed using a constant spindle speed on a flat surface. Burnishing feed rate, stepover, penetration depth, the number of passes, burnishing direction and coolant were chosen as process parameters. First, optimum parameters were stated, then macro and microstructure of the burnished surfaces were examined, and roughness and hardness measurements of surfaces were carried out. Results show that burnishing increased the surface quality and microhardness of flat milled surface. The penetra tion depth has the maximum and stepover has the minimum effect on surface quality. The coolant has the highest effect on microhardness. The burnishing direction has a significant effect on both microhardness and surface quality. It can be briefly stated that burnishing is an economic and feasible surface treatment process for finishing operations of die surfaces. © Carl Hanser Verlag, Münhen.
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    Analysis of the incremental sheet forming process and process parameters on aluminum sheets based on the vertical step sizes
    (SAGE Publications Ltd, 2022) Malyer E.; Sönmez F.
    The incremental sheet forming (ISF) is an effective forming method developed especially for rapid prototyping and small-batch production of sheet metals. The selection of parameters (in particular, vertical step size and toolpath geometry) in ISF is crucial. Besides, each parameter has different effects on the desired geometry, sheet thickness, forming time, and productivity. In this study, the ISF process was analyzed by investigating the effects of ISF parameters. For this purpose, AA5754 sheets were formed by different ISF parameters. The effects of toolpath strategies (based on the vertical step size) were examined with three spindle speeds and three feed rates. To achieve that objective, constant, increasing, and decreasing vertical step sizes were used for the first time in the same study. After the forming, the forming time, geometric tolerance, and thickness values were analyzed. Besides, the efficiency of each parameter on the ISF process was investigated with the Pareto analysis. It has been revealed that each strategy has some advantages and disadvantages in ISF. The shortest forming time (1.55 min), the best geometric tolerance values (−0.05 mm, +0.2 mm), and the best thickness values (0.58 mm, 0.51 mm) were achieved following toolpath strategy 1, strategy 2, and strategy 3, respectively. The Pareto analysis showed that spindle speed and feed rate have a significant effect on toolpath strategies. The results obtained from this study will shed light on the effective advancement of small-batch production of sheets. Furthermore, the study contributes to the determination of parameters according to which of the sheet metal properties are desired. © IMechE 2022.