Effect of Feed Rate, Tool-Path and Step over on Geometric Accuracy of Freeform Surfaces when 3 Axis CNC Milling

2019 ◽  
Vol 889 ◽  
pp. 107-114
Author(s):  
Quy Hoang Van ◽  
Tuyen Bui Ngoc

The use of freeform (sculptured) surfaces in the product design process is accelerating at an exponential rate driven by functional as well as esthetics demands. CAD/CAM software is a must in their design are relatively well-covered, issues still remain when it comes to the actual manufacture of freeform surfaces. The major issues are related to the chosen feed rate, toolpaths and step over that would assure the required surface quality, the minimization of the total machining time, etc. This research presents an experimental study to define the effects of machining’s parameters (including: feed rate; toolpath and step over) for CNC 3-axis ball end milling process. The result shows a model for cutting is formulated and incorporated into the parameters of machining that is compatible with all CAD/CAM systems. This result can be used to choose parameters of optimum including federate, toolpath and step over when machining of other freeform surfaces. Keywords: Freeform surface; tool path; ball end milling

2020 ◽  
Vol 10 (3) ◽  
pp. 179-190
Author(s):  
Paulus Wisnu Anggoro ◽  
Abet Adhy Anthony ◽  
Mohammad Tauviqirrahman ◽  
Jamari ◽  
Athanasius Priharyoto Bayuseno ◽  
...  

In this study, ethylene-vinyl acetate (EVA) foam orthotic shoe insoles with different surface roughnesses (Ra) are investigated in terms of CNC milling strategy. Based on a hybrid Taguchi-response surface methodology (TM-RSM) approach, machining parameters, including tool path strategy, spindle speed, feed rate, and step over, as well as material hardness, are of particular interest. The main aim of this work is to develop mathematical models and determine the optimum machining parameters. Experiments are conducted on a CNC milling machine with a standard milling cutter and run under dry coolants. The optimal conditions are established based on TM and then used to determine the optimum values in the RSM modeling. The main finding of the present work is that there are significant improvements in the Ra, by up 0.24% and 4.13%, and machining time, by up 0.43% and 0.41%, obtained with TM-RSM in comparison to TM analysis.


2015 ◽  
Vol 15 (3) ◽  
pp. 293-300 ◽  
Author(s):  
Nandkumar N. Bhopale ◽  
Nilesh Nikam ◽  
Raju S. Pawade

AbstractThis paper presents the application of Response Surface Methodology (RSM) coupled with Teaching Learning Based Optimization Technique (TLBO) for optimizing surface integrity of thin cantilever type Inconel 718 workpiece in ball end milling. The machining and tool related parameters like spindle speed, milling feed, axial depth of cut and tool path orientation are optimized with considerations of multiple response like deflection, surface roughness, and micro hardness of plate. Mathematical relationship between process parameters and deflection, surface roughness and microhardness are found out by using response surface methodology. It is observed that after optimizing the process that at the spindle speed of 2,000 rpm, feed 0.05 mm/tooth/rev, plate thickness of 5.5 mm and 15° workpiece inclination with horizontal tool path gives favorable surface integrity.


2016 ◽  
Vol 4 (2) ◽  
Author(s):  
Abdolreza Bayesteh ◽  
Junghyuk Ko ◽  
Martin Byung-Guk Jun

There is an increasing demand for product miniaturization and parts with features as low as few microns. Micromilling is one of the promising methods to fabricate miniature parts in a wide range of sectors including biomedical, electronic, and aerospace. Due to the large edge radius relative to uncut chip thickness, plowing is a dominant cutting mechanism in micromilling for low feed rates and has adverse effects on the surface quality, and thus, for a given tool path, it is important to be able to predict the amount of plowing. This paper presents a new method to calculate plowing volume for a given tool path in micromilling. For an incremental feed rate movement of a micro end mill along a given tool path, the uncut chip thickness at a given feed rate is determined, and based on the minimum chip thickness value compared to the uncut chip thickness, the areas of plowing and shearing are calculated. The workpiece is represented by a dual-Dexel model, and the simulation properties are initialized with real cutting parameters. During real-time simulation, the plowed volume is calculated using the algorithm developed. The simulated chip area results are qualitatively compared with measured resultant forces for verification of the model and using the model, effects of cutting conditions such as feed rate, edge radius, and radial depth of cut on the amount of shearing and plowing are investigated.


2014 ◽  
Author(s):  
Nandkumar N. Bhopale ◽  
Raju S. Pawade

The paper presents the surface integrity analysis in ball end milling of thin shaped cantilever plate of Inconel 718. It is noticed that the workpiece deflection has significantly contributed to machined surface integrity in terms of surface topography and subsurface microhardness. The ball end milling performed with 15° workpiece inclination with horizontal tool path produced higher surface integrity which varies with the location of machined surface region. In general, the mid portion of the machined plate shows lower surface roughness and microhardness with less surface defects.


Author(s):  
Zhiyang Yao

In fabricating free-form surfaces, ball end mills are mainly used to reach the final surface finish requirements. In the milling processes, cutter engagement value measures what portion of the cutter is involved in machining at a given instant of time. This paper presents geometric algorithms for estimating cutter engagement values for ball end milling processes of tessellated free-form surfaces. The cutter engagement value calculated here can be used later on in generating efficient cutter paths, as well as performing adaptive feed rate controls.


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