Advisor: Dr. Khalifa Harib Machining of sculptured surfaces using CNC Machine Tools (Mechanical Engineering) Ahmed Ishaq Al-Balooshi Abdulaziz Al-Obaidli Mohammed Al-Habshi Advisor: Dr. Khalifa Harib

Preview Abstract Background Theory Methods & Techniques Results & Discussions Concluding Remarks Questions

Abstract Goal To Achieve This Goal To machine 3-D sculptured surfaces using CNC machine Tools. To Achieve This Goal Sculptured Surface representing the 3-D shape of a shoe sole was selected

Abstract The importance of this project What is new in this Project ? The need of background theory

Abstract Project Modules Establishing the link between the CNC & PC Acquisition of control points of a shoe sole for geometric modeling using parametric surfaces Geometric modeling of the shoe sole Machining of the shoe sole cavity

Background Theory

Background Theory Fundamentals of Milling Milling is the process of cutting away material by feeding a work-piece past a rotating multiple tooth cutter

Background Theory Fundamentals of Milling Milling Machine The machine for holding the work-piece, rotating the cutter, and feeding it is known as the Milling Machine

Background Theory Fundamentals of Milling CNC Machine CNC: Computer Numerically Controlled The most advanced CNC milling-machines is the 5-axis machine

Background Theory Fundamentals of Milling History The first NC machine was developed by MIT by a commission from US Air Force in 1949. It was demonstrated in 1952 Advantages Easier to program, change a program NC machines are safer to operate Cheaply production of Complex geometry Usually generates closer tolerances than manually operated machines

Background Theory Fundamentals of Milling CNC Tools Material Blanks Work-pieces Cutting Tools End-mills, V-mills Nose-Ball mills Collets Tools Holders

Background Theory Fundamentals of Milling NC Programming The programmer writes the instructions for the machine controller to specify: Loading/unloading cutting tool Cutting conditions (speed, feed, coolant) Start point and end point of a motion segment How to move the tool with respect to the machine?

Background Theory Fundamentals of Milling NC Programming The format for each “instruction" is: ADDRESS[VALUE] Cartesian system used to specify positions Left Hand rule used to specify the motion direction

Background Theory Fundamentals of Milling Modern Machining System Complex shapes need to be produced Complex Mathematical Functions & Programming CAD/CAM Softwares

Background Theory Connection Cable Interface Ethernet Connecting Ethernet is a local area technology, with networks traditionally operating within a single building, connecting devices in close proximity

Background Theory Fundamentals of NURBS NURBS: Non-Uniform Rational B-splines Considered as a powerful tool for geometric design. Played a pig role in the CAD/CAM world

Background Theory Fundamentals of NURBS A NURBS surface with control points Pij (0≤i ≤ m, 0 ≤ j ≤ n) can be defined as

Background Theory CAD/CAM Softwares MasterCAM Founded in 1984. MasterCAM is an integrated CAD/CAM software package. By MasterCAM we can create geometries and prepare engineering details, graphical tool-paths, and NC code.

Background Theory Fundamentals of Machining Parameters Feed rate (mm/min) = feed per tooth (chip thickness) = number of cutter teeth = rotation of the cutter, rpm

Background Theory Fundamentals of Machining Parameters Cutting Speed & Spindle Speed S = Cutting Speed in m/min D = tool outside diameter rpm = tool rotational speed Cutting speed should be in the range of 80 – 100 m/min

Methods & Techniques

Methods & Techniques Procedures “General” Geometric & Tool-path Modeling CNC Machine Tools Machining PC to CNC Link Real Object No Yes Accepted Finish

Methods & Techniques Procedures “Our Case” Familiarization with the machine Machining Establishing Connection CNC  PC No Yes Accepted Finish

Methods & Techniques Selected Application Application: Create a casting mold for the shoe sole as one part In-Sole Out-Sole Slip-Sole

Methods & Techniques Selected Application After Casting is taking Place Male Part Female Part

Methods & Techniques Creating the Male Part of the Mold Complexity of the Male Part The male part couldn’t be designed on any CAD/CAM software using the standard 3-D shapes i.e. box, sphere, cone …etc. The complexity of the male part design is coming from the fact that the male part surface should reflect the curvatures of the human foot

Methods & Techniques Creating the Male Part of the Mold To understand the curvatures of the human sole a clay sculpture of a human sole was created.

Methods & Techniques Creating the Male Part of the Mold Control Points Digitizing

Methods & Techniques Creating the Male Part of the Mold 1st Technique : Modifying the digitized data and use it as control points to define different splines. Creating rule surface from the defined splines 2nd Technique : Define cross & along splines from the digitized data Creating swept surface from the defined splines

Methods & Techniques Creating the Male Part of the Mold 1st technique Modification: 1. Taking less number of control points in drawing each spline. 2. Changing the depths which make the complex curves to acceptable values. 3. Drawing the splines in y-direction instead o x-direction

Methods & Techniques Creating the Male Part of the Mold 1st technique Modification: y y x x Splines Drawn in X-Direction Splines Drawn in Y-Direction

Methods & Techniques Creating the Male Part of the Mold Modification Result: Result still very hard to machine and still need more modification Unneeded details This area should be scaled down New modification includes: Scaling dawn the heel area Changing some control points at finger area Appling slope of 0.1

Methods & Techniques Creating the Male Part of the Mold 2nd Modification Result:

Methods & Techniques Creating the Male Part of the Mold 2nd technique: Cross Splines defined by 3 control points Control Point 1 X Y Z located on the internal shoe boundary from left 0 + elevation coming from the slope Control Point 1 X Y Z Middle point z + elevation coming from the slope Control Point 1 X Y Z located on the internal shoe boundary from right 0 + elevation coming from the slope

Methods & Techniques Creating the Male Part of the Mold 2nd technique: Along spline defined by 4 control points Along Spline C 1 C 2 C 3 C 4 55,3,25.7 60,50,21 70,130,13 75,260,0

Methods & Techniques Creating the Male Part of the Mold 2nd technique:

Methods & Techniques Creating the Male Part of the Mold 2nd technique Result: The result of the second technique was satisfied The heights of the shaded area were decreased more

Methods & Techniques Creating the Female Part of the Mold Importance of the Female Part The female part of the shoe sole mold is important as much as the male part, because it contains the cavity, the 2-D boundary of the shoe sole, and the pattern of the bottom shoe sole which is the slip-sole area

Methods & Techniques Creating the Female Part of the Mold The inner boundary was created by offsetting the outer one and by applying trimming functions The 2-D outer boundary was created using control points defined from digitized hand 2-D sketching

Methods & Techniques Generating NC Code files Tool-path of the cutting tool should be created in order to generate the NC code files and send it to the machine for machining. Tool-paths were created in MasterCAM software.

Methods & Techniques Generating male part NC Code Stock was defined for the created male part surafce

Methods & Techniques Generating male part NC Code Surface Rough flow line tool-path 2-D contour tool-path Tool = HSS ball nose D(14mm) Feed = 1000 mm/min Spindle = 2000 rpm Max Depth = 4 mm Width = 14 mm Tool = HSS ball nose D(14mm) Feed = 1000 mm/min Spindle = 2000 rpm Depth = 5 mm (7 layers) Width = 14 mm

Methods & Techniques Generating male part NC Code

Methods & Techniques Generating male part NC Code Surface Rough flow line tool-path 2-D contour tool-path Tool = HSS ball nose D(14mm) Feed = 1000 mm/min Spindle = 2000 rpm Max Depth = 1.25 mm Width = 14 mm Tool = HSS ball nose D(14mm) Feed = 1000 mm/min Spindle = 2000 rpm Depth = 5 mm (7 layers) Width = 14 mm

Methods & Techniques Generating male part NC Code

Methods & Techniques Generating male part NC Code Surface Rough flow line tool-path 2-D Pocket tool-path Tool = HSS end mill D(14mm) Feed = 1000 mm/min Spindle = 2000 rpm Max Depth = 4 mm Width = 14 mm Tool = HSS end mill D(14mm) Feed = 1000 mm/min Spindle = 2000 rpm Depth = 5 mm (7 layers) Width = 14 mm

Methods & Techniques Generating male part NC Code Surface finish flow line tool-path Tool = HSS ball nose D(14mm) Feed = 1000 mm/min Spindle = 3000 rpm Max Depth = 1.25 mm Width = 1 mm

Methods & Techniques Generating male part NC Code Unsatisfied Unsatisfied Satisfied

Methods & Techniques Generating Female Part NC Code Stock was defined for the created male part surface

Methods & Techniques Generating Female part NC Code 2-D pocket tool-path 2-D pocket tool-path Tool = HSS end mill D(14mm) Feed = 1000 mm/min Spindle = 2000 rpm Depth = 5 mm (8 layers) Width = 14 mm Tool = HSS ball nose D(8mm) Feed = 1000 mm/min Spindle = 2000 rpm Depth = 3 mm (1 layers) Width = 8 mm

Methods & Techniques Generating Female part NC Code . Result was verified and satisfied

Results & Discussion

Results & Discussions Machining the mold After verifying the geometry design of the two parts of the mold, the NC codes files were sent to the CNC machine. The machining take place on three different materials: wood, acrylic and mild steel.

Results & Discussions Machining Male Part Used tool-paths: Surface rough flowline 2-D contour Result of machining the male part created by following the 1st technique on wood work-piece

Results & Discussions Machining Male Part The work piece break Used tool-paths: Surface rough flowline 2-D contour Result of machining the male part created by following the 2nd technique on acrylic work-piece

Results & Discussions Machining Male Part Used tool-paths: Surface rough flowline 2-D contour Result of repeating the machining the male part created by following the 2nd technique on wood work-piece

Results & Discussions Machining Male Part Used tool-paths: Surface rough flowline 2-D pocket Surface finish tool-path Result of machining the male part created by following the 2nd technique on wood work-piece

Results & Discussions Machining Male Part Used tool-paths: Surface rough flowline 2-D pocket Surface finish tool-path Result of machining the male part created by following the 2nd technique on acrylic work-piece

Results & Discussions Machining Female Part The tools exceed the supposed depth and break through the work piece Used tool-paths: 2-D pocket in two operations Result of machining the female part on acrylic work-piece

Results & Discussions Machining Female Part Break reasons & soltions The break through was happened because the 8 mm in diameter cutting tool was longer than the 14 mm in diameter cutting tool which was used to take the datum point of the work piece. An offset of difference in length between the two cutting tools should be considered and defined on the CNC machine in order to avoid this problem

Results & Discussions Machining Female Part Used tool-paths: 2-D pocket in two operations Result repeating the machining of the female part on acrylic work-piece

Results & Discussions Machining Female Part Used tool-paths: 2-D pocket in two operations Result of machining the female part on mild steel work-piece

Results & Discussions Machining Female Part Break reasons Tool break was happen because the cutting tool was entered the work-piece suddenly and perpendicularly to a depth of 5 mm and experienced a very high reacting force which resulted in the break of the tool.

Results & Discussions Machining Female Part Solutions: Changing the method of entering the work piece from a sudden perpendicular entering to gradual helical entering. Using carbide cutting tools with two flutes. Using a coolant while machining taking place. Using mild steel manufactured for machining purposes

Results & Discussions Casting result After machining the two parts of the mold, wax is injected in the mold in order to create the designed shoe sole.

Concluding Remarks

Concluding Remarks Machining Female Part The objective of the project was achieved EDM technique can be used for machining molds on mild steel or other tough materials It is recommended to involve industrial partner to such projects so that the project outcomes can be transferred to the industry

Concluding Remarks Machining Female Part 4. customized geometric modeling software can be developed to optimize the machining of sculptured surface by optimizing the NC program. 5. This project will be beneficial for UAE University students by encouraging them to do similar projects and transfer this technology to the society to build healthy and diversity UAE economy.

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