STUDENT ENGINEERING SHOP CNC STARTER MANUAL

STUDENT ENGINEERING SHOP CNC STARTER MANUAL VERSION 1.0 OCTOBER 19 TH 2016 JASON ZENG GRAEME ADAIR PHIL LAYCOCK KENNETH WONG

Contents 1.0 Introduction... 1 1.1 Toolpath Generation... 1 1.2 Allowed Materials... 2 1.3 Background Information... 2 1.4 Equations... 3 1.5 Available Tools... 4 2.0 Milling Operations... 6 2.1 Cutting Methods... 6 2.2 Cutting Operations... 7 3.0 CNC Operations... 8 3.1 Turning on the Machine... 8 3.2 Jogging the Table... 9 3.3 Clamping Work Piece... 10 3.4 X and Y Axis Coordinate Zeroing... 11 3.5 Z Axis Offset... 13 3.6 Loading Toolpath onto CNC... 15 4.0 Citations... 16

1.0 Introduction The purpose of this guide is to introduce the student to using the Computer Numerical Control (CNC) machine within the E5 student machine shop. Students are welcome to and are encouraged to make suggestions and additions to this guideline. This guide is split into 3 sections. The first section will talk about general background on milling, machining, and tool speed calculations. The second section will introduce some general Mastercam usage tips. The third section are the instructions for operating the CNC machine itself. Consult with a shop technician prior to starting your job. Bring a drawing to discuss your part with the technicians. Speak with the manager at the main Engineering Machine Shop (E3 2121) and fill out a form to bring to the student shop CNC technicians to set up an appointment. You will then need to purchase stock material from Engineering Machine Shop (will need an account number or money on Watcard) and machine it to proper dimensions prior to loading it on the CNC. 1.1 Toolpath Generation Create your CAM (Computer Aided Manufacturing) toolpaths by Mastercam; Mastercam X9 is installed in the Gear, Helix and Wedge lab computers. Students can sign out a dongle to access the CAD room computer. Students are required to bring in their CAM toolpaths to the technicians for inspection prior to using the CNC machine. Students are expected to learn Mastercam through self-study and can get help from the technicians. There are a number of online resources to help you with this, Mastercam Getting Started Series is a good start. Students are also required to know machining fundamentals. This guide will provide some of the main concepts, more can be found through other online resources. Mastercam Getting Started Series see Machine Shop Website for link Helman CNC G Code - Beginners guide to G code (not essential, good to know some to understand the language used to control CNC machines) http://www.helmancnc.com/simple-g-code-example-mill-g-code-programming-for-beginners/

1.2 Allowed Materials Below is a list of the materials that are allowed to be machined on the Engineering Student Machine Shop CNC. Aluminum Mild Steels Plastics Brass Bronze See Engineering Machine Shop (EMS) CNC Operators or student shop CNC operators about any other materials 1.3 Background Information Here is a list of background information and tools for generating the speeds of the CNC machine for your toolpath. A general milling diagram with important terminology can be found in Figure 1. Figure 1 - General Milling Diagram [1] Feed Rate (Milling Machine) refers to how fast a milling-tool moves through the material being cut. This is calculated using the Feed Per Tooth (FPT) to come up with the Inches Per Minute (IPM) that a milling cutter can move through a particular type of material. Thus,

a Four-Flute End-Mill will cut through material at twice the speed of a Two-Flute End Mill. Feed Rates will decrease with dull tools, a lack of coolant, or deep cuts. Diameter refers to the diameter of the cutting tool-bit(mill/drill). *As the diameter gets bigger use a slower RPM. RPM (Revolutions Per-Minute) is the turning speed of whatever is spinning. On a Mill or a Drill it is the rotation speed of the cutting-tool. *Using Cutting Speed and Diameter you can calculate RPM as shown further down on this page. When calculating spindle speed (RPM), round down to the slower speed option offered by your Lathe/Milling Machine/Drill. Operations like Threading, Knurling, or Parting-off, require much slower speeds (Generally 1/3 to 1/4 Calculated RPM for Threading, Knurling & Parting-off). 1.4 Equations Using the following formulas and Table 1-3, calculate the spindle speed, cutting feed and feed rate for your part. Use the lower bound speeds, only use higher speeds after consulting a technician. Spindle Speed (RPM) Spindle Speed = Cutting Speed (Suface Feet per Minute) 12 Tool Diameter (D) π *note SFM values are different for milling and drilling Cutting Feed (IPR) Cutting Speed (IPR) = Feed per Tooth (IPT) Number of Teeth Feed Rate (IPM) Feed Rate (IPM) = Cutting Rate (Inches Per Revolution) Spindle Speed (RPM) Table 1 - Approximate Material Cutting Speeds Material Cutting Speed High- Speed Tool (SFM) Cutting Speed Carbide Tool (SFM) Low Carbon Steel i.e SAE 1020 High Carbon Steel i.e. SAE 4140, 4340 80-120 300-400 60-100 200 Aluminum i.e. 6061 400-700 800-1000 Brass & Bronze 110-300 600-1000 Plastics 200-500 1000

Table 2 - Approximate feed rates for end mills (Feed Per Tooth) Material.050 Depth of Cut.250 Depth of Cut 1/8" 3/8" 1/2" 3/8" 3/4" Plain Carbon Steels (SAE 1020) High Carbon Steel i.e. SAE 4140, 4340 Cast Aluminum - Hard.0005-.001.002-.003.003-.004.001-.002.002-.004.0005-.001.001-.003.002-.004.001-.002.003-.004.001.003.005.003.006 Brasses & Bronzes.0005-.001.003-.004.004-.006.002-.003.004-.006 Plastics *Much Variation.002.004.005.003.008 Table 3 - General table for drilling speeds (DFM, RFM) Material AISI/SAE/ASTM Designation Drilling Feet/Minute Reaming Feet/Minute Free machining plain carbon steels 1108, 1109, 1115, 1117, 1118, 1120, 1126, 1211 100-120 75-80 Free machining alloy steels (resulfurized) Wrought aluminum 4140, 4150 30-90 15-60 6061-T6, 5000, 6000, and 7000 series. 350-400 350-400 The student machine shop has tool libraries available for aluminum and steel for use in creating toolpaths Mastercam. The tools in these libraries have calculated feed rates and spindle speeds contained within them. Ask the CNC Technicians from the Student Engineering Machine shop in order to obtain the libraries. You can use the equations and tables above for reference and for future calculations for any new tools or perhaps on your own CNC machine. 1.5 Available Tools Choose the appropriate tools for your job. Pick a tool with a length and diameter that is sufficient for the cutting procedure. The tools in Table 4 are available in the Engineering Student Machine Shop. Please inquire about additional tools from the Student Shop Technicians if additional tools are required.

If you load in a new tool by yourself, it is VERY IMPORTANT that you enter tool offsets properly and get a technician to verify it before starting your job. Table 4 - Tools available in the Engineering Student Machine Shop Tool # Tool in use 1 1/4 Spot Drill 2 1/8 Carbide End Mill (4 Flute) 3 3/16 Carbide End Mill (4 Flute) 4 1/4 Carbide End Mill (4 Flute) 5 5/16 Carbide End Mill (4 Flute) 6 3/8 Carbide End Mill (4 Flute) 7 1/2 Carbide End Mill (4 Flute) 8 3/4 HSS End Mill (4 Flute) 9 1 End mill (3 Flute Index able insert) Used for Facing and Roughing 10 2 Face Mill Used for Facing 11 3/8 Bull Nose End Mill (4 Flute) Used for Roughing 12 1/4 Ball Nose End Mill (2 Flute) 13 3/8 Ball Nose End Mill (2 Flute) 14 1/2 Ball Nose End Mill (2 Flute) 15 16 17 18 Drill Chuck 19 Drill Chuck 20 Drill Chuck ( Used for set up)

2.0 Milling Operations This part will introduce methods and operations of milling. 2.1 Cutting Methods There are two methods of cutting when milling, conventional and climb milling, which can be seen in Figure 2. Conventional Milling Cutter rotates against the direction of the feed Width of metal chip starts from zero and increases as the cutter finishes slicing Upward forces are created that tend to lift the workpiece during face milling Surface finish is worse because chips are carried upward by teeth and dropped in front of cutter Tools wear faster than climb milling Climb Milling Cutter rotates against the direction of the feed The width of the chip starts at maximum and decreases Chips are dropped behind the cutter, less chips getting cut Less wear, with tools lasting up to 50% longer Improved surface finish because of less recutting Figure 2 - Conventional versus Climb Milling [2][3] Conventional milling is suggested on manual machines since these machines are prone to backlash. The table and the workpiece tends to be pulled into the cutter when climb milling. If there is any backlash, the tool may break if the cutting forces are great enough.

On the CNC, conventional milling can be used to make rough cuts, and a fine or smooth surface finish cut can be done by climb milling. 2.2 Cutting Operations These are some of the basic operations that can be used on the CNC machine. They can be generated in a toolpath through Mastercam. Facing milling of work piece surfaces produces flat surfaces to required length Tool #10 on the CNC tool carousel Figure of facing to the right [4] Pocketing An end mill is fed across the workpiece at a certain spindle RPM to make features such as a profile, slot, pocket, or even a complex surface contour The depth of a feature can be made in one pass or in multiple passes of small depth of cuts. Multiple passes is generally preferred to reduce load on cutter tool A roughing pass with a rough cutting tool is typically first used to cut most of material and then a final finishing pass with a sharper tool is used for a better surface finish Figure of facing to the right [5] Drilling Use tools #18 and #19 for attaching desired drill bits Use a spot drill or center drill the hole to initially mark hole positions Make the drill operation deeper for through holes such that the drill passes the bottom of stock Can also drill a pilot hole and drill at a manual drill press Figure of drilling to the right [6]

3.0 CNC Operations The CNC is NOT to be operated without supervision by an approved CNC technician. Students should be first trained by a technician prior to using the machine. The following sections should only be used for reminders/references. 3.1 Turning on the Machine 1. Press POWER ON 2. Make sure EMERGENCY STOP is off 3. If machine has not been operated on for more than 3 days, run a spindle warmup program. This will be a half hour long program. Figure 3 - Start and Emergency Stop

3.2 Jogging the Table To jog the table: 1. Press the HANDLE JOG button on the panel 2. Select the axis you would like to move i. E.g. Move X axis, press +X or -X 3. Select the jogging step size. 0.01 or 0.001 or 0.0001. 4. Rotate the handle jog dial to move the axis Figure 4 - Manual Jog Controls Figure 5 - CNC XYZ Coordinates

3.3 Clamping Work Piece The following is an example of clamping in a cubical work piece. Setup may be different for different work piece shapes and sizes. 1. Make sure that the work piece is clamped in the vice 2. If workpiece is mounted parallels, half tighten clamp and use a rubber hammer to hammer down the work piece until the parallels are tight and cannot slip out. Then fully tighten the vice Figure 6 - Clamping Workpiece in Vice

3.4 X and Y Axis Coordinate Zeroing An example is shown below for finding the X and Y coordinate zeros for a rectangular work piece. Depending on your work piece, the edges may be different but the process of inputting the zero coordinates into the machine will not. The process is as follows: 1. Switch to tool 20, the empty drill chuck, to hold the edge finder 2. Press MDI, then ORIENT SPINDLE to lock up spindle to tighten edge finder easier (DO NOT TORQUE TOO HARD) 3. To switch the tool: i. Press MDI/DNC ii. Type in T20 This will select Tool #20, which is the empty chuck iii. Press ATC REV 4. The edge finder needs to be rotating when it is finding an edge i. Press MDI/DNC ii. Should read S750 M03 on the Memory panel. Can also manually type in S750 M03 to start spinning the spindle at 750 RPM iii. Press ENTER to run program, spinning spindle at 750 RPM 5. Handle jog the edge finder to the Y axis reference point 6. Slowly jog the edge finder until it touches the edge and the bottom moves Figure 7 - Using the Edge Finder to Find Y Zero Offset On the panel: 1. Press Position 2. Select the axis you want to zero and then press Origin 3. Offset the radius of the edge finder by moving in 0.100 4. Press Origin 5. Press OFFSET until WORK ZERO OFFSET is highlighted

6. Scroll over to the Y axis column 7. Press PART ZERO SET to set the zero coordinate to this location Figure 8 - Y Axis Zero Offset On Panel Above is an image of the work panel screen after you have found the zero coordinate for the Y axis. Notice at how for the Work G54 column, the value is 0.0000. Figure 9 - Using the Edge Finder to Find X Zero Offset

For finding the X axis zero coordinate, the process is the same as above, except the edge finder needs to be moved to the edge you want to zero. 3.5 Z Axis Offset To pick up the zero coordinate on the z axis: 1. Mount a dial gauge into the empty chuck (Tool 20) 2. Place a 123 bar vertically onto the platform 3. Adjust the dial gauge such that the tip will touch the 123 block at an angle 4. Slowly jog the Z axis down for the dial gauge to touch the 123 block 5. Bring down the dial gauge until you get a reading on the dial gauge (remember the value of the reading on the dial gauge) 6. On the panel, i. Press POSITION ii. Press Z+ or Z- to access the Z axis coordinates iii. Press ORIGIN 7. This process will give you a reference point for zeroing the top face of your work piece Figure 10 - Z Axis Zero Offset 8. Next, jog up the dial gauge to touch the top face of your workpiece

9. Lower the Z axis until the dial gauge reads the same value as previously on the 123 bar Figure 11 - Z Axis Offset On Panel 10. On the panel, i. Press Offset until the WORK ZERO OFFSET panel is highlighted white ii. Type in the value indicated in the operator column for the Z axis on the Work Zero Offset Z axis column iii. Press F1 to zero the work piece top face

3.6 Loading Toolpath onto CNC To load your toolpaths: 1. Insert a USB stick onto the side panel 2. Press LIST PROGRAM 3. Select over to the USB tab 4. Select your NC toolpath 5. Press SELECT PROGRAM 6. Press Enter After going through these steps, your generated toolpath will be copied over to the machine and machine is ready to run your toolpath. Figure 12 - Loading NC Program into CNC

4.0 Citations [1] CustomPartNet. Milling Speed and Feed Calculator. Digital image.custompart.net. N.p., 2008. Web. 24 May 2016. <http://www.custompartnet.com/wu/milling>. [2] Rocketmagnet. Conventional Milling. Digital image. Wikipedia, 13 Aug. 2007. Web. 24 May 2016. https://commons.wikimedia.org/wiki/file:conventional_milling_01.png [3] Rocketmagnet. Climb Milling. Digital image. Wikipedia, 7 Aug. 2007. Web. 24 May 2016. <https://commons.wikimedia.org/wiki/file:climb_milling_01.png>. [4] CustomPartNet. Face Milling. Digital image. Custompart.net. N.p., 2007.Web. 24 May 2016. <http://www.custompartnet.com/wu/milling>. [5] CustomPartNet. Axial Depth of Cut. Digital image. Custompart.net. N.p., 2007. Web. 24 May 2016. <http://www.custompartnet.com/wu/milling>. [6] CustomPartNet. Drilling. Digital image. Custompart.net. N.p., 2007.Web. 24 May 2016. <http://www.custompartnet.com/wu/milling>.