Using Pro/MFG Milling Operations Creo 2.0 Machining a Mast Step If the Trim option is grayed out when trimming the mill volume, Save (making sure the.asm file is going to the correct subdirectory), Exit and Restart Creo. Important Note: Color prints must be printed on a color printer! Don t even begin this assignment without having a basic understanding on how this part is to be machined! Goals: 1) To become familiar with creating tool paths using Pro/Manufacturing Assembling part, work pieces and fixtures Setting up machines and tools Defining operations and NC sequences Creating route sheets 2) To check tool paths for proper operation Using Vericut Important Note 2: There have been cases where Pro/E cannot retrieve a manufacturing file. This is usually because the.asm file associated with the manufacturing operation has somehow been removed from the current directory, or been placed in a different subdirectory. Make sure that your.asm file is in the appropriate working directory before exiting Pro/E. Students have had to start over due to this issue. Basic Start Up Procedure: 1. Copy (Down load) the Kurt Vise files from the 306\kurt_vise_modifiable subdirectory on the V drive. This assembly will be your fixture. 3) Download Raw_stock.igs for the workpiece. Create a part file from this. From the Model tab select Import from the Get Data drop down arrow. The system will set the stock color to be green when assembled as a workpiece. Note that this stock has the bottom surface trued up as well as the side surfaces squared off for fixturing purposes. 3) Download Mast_step.igs for the part to be machined. Create a part file from this. The color should already be set to a bronze shade. Start a Manufacturing File. Use FILE - NEW MANUFACTURING and set the type to NC-Assembly. Use the default Template (do not use the Empty file). Assemble the reference model. Confirm the accuracy setting when prompted. Important Note 1: If the components disappear off the screen, they have been blanked. Select the Unblank option in the Visibility area of the View tab. 1
Assemble the workpiece (the raw stock). This is the Workpiece option in the Components area of the Manufacturing tab. When assembling, ALIGN the underside surface of the Mast Step and the underside surface of the work piece. Simply ALIGN the vertical datum to center the part. Initial machine setup: Select the Work Center Option (Machine Tool Setup area on the Manufacturing tab) and select Mill. Accept the defaults in the Milling Work Center dialog box. Select Operation in the Process area of the Manufacturing tab. Select the Fixture Setup tab. Select the Add a fixture component icon. Assemble the vice. Select the Clearance tab. Define a surface 2 above the bottom of the workpiece. 2
On the Model tab, create a coordinate system to use as the machine 0. You will not be able to create any tool paths unless Z is pointing up! This will be the corner forward left corner of the vise. Note: x is right (short axis of the vise), y is back (long axis) and z is up. Define this coordinate system as the program 0 point. On the Manufacturing tab select the Cutting Tools icon from the Machine Tool Setup area. Set the Name to T1_50_FLAT, the type to END MILL, Cutter Diameter to.50 and Length to 4. The Tool Number (Position) must be set to 1 under the Settings Tab. Apply these modifications. Add the following tools: Note there are additional tools such as a drills and a counter sink for the level 8.5 portion of the assignment. You can add these if and when you get to that point. 3
Volume Milling In order to roughly carve out the inside of the mast step, we will perform a Volume Milling NC sequence. This requires a Mill Volume to be created. Select the Mill Volume Icon from the Manufacturing Geometry group of the Manufacturing tab. You will Sketch (as an extrusion) this volume. The volume starts on the surface where the counter sunk holes are located and will extend 2 above the sketch surface. Make sure you Trim the volume with the mast step before leaving this function. After trimming, make sure your volume is correct by hiding the Mast Step, Raw Stock and the Vise. The shaded image should appear similar to the one to the above. The purpose of this volume is to define the region where the roughing operation will be performed. The tool will stay within the mill volume. Screen Capture the three images shown on this page. They will fit on one sheet. Make sure the model tree is shown on the third image. 4
Selecting the workpiece and in the Model Display drop down under the View tab, select wireframe to clean up the display a bit. Capture this image and add it to the screen captures of the three images. This documents that you have fixtured your part and generated a mill volume properly. Print this page with the four screen captures. We can now do volume rough milling on this region. Select the Volume Rough icon from the Roughing drop down arrow in the Milling region of the Mill tab. The Seq Setup menu appears. Make sure Tool, Parameters, Volume, Start and End are checked. Select Done. Select the ½ flat end mill. The Mfg Params menu appears. Select Set and define the Parameters as follows: Set the Bottom_Stock_Allow to 0 otherwise a - value will default to the prof_stock_allow for Volume milling 5
Select OK. Select your mill volume (from the graphics area, not model tree). When prompted to Select a datum point for the tool s original location, create and select a datum point 2 inches above your machine zero coordinate system for start and end points. It is critical that all your tools start and end at this location. Set the display to wireframe mode (set the vise to shaded) and then Select Play Path - Screen Play and hit the Play forward button. If the tool is not shown at APNT0 then choose SEQ SETUP and check the box for Start and End again. Repaint the screen and re-run the path. If you don t like something, or need to make a change to any parameters, simply select the appropriate option from the SEQ SETUP menu select Done, you are prompted for your change and eventually you can re-run your path. This is the methodology for making changes. You need to get used to using it. Screen Capture an image similar to what is shown to document your roughing tool path. The instructor is looking to see the red center line of the tool as well as checking to make sure the tool starts and stops at the correct location. Select NC Check from the NC Sequence Menu Manager to double check the tool path as a shaded image. This starts up VERICUT. Important VERICUT notes: VERICUT will have problems if: You have assembled the workpiece BEFORE you assembled the part (mast step) You have duplicate tool numbers (postion) set for different tools You run out of disk space (Pro/E and Vericut exit, and then every time you load your mfg file, Pro/E exits). Delete the last.tph file to cure this problem. Be patient while the model loads, then zoom out (in Vericut) until the entire model fits in the window. It is best not to zoom or pan the Vericut image after this point or the resultant display will be poor. Vericut only shows maching on the Workpiece. This means that if the workpiece is not assembled correctly, Vericut will appear to be offsetting the tool path incorrectly relative to the workpiece itself. You will not see the bottom of the vise as that is surface geometry. If you rotate the image in Vericut, resolution suffers. Rewind and re-run the tool path to improve the image. 6
Select Ignore All Changes when ever this dialog box appears Exit Vericut and return to Creo. Local Milling One a roughing sequence has been performed, we would like to go in with a smaller tool and remove material that wasn t hogged out with the large tool before finishing the surface. This will be accomplished using the following methodology: Select the down arrow from the Milling group on the Mill tab. Select Local Milling, Previous Step. Select the Volume Mill NC Sequence. Tool, Parameters, Start and End must also be checked. Use the ¼ Flat end mill and set the Parameters as shown. Run your tool path, making sure the tool starts and stop in the correct location. Run both the Volume Mill and Local Mill toolpaths in Vericut, following the instructions below. Mouse pick both nc sequences, RMB and select Material Removal Simulation. This will execute both tool paths in Vericut, one over the top of the other to verify that your tool paths are executing properly. 7
Surface Milling Create a new NC sequence to machine the interior of the mast step (see below). This will be done as a surface mill using the 1/4 inch ball end mill. Don t forget to select the proper tool and the start and end locations. The Mfg Params are set as shown. Note that in real life, the step over would be set to a real small value to improve the surface finish. We are using.02 so the instructor can check the tool direction and so that the tool path generates faster, reducing the amount of time waiting on the computers. The surfaces to mill are shown below. If you skip over the Cut Definition, select the Define Cut option from the Seq Setup menu. When specifying the Cut Definition Cut Type, select From Surface Isolines and toggle the direction (button at the lower left corner of the Cut Definition dialog box, so the cuts are made as shown. The White arrows show where toggling was performed (the icon right above the OK button. Run the toolpath. 8
Use the Preview option in the Cut definition dialog box to display the actual tool path. It will show as pink and you can see if you toggled the dirction correctly. Screen Capture the images similar to the ones shown above and print this documentation of this tool path as before. Note: Answers to all questions should be placed on a separate, single sheet of paper using a word processor. Question 1. a) What is the default SCAN-TYPE? This refers to the PARAMETERS for the Volume Milling NC sequence. b) What is the definition of this? (See help pages) c) What is the default ROUGH_OPTION for the Volume Milling NC Sequence? Question 2 a) What is the definition of Prof_Stock_Allow b) What is the definition of Bottom_Stock_Allow? b) Why would you use them? Use Vericut to display and print all the cutting sequences using the methodology on page 8. We need to change some colors first. To change the background color to white, do the following: Select EDIT COLORS and Under the Define tab, Select on BACKGROUND button under Flat Colors.Move all the sliders to 255 (white) Select Apply and OK Note: the screen background will not have turned white yet. Next select View-Attributes and set the Background Style to Flat. The background should now be white. 9
If you are not doing Level 8.5 or 10 then on the Tools tab, in the Investigate region select Manufacturing Info and pick on the Route button. Screen capture this data, add your name, MET 306.00X at the top of the page. 1) Display your Tool Setup Table, screen capture this and paste it below the Route sheet. Make sure the Cutter Diameters are visible. This will be the last page in your packet. End Level 7 Begin Level 8.5 It is now possible to drill some holes inside the cavity that will be used to fasten this part to the deck of the boat (and also allow us to fixture the part for doing final machining). Holemaking (Standard, from the Holemaking Cycles area) Make sure you label these images similar to Level 7. Note that the center lines of the holes come in as curves (yellow) and not feature axis from the IGES file. You would need to use the datum points that locate the center of the holes to produce your own axis for the drilling operation. This would be done at the part level. We need additional tooling; specifically a.1 diameter center drill with a length of 1, a.201 diameter drill with a length of 2 and an 82 degree countersink with a cutter diameter of.75 and a length of 2. Add these tools to your tool table. Center drill the holes, drill through the part with the.201 drill and finally countersink the holes. Note the dimensions for the center drill. If you have the length dimensions incorrect (the overall length shorter than the short length) Vericut will not display the center drill operation properly 10
Use a Cut_Feed of 15, a Spindle_Speed of 2500 and a Clear_Dist of.25. for all of these tools. Create NC Sequences in this order, remember to set the start and end points (see Clearance tabs): 1) Center drill the holes.1 as in point one inches deep (Standard Drilling) 2) Drill the holes. (through) 3) Countersink the holes. Hints: The short axis on the mast step are a function of the iges import. You cannot select on these axis for drilling purposes. Create new axis at the part level. Select both the start and end heights. Screen capture images similar to the two show below to document the Center Drill sequence. Hide geometry so we can see the net result! The tool is positioned in the Front view by using the Position Cutting Tool button in the Play Path dialog box. Remember, you are documenting your work. The instructor is checking to make sure the tool and holes are in the proper position. If it is not readable, you will not be given credit! 11
Screen capture as before and print one page with two images to document your Drilling NC sequences. Screen capture as before and print one page with two images to document your Drilling - Counter Sink NC sequence. Hint: Use your Mast Step part file for determining dimensional values. Look at the Details option under the Reference tab. Pay attention to all the options available to you in the Holes dialog box. Answer the following question (on this page). How did you determine how deep to specify the countersink? 4) Run all your NC sequences in Vericut and screen capture and print the result. 5) If you are not doing 10 then on the Tools tab, in the Investigate region select Manufacturing Info and pick on the Route button. Screen capture this data, add your name, MET 306.00X at the top of the page Display your Tool Setup Table, screen capture this and paste it below the Route sheet. Make sure the Cutter Diameters are visible. This will be the last page in your packet. End Level 8.5 12
Final Machining Operations Begin Level 10 We wish to machine the rest of the surfaces. The mast step will be removed from the vise and simply mounted on a square post (4 x 4 x 5 high) using the drilled and counter sunk holes to attach the step to the fixture. It is easiest to edit the definition of OP010 and hide the old fixture and assemble a new one. Hints: Make sure that your mill volume encompasses the entire workpiece and has a hole in it to reduce the air milling that would be done if solid. Shaded Mill Volume: Screen capture the images similar to the ones shown above and place on a single page in an artful manner. We need another tool, a ½ ball end mill. For the Volume Rough Mill sequence, select Rough_Only, not Rough and Profile. Use a Type_Spiral Scan_Type and not Type_3. Use the same milling parameters as done for the Rough Mill in Level 7. 13
Run this through Vericut to get an idea of how the tool path will effect material removal. Document both of these as shown below and Print. Do not do a Local Mill. Create a surface mill NC Sequence, with a ½ diameter ball end mill with same speeds/feeds and step over that was used in the cavity. Not that the tool goes around the part, and does not machine in the vertical direction. Hint: Hide the stock, volume mills etc. to allow easier surface selection. Do not select the small, vertical surfaces Document as before, two captures as above and Print. 14
Note that the bottom outside edge needs machined. This needs to be cleaned up with a Trajectory milling NC Sequence. Use a ½ flat end mill, use the bottom edge of the part for the trajectory, making sure the tool is on the outside of the part. The feed rate should be set to 10, the clearance distance to.25 and the spindle speed to 2000. Hints: When doing the Trajectory Mill. The Tool Motion (tab) is a function of a curve. IE create a curve (path for the tool to follow) in the Mast_Step part. Document as before and Print. If you are finished the Level 10 portion: On the Tools tab, in the Investigate region select Manufacturing Info and pick on the Route button. Screen capture this data, add your name, MET 306.00X at the top of the page. Display your Tool Setup Table, screen capture this and paste it below the Route sheet. Make sure the Cutter Diameters are visible. This will be the last page in your packet. End Level 10 Keep reading; more information follows on the next page. 15
Level 7 (6 pages + cover sheet) Required Documentation 1) Screen Capture four images, initial set up from page 4 & 5. 2) Screen Capture Creo images for Volume Mill, Local Mill 3) Screen Capture two images for Surface Mill 4) Answers to Question 1 & 2 5) Screen Capture Vericut result 6) Route sheet and Tool Table Level 8.5 (10 pages + cover sheet) 1) Items 1-5 from Level 7 2) Screen Capture two images for Center Drill 3) Screen Capture two images for Drill 4) Screen Capture two images for Counter Sink 5) Screen Capture Vericut result 6) Route sheet and Tool Table Level 10 (15 pages + cover sheet) 1) Items 1-5 from Level 8.5 2) Screen Capture three images showing fixture and mill volumes 3) Screen Capture two images for Volume Mill 4) Screen Capture two images for Surface Mill 5) Screen Capture one image for Custom Trajectory 6) Screen Capture Vericut result 7) Route sheet and Tool Table All color prints, no exceptions. 3 point penalty for non-compliance. This means you! Other Deductions: Incorrect answers to questions -.25 No Route Sheet -1 Start/End locations for tools not correct -.5 Incorrect tool chosen -.5 Other Possible Errors and How to Correct Them If there is major gouging in the surface milling nc sequences, check the Screen Play to see if there are rapid movements (yellow dashed lines) that are intersecting the reference model geometry. If that is the case then more than likely a retract surface has not been set. The only fix is to delete the NC sequence in question, set the retract surface in the Operation Setup and recreate the NC sequence. Other notes (valuable if you plan on taking METBD 452 Rapid Prototyping): If you were to take these files to a specific CNC machine, you would need to do two things. The first would be to generate APT code and the second would be to take this APT code and post process it for the specific controller on you CNC machine. To write out the APT code to disk Select Save A CL File in the Output region of the Manufacturing tab. Select the entire Operation. Then you would Post a CL File (same location in the ribbon). Select the appropriate post processor from the list shown (pay attention to the prompt line to see the description). A file.tap file is then generated with the appropriate G codes. 16