Fundamentals of Mechanical Engineering CAE Project

 

    This project emphasizes the modern practice of “paperless” engineering design, analysis, and manufacture.  In teams of two, you will design a wrench using the software package ProEngineer (available in the mechanical engineering and Wean Hall computer clusters) to produce a two-and-a-half-dimensional extruded model.  You will also dimension the drawing.  In the second part of this project, completed mid-semester, you will analyze the stresses within the wrench using a computer-generated finite element model with the program Ansys.  You will also compare the results of the model to hand calculations of stresses in the wrench’s handle based on beam bending theory.  Finally, near the end of the semester, you will program a Haas multi-axis CNC milling machine using the software ProManufacture, and them mill a wrench from the aluminum blank that you will have already made in the student machine shop.  In each step of this project, you will be working with industrial-grade engineering software and equipment.  At the end of the semester, you will have in hand an aluminum wrench that you designed, analyzed for stress, and manufactured without needing to use a sheet of paper.

    This first module of instruction is designed to take a person who has never used ProEngineer through the process of creating a two-and-a-half dimensional component.  That terminology refers to a part that is drawn in a plane and then extruded perpendicular to that plane.  These instructions are not a complete guide to using ProEngineer.  For that, you are referred to the extensive set of instruction books available in the mechanical engineering computer cluster.  The Department of Mechanical Engineering also offers non-credit self-paced minicourses in ProEngineer and other CAE packages.  Once you understand these instructions, however, you should be able to read the ProEngineer “Parts” volume and be able to create more complex three-dimensional parts.

   

Part Modeling in Pro/Engineer Wildfire

Developed by John Bellinger

Last Updated: February, 2006 for Pro/E Wildfire 3.0 by David Urban 

Introduction

    In this tutorial we will be creating a three-dimensional model of a wrench. Three dimensional modeling is a vital part of the CAE process; without a model there would be nothing to analyze or machine. The wrench you will be making is double ended, with jaws of 1 and 1.25 inches. It will be made from aluminum. When you are finished your model will look like below.

 

Setup

    

 

Step 1: Start ProE Wildfire from Start - All Programs - PTC - Pro/Engineer - proewildfire

 

Step 2: From the left side of the screen, right-click on your W: drive (near the bottom of the tree). Select New Folder and name it Wrench. Now select this folder as your working directory (making sure it’s highlighted like “temp” is in the figure below) 

 

Now that ProE is loaded and using the correct directory, we will create a new part that will become the wrench.

 

Step 3: Select the Create New Object icon  . This will bring up the New window.

 

Step 4: In the Name dialog box type in your name (ignore the “group xx” in the figure below).

 

Step 5: Unselect Use Default Template. At this point the New window should look like this

 

 

Step 6: When the New window is correct, click OK. This will bring up the New File Options window.

 

Step 7: Select inlbs_part_solid. Pro/Engineer lets you work in either the metric or imperial system. Also you can make sheet metal or solid parts. We will be making a solid part in the imperial system.

 

Step 8: Type “24-101 Wrench Project” into the DESCRIPTION box

 

Step 9: Type your name into the MODELED BY box. When you are finished the window should look like this.

 

 

When your window matches the window above, click OK. The screen will change to the Modeling view, which looks like this. The modeling view is used to view and edit three dimensional parts. Later we will see the Sketcher view, which lets us create two-dimensional sketches which we will then turn into solid parts.

 

 

Sketching the wrench body

    In this tutorial, we are creating the wrench as an extrusion. Extrusions are parts with two dimensional geometry and a uniform thickness. To create the body of the wrench, we must sketch the outline in the two-dimensional sketcher view and then give it a thickness to extrude it into three dimensions. We start by modeling the body of the wrench.

 

Step 1: Click the Extrude Tool icon, which is in the toolbar on the right side of the

screen.

The bottom of the screen will change to the following

 

 

Step 2: Press the Placement button (in Red). A tab will pop up as shown:

 

 

Click the Define… button

 

A Sketch window will appear and the prompt at the bottom of the main screen will ask you to Select a plane or surface to define sketch plane. We will be sketching on the plane labeled TOP. Mouse over the label of the TOP plane and it will highlight, as in the picture below.

 

Step 3: Click on the TOP datum plane and click Sketch in the section window. This will bring up the References window. Click Close.

 

NOTE: If the reference window does NOT come up, don’t be alarmed. ProEngineer assumed your references as the other two planes, since there are no other objects to act as references.

 

The screen is now the Sketcher view. Sketcher is used to create or modify two dimensional geometry.

 

 

A quick explanation of the sketcher toolbar is in order next. Not all the tools are used in this tutorial.

 

 

Step 4: The wrench we will be making is symmetric about the horizontal axis. We can therefore save ourselves some time by modeling only the top half and mirroring the features to make the bottom half automatically. Because we know that we will be mirroring the wrench, we should start by making a centerline. Select the right arrow next to Create Lines and select the Create 2 point centerlines button shown here

.  Click on the left side of the horizontal axis, and then the right side of the horizontal axis. This will create a red centerline coincident with the horizontal axis as shown below.

 

Step 5: Now we will create the end of the wrench. Click the right arrow next to the Arc tool to select the Arc fly-out and pick Create an Arc by selecting its center and

endpoints as shown. . Click once on the horizontal axis to the left of the vertical axis to set the center point, then on the horizontal axis further left to set one end point. Move the mouse cursor up and over the center, then back to the horizontal axis and click a third time to finish the arc. The size is not important right now. The finished arc should look something like below.

 

Step 6: We will be dimensioning the arc to be the proper size.

 

Select the blue arrow  at the top right of the screen. When your mouse is over the dimension number you wish to change, it will turn blue as shown:

 

 

Now Double Click the number and you will be able to enter a new value for this dimension:

 

 

Step 7: Change the value of the dimension to 3.00 inches by typing in 3. This will change the distance between the center of the arc and the vertical axis to 3.00 inches.

 

Step 8: Change the radius dimension (shown in blue) to 1.00 inches.

 Your screen should look like this:

 AN ALTERNATIVE WAY OF DEFINING THE RADIUS:

As you will see in the later screenshots, the 1” dimension we just defined can be defined like the 3” dimension shown above (as a distance, not a radius).

Select the “Create Defining Dimension” tool from the right side toolbar.

Click the left end of the arc, then the centerpoint of the arc, then CLICK WITH THE MOUSE WHEEL between the two. This defines the distance between the center and endpoint of the arc (essentially the radius).

Now deselect the tool and double click the dimension value to change it to 1”.

RESUME

Step 9: You can zoom in and out of your sketch by rolling the mouse wheel back or forth respectively. Zoom out slightly so you can see an area of the screen as shown below.

 

Note: The position of your mouse will affect the lateral motion of the zooming while you scroll. Try it

 

Note Also: If the rectangle in the background, or the labels FRONT, PRT CSYS DEF are distracting, you can turn these labels off in the toolbar on the top of the screen. The one on the left turns Datum Planes ON/OFF, and the one on the right, turns the Coordinate System ON/OFF. The other two are irrelevant for now.

 

 

 

 

.

 

Step 10: Create an identical half-circle on the right side using the same technique. The resulting display should look as follows:

 

Step 11: We will be creating the handle between the ends of the wrench. Select the

Create 2 point lines button from the line fly-out as shown . Click on the middle of the right side of the left arc and draw a horizontal line over to the right arc. Click on the right arc and then center click to stop drawing lines. The end result should look like this.

 

Step 12: Create a dimension from the handle to the horizontal centerline by selecting the

“Create Defining Dimension tool” , clicking on the line you had just created (left click), clicking on the horizontal axis (again, left click), and then clicking the middle button (scroll wheel) between the two. Change the dimension to .60 inches. The result is shown below.

 

 

Step 13: Next we will trim off the arc where the wrench end meets the handle. Select the

Trim button  and click on the arc segment between the handle and the horizontal axis. It will disappear. Repeat on the other side. The trimmed sketch will look like the following.

 

 

Sketching the wrench jaws

    Now we will create the jaws. The left jaw will have a one inch opening and the other will be 1 and 1/4th inches. We will do this by removing material from the sketch you have just created,

 

Step 1:  Begin by creating a horizontal line from the leftmost arc to almost the center of the arc. Zoom in so the display shows only the left end of the wrench. After creating the first line the view should look like the image below.

 

Step 2:  Dimension the new line so that it is .577 inches long and .5 inches from the horizontal axis. Properly dimensioned it looks like the following.

 

Step 3: Next we will create an arc that will form the base of the jaw. Select Create an arc by three points or tangent to an entity at its endpoint from the arc fly-out

. Click once on the horizontal centerline to the right of the center point of the jaw, then once on the right end of the line you created in Step 1. At this point an arc will follow your cursor. Move the cursor to the right , and the arc will follow the cursor. When the center point of the arc you are creating (the yellow crosshairs) is on the horizontal centerline, there will be a red dot in the middle of the crosshairs. Also make sure that the center of the arc is not coincident with the center point of the jaw, and there is no letter T appearing at the left end of the arc.

 

INCORRECT PLACEMENT OF THE ARC:

The red lower case T means that the arc is Tangent to the line. It is not supposed to be.

 

When all these criteria are met, left click again to finish the arc. When properly completed, the arc will look like below.

 

 

Step 4: Create a horizontal dimension between the ends of the arc. Select Dimension , then click the two endpoints. Center click in the space high above and between the two endpoints to create a horizontal measurement. Modify this dimension to be .288 inches. It will look like the following when you are completed.

 

Step 5: Trim the excess arc from the end of the jaws. The completed jaw will look like the following.

.

 

Step 6: Repeat steps 1 through 5, using the other end of the wrench. Dimension the right end so that it matches the following image.

 

 

Finishing the sketch

    At this point we have a sketch of half the wrench. Fortunately, you do not need to model the other half of the wrench. Because the wrench is symmetrical about the

horizontal axis, we can mirror all the geometry from top to bottom. Mirror is a great time-saver. After we mirror, we will extrude the sketch into three dimensions. 

 

Step 9: When you are certain your sketch matches the sketch above, click the Select

Items button , Drag a rectangle (shown in white) around ALL of the sketch components. When you let go, all the entities will be highlighted in RED

 

 

.

 

Step 10: With all the geometry selected, we can mirror the wrench to obtain the complete

geometry. Select the Mirror button  and click on the horizontal centerline. The result will be as follows. At this point, take a screenshot of  your view to include with your lab write-up. Here is a procedure for taking a screenshot.

        i. Make sure that the main pro/Engineer window is in the foreground by clicking on the window.

        ii. Hold down the Alt key and press the Print Screen key on the keyboard, then release both. This copies the foreground image to the windows    clipboard.

        iii. Start Microsoft Paint from the Start menu: Start- All programs -Accessories - Paint.

        iv. Paste the image into paint by holding down the Control key and pressing V, then releasing both.

        v. Save the image to c:\temp and close Paint

 

Step 11: The mirror completes the sketch, so click the Continue with Current Selection

button . The view will change to look like the following.

 

Step 12: Change the extrude depth to .25 inches by typing .25 in the dialog box shown below, then click the GREEN check mark in the lower right.

 

 

Filleting the 3d wrench

Fillets are gradual curves that connect geometry replacing sharp corners. They are used because sharp corners cause stress concentrations, which are areas of higher stress than the area away from the corner is experiencing.

 

Step 32: Select Hidden Line view style from the top toolbar  and then rotate the part to the angle shown below by holding down the mouse wheel and dragging the part.

 

Step 1: Create fillets on the corners connecting the handle to the jaws. Select the Round

Tool button from the right toolbar .

 

Enter 0.5 for the Fillet Radius in the bottom left:

 

Click on the four corners shown to create the four fillets. The first one is highlighted in Blue in this picture:

Once you’ve clicked all the corners, your screen should look like this:

 

 

Click the GREEN check in the bottom right of the screen.

 

Wrap-up

Finally, you must capture a copy of your completed wrench to include with your write-up. Make sure to save your wrench.

Step 1: Switch to Shading display mode  and verify that your final wrench looks like the following picture.

.

 

Step 2: Rotate your wrench to an interesting angle and take a screenshot to include with your write-up.

 

 

Your Lab Write-up

 

Each team should prepare and hand in one write-up.  Your write-up should include the following:

 

1.      A cover sheet that has the title "CAE Lab1 Write-up", names of the team members, and date of the lab.

2.      Include the two-dimensional, dimensioned line drawing of the wrench.

3.      Include the three-dimensional, shaded drawing of the wrench. 

4.      Consider the case in which the wrench is used to tighten a nut and bolt to a torque of 50 ft-lbs.  Use the actual dimensions of your wrench for the length of the handle and the size of the jaw.  Using methods of statics, calculate (i) the force that must be

applied to the handle, and (ii) the magnitude of the two forces produced at opposite corners of the hexagonal bolt head. Include all calculations, and follow the same guidelines as you do in completing your homework.

 

The write-up should be handed in at the beginning of the recitation two weeks from the lab date.

Wrench Analysis in Pro/Engineer Wildfire

 

Introduction

Pro/Engineer’s suite of tools includes a package called Pro/Mechanica which allows designers to analyze structural, thermal and motion properties of parts and assemblies.  Mechanica also has a toolset that can automatically optimize designs to meet certain design criteria while minimizing cost, size or other factors. We will be using Pro/mechanica to analyze the stresses and deformations of our wrench when it is being used to tighten a nut.

 

 

Setup

 

Step 1: Use an FTP program to move the wrench you made during the Modeling portion of the project to c:\temp. Instructions for using FTP can be found here.

 

Step 2: Start ProE Wildfire from Start - All Programs - PTC - Pro/Engineer - proewildfire

 

Step 3: Change the working directory. Go to File - Set Working Directory, and this will bring up a window for you to choose the directory where your wrench file has been saved. Choose c:\temp as your working directory.

 

Step 4: Load your wrench. Click the Open an Existing Object button  and find your wrench in c:\temp, then highlight it and click Open.

 

Step 5: Select Applications from the top menu and switch to Mechanica as shown below. Mechanica has a set of tools used to analyze stresses, strains, and deformations. Here we will be using it to perform a static analysis.

 

 

Step 6: This will bring up the Unit Info screen. This screen informs the user of the system of units being used in Mechanica. This is important because the analysis will not display units, it is up to the engineer to read them correctly. If your screen looks like below, click Continue.

 

 

 

Defining the wrench

    Before one can analyze a part with a finite element package such as Pro/mechanica, the computer must know certain things about the model. To perform a structural simulation, the computer must know the object's material properties and what type of analysis to perform

 

 

Step 1: Mechanica will now load. On slower computers this may take a minute. A new window called Menu Manager will appear. Make sure that the check box next to FEM mode is clear as shown below. We will be doing a static structural simulation, so select Structure.

 

Step 2: The MEC STRUCT menu will appear as follows. To perform an analysis of the wrench, we need to tell the program what the loads on the wrench are, what the constraints on the wrench that resist these loads are, and what material the wrench is. We also need to tell it what type of analysis to perform. We start by assigning a material to the wrench. Our wrench is made of 6061 aluminum, which is a general-purpose aircraft grade aluminum. Click on the Materials selection as shown below.

 

Step 3: We will now add 6061 aluminum from the library of pre-defined materials. The materials window will open. Select AL6061 and then press the right arrow to add that material to the simulation.

 

Step 4: We must now assign that material to your wrench. Click the Assign button. Select part as shown below.

 

Step 5: Click on your wrench. It will turn red to show that it is selected. Click OK in the small Select window that has popped up, shown below.

 

Step 6: The Materials window will reappear. Click Close. Your wrench is now made from aluminum.

 

Step 7: We need to tell the program to use the 3d model type. This is the slowest, but most general type of solution. Click Model Type in the Menu Manager window. Select 3D if it is not already selected and click OK.

 

Adding loads and constraints

    The program also must know the forces and reactions which are applied to the model. The following loads and constraints will simulate the wrench tightening a nut by someone applying fifty pounds of force to the end opposite the jaw. The nut provides the reaction moment which prevents the wrench from turning.

 

Step 1: We will now add the force applied by the person tightening the nut. We are modeling this force as a 50 lb force downwards applied on the right wrench head. Select

New Surface Load  from the right toolbar. This will bring up the Force/Moment window shown below.

 

Step 2: Our problem is simple enough that it is not necessary to name our loads. However, for problem with multiple loads it would be wise to name the load “hand force” or something similar. Click the arrow under Surfaces to select the wrench head we will apply our force on.

 

Step 3: Click on the top of the far wrench head. It will turn pink. When it does, click OK in the small select window.

 

Step 4: When the Force/Moment window reappears, type 50 into the Force… Z text box as shown below. When your window matches the one shown below, click OK.

 

Step 5: Next we must create constraints on the wrench to model the force exerted by the

nut. Click the New Surface Constraint icon  to create a constraint on the bottom jaw of the wrench. This will pull up the Constraint window shown below.

 

 

Step 6: Select the arrow below Surfaces and select the near bottom jaw of the wrench in the same way you did for the load in step 3. When properly selected, it will be pink as shown below. When your display looks like the image below, click OK in the Select window.

 

Step 7: We want to prevent the surface from moving, but we do not want to prevent the surface from rotating. When the Constraint window reappears, select the Free button for each of the three axes under Rotation (Radians).

 

Step 8: When your Constraint window looks like the following, click OK.

 

Step 9: Repeat steps 5 through 8 with the upper jaw. You may need to rotate your model to select the upper jaw. To rotate the model, hold down the center mouse button while moving the mouse. When you are finished constraining the model, it will look like below. If it does not, ask a TA for assistance.  Take a screenshot of your work at this point.

.

 

 

Running the analysis

 

Step 1: Next we must set up and run the analysis of the wrench. From the Menu manager window, select Analyses/Studies.

 

Step 2: From the Analyses and Design Studies window, select File-New Static as shown below.

 

Step 3:  The Static Analysis Definition window will appear. Because we only have one constraint set and one load set, there is nothing more we need to select. Click OK.

 

Step 4: We will now run the simulation. Click the Start Run button . The program will ask if you want error detection. Click Yes.

 

Step 5: When the Analyses and Design Studies window reappears, click the Display

Study Status button . Once the run completes, click Close.

 

Step 6: Close the analysis and design studies window.

 

 

Viewing and interpreting the results

    Now that the run is completed and the data saved, it's time to look at the results. pro/mechanica has a special interface from which to do this, because the same analysis

includes many different results. In our case our one analysis will yield results for stress, strain and deformation.

 

Step 1:From the Menu manager, select Results

 

Step 2: A new window will appear. In the top toolbar select the Insert a new definition

button

 

Step 3: We must tell the program which results we want to see. Click the Open button.

 

Step 4: Select (single click) the Analysis1 folder. With that folder selected, click Open

 

Step 5: The first thing we want to investigate is the bending stress in the X direction. Select XX from the list below Component as shown.

 

Step 6: Next we want to tell the program how to display its results. Click the Display Options tab. Select Continuous Tone, Deformed and Overlay Undeformed as shown below. When you are finished click OK and Show to view the results.

 

Step 7: The display now shows the deformed and undeformed shape of the wrench. The deformed shape is greatly exaggerated because the true deformation is too small to see. We will investigate that later. If your screen looks like below, take a screenshot of your work.

 

Step 8: Next we want to determine the displacement the wrench experiences. Select Edit-Result window from the top menu to change which results you want to view.

 

Step 9: The Result Window Definition will reappear. Change the quantity to Displacement and click OK and Show.

 

Step 10: If your result looks like the following, take a screenshot of  your results.

 

 

Step 11:  Save your work. Once again, you will need to FTP your wrench to yourself. Instructions for using FTP can be found here.

 

Your report

    Like you did in the previous tutorial, you must now save your work, upload it to your Andrew space, and write the report. Hand in one report per team, and your report should include the following:

1.     A cover sheet that has the title "CAE Lab2 Report", group number, names of the group members, and date of the lab.

2.      Include the drawing that shows the force applied at the handle and the boundary conditions applied at the jaw.

3.      Include the shaded contour drawing that shows the contours of stress in the x-direction in the wrench.  On this graph, indicate the points of maximum stress.

4.      Include the shaded contour drawing that shows the displacement of the wrench.

5.     Using the equations developed in lecture and the textbook for stresses in a cantilever beam under bending, calculate by hand the peak stress in the handle at the base where the handle connects to the jaw. Compare these stress values to those determined through the computer solution.

6.      The wrench blanks, and the final wrench produced with the CNC machine, will be made from 6061-T6 aluminum alloy.  With a factor of safety of 2, determine (i) the maximum force that can be applied to the handle, and (ii) the maximum torque produced by the wrench in tightening a bolt, both before yielding will occur. Draw a FBD of the wrench when you do the calculations.

 

      The report should be handed in at the beginning of the recitation two weeks from the lab date.

Manufacturing with Pro/Engineer Wildfire

 

Introduction

    This is the final tutorial in the wrench project. When you have completed this tutorial, you will have generated a file that the computer-controlled mill can use to make your unique wrench. Before you create that file, however, you must add text to personalize your wrench. We did not include the text until now because it would have needlessly complicated the analysis from the pervious section. After you have modified your wrench, you must tell pro/Engineer what type of machine it is creating a file for, define the blank from which the wrench will be cut and the tooling, and then create the path the tool will take. Finally, you will translate the output into the mill's native file format and send the finished product to the shop.

 

 

 Setup

    Unlike the previous tutorials, this one requires some files we have made beforehand. These include a model for the aluminum blank you made in the shop, the mill and the cutters. You will need to save these files to c:\temp. Right-click on the zip file below and select Save Target As..., then save to c:\temp. Unzip the file and there are 8 files contained in this zip file. Make sure to move all 8 files to c:\temp.

Manufacturing.zip

 

You will also need to use an FTP program to copy your wrench to c:\temp. Click here to open a tutorial on using WS-FTP if you do not know how.

 

Adding text to the wrench handle

The first thing we need to do is add the writing on the front face of the wrench. We have not included it to this point because it has negligible effects on the strength of the wrench. In general, one should analyze the simplest problem that will yield a correct solution.

 

Step 1: Start Start ProE Wildfire from Start - All Programs - PTC - Pro/Engineer - proewildfire

 

Step 2: Change the working directory. Go to File - Set Working Directory, and choose the directory where your wrench file has been saved. Choose c:\temp as your working directory. Load the wrench.

 

Step 3:  Reorient your view to the Standard Orientation. This is found in View-Orientation-Standard Orientation in the top menu.

 

 

Step 4: Next we will be adding the text of the writing. Text is added as a groove feature, so we can use an engraving machining operation later on. From the top menu select Insert – Cosmetic – Groove.

 

 

This will bring up the select window.  Click on the top face of the wrench. Properly selected, the top face will turn red and look like below. When it does, click OK

 

Next click  Done Refs In the Menu Manager window.

Manu manager will change to the following screen.

 

Select Use Prev and click Okay. The screen will change back to the sketch view and a References window will appear. Click Close. Your screen should look like the following.

 

 

 

Step 5: Select the Create text as part of a section button . Click once on the bottom left portion of the handle, then move the mouse vertically upwards to create a vertical line. When you reach the upper left quadrant, click again. If you receive an error message asking if the selected entities should be aligned, click No.  The following Text window will appear.

 

 

You may add any text you wish, up to a maximum of approximately 10 characters. The example will be adding the text “24-101” to this particular wrench. Type your text into the box labeled Text Line. As you are typing, the text will appear on your wrench. If your text looks approximately like the following, you’re okay. When it does, click the green check button.

 

Step 6: We need to dimension our text. This is often easier to do by changing the grey weak dimensions than by creating new ones like we did in the first tutorial. Click the

Select Items button and then double click the grey dimension below the text. A text box will appear as shown below.

 

Change that dimension to 1.5 inches and hit enter. This is the other main way to create

dimensions. Zoom in on the leftmost piece of text with the Zoom In button . Your screen should look like the following at the appropriate zoom level.

 

There are two more grey dimensions. One is the height of the letters, the other is the distance the letters are from the centerline. Change the smaller dimension to .25 and the larger to .5, then zoom out. Your wrench should look like the following.

 

 

Play with the text until you are happy with the placement and are sure the text extends no more than 1.5 inches on either side.

When you are happy with your text and placement, click the Continue With Current

Selection button  from the right toolbar.

 

Your wrench should look like the following (with your text). If it does, save it and continue on. If not, contact the TA.

 

Attaching the wrench to the workpiece

    The wrench you have created will be cut from a blank of aluminum that you made in the machine shop. we must tell the program the size and shape of that blank, so that it

knows how much material must be removed. We must load this blank and place your wrench in the center of it.

 

Step 1: We now need to make a manufacturing file. Press the Create a New Object

button on the top toolbar . From the screen that appears, select Manufacturing from Type and NC Assembly from sub-type. Enter your group number in the Name  field and press OK. It may take a minute for the manufacturing portion of Pro/Engineer to load.

 

 

Step 2: Next we must load our wrench into manufacturing. From the Menu Manager window, select Mfg Model.

 then select assemble. .

 

Your wrench will be loaded as a “reference model” because it is used as a reference to create the toolpaths. Click Ref Model. When the Open window appears, find your wrench file and click the Open button as shown below

 

Step 3: Next we must load and assemble the workpiece. The workpiece represents the blank from which the wrench will be cut. Select Assemble from the MFG MDL subheading and click Workpiece.

 

 

This will bring up the Open window. Select Blank.prt from C:\temp as shown below, then click the Open button.

 

.

 

When the workpiece loads your view should look like the following.

 

 

Step 4: Now we must move the workpiece so that the model is contained inside it. To do this we set a constraint as follows: From the Component Placement window select the Type dropdown and change it to Coord Sys as shown below.

 

 

Step 5: Next we must select the coordinate system of the workpiece. Click the arrow in the Component Reference box. Next click on PRT_Csys_Def inside the blank as shown below.

 

Next select the arrow in the Assembly Reference box and select the PRT_Csys_Def  inside your wrench as shown below.

.

 

The workpiece will move to cover the wrench. When it does click OK in the component placement window.

 

 

Step 6: The next thing we need to do is make sure that the engraving bit that writes your text will not impact the mounting bolts that keep the blank fastened to the mill while it is

being machined. From the top toolbar select Hidden Line view . Your wrench should change to look like the following image.

.

 

The green represents the workpiece while the white represents the reference model. The holes in the green part are mounting holes that hold your workpiece to the mill. These must not be touching or overlapping your text or your wrench will not machine properly, and it will break the mill's cutter. If your text does not touch the green mounting holes, proceed to the next step. If it does, contact the TA immediately.

 

 

Defining the mill parameters and making the rough cut 

    We must now create a representation of the machine shop's mill. We also need to tell the mill what speed to turn the cutter, how fast to travel, and other parameters. These rates are determined by a number of factors and have been packaged into parameter files for you. You must, however, tell the program which set of parameters to use for different operations. For example, the mill turns faster with the .125 inch bit that writes your text than it does with the half inch bit that cuts out the bulk of the material.

 

Step 1: Next we must define the machine which will be doing the cutting. From the menu manager, select Mfg Setup.

 

This will bring up the Operation Setup window. The first thing we need to do is name the machining operation. Name your operation GroupXX_Mfg as shown below.

.

 

Next we will load machine data for the mill we will be using. Click the Open Machine

Tool icon .

The Machine Tool Setup window will open.

Click the Retrieve Machine button  and load HAAS_Mill.Gph

 

 

Finally click OK in the Machine Tool Setup window.

 

Step 2: Next we need to give the mill a reference point from which to machine the wrench. In the Reference box of the

Operation Setup window, click the arrow. Now we must select a coordinate system for the mill. There are multiple coordinate systems with different orientations at the center now. The one you want is named Mill_CS. When it is highlighted, click on it.

 

When done correctly, it will create a new coordinate system named ACS0 which will have the Z axis pointing upwards and X to the right. If it is not, repeat step 2.

 

 

Step 3: Finally, we must select a retract, which is the position to which the cutter head moves when it is not cutting in order to completely clear the workpiece. Select the arrow in the Retract box, and the Retract Selection window opens. Click the Along Z Axis button, then enter 1 for depth. This will make the cutter retract one inch above the workpiece when not in use. When your window looks like below, click OK

 

 

When your part look like the image below, click OK to close the Operation Setup window.

 

Step 4: Now that the machine is set up properly, we must create the paths which the cutter will follow while machining the wrench. We will be machining using a Profile operation, which is used to cut two dimensional parts from flat blanks by cutting along the edges. From the Menu Manager window, select Machining. Next select NC

Sequence from the options which appear. Click on Profile and then click Done as shown below.

 

The Menu Manager window will change to show options for the operation. Select Name, Tool, Parameters, and Surfaces as shown below and uncheck all the rest. This tells the program that you want to name the cut, select what tool to cut with, the speeds and settings and where the cut will be. The other options are not necessary as the ones we already set up are correct for all the operations we will do. When your menu looks like the following, click Done.

 

Step 5: We now will enter the data for the operation. The first thing the program asks for is the name. When you clicked Done at the end of last step (Step 4), the bottom of the main window changed to a text box as shown below. This is asking you to enter the name of the cut. Name this one RoughCut, because we will be using a large cutter to quickly cut most of the material away. When you have entered the name, click the green check box as shown below.

 

Step 6: Next we must tell the mill what cutter to use. The mill has a table of cutters from which it can select the proper one for a particular operation. In this way, the machining time is reduced because the machine does not have to stop between cuts. The Tools Setup screen will appear.

If there are already tools present, delete them by selecting them and

pressing the red X. Click the Open button  and load t500.tpm from c:\temp. This is an end mill half an inch in diameter. When your window looks like the one below, click OK.

 

Step 7: Next we must set the Manufacturing Parameters for this cutter. These include the cutter speed, the speed the mill travels, the coolant options and so forth. We have already

saved the proper dimensions, all you need to do is load them. The Menu Manager window will show MFG PARAMS.  Click Retrieve as shown below to load the data.

 

The Open screen will appear. Select Rough.mil from c:\temp and click Open.

 

Finally click Done on the Menu Manager window.

 

Step 8: Next we must select the model which contains the surface information. The Menu Manager window will have a Surf Pick window. We must select your wrench model. However, it may be difficult to do that by clicking on the wrench, because the workpiece is coincident with it. Select your wrench by clicking on GroupXX.PRT in the left model tree as shown.

 

Your wrench will turn red. When it does, click Done in the Menu Manager window.

 

Step 9: Now we must select the surfaces which will be machined. All the edges will be machined in this operation, but not the faces. Start by clicking on the handle edge as shown below

 

Next, hold down the Ctrl key and select the rest of the edges of the wrench. When you are done your wrench should look like the following.

 

When it does, click Done in the Menu Manager window and then Done/Return in the same.

 

Step 10: Next we must make sure that the sequence is set up properly. We do this by displaying the cutter head on the screen. Click Play path from the Menu Manager window, as shown below.

 

 

Now, check the Compute CL checkbox to have the computer calculate the position of the cutter head and click Screen Play as shown below.

.

 

The Play Path window will appear. Click the Play Forward button  and you will see an on-screen representation of the cutter path.  When the program finishes displaying the path, your model should look like the following. The yellow bit  may be either in it's start or end position.  If the red path does not look like the image, contact your TA.

 

When your screen play is finished, click Close on the Play Path window and then click Done Seq in the Menu Manager window as shown below to finish the Rough cut.

 

Finally, click Done/Return.

 

Creating the finish cut

    Next we will be making a finish cut on the same surfaces. Because the cutter does not have to remove much material, we can run the mill at a high speed with a small cutter. This will give a very clean appearance to the finished wrench.

 

Step 1: Again from Menu Manager select Machining and then NC Sequence. Then, click New Sequence as shown below.

 

Again select Profile and click Done. Our second operation is exactly like the first, except with a different tool and manufacturing parameters. From the Seq Setup portion of Menu

Manager, check Name, Tool, Parameters and Surfaces. When you have selected these four as shown below, click Done.

 

Step 2: Again at the bottom of the main screen we must enter the name of the operation. In this case name the operation FinishCut and click the green checkmark button.

 

Step 3: Now we must load the tool we will be using. Using the same technique with which you loaded the half inch end mill, load the quarter inch end mill named t250.tpm. When your Tools Setup window looks like below, click OK to close it.

 

Step 4: Click on Retrieve in the MFG PARAMS section of  Menu Manager and load finish.mil as shown below. When it has loaded, click Done in the Menu Manager window.

 

Step 5: Select your model named GroupXX.PRT from the left model tree view, and then click Done in the menu manager window. Because we are using the same surfaces as in RoughCut, we do not need to manually select all the surfaces again. From the NCSEQ SURFS portion of Menu Manager, click From Prev Seq. When the window changes, click on ROUGHCUT to check the check box next to it and click Done Sel as shown below.

 

Click Done/Return to finish the sequence.

 

Step 6: Next we must play the path to make sure it is correct. Click Play Path in the Menu Manager window, check Compute CL and click Screen Play.

 

Play the tool path like you did for RoughCut. It should look like the image below. If it does not, contact your TA.

 

When you are certain that your FinishCut operation is correct, Close the Play Path window and click Done Seq and then Done/Return in the Menu Manager window.

 

 

Engraving the text

    Our last operation is the writing on the face of the wrench. This is not a Profile operation but uses the Engraving type instead. Engraving is used to make shallow passes on a flat face. Engraving follows cosmetic groove features, instead of model geometry.

 

Step 1: From Menu Manager, select Machining, NC Sequence, New Sequence like you did for FinishCut. Select the Engraving option as shown below and click Done.

 

Step 2: In the Seq Setup portion of the Menu Manager window, check Name, Tool, Parameters and Groove Feat. When you have those four selected, click Done. You will once again be asked for a name. Enter WritingCut as shown below and again click the green checkmark.

 

Step 3: Next load t125.tpm from the Tools Setup window. t125.tpm is an eighth inch cutter with a rounded end. This creates a wide, readable groove which makes attractive lettering. When your Tools Setup window looks like below, click OK

 

Step 4: From the MFG PARAMS section of the Menu Manager, click Retrieve and load Writing.mil. Click Done in Menu Manager. This will load the proper parameters for the engraving.

 

Step 5: A Select window will prompt you to Select groove Features. You want to select the writing on your wrench by left clicking it as shown below.

 

 

Step 6: Click Play Path to show the tool path in the same way you did for the last two operations. Again select Compute Cl and click Screen Play. The animation should show each letter being machined, and the end result should look as follows.

 

If it does, Close the Play Path window and click Done Seq in the Menu Manager window. Click Done/Return to finish the machining operations.

 

Post-processing the wrench 

Step 1:  Now we have to tell the program to create code that the CNC mill in the machine shop can read. Select CL Data from the Menu Manager window as shown below.

 

You will be prompted to select an Operation or NC Sequence. We want to process all three sequences we have just made, so select Group00_MFG from the left Model Tree view as shown below. This group contains all three sequences.

 

When you have selected the group, click Done in the Menu Manager window. You should see all three operations display on the screen in their proper order. The result should look as follows.

 

 

Step 2:  When you are certain that all three operations are correct, it is time to create a file that the mill can read. Click File from the Menu Manager window. Select CL File, Interactive and Compute CL. When you have these options selected, click Done.

 

The Save a Copy window will appear. Type in your group number as the name and click OK as shown below.

 

Step 3: Now we must translate the data from an .ncl file, which is a generic computer control language, to a file that the mill can read directly. Select Post Process from the Menu Manager window as shown below.

 

The program will prompt you for a file to post process. Select the file you just created as shown below and click Open.

 

Next click Done in the Menu Manager window.

 

Step 4: Select UNCX01.P02 from the list shown in Menu Manager. A black DOS window will appear and prompt you to select a program number. Enter <the number of your group (NUMBER ONLY)> and press the Enter key.

 

Step 5: A status window showing the results of the post processing operation will appear. Close it.

 

Step 6: You have completed the manufacturing section of the wrench project. Save your work by selecting File from the top menu and choosing Save as shown below and clicking the green check button at the bottom right corner of the screen.

 

Step 7: Log into blackboard and go to the Tools section of the 24-101 page. Select "Digital Drop Box" and upload your .tap file.  Name it with your group number (i.e.

1.tap, 32.tap). When you have uploaded your .tap file, select Send Files and send it. You will be assigned a date and time to go to the machine shop and cut your wrench. There is no written report for this portion of the tutorial.

 

Using KerbFTP

 

Because the computers in the cluster erase c:\temp as soon as you log off, you must transfer all your files to your Andrew file space before you log off. This is done using FTP, (File Transfer Protocol.) The program we will be using is called KerbFTP and is installed on all cluster computers.

 

Step 1: Start KerbFTP. From the start menu, select All Programs, then Communications, and finally click on KerbFTP. The program may take a moment to load.

 

Step 2: Upon startup you will be presented with the following screen. You will need to fill in the correct information. In Hostname, enter unix.andrew.cmu.edu as shown below. When you have entered the address of the host, click the Connect button.

 

 

Step 3: You should now be connected to your Andrew file space. The following image is an example of the main KerbFTP interface. The top window is the file system of the local computer where you are sitting. The bottom window is the file system of your Andrew space. This is where you should keep your files in permanent storage between tutorials.

 

 

Step 4: You must set the local system directory to c:\TEMP. To do this, click on the box with a plus sign next to C:\ and navigate to c:\TEMP as shown below.

 

Step 5: To upload a file from the local computer to your Andrew space, select the file you wish to transfer from the top window and drag it to the right side of the bottom window. This is typically done at the end of a session to save the work you have done.  Before the file transfers, the following confirmation window will appear. The path will be different depending on your User ID.

Step 6: To download a file you have previously worked on, follow the same procedure as step five, but instead select the file from the bottom window. Drag the file from the bottom remote window to the top local window, and wait until the transfer finishes.

 

WarningBecause the cluster computers are a shared resource, all your personal files are deleted when you log off. As a result, if you do not successfully FTP the files to your Andrew space before you log off, you will have to repeat the previous tutorials before you can continue. After you transfer a file, ensure that it is in both the local and remote directories. If it is not, then the transfer did work.

Step 7: When you are certain that you have transferred all the files you will need at a later time, close KerbFTP.