Engineering Model Design (Lab Report Sample)

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INTRODUCTION
This coursework has been set up to carry out three main tasks which are: Model Design, Mould Design and Machining Simulation optimisation. These will ultimately help in understanding of machining constraints and economics in the development of product designs for manufactures. It will enhance the knowledge already gained in the use of CNC and CADCAM applications like pro engineer Wildfire
CREATING THE MODEL
In the next view, a sketch plane is selected, upon clicking the sketch button, a rectangle can be drawn as shown, in figure 2.This is then extruded using the extrusion button
from the toolbar; the desired dimensions like the thickness are entered. Other extrusions were carried out to get the desired shape and dimensions as shown in figure 4. Ribs were added to improve model resistance to deformation. Shelling was done to the bottom part of the model, and the result is shown in figure 5
PLASTIC ADVISOR
Go to Application drop down menu, select Plastic Advisor. When asked to select point, click OK, figure 12 is gotten.
First step taken in this window, choose the plastic injection locations button,
an appropriate level is chosen on the model as shown in figure 13.
The modelling tools button
is not selected.
Second step, select the pre-analysis check button
; a pop up window gives information that there are no errors.
Third step selects the study wizard button
. A new window appears as in fig 14.
The first section to choose here is the Gate Locator, Double click Next and Finish. Allow time for Plastic Advisor to carry out Analysis. In the Result Summary Window, Click CLOSE. Figure 15 is arrived at. As the colour bar shows, red is the worst location for the gate and blue is the perfect location for the gate. This image shows there is a need to change the gate location.
The analysis suggests the best place (geometrically) to make injection site given the material selected and existing injection locations.
PLASTIC FILLING
Check Plastic Filling, Select Next twice and Finish. The result window is shown as in fig 19. Click Close.
The Confidence of Fill result displays the possibility of plastic filling anarea within the gap under conventional injection moulding conditions. This result is derived from the pressure and temperature results.
The Confidence of Fill result does not always predict a brief shot (the cavity does not fill), but still states that a good quality piece cannot be moulded. This is because the conditions at the end of the filling form are not suitable for the area to be adequately packed during the packing phase. The Filling Analysis gives information that the part can be easily filled, but the part quality may not be sufficient, all in Green in Figure 20 shows good results
Cooling Quality
This is the extra time after the end of packing ittakes 90% of sectiondepth to extend its freeze temperature and become solid. Where there is red pigment, the temperature is fairly different from the average, and the time to freeze is much lower than the average. Where there is yellow tint, the temperature is quite different from the average.
The green colour shows good cooling quality.
Sink markEstimate
Sink marks due to shrinkage of the material at deep sections without sufficient compensation. They are caused primarily by thermal shrinkage during cooling. After the exterior material has cooled and solidified, the core material starts to cool. Its shrinkage pulls the surface of the main wall inward, causing a sink mark. They do not affect part strength or function, they are perceived to be excessive quality defects.
The areas of the model liable to sink marks have been improved from about 3 per cent to less than 1%. The final sink spot diagram is shown in figure 27. The blue part has the lowest depression while the red shows the highest depressions and ranging from 0mm to 0.029 mm respectively. For the model, considering the sink marks are usually situated on the part number and logo, quality should be sufficient.
MOLD CAVITY
Preparation for mould design
A new subdirectory was created, and named Mould Cavity inside the MCAEPM Semester 2 Popov’. The current model design was copied from the Main folder inside the new subfolder. ProEngineer is opened; working directory is set to the Mould Cavity, Select File Drop down Menu, then New. In the New window, Select Manufacturing, then Mould Cavity as shown in Figure 29. Name it mould.
In the New File Options window, Empty is selected, then OK. There is aclearpro engineer window while the history tree contains MOLD.ASM.
On the Menu Manager on the top right, Mould Model is selected, then Assemble, then Ref Model as in Figure 30. In the next window, the Design model is selected, ashtray. prt.16.
In the next window, ProEngineer suggests to Create Reference Model, MOLD_REF. Click OK.
This is shown in figure 31.
Creating the Work Piece
In the Mould Model window similar to figure 30, select Create – Work Piece – Manual. In the Component Create window, Part and Solid are unchanged, and Block is given as Name shown in Figure 32.
In Creation Options window, Create features is selected, click OK. In the FEAT OPER window, Solid – Protrusion – Extrude – Solid and done are selected respectively.
Select Placement in the dashboard, then Define. A rough plane was selected; this did not go through the middle of the Reference Model but at its bottom. A reference plane was selected perpendicular to the previous selected plane.
A References window is shown the axis is selected. Arectangle, which is approximately three times bigger in dimensions than the Reference design is drawn using the Crate rectangular icon. The blue tick icon is selected and in the next window, select Extrude on both Sides icon,
, and anintensity value 430mm which is approximately three times the model is entered. The green tick is clicked. In the Feat OPER window, click Done/Return and to the Mould Model window, click Done/Return.
After the creation of the work piece, it was noted that the size was not evenly distributed on both sides of the reference model. Reason being that the sketch plane selected to illustrate the work piece curves did not go through the middle of the reference model. This problem could cause extensive damage during moulding. Thebuild-up of pressure on one side of the work piece would be larger than the other side which could lead to an explosion. Therefore, this problem would be reverted by redoing the work piece. The sketch plane selected was a datum plane created which passed through the middle of the model. This corrected the inconsistency and the block and reference model are shown in figure 33.
Creating the Parting Surface
A parting surface is a surface feature, which can be used to separate either a work unit or die block, or an existing volume, including surfaces of one or more character parts. In this coursework, it is used to separate the whole block above in fig 33. The Parting Surf Tool icon is selected from the tool-chest on the right hand side, and then the Extrude icon is selected. From the dashboard at the bottom of the window, Placement is seated, and thendefines, one of the datum planes going through the middle of the design and block which was created earlier is selected and the second is selected, and it is expected to the first data selected. References were selected, and solved in the sketch window, and a line is sketched across the block, just cutting across the bottom of the model as shown in figure 34.
Click the blue mark icon, and then in the next window, the depth of the extrusion is 420mm, which goes through the whole design as shown in figure 35. Click on the green spot to finish.
Splitting the Work Piece
Here, two volumes are created from the firstdimensions shown above in figure 33. The Split into two new icons from the tool chest is selected and in the Split measure window shown next, Split, then two volumes, then All Work pieces are accepted. The created parting plane is selected from the model and OK is clicked. The relevant islands are selected in the ISLAND LIST as shown in figure 36. Three islands are provided, and ISLANDS 2 and 3 are selected as they are the correct ones. Click Done Select and click OK in the window Split as shown in figure 37.
The mould Volume names 1 and 2 are accepted with OK and Done/Return, then a final Done/Return.Extracting the mould volumes from the Work Piece
Select Mould Comp, Extract. Select each volume one at a time from the model tree. Click OK in the Create Mould Component window shown in figure 38 and Done/Return.
Examining the Mould
The mould will be examined and draft survey done, therefore it must be opened. To open the mould, Click Mould Opening – Define Step – Define Move, then Mould 1 is selected from the model tree. The top level is selected as the direction to open the Mould 1, click OK. A prompt appears to enter the interval for movement; 100 mm is typed in in figure 38. When done is clicked, the mould opens. The same steps are taken to startMould 2.
The parting surface is selected, then hidden by going to View drop down menu, select Visibility then Hide. The melds are open as shown in the figure 39.
Draft Angle Check
Draft angles are applied to the reference model so that the opening of the mould after cooling will be easy and the region will be properly moulded.
Draft angles are to be checked, the draft position used in the model is 2 mm. Click Analysis from the top Menu, select Mould Analysis and in the new window, under Type, select Draft Check under Type. The Surface (Part) is specified, and the Pull Direction is outward is selected, and a Draft position lower than that applied to the reference model is e...