Week 10 - Challenge 3 - Door Trim Lower with Engineering Features

AIM: Create the Door Trim Lower Plastic component through the given Class-A surface. To begin with, the tooling axis for the given Class-A Surface should be created meeting the requirements of the draft angle and at the end perform the Draft analysis on the model.

Create the Heat Stakes and the locators considering the design rules mentioned in the video for the door applique.

THEORY:

Draft: The draft is the amount of taper for moulded or cast parts perpendicular to the parting. line. Draft angles are a design consideration that makes it much easier for a part to release cleanly from a mould. A draft angle is calculated as a degree measurement (or, less often, an inch or millimetre measurement) from the vertical axis of a mould, and it helps account for thermoplastic shrinkage, a practical reality of the injection moulding process for most materials.

Draft angles are generally a requirement of injection moulding design (though there are a select few soft materials, like nylon, that can get away with draft angles of zero). The draft should be a part of the design for manufacture, and all stakeholders and contributors should be aware of its need at the outset of the design process. This includes product designers, design engineers etc and this allows considerations for design requirements to be taken into account. Any draft is always better than no draft.

Importance of Draft:

By accounting for thermoplastic shrinkage during the cooling process, draft angles significantly reduce friction between the finished, cooled part and the side of the mould, Not only does this create a much easier release process, but it also offers several other benefits, depending on the design of the part which is as follows:

• Reduces the chance of damage to the part due to friction during the release.

• Reduces wear and tear and chances of damage to the mould.

• Ensures a uniform, smooth, unscratched finish when required. • Ensures the integrity and uniformity of other surface finishes and textures.

• Reduces overall cooling time by lessening or eliminating the need for unconventional ejection setups.

• Most, if not all, of these benefits, offer either direct or indirect overall production cost reductions.

PROCEDURE:

1. Open the given class A surface. Ensure that all its boundaries are connected.

TOOLING AXIS:

To create the tooling axis, I extracted a surface from class A and created a point in the middle of the surface by using the point command and created a line at that point through they-axis. Now, I performed a draft analysis check from that line whether the created tooling axis is in the correct position or not. If in the draft, analysis check the surface highlighted with green colour on both sides of the surface the tooling axis is in the correct position and direction.

Tooling axis:

DRAFT ANALYSIS FOR CLASS A SURFACE:

We do perform the draft analysis check for class A surface before we make solid and creation of B-side features. Initially I align the compass to the tooling axis and I gave a 3deg draft angle for the green colour in the colour bar. If the surface is highlighted in green colour the draft angle is given properly for class A surface. If the class A surface is not highlighted fully in green colour, that might be the reason for the draft angle of the class A surface.

CLASS B SURFACE:

To create the class B surface, offset the class A surface inside as per our thickness requirement (here the thickness is 2.5mm, so I offset the class A to 2.5mm inside). Once the offset is created, we can observe some patches on the offset surface by taking the boundary for the offset surface, those patches are formed due to the fillets on the class A surface. We need to cover those patches with the help of the multi-section surfaces command by extracting the patch boundaries. Once all the patches on the offset are covered properly join all the patches with the offset surface, to get the replicated surface of the class A surface.

PATCHES

class b after the patches have been reworked

LASS C SURFACE:

I used the sweep command to create the class C surface concerning the boundary of the class A surface. Initially, I extracted the boundary of the class A surface with tangent continuity, and I sweep the extracted boundary concerning the surface at 93deg (for draft angle) for 4mm to intersect properly with the class B surface. Once we sweep all the surface boundaries of class A, extrapolate the sweeped surfaces until both surfaces got intersect properly, and trim them to remove extended extrapolated surfaces to get a proper sweep boundary throughout the entire surface, including the centre hole of the door trim. Now, join both class A and sweep boundary to get the complete class C surface.

Class C surface:

6. Join the C surface with the A surface.

7. Trim the B surface with the above surface to obtain a closed hollow body using surfaces.

8. Convert the surface body into part body using the feature close surface.

9. Perform Draft analaysis on the solid part.

10. Create a 4 way locator using a sketch on the body. After creating the sketch, pad it 20mm in height and thicken it to 1mm and draft it with 0.5deg in the direction of the tooling axis. Give 5mm of chamfer with 45deg of inclination and a fillet of 0.25mm radius.

Use copy and paste the 2 nd 4 way locator using the translate feature.

11. Create Heat stake. Draw a sketch on the surface. After the creation of the sketch, Pad it to 18mm height and a draft angle of 0.5deg on both sides (inside and outside) and then provide a fillet with a 0.20mm radius. After creating the heat stake, create the ribs for supporting purposes. To create the ribs, draw a sketch and padded it to height less than that of the heat stake and 1mm in thickness. After padding the ribs, drafted 0.5deg in the tooling axis direction and fillet it with a 0.20mm radius. Finally, use union trim on the ribs with a heat stake to remove the ribs as per the requirement, which are present inside the heat stakes.

Copy and translate the heat stake to all the positions as needed.

13. Perform draft analysis on the part. for inspecting the features which are added later on the B surface.

From above we can find that the componen is manufacturable.

Views:

CONCLUSION:

Thus by following the above we crate the door trim with B class features (heat stake and locator pins).