Week 9 - Project 1 - Door Trim Lower with Engineering Features

DOOR TRIM LOWER

Aim: To Create the Door trim lower component through the given Class-A surface.

Objectives:

• Creation of Tooling axis with appropriate draft angle.

• Creation of other surfaces (eg, B and C surfaces) for creating a solid component. • Perform Draft analysis on Class A surface and Solid model hence created.

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 for creation of Solid model:

The image below shows the given class A surface for which a solid model is to be created.

Tooling Axis creation:

It is defined as the direction in which the mould/core and cavity open. Selection of the direction of the tooling axis depends on the ease at which components can be easily ejected.

By analysing the component the most easily ejectable direction is somewhere close to the Z direction,(might be inclined to it) so we have made a sketch on the YZ plane of Axis System) to create a bisecting line considering the 2 faces which might be difficult to be tooled.

Draft Analysis of Solid Model

Same steps are followed to get the draft analysis of the solid part as in Class A Surface

As we know minimum draft angle for the faces of the plastic component should be 3 degrees. So the value of 2.9 degrees (considering tolerance) is provided in the Draft analysis colour mode window Inside the colour scale, the GREEN bar shows the draft angle of 2.9 or above 2.9 degrees. The blue bar shows below 2.9 degrees draft angle the other limit being and the RED bar shows the negative draft angle. As shown in the image below all the top faces and side faces of the component are green, while the bottom faces are red. The line of demarcation between the green and red faces is the parting line which divides the core and cavity halves.

The draft is applied to the sides of the ribs. As per the design rule, the ideal draft angle is 0.5 deg

The door applique is fixed on to the door surface with the help of locators and heat stakes. Every component in space has 12 degrees of freedom. So these locators and heat stakes restrict all these degrees of freedom.

Locators are 4-way locators. The locators will follow the rib design guidelines and will be given a minimum draft of 0.5 degrees and a minimum fillet of 0.2mm and an entry chamfer of 3mm. This entry chamfer is given so that the locators can mate with the other part easily.