Design Door Trim Lower with Engineering Features

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

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.

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

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 solid model has cleared the draft analysis successfully as shown in the image below.

CREATING THE RIB

Ribs are thin wall protrusions that extend perpendicularly from a wall or plane. They are usually found in clusters offering support to a plane that would have otherwise been too thick, but can also be stand-alone support for a single wall. They are commonly used to provide additional support & strength to a part. Thickness and location are essential to rib design. Firstly, the base surface where the rib has to be created is extracted using the Extract command.

Next, the profile is extruded, to find the height,h=Wall thickness*5 = 2.5*5 = 12.5 mm

Thickness, w = 0.4*t =0.4 2.5 = 1 mm

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

Then fillet is applied to the faces of the rib. As per the design rule, the fillet can be 0.25 mm.

CREATION OF DOG HOUSE:

Dog house is an engineering feature used in plastic trim design. Dog houses are used as supporting feature. Sometimes other engineering features like snaps; locators etc. are mounded on them to increase their strength.

• To create the Dog house, I draw a sketch and padded it to 18mm in height .
• After padding in the direction of tooling axis, I drafted 3deg in the tooling axis direction and filleted it with a 3mm radius.
• Than i remove the material from the base of it having a thickness of 0.4*T=1 mm.
• Than provide draft it to 0.5degree in the direction of side core axis.
• Then shell the main padded structure to 0.7*T=1.75mm.
• Remove the second bbody from the first body .
• After joining both the bodies translate it to required points and rotate it with respect to its edge

DRAFT ANALYSIS FOR PART BODY: