Week 9 - Project 1 - Door Trim Lower with Engineering Features
DOOR TRIM LOWER
Aim: To Create the Door trim lower with Engineering Features 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.
- Create the Heat Stakes and the locators considering the design rules .
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.
METHODOLOGY:
In this model we have focused on the following things:
- Tooling axis
- Draft analysis
- Class-B surface
- Class-C surface
- Making a solid model from surface.
Following tools were used to reach the final step:
- Trim
- Extrapolate
- Offset
- Split
- Multiple-Extract
- Multi-section surface
- Boundary
- Sweep
- Join
- Close (part design)
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
Below is the class A surface which was incorporated in the Catia V5 work bench to work upon.
Tooling axis & Draft Analysis: The direction in which the mold or core and cavity opens is the 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 the x-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.
CLASS B SURFACE:
To create the class B surface, offset the class A surface inside as per our thickness requirement ( 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.
PATCH-1
Repaired Patch-1
Patch-2
Repaired Patch-2
After Fillin Patches Class B Surface
CLASS C SURFACE:
To create the class C surface concerning the boundary of the class A surface, I used the sweep command. Initially, I extracted the boundary of the class A surface with tangent continuity, and I sweep the extracted boundary concerning the surface at 90deg (for reference Surface) for 5mm 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 intersected 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 lower.
Class C Surface
Now, join both class A and sweep boundary to get the complete class C surface.
Now, unhide the class B and class C surfaces. Check whether all the sides of class B and Class C surfaces are intersecting properly with each other, to get a closed surface by trimming class B and class C surfaces. If the class B and class C sides are not intersected properly, we need to extrapolate the sides of the class B surface which are not intersecting with the class C surface. Now, check class B and class C surface boundaries whether all the sides are intersecting or not with each other. Once the surfaces are intersecting properly trim them together to get a closed surface.
In the above-given image, the sides are not intersected properly. I extrapolated the surfaces which are not properly intersected with each other like above.
The below-given image represents the sides which are extrapolated until the surfaces are intersected.
CLOSED SURFACE
Trim
PART BODY:
To create the solid part body from the closed surface, I used the closed surface command in the part workbench.
Engineering Features
- Dog house
- Heat Stakes
- 2 & 4 Ways Locators
2 & 4 Ways Locators
The locators restrict all the other degrees of freedom except the translation along the direction of tooling axis Le along y-axis. For restricting that degree of freedom we will be using the heat stakes.
In heat staking, we use local heating and cooling to raise the temperature of plastic components and allow plastic reforming to be carried out.
Then fillet is applied to the faces of the rib. As per the design rule, the fillet can be 0.25 mm.
The Yellow colored components is the 4 Way Locators.
The Dark Blue colored components is the 2 Way Locators.
Heat Stakes
The Pink colored cylinders are the heat stakes.
These heat stakes will enter the mating component and using a heat staking machine these heat stakes are melted and cooled. When cooled this will get hardened and the two components will stick together. Thus all degrees of freedom are arrested
Then, the ribs are created by following the rib and Cylinder design rules.
CREATING THE DOGHOUSE
The dog house is an engineering feature used in the plastic trim design. Dog houses are used as a supporting feature. Sometimes other engineering features like snaps; locators, etc. are mounded on them to increase their strength.
The doghouse is created by following the design rules.
The Orange colored component is the Dog House.
An important thing while designing a doghouse is to maintain 40% less thickness than the wall thickness (T) at the area of the intersection to avoid sink marks.
Draft Analysis
RENDERED IMAGES
FINAL MODEL