Week 8 - Challenge 1 - Base Bracket Design
AIM
Create the Base Bracket 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.
REPORT
CLASS A SURFACE
In automotive design, a class A surface is any of a set of freeform surfaces of high efficiency and quality. Although, strictly, it is nothing more than saying the surfaces have curvature and tangency alignment – to ideal aesthetical reflection quality, many people interpret class A surfaces to have G2 (or even G3) curvature continuity to one another. It gives the aesthetic of the component which is created by the styling team and gives to the part design engineer to create the part with all engineering aspects.
CLASS B SURFACE
Class-B surface means the thickness of a part it is not visible and is inside part. In other words, the Class-B surface is a surface below a certain thickness from the class-A surface. This is the surface that contains engineering aspects of a model.The Class B finish is a quality finish with only minimal imperfections. A Class B finish is the most common finish for exterior surfaces. It is normally specified on surfaces such as external covers, panels, and parts that are fairly prominent.
The surface that joins class-A and class-B surfaces are class-C surfaces. Class C is often specified for interior surfaces not readily visible, surfaces that will be covered by another part when assembledThe Class C finish allows more imperfections than Class A or B. Class C is often specified for interior surfaces not readily visible, surfaces that will be covered by another part when assembled, or surfaces which the Customer feels do not need to meet a high cosmetic finish.
DRAFT ANGLE
When developing parts for plastic injection molding, applying a draft (or a taper) to the faces of the part is critical to improving the moldability of your part. Without it, parts run the risk of poor cosmetic finishes and may bend, break, or warp due to molding stresses caused by plastic cooling. Equally important, an absence of draft may prevent parts from ejecting from the mold, damaging not only the parts but possibly the mold itself—a costly and time-consuming detour.
STEPS
CLASS A SURFACE
We have been given the Class-A surface and the first thing to do is to make sure that the given surface has no gap in between them. We can check it visually and also with help of Join or boundary commands.
The given surface has only three boundaries which are one outer boundary and two inner circle boundaries. So, there are no other gaps found.
TOOLING AXIS
The direction in which the mold or core and cavity opens is the tooling axis.
Dummy tooling axis
By checking the all three axis the best tooling direction is determined.
Along X and Y direction it is notclearing the circles. For manufacturing in sidecoreis needed and it will increse cost of production
Along Z direction It clears both holes. Hence, there is no need to implement side cores, which leads to less cost for molding.Here Z axis is the best possible direction for tooling
Creating the Dummy tooling axis
A mid point is created in circlular portion
A line is drawn though the point in Z direction. the Dummy tooling axis is created
TOOLING AXIS USING BISECTING METHOD
Tooling axis for the part is created by using the dummy tooling axis using the bisectiong method .In order to check whether the part is toolable in the direction,the class A surface is analysed and the walls which are doubtful of clearing the 3 degree draft angle to the dummy tooling axis is identified.
an intersect is created in xy axis
line is created on the walls
a bisecting line is created and thiis the tooling axis for the part
DRAFT ANALYSIS OF CLASS A SURFACE
Change the view to material mode for draft anlysis
draft analysis is done using featured draft analysis tool
Use the compass fucnction to aling the compass to the tooling direction and lock the direction using lock function in the draft analysis tool bar
the surface is showing green colour so that the surface clears the minimum draft angle of 3 degree
By using the analyses under the running pointwe can check draft angle on the individual faces. It shows how much draft on specific points when we move the cursor point.
Green colour - above 3 degree positive draft
Red colour -between 3 and 0
orange colour- below 0 degree
CLASS B SURFACE
B surface gives thickness to the component. all the engineering features are made in the B surface
RIB -1
extracted the surface
untrim the surface
Extrapolate the surface
Trim the surface
offset to the thickness
Rib -1 is created
RIB -2
Similiarlly RIB-2 is also created
BASE SURFACE
extract surface 1
untrim surface 1
extract surface 2
untrim surface 2
Offset to thickness
FINAL TRIM
Fillet provided
CLASS B SURFACE
CLASS C SURFACE
The first step is to create the boundary of the CLASS-A surface using the boundary command.
Then using the sweep command create the CLASS-C surface
CLASS C SURFACE IS FORMED
CLOSED SURFACE
CLASS A B & C trimmed to form CLOSED SURFACE
TREE STRUCTURE
PART BODY
Close Surface feature usedto make a solid body from the surface.
DRAFT ANALYSIS OF COMPONENT
draft analysis is done using featured draft analysis tool
Use the compass fucnction to aling the compass to the tooling direction and lock the direction using lock function in the draft analysis tool bar
the surface is showing green colour clears the minimum draft angle of 3 degree
By using the analyses under the running pointwe can check draft angle on the individual faces. It shows how much draft on specific points when we move the cursor point.
Green colour - above 3 degree positive draft
Red colour -between 3 and 0
Blue colour- below 0 degree
CONCLUSION
- Created the Base Bracket Plastic component through the given Class-A surface.
- the tooling axis for the given Class-A Surface is created which meeting the requirements of the draft angle
- Draft analysis is done on the CLASS A surface
- Draft analysis is done on the model.
- Using the Close Surface feature solid body is created from the surface
- Publications: Tooling Axis Class A, B, and C surface and solid body
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