Door Arm Rest Week 8 Challenge

Introduction

Having easier ejection from the mold may seem like a minor concern, but draft is crucial to manufacturing parts that meet your quality standard. Without draft, major problems can arise in the injection molding process that increase the time and cost of production.

When no draft is designed into the part, problems can come from friction and vacuums. These issues can damage both your part and even your mold in extreme cases. These problems are a direct result of having insufficient draft. Because plastic shrinks as it cools, portions of the part may pull away from the mold while others grip the core. If there is no draft angle that allows a simple push from the ejector pins to pop the part out of the mold, the part’s surfaces will often drag along the mold as it is being ejected. This friction between the two surfaces can cause scratches or gouges in your part and affect the appearance. This is particularly troublesome if your part is being molded with a surface finish or texture. The friction will scrape away texture and leave you with many rejected parts.

3 degree is the nominal draft

0.5 is the minumum draft which increases the manufacturing cost

Above 5 degree for textured face

Procedure followed for draft analysis

1)check for any gap between the surfaces and make sure there is no gap by visually or by checking with boundary feature if the gaps are found out make sure to joined

Creating the Main tooling axis along Z direction

Analysis with respect to main tooling axis

As underscuts were noticed we need to create slider tooling axis along y direction

Slider tooling axis

Analysis with respect to slider tooling axis

Designing the class B surface from the given class A surface is the next step to be followed

• As the fillets gives problem during the thickening we extract the required surface and offset all the extracted surfaces towards the class B region by 2.5mm and trim them and provide the necessary fillets following the rule(Radius of the fillet of class A surface) ±(the offset value) to get the class B surface

Class C surface

Class C surface are once which lies between the Class A and B surface . while creating the class C surface we have provided the draft greater than 3 degree in such a way that the parting line lies at the B surface. And this is done to prevent flash on the Class A surface.

Class A , B , C surface after the final trim

Tree Structure

Publication is done as it is easy to access the tooling axis and the Class A surface

Colour scale which indiactes the degrees at sepecific location

Draft angle in various orientations

Isometric

Front

side

top

Zones of undercut

Conclusion

The Door arm rest's class B and C surface was designed successfully for the give Class A surface.