The good part… a start part II

Part Design:
In the last installment we started on part design and basically gave a listing of some basics…
Uniform wall thickness,
Radius the corners
Holes away form sidewalls
Where can we put the gate?
What type of visage is allowed?
Surface finish, cosmetic details, color
What assembly methods are to be used?
Draft in the part
Parting line location
Ejector pin location, allowable marks.

As can be seen we only touched on some of the points, for further reference check with your supplier of materials and the great books available for part design. The real thing here is to start to involve the other players in the group. The design is done or ready for review and let people do that, the molder, tool builder, material supplier and all.

When you look at the print and the notes are they clear in definition? Are they general in that it states radius all inside corners? Is there an isometric view of the part on the page? If the part is small is there an actual size print/view of the part?

Now within the aspects of the part design the selection of material must be done.  This is where the designer or inventor has a need for specific functions of the part and its design. It is important at this point to note which functions of the part are material specifics and those that are design specific. For example clarity, is a material functions. While stiffness may be a material function, it can also be a design function in that we can go thicker on the part or use a rib. Or if we are designing a thin wall application we may need to look at the stiffness of the material because we do not have the option of designing in the ribs or wall thickness. It would be nice to have generalities, basically if it has to do with clarity; chemical, solvent, and temperature resistance may be more material dependent. While stiffness, flexibility, impact can be affected by design.  Please understand we are being very wide here with the ole thumb.

To be continued

Thanks for the time….

Steven L Silvey
Sr. Technical Service
GP-ADC
Slsilvey@ashland.com