1. Parting of Moulded Parts Adapted from: http://www.solidworks.com/swexpress/april/200204_techtip_02.cfm

2. What is the different between this two chairs? “Solid”stool by Patrick Jouin Chair One by Konstantin Grcic for Magis Design optimised for moulding Design optimised for layered-manufacturing

3. 模 mó 模本、模范、模仿、模型、 模压、模拟、模糊、模棱、模 式、模特儿 mú 模板、模具、模样、模子

4. Drafting and Parting in Form Exploration Draft is a matter of fact for all hard-moulded parts  Injection moulding of plastic and die-casting of metal  Sand casting or shell-casting of metal  Vacuum forming of sheet plastic  Hot and cold pressing of sheet metal The tool designer typically drives the location of the parting lines with input from the design engineer, whom in turn gets input from product designer Adapted from: http://www.bpf.co.uk/downloads/files/InjectionMoulding.swf

5. Gate The gate is the point at which the plastics will flow into the part The functional concern is that the plastic flows into the part easily and at a desirable location based on how the part will fill The cosmetic concern is if the gate will leave a mark on the surface. It is, therefore, typically placed on an inside surface

6. Parting Line The parting line is the location at which the two halves of the mold meet The selection of the parting line is important for both functional and cosmetic reasons Parting lines can be simple or more complex (stepped) based on the part design

7. Direction of Pull The direction of pull defines the normal direction for the draft feature The direction of pull is created from a part edge, face, or plane that defines the normal (perpendicular) direction of the draft feature Does not effect the tilt location for the draft feature. The feature is tilted from the parting line location.

8. Size Deviation All 3 examples assume the draft feature is being created to allow tool to be pulled from the top of the part The top-right method (split) has the smallest effect on the geometry. The reason for this is a portion of the face is made smaller and a portion is made larger The other examples either completely add or subtract from the size of the part

9. Neutral Draft Plane A CAD concept The selection of the neutral draft plane determines the way the draft faces is created Different draft plane location affect the size of the part differently Designer needs to determine which neutral draft plane will produce the desired results

10. Design for Manufacturing Zero draft impossible to de-mould Draft added easy to de-mould form compromised Change direction of pull or no. of parts easy to de-mould but more complicated

11. Discussion What is the general rule for product parting design? Design the form as a blob Try to find out a de- mouldable direction of pull Define direction of pull and part- line Resulting part-line too costly or risky to make! Divide problematic form to more parts Number of parts exceed budget! Add draft by modify the form Form looks bad!Modify the form

12. Parting Follows Form

13. Myto by konstantin grcic

14. Form Follows Parting

15. Example - Art Lebedev Reflectius

16. Example – Electrolux Trilobite

17. Citroen C-Cactus concept

18. Product Design Considerations There is always a trade-off between aesthetics, design considerations, and mouldability Designer can only assure authenticity by taking drafting and parting decision in his own hand Current main-stream CAD application can only perform automatic draft operation on straight-up side walls For curved or double-curvature side walls draft feature must be place in the model early on