In this blog post, I present
you another rule of thumb for your daily polymer engineering operations.
There are several factors
which impact plastic part performance. Altogether, we can divide them into four
major categories [1]:
- Material and materialselection: 45% of cases related to part failure [2], are due to wrong material
selection, together with insufficient specifications.
- Component design: there are
10 basic design rules [3] which serving as a helper when designing for
injection moulded products:
1. Wall thickness as thin as
possible
2. Continuous wall thickness
to prevent accumulation of mass
3. Corners and edges with
radius
4. Ribs designed for
moulding: 40-60% of wall thickness for ribs
5. Avoid plane and even
surfaces
7. Avoid undercut sections
8. No more accurate
machining as necessary
9. Check for possibilities
of function integration
10. Past performance of
design can be guarantee of future results
- Part processing and assembly:
depending on the processing technique involved, it is important to take proper
care of the material (e.g. drying), mould (e.g. temperatures), machine conditions
(e.g. temperatures).
- Service conditions of the
part: this is linked to the first point “material”. If the requirements are
well explored, then specifications are properly set which in turn allows optimal
material selection. If e.g. the continuous service temperature is too high,
reduction of mechanical properties may occur, together with material degradation.
The four categories are schematically shown in the above figure.
In case of a plastic part failure, several factors
combined lead to failure and it is rare that a single factor leads to part
failure.
Therefore, keeping all four categories in mind during
part design will reduce part failure and allow you to get the best performance
out of your part.
Thanks for reading and #findoutaboutplastics
Literature:
[1] Jeffrey A. Jansen: Finding Fault, applianceDESIGN, 2006
[2] David Wright: Failure of Plastics and Rubber Products,
Rapra, 2001
[3] https://www.findoutaboutplastics.com/2018/04/plastics-part-design-10-holy-design.html
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