Residence Time - Fake News
RESIDENCE TIME is not a definitive data point.
It’s a reference only.
A reference that makes the Tooling Engineer say . .
" Hmmmm, that could be an issue;
Worth checking out a bit more. "
You are probably thinking - I thought Residence Time was a clear go - no-go?
Why is Residence Time just s reference?
Seems different to what I have been taught. Help me understand this better.
A five minute vs seven minute residence time should be a clear decider.
It's science . . . RIGHT?
Well
Kinda
Yes and No
This needs several extra blogs to explore.
How can a seven minute residence time be ok for one part,
and . . . a killer for another?
Answer
Because each part and tool comes with a truck load of variables.
Part size
Wall section
Flow length
Tool size
Cavitation
Feed system
Molding process
Different machines
Different flow patterns
Material preparation
Complicated geometry
Every part is unique.
Every part has a different combination of the above elements.
Every part has a different hierarchy listing for the above factors.
Now you have a more nuanced understanding of Residence Time as a single data point.
A data point in a cloud of inter-acting variables.
Residence Time is a single variable.
It’s the blade of grass the golfer throws in the air
to judge wind speed and direction.
Here’s an exaggeration to help you capture the concept
Part A
Ten minute residence time.
MFI and mechanical performance are good.
Part B
Six minute residence time.
MFI is high. Mechanical performance is poor.
Residence Time is not the Full Picture