Pmack
1st December 2018, 12:04 AM
Hi all,
I've designed a part for a personal project, and had the first off tool samples sent to me.
It's essentially a large clear polycarbonate container.
Dimensions are approximately 280mm square, and 400mm tall. Wall thickness 2.5mm. Weight ~1.2kg
A simple core and cavity with no inserts (apart from logo).
Ignoring the discoloration and lack of transparency (presuming this is just lack of cleaning the tool and rough surface finish, or perhaps it's intentionally dirty so you can observe the flow?), main issue is flow lines.
Due to the channel, the flow moves slower over there and that seems to be why we have the flow lines you can see in the second picture.
316
317
They want to know if they can increase the radius on the channel, and increase the wall thickness on the top and possibly also the rear of the part (behind the channel).
I definitely don't want to increase wall thickness if I can avoid it as I need to keep material and cycle times down, this will be made locally not china also.
To me, it seems the problem is the size of the gate, and or perhaps the location of the gate.
The gate measures only 2 or 2.2mm in diametere.
A simillarly sized mass produced polycarbonate container (https://www.webstaurantstore.com/cambro-rfscw22135-camwear-22-qt-clear-round-food-storage-container/214RFSCW22.html) with the same wall thickness of 2.5mm, has a gate about 7-8mm in diameter.
The external fillet on all edges you see is 6mm (cavity side), which means the internal radius's (core side) are all either 3.5mm or 8.5mm depending on the edge.
The tool maker also wants to increase the 3.5mm fillets on the core to around 5mm.
My first problem with that is that I need this tight radius for inserting a part for which I've already made a compromise for.
i could have them increase the first tight internal fillet the flow hits where I've highlighted in orange, however my question is:
1. Increasing the fillet on the core will mean the cross section becomes inconsistent, does this cause problems?
2. They want to increase the overall wall thickness where I've highlighted in yellow, and potentially the rear of the part too, by around 0.5mm. This doesn't sound ideal, thoughts?
3. Won't increasing the gate diameter achieve the required result, or does the gate location need to be moved further to the back?
4. Oh also on the core side (gate is on cavity), there is a small dome around 10mm in width and 1-2mm in height (protruding from the internal surface).
They want to make this larger. Good idea?
Thanks in advance for any help :)
Cheers,
Paul
I've designed a part for a personal project, and had the first off tool samples sent to me.
It's essentially a large clear polycarbonate container.
Dimensions are approximately 280mm square, and 400mm tall. Wall thickness 2.5mm. Weight ~1.2kg
A simple core and cavity with no inserts (apart from logo).
Ignoring the discoloration and lack of transparency (presuming this is just lack of cleaning the tool and rough surface finish, or perhaps it's intentionally dirty so you can observe the flow?), main issue is flow lines.
Due to the channel, the flow moves slower over there and that seems to be why we have the flow lines you can see in the second picture.
316
317
They want to know if they can increase the radius on the channel, and increase the wall thickness on the top and possibly also the rear of the part (behind the channel).
I definitely don't want to increase wall thickness if I can avoid it as I need to keep material and cycle times down, this will be made locally not china also.
To me, it seems the problem is the size of the gate, and or perhaps the location of the gate.
The gate measures only 2 or 2.2mm in diametere.
A simillarly sized mass produced polycarbonate container (https://www.webstaurantstore.com/cambro-rfscw22135-camwear-22-qt-clear-round-food-storage-container/214RFSCW22.html) with the same wall thickness of 2.5mm, has a gate about 7-8mm in diameter.
The external fillet on all edges you see is 6mm (cavity side), which means the internal radius's (core side) are all either 3.5mm or 8.5mm depending on the edge.
The tool maker also wants to increase the 3.5mm fillets on the core to around 5mm.
My first problem with that is that I need this tight radius for inserting a part for which I've already made a compromise for.
i could have them increase the first tight internal fillet the flow hits where I've highlighted in orange, however my question is:
1. Increasing the fillet on the core will mean the cross section becomes inconsistent, does this cause problems?
2. They want to increase the overall wall thickness where I've highlighted in yellow, and potentially the rear of the part too, by around 0.5mm. This doesn't sound ideal, thoughts?
3. Won't increasing the gate diameter achieve the required result, or does the gate location need to be moved further to the back?
4. Oh also on the core side (gate is on cavity), there is a small dome around 10mm in width and 1-2mm in height (protruding from the internal surface).
They want to make this larger. Good idea?
Thanks in advance for any help :)
Cheers,
Paul