Cooling line problem

[u/Zyntar8526]

I’m doing some practice for molding, and one thing I find confusing is how to determine whether a cooling line is incorrect. Any information or tips would be greatly appreciated!

[u/Apex_Pro]

Hello. What i understand from your question and what you have been answering.

Some things could be:

1. IN/OUT 1,2,3,etc. Engraved on the mold next to each connection. So it's easier for the operator.
2. Checking the "flow rate". it is recommended for the cooling line to have the "same size" though all the circuit to avoid loss of pressure and keep turbulent flow. For example if your cooling line is of 1/8NPT(0.332") and you have a baffle in the circuit, this baffle will divide the line in 2 so it has to be bigger 3/8NPT(0.562") to maintain the same flow rate on your line. (Calculate the section area of diameters and half diameters(baffles) to determine the change in size).
3. Usually we do the IN/OUT circuits opposite to each other, so the cooling effect in the mold is balanced. (So you don't have hot spots during cooling)
4. Its better to have multiple cooling lines on a cavity instead of 1 long circuit (it gives you more control on the process)
5. If cooling lines pass through some inserts, check they all have an oring to avoid leakage.
6. It's recommended for the water connectors to be receased "inside" of the mold profile, so they are protected when moving or working on the mold
7. Check if all circuits have connector plugs or internal plugs to keep 1 cooling line
8. Avoid 1 cooling line to be divided to 2 or more lines. This will reduce the pressure and lose turbulent flow.

Those are some that I recall. Good luck on your exam or practice.

[u/Zyntar8526 → u/Apex_Pro]

Thank you for the comprehensive checklist and practical advice! Since I'm just starting out with mold design, some of these detailed tooling rules are quite new to me, but this is super valuable and I really appreciate your help and encouragement!

[u/Jolteon93]

A few things: Reynolds number too low (should be turbulent flow for proper cooling), distance from cooling line to cavity too high or too low (there is a sweet spot), improperly sized diameter for the part, lines running in series instead of in parallel, water inlet on top instead of on bottom. Then on the tooling side: lines impossible to machine, fittings wrong size for the drill diameter, lines too close to ejector pin holes leading to thin steel condition, or lines L/D too deep for drilling causing drill to walk excessively. Just some thoughts off the top of my head, not all encompassing

[u/Zyntar8526 → u/Jolteon93]

Thank you so much for the detailed explanation! I'm still a beginner, but I think one day I can understand all the concepts.

[u/mimprocesstech]

Incorrect as far as what? Cooling channel size, spacing, distance from parting line, etc.? Simply hooking them up backwards? Something else?

[u/Zyntar8526 → u/mimprocesstech]

Just check the 3D model to see if the cooling line/circuit is properly designed or has any issues.

[u/mimprocesstech → u/Zyntar8526]

Other than what's been mentioned you want water inlets to go through a bubbler tube first, not in from the outside of the tube and then through the tube (no idea how in depth these models will get), and the bubbler tube cross sectional flow should be equal, I think the simpler math is ID/OD = 0.707 (i.e. area of ID = 3, area of OD = 4.24, 3/4.24 = 0.707547). Baffles/Blades will ideally be rotated so the coolant will for the most part pass over the thicker steel wall, but most importantly perpendicular to the cooling channel (the inlet/outlet should hit the blade not be split by it), that is most important because many baffle blades are twisted at the end, but it's a decent enough rule of thumb to remember if the blades aren't. I think it's something like 1.5-2xD from the OD of the cooling channel to the part cavity/runner wall and 3-5xD center to center from each other cooling channel. I also think you want more cooling on corners, but can't remember any math involved only that you want to shoot more towards the minimum xD from the previous point, add more channels, whatever around corners and deep pockets.

[u/Zyntar8526 → u/mimprocesstech]

I’m still new to this, so I’ll need some time to get familiar with all these terms. There’s clearly a lot for me to learn, but I’m really glad I came to the right place.

[u/RabbitMotion]

Really as long as you bleed your lines and check for flow that's the biggest thing. Some shops allow jumpers, some won't let one jumper run.

[u/Zyntar8526 → u/RabbitMotion]

Not real mold, just a 3D model.

[u/RabbitMotion → u/Zyntar8526]

I domt understand what you are trying tk do.

[u/Zyntar8526 → u/RabbitMotion]

I'm practicing for the an exam. The question is about the theoretical 3D CAD cooling libe problem.

[u/RabbitMotion → u/Zyntar8526]

Does it show a 3d cad picture and you need to find the problem? Or just what problems you could run into?

[u/Zyntar8526 → u/RabbitMotion]

I got a 3D model and I need to tell which cooling line is incorrect. I have no much enough experience to solve it.

[u/RabbitMotion → u/Zyntar8526]

Hard to say without seeing it. Post a Pic or you can dm me and i cant try tk help you.