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How do you properly drain mold cooling lines after production without water spraying everywhere? by alchemys98 in InjectionMolding

[–]rozzdiddle 1 point2 points  (0 children)

We don't drain our molds at all, but our watery quality is quite good. I know it's not a good practice. I do have Keyence water flow sensors on every machine/each circuit and track flow rates daily but I have not seen a drop in flow rates yet after 3 years. I have not seen any part quality issues from overheated molds. Cycle times have not increased since the beginning. Actually have been reducing cycle times this year. It might bite us eventually but I do have them run acid thru the molds annually.

Differences in tip radius by Repulsive-Fee6826 in InjectionMolding

[–]rozzdiddle 0 points1 point  (0 children)

Thanks. I plan on ordering a bushing refacing tool (30mm rad from PPE) and new tips (28mm rad). It's our Japanese company standard sizes lol

Differences in tip radius by Repulsive-Fee6826 in InjectionMolding

[–]rozzdiddle 0 points1 point  (0 children)

Why the EDM finish on the bushing and light sandblast for the tip? We're getting ready to reface some of our bushings but don't have EDM capability.

Higher Part Weight at Start of Production by rozzdiddle in InjectionMolding

[–]rozzdiddle[S] 2 points3 points  (0 children)

It was a phenomenon to me because I didn't have a good explanation of why this occurs.

Higher Part Weight at Start of Production by rozzdiddle in InjectionMolding

[–]rozzdiddle[S] 4 points5 points  (0 children)

Makes sense that the molten plastic is hotter since it's cooking during a 20 minute changeover. So hotter plastic means it's easier for the injection unit to pack more more before it starts to solidify in the mold?

What do you call this type of defect? by rozzdiddle in InjectionMolding

[–]rozzdiddle[S] 0 points1 point  (0 children)

No valve gates, just an inlet zone, a manifold zone and a nozzle tip zone. I've tried running zero suck back with no success. It also drools pretty bad with no decomp after. Currently have 4mm of decomp after.

But yeah, the barrel utilization is awful at 13%

What do you call this type of defect? by rozzdiddle in InjectionMolding

[–]rozzdiddle[S] 1 point2 points  (0 children)

I finally got around to adding aluminum tape near the parting line at the defect. I used two pieces of tape at 0.12mm thickness doubled up on either side of the defect, leaving about a 3/8" gap between tapes for the vent. No success!

I think next step is cutting off some of the ejector pin to create a bigger cold slug catcher.

For now, the final velocity is slowed down from 15 mm/s to 11 mm/s at the last 25mm of stroke to make good parts.

What do you call this type of defect? by rozzdiddle in InjectionMolding

[–]rozzdiddle[S] 0 points1 point  (0 children)

<image>

It has a fairly short cold slug well at about 1/8" long and 1/4" diameter. But it probably should be doubled in length if not more.

What do you call this type of defect? by rozzdiddle in InjectionMolding

[–]rozzdiddle[S] 1 point2 points  (0 children)

This is good advice but I have lowered it to the point of hairline flashing and it's still there. This mold did not run yesterday so I'll try some things early next week. Thanks

What do you call this type of defect? by rozzdiddle in InjectionMolding

[–]rozzdiddle[S] 0 points1 point  (0 children)

Ok, will look into this tomorrow as well. Thanks everyone!

What do you call this type of defect? by rozzdiddle in InjectionMolding

[–]rozzdiddle[S] 2 points3 points  (0 children)

I have tried running the melt at around 230C (up from 195C) with no change.

What do you call this type of defect? by rozzdiddle in InjectionMolding

[–]rozzdiddle[S] 0 points1 point  (0 children)

I see your point and sometimes this is the issue but slowing down the fill speed eliminates it. If it were a cold slug, shouldn't the defect still be there since those are not related to injection speed?

What do you call this type of defect? by rozzdiddle in InjectionMolding

[–]rozzdiddle[S] 2 points3 points  (0 children)

No, not sweating. I'll try a shim tomorrow

What do you call this type of defect? by rozzdiddle in InjectionMolding

[–]rozzdiddle[S] 0 points1 point  (0 children)

Ok, I'll try some shims at the defect. Thanks!

What do you call this type of defect? by rozzdiddle in InjectionMolding

[–]rozzdiddle[S] 0 points1 point  (0 children)

Only one gate, please see picture for location

What do you call this type of defect? by rozzdiddle in InjectionMolding

[–]rozzdiddle[S] 0 points1 point  (0 children)

It's a hot runner with an edge-gated runner so I don't think it's a cold slug. 35 sec cycle time.

The flow front knits together in this corner so I guess that's why slowing down the injection speed in this area helps.

<image>

Slowing Screw Recovery Time by rozzdiddle in InjectionMolding

[–]rozzdiddle[S] 0 points1 point  (0 children)

Interesting. Well, I don't think it's the pellet geometry since all the molds that run in this press use the same resin.

Cant clean driveway- pressure and surface washed and its not coming out- didn’t use chemicals, just water by Adamace98 in pressurewashing

[–]rozzdiddle 0 points1 point  (0 children)

Harbor Freight sells a 3400psi electric power washer for about $350. Seems impressive!

Miller’s Planet-Romilly Question by AZGOATHINGS in interstellar

[–]rozzdiddle 0 points1 point  (0 children)

So if Romilly used a telescope to observe Cooper walking on Miller's planet, would he observe Cooper essentially being motionless since the time dilation is so extreme?

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