Plastic Injection Mold

[gyronikeleg]

Hi Everyone!

I am new to injection molding but I am very interested in learning more. I am currently designing a part for a mold that I am going to make on my PCNC 770 out of aluminum. I was hoping someone could give it a quick look and see if I am leaving anything out or if it would produce defective parts in any way.

I plan to produce around 5000 parts out of ABS for this mold.

I have attached a pdf and I also have step files if you would like to take a look I can email them to you.


Thanks!
Greg

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[Mike 1948]

Ejector pins???? Waterlines for cooling the mold??

[gyronikeleg]

Thanks Mike!

I had considered added those. I didn't know if they were necessary for short run molds <5000.

Can the parts be removed by hand? or is that not typically done?

Can the mold be cooled on its own? or, again, is that not typical?

Thanks
Greg

[Mike 1948]

The shape of the part dictates the ejection requirements, not the length of the run. You "maybe", 'might", get by doing it by hand but remember when the part shrinks on to the ejector half it will probably tough to get off.
As far as cooling, the heat has to go somewhere. You could let the mold cool on its own when it gets hot. But that could make for a long time to make 4-5 thousand parts.

Mike

[mtparker18]

Hi Everyone!

I am new to injection molding but I am very interested in learning more. I am currently designing a part for a mold that I am going to make on my PCNC 770 out of aluminum. I was hoping someone could give it a quick look and see if I am leaving anything out or if it would produce defective parts in any way.

I plan to produce around 5000 parts out of ABS for this mold.

I have attached a pdf and I also have step files if you would like to take a look I can email them to you.


Thanks!
Greg

Greg, there's more to building a mold than just throwing it in a mill, cutting the cavity, and running some parts. You have to make sure you oversize the part to allow shrinkage, add waterlines (see below), knockout/ejector pins (see below), as well as polish the cavity. There's a lot to learn, and it's not easy, but it's learnable to average people. What's the part for? and do you have an actual part drawing? Also, what machine do you plan on running this in?

The shape of the part dictates the ejection requirements, not the length of the run. You "maybe", 'might", get by doing it by hand but remember when the part shrinks on to the ejector half it will probably tough to get off.
As far as cooling, the heat has to go somewhere. You could let the mold cool on its own when it gets hot. But that could make for a long time to make 4-5 thousand parts.

Mike

Agreed, you need ejectors, period. for 5k parts, is 2500 shots (I believe the drawing is for a 2 cavity mold). 2500 shots at 30 seconds a shot is roughly standing there for 21 hours. If you're not running cooling lines, you can almost triple that time. Ejection makes it that much easier. for a 5k run, you can knock out the run in around 16 hours, and that's automated, falling into a box. All you have to do is trim it and do what you gotta do with them.

Thanks Mike!

I had considered added those. I didn't know if they were necessary for short run molds <5000.

Can the parts be removed by hand? or is that not typically done?

Can the mold be cooled on its own? or, again, is that not typical?

Thanks
Greg

It's a necessity on every mold. You need to dissipate the heat from the plastic, or else you're going to be tripling the time you're running your parts.
Ejector; you're not removing parts by hand, especially ABS. It's going to shrink against the cavity during the cooling cycle, then you're not getting it out by hand. Just do it, believe me.

Let me know if you need anything else!