Name: This Technique Changed Mold Making Forever
Uploaded: 2025-04-21T07:30:56.000Z
Duration: 8 min 36 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

This is a graphite electrode, and we're going to use it to burn subgates into this 56 Rockwell H13 mold insert.

We're going to talk about what subgates are, how they simplify the molding process, and how they affect your day to day life.

Subgates are used to deliver molten plastic into the cavity of an injection mold that makes the products you use on a daily basis.

Using this method completely eliminates an entire part of the molding process.

Before we burn our subgates, first we need to burn the main cavities of our mold insert.

These are the features that are going to make up our molded part when it's all said and done.

For this project, we're using Poco EDM3 graphite from Integris.

Now, Poco graphite is the graphite that I prefer to use for all my sinker EDM work.

And since we don't have graphite milling capabilities, we went to our friends at Graphel to machine all these graphite electrodes.

And as you can see by looking at them, they are top notch, super precise, great people to work with.

So, thank you to Graphel for providing all these machined electrodes for this project.

Now that we're done setting up our electrodes, it's time to set up our part.

Now, Jesse went ahead and roughed out the cavities and machined the runner into our insert.

And roughing out the cavities is going to decrease the amount of time it takes to finish burn this part on our sinker.

And machining the runner is going to prepare us to burn the subgates later on.

To hold our part, we're using a magnetic chuck from Shunk.

Since the sinker EDM process doesn't exert a lot of force on our part, we can use this magnet and it's a simple and precise way to set up our workpiece.

To make this part, we're using our SOTIC AL40G sinker EDM.

If you're new to the channel, EDM stands for Electrical Discharge Machining, a process that removes material using electricity instead of cutting force.

For our main cavity burn, we're using a 5,000 spark gap.

Now, the spark gap is going to be the distance between the wall of our electrode and the wall of our part.

That gap is going to be taken up with the spark, which is actually going to erode our material.

Now, the orbit pattern we're using is a circular orbit.

That means our electrode is going to move in a circular pattern right at the end of our program, and that's going to finish up all the features that make up our main cavity.

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So now that we're done burning our main cavities and our features look nice and sharp and our surface finish looks great, it's time to burn our subgates.

But before we get into that, what are subgates and how do they work?

The term subgate is short for submarine gate.

Now the way it works is molten plastic is going to travel through this center hole through a part called the sprue bushing.

Then it's going to travel through these channels, which are called runners, and it's going to shoot the molten plastic through the subgate at high pressure, and then it's going to fill this part cavity and it's going to cool.

Once that happens, we'll be left with parts that look like this that are sitting inside of our mold insert.

Well, typically what you would have is you would have the parts all connected to the runner and the gate all as one, but these are actually four individual parts.

So essentially we need to separate the parts from the runner system.

Now it's called subgate because it tunnels underneath the parting line of our mold insert, and that's going to create a knife edge right here so that when the parts are ejected from the cavity, they're going to automatically shear all four of these parts from their runner system and it's going to put the parts in one bin and it's going to discard the runner.

And that's all going to happen automatically, so we don't have to have a secondary process that's going to trim our parts from our runner system.

Let me show you guys a little bit more common method of gating our parts called an edgegate.

So this is the exact same four set of parts, but instead of using a subgate, we've used an edgegate, and as you can see, the difference is this is going to come straight across into our mold cavity instead of tunneling underneath our parting line like our subgate does.

Now I've modeled up the exact same parts to show what it would look like after these are molded, and as you can see, there's nothing up here to shear our part from our runner system, which means if you molded your parts like this, you'd either have to have a person or a secondary operation that's going to cut the parts from the runner system.

The problem with that is you could have inconsistencies right here where you separate the parts from the runner.

You could have a bulge or maybe some inconsistencies from part to part with that gate vestige, and if you have subgates, it's going to be very consistent.

Every part is going to look the same, it's going to be nice and smooth, so you're not going to have some of those issues associated with the edgegate.

Now subgates only work on small parts because it's such a small hole that you can only push so much volume through it.

So we're talking things like electrical housings, little parts for the electronics industry or maybe even the medical industry.

Things that you don't necessarily notice in your day-to-day life, but this is how they're made and they definitely impact you on a day-to-day basis.

So the biggest benefit to subgates is they automatically remove the parts from the runner, whereas the edgegate requires a secondary process.

I'm super happy with how this turned out.

Our AL40G performed awesome, burning our main cavities and our subgates.

And as you can see, using subgates in your mold design completely cuts out part of the process when it comes to making molded parts.

And the molded parts that stuff like this make impact your life in a big way.

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