Inclusions and Sand in Molding

[Pipescs]

I have had a discussion for some time on the Artfull Bodgers Furnace but I believe we have put that to bed. It is a great little furnace that was fun to build and having done it I would have made few changes or improvements. It is just a matter of me getting more practice

I would like to start a discussion on sand or inclusions and how to keep them out of the mold.

I have read a lot of input on slowing the metal down to let the sand drop to the bottom of the gate prior to going into the mold. Does this happen or does it rise to the top?

[Harold_V]

I'm struggling with the notion that sand will drop to the bottom, in particular in brass or bronze. Seems to me it would be inclined to float.

Harold

[Pipescs]

I have to agree with Harold here. Of course I am only a beginner with about half a dozen attempts under my belt.

It seems on all my attempts the sand that has washed in along with any slag inclusion has been on the top of the casting.

This shows the front and back of an attempt the suffered from sand and the metal not being hot enough

This casting of the hinge block for the trailing truck was fed from the large ring. You can see the sand that was washed in to the mold cavity in the center top.

[Fender]

Charlie,
I think the idea is to set up your ingates so that when the first metal is poured in, any loose sand or inclusions will be carried into a "dead end" passageway. Therefore, the loose sand will be trapped there, and the mold will be filled with clean metal. My experience is that it is nearly impossible to completely eliminate this problem, so it's desirable to set up the mold so the "front" side of the casting is on the bottom, and the "back" on the top. Therefore, if there is some sand or inclusions it will float to the top of the casting and be on the back side where it won't show as much. Alternatively, you can add some thickness to the back of the casting, which can be machined off.
A riser can also allow the loose sand to pass through the mold and float to the top of the riser, so that when you cut the riser off the casting, the sand will be removed too.

[Pipescs]

Tried to do a couple of sketches to see if I can capture what Fender has described.

After I drew this I realize Fender is talking about a lower level trap that is dead ended

My first drawing while it would slow the metal down to let it settle out could still pull the dross across the top.

[Pipescs]

Taking Fender's idea I am putting a trap into the lower section of the Drag. It will have to fill completly up prior to the metal flowing out in the gate cut into the cope going to the mold.

I am thinking I might add a blind riser just prior to the metal going into the mold cavity to give a column of metal to let the shrinkage draw from. Any thoughts?

[Fender]

I think you have it!
Except, shorten the green feeder to the mold. There is no reason for it to be that long. A riser on the main body of thr casting is also a good idea.

[Pipescs]

Nothing in the drawings is to scale. It was a concept model. By close of buisiness tomorrow I should have most of the gates on the Journal Boxes Cut. Also I am working on the top and bottom core prints along with the core models to make the journal boxes hollowed out.

[Pipescs]

Giving Fender's dead end gate idea a try.

On the Drag side I have placed a runner leading to a larger area to capture any early slag.

After the metal fills the lower Drag area, hopfully having pulled in all the dross, the pour will then start to fill the mold cavity thru the feeder that is only on the cope side.

I will put in two risers directly off the top of the mold to have plenty of metal to fill the area as it cools. There is a core set up being drawn that will be added to the patterns as core prints on the top and bottem along with the core.

[Pipescs]

Talking with Fender, we agree my trap is too big and will take a lot of metal to fill up. Oh well.....

[Harold_V]

In the very distant past I recall reading about a horn gate. Problem is, I don't recall the purpose, but I keep connecting its use with casting brass/bronze. Would it be of any use in your endeavor?

Harold

[Pipescs]

I rememger something in my Navy Foundry Manual but as it is at Fenders I will have to ask what one is.

In the mean time I have just knocked out the drawings for the patterns for core prints and the core halves for th Journal Boxes. Originally I was going to go with a solid casting but after working with Trainmanon a project I decided to do a quick set of patterns for adding a core. This required core prints to add to the pattern and a master to cast a plastic core box off of.

trying to load photos but oh well....