Alternative molding, Block filling a flask

From molding systems to gating, what goes on at the molding bench will make or break a casting.
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Harry
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Alternative molding, Block filling a flask

Post by Harry »

On my small flasks I have been using a 1 1/2" high drag and a 3 1/2" high cope. My thought was to reduce the sand used by using a wood block to take up some of the space. I was also trying to figure out how to keep my jolt squeeze from breaking any more of my patterns, that thing has some power.

One of the problems using the squeeze is have to use a block on the first lift to push it down then top it up. My squeeze isnt set up in spot where I can not worry about spilling sand because it will be lost in the dirt. Plus just the pain of having to press it twice so it occurred to me why not leave the block in place?

I made a set of two blocks for each of the four 6 x 8 flasks. One block is just a single 2 x 6 that just fits inside the flask. The other is two 2 c 6 screwed together for the cope, this also has a 2" hole drilled through where the sprue goes.

I lay the matchplate pattern down and put the drag on and sieve on sand to slightly over fill the short flask. Press in the single 2 x 6 by hand and flip it, set on the cope side of the flask and fill (no sieving on the flat back side) strike the loose sand off flat and press in the double block with the large hole then shove some sand in the hole and strike it off.

This whole stack goes into the squeeze and when it comes out it is ready to poke the sprue then open and remove the pattern, blow it off, close and pour.

This whole process happens in just a couple of minutes and is not 1/4 as strenuous as all of the activity involved in hand ramming the mold or even using the squeeze the way I was before. This also uses less than 1/2 the sand in the same flask. It does require blocks for each different pattern if the sprue is in different locations and I am probably going to do a negative carving for some of my larger parts that have steep sides so it will compact evenly.

This is looking like a huge improvement in many aspects, mold weight, time to prepare and amount of sand processed per part. This afternoon I made 28 small parts in a little over 2 hrs and these were one part per flask.

While the squeeze is quite fast I think anyone wanting to use this method could do so by getting one of those air over hydraulic rams from HF and build a frame for pressing them. For production molding the time and effort saved and the lower sand usage which is more time and effort saved is just awesome.

Here is some pictures of the process using blocks in a 15" flask.

Ready to go, the block in the back with the holes is actually for the cope and this is the drag.

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Filled flush with sand and struck off then the block pressed in.

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Flipped, sand dropped in and block pushed in again by hand. Also pushed a little sand into the sprue and riser.

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In the squeeze and blocks pressed in.

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Spreu and riser cut before removing pattern, pattern removed and gating cut. Will be putting this gating on the pattern so it will just be open, remove pattern, blow and close.

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Close of how the sand protects the wood in the sprue and riser.

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Little sprue will I was playing with, dont really need it as I can hit the 1" hole fine but could be useful if I need more pressure.

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This is one flip in putting the stack together and open and close to get the pattern out after one squeeze. That was my first one using the 15" sq flask and it took me less than ten minutes and very low on the effort scale where before it was 30 minutes of shoveling and pounding. I can also now handle this flask complete instead of one half at a time. This is just huge for me in terms of cutting the labor which as any of us know is the biggest part of what we do so everything that can be cut on labor is money in the pocket. I am loving life with this.

Now deeper parts will be a different story, this works great for low profile parts but I have a plan for the parts that are thicker and project onto the flask further. I will be making a negative block with about a half inch larger cutout so it will extend into any areas of the flask that are deeper yet leave room where the part stands up.

I still have a few more ideas to make this even better and faster, if I can get a 15" mold down to 5 minutes I will be set right up.
I'd rather laugh with the sinners than cry with the saints the sinners are much more fun...
Muller
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