Some 3D Mold Work

I do work for the areospace sand casting industry. I deal mainly with the pattern maker. So, a short sand casting lesson: The pattern maker makes a wooden model of the casting with draft and shrinkage built in. Draft is mainly all vertical walls have a 2-3 degree taper. This is so the casting will come out of the mold. Shrinkage is built into the pattern. Ex: aluminum shrinks as it cools, so the mold has to be oversize, so the pattern has to be oversize. The pattern is what makes the sand mold, which makes the casting.

The sand box is called "The Core Box". The core box is made up from several small cores that interlock with each other to form the shape of the casting. They fit together like one of those wooden puzzels you've seen.

Ok, lesson over. Ya, the tooling for sand castings is very complicated. So, the pics I have below is a small core. One of many that go with this core box. This core is know as a "Gate". A gate is the fill tube, or tubes, which the filler metal is poured. The gates also hold an excess of molton alum so as the mold cools, it draws from these tubes so that the mold doesn't run out of material.

In the 1st cad model pic, you see the 2 vertical tubes with a plate connecting them. This plate is a test coupon. This gate/coupon mold will be cut off down at the small end after casting is cooled. These coupons are kepted and tested to ensure a good pour.

I only make half the mold. The they will put two of these molds together face to face and tadaaa! You have a mold.

The material I'm cutting is know as "Ren Shape". It cuts like cured bondo. It's a machining foam. In the pics, you see the rough pass on one half, and finish pass on the other. The outer vertical walls of the block are cut with a 7 degree end mill so that the cores don't get jamed in the core box and are easily removed.

So lastly, the core box makes the sand mold. Then they remove those sand molds from the core box and put them into another box that will get the molton material and make the casting.

HEY!!!!! ARE YOU STILL WITH ME?!!!!!!!! lol lol lol

I'm not super familiar with the Sand Casting process as a whole.. Most everything I ever cast we did Investment Casting, or Rubber Plaster Molding.


I see your cutting the Negatives in Ren Shape.. The Ren Shape is going to be the end mold?

RD

No. the Ren Shape (or core) is just to form the sand. Then they vibrate, pack, and heat the sand and it sticks to itself, forming the cavity shape. Then they remove these sand pieces from the core box and put them into another box which finally becomes the mold.

After the pour and the casting is cooled, they break open the mold box and remove the casting from all the broken up sand pieces. Then they smack the casting with something hard, and all the packed sand becomes loose again and they shake it out. The used sand is run thru a screen and used over and over again.

So an Edelbrock torquer intake manifold sand core looks like a big spider. Then they smack it and pour the spider out.