Blanchard grinding castings Best process?

I am designing a ductile iron casting that will be a flat plate about 3.5" thick and about 12" square. It will have a bunch of cored holes through the 12x12 face. I want to flatten both sides of the casting to remove small steps .030" left in the face from draft in the coreboxes and to level things out after the foundry's grinding off of flash. I am thinking I need to remove 1/16"-1/8" per face. Final thickness is not critical. I just want 2 cleaned up faces that are fairly flat.

I will be doing these in batches of 50-100 at a time. Is blanchard grinding the best/cheapest way to do these? A decent face milled finish would be acceptable but sticking these down on a mag chuck will be much faster than clamping in a mill, but I have no idea about the grinding speed.

I would agree with your idea. Blanchard grinding is fast, cheap, and relatively precise.

Blanchard grinding is stupid fast for the right part. I don't understand your comment about grind to remove draft. Will the part have a face than can be hit with a belt sander and set flat on the chuck or will the part have to be shimmed to account for draft on the chuck side?

Thanks sounds like this may be the way to go. There will not be draft on the 12x12 face of the pattern as it is not a draw face it will be the top and bottom of the mould. With 16 cored holes I plan on ganging the cores into 4 coreboxes so the coreboxes will have draft on them so there will be some tiny steps on the face because of draft on the casting face of the cores.

Normal casting practice is to add metal with draft. I had been thinking this would be better as less metal would have to be removed to get a flat face. But maybe it makes more sense in this case on one face to have any draft cause a slight pocket in the face so there would be a good surface for the magnet. The draft steps will be only around .030 max.

Blanchard grind is a good way, just remember on the first side you will be locating off the rough casting. depending on how good/bad the casting is you may/may not have to do some extra shimming/blocking.

Grinding casting will make your machine black inside and if this is is going to be a long term production run just be aware it will take its toll on you machine.

The super fine dust gets in everywhere.

There will be batches of 100 probably about once a year. I don't have a blanchard grinder and will be subbing it out.

Pattnmaker said:

I want to flatten both sides of the casting to remove small steps .030" left in the face from draft in the coreboxes and to level

Click to expand...

Just an idea, make the holes smaller and drill them to remove the step would save a lot of grinding. May not work for what you need.

CarlBoyd

I am still designing this part and the draft will be added in the model of the corebox and not the model of the part so I did a little model to show what I am talking about with the model. There will be 4-5 cored holes in each corebox as opposed to the 2 shown. As well the parting line of the corebox is going to be much more complicated than shown but this gives the idea.