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Optimize Scallop for good surface finish for foundry pattern tooling

natemclain
Enthusiast

Optimize Scallop for good surface finish for foundry pattern tooling

natemclain
Enthusiast
Enthusiast

Can anyone give suggestions on the best way to optimize a finish scallop operation (see attached example file) for good surface finishes?

I know the tool & die, investment tooling pattern makers, etc. must have some tricks to reduce the cycle time and still give some great surface finishes.

Using a bull nose with a 0.015-0.025 step over to give some good scallops on vertical walls that require draft angle, it seems that the scallop operation doesn't recognize when there is a large flat area so it takes along time to get those area's machined with that small step over.

 

Do you typically use the contour or only select the vertical walls for the scallop operation to speed it up?

 

Does anyone have any advice?

 

TIA,

 

Nate

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LibertyMachine
Mentor
Mentor

You totally want to target your 3D operations. Selections, touch/avoid are going to be your friends. I'll try to get into your file later today, but that's the advice I'd give. Don't look at any one tool as a complete solution.


Seth Madore
Owner, Liberty Machine, Inc.
Good. Fast. Cheap. Pick two.
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randyT9V9C
Collaborator
Collaborator

What is your pattern material? Wood, butter board, aluminum?

 

The first foundry pattern I made the foundryman  laughed at how polished it was. Most short run patterns are wood. Sanded and painted is usually good enough. One time I had a pattern maker convert one of my patterns to urethane for better durability... he covered the whole pattern in tape, made a plaster mold, and cast the urethane from that. Looks every bit as good as the original.

 

I normally do my drafts using tapered end mills so I can finish the walls in one or two passes.

 

In your case contain your wall finishing and use a separate operation to finish the flat with a larger step over. Something like this.

 

scallop4.pngscallop3.png

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natemclain
Enthusiast
Enthusiast

Material is Pattern Plank (red board).

This is the durable, heavy tooling plank. Wears allot like aluminum from my experience.

 

I see how you used the boundary to prevent machining the large flat area with a small scallop step over. Good tip.

I suppose you can just go back and machine the large flat with an appropriate tool and step over to get it machined efficiently.

 

And you are correct, most foundries don't "require" the tooling to be polished. It's a point of pride for myself and something that I was taught to do when producing tooling.

The casting will only be as good as the pattern tooling.

But you are correct, most foundries don't worry about polishing the surface of the pattern & core box.

With 3D printed sand molds you would be surprised with the amount of surface finish. Some are fairly coarse. In the case of a machined sand mold (Southern Cast Products - Jonesboro) the surface finish of the mold is fairly rough and it still seems to produce a good casting finish once it has been shot blast & machined. :slightly_smiling_face:

 

Thank you for the tips, I will keep playing around with it and see how much time we can shave off the program.

Since most pattern tooling programs are used 1 time it makes it harder to spend allot of time dialing in the program so you usually try to find the low hanging fruit for optimization.

 

Again, thank you.

 

Nate

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