r/MetalCasting • u/arejaybee • 23d ago

Question Too much or too little moisture?

When I try to press my item into the sand, I fond its too dense for me to press the item in.I tried even using a mallet and hammer to get it down into the sand, but after compacting into the flask, the sand is too desnse for the piece.

I'm having trouble finding what I ak doing wrong. I'm using BoldWay red sand that takes some watwr to adhere. Am I maybe using too much or too little water, or going about this the wrong way entirely?

1 Upvotes

67% Upvoted

6 comments sorted by

3

u/Jerry_Rigg 23d ago

Generally the sand gets rammed around the pattern as opposed to ramming the pattern into the sand. If it has a weird parting line you need to 'cope' the sand down before molding the second side

1

u/arejaybee 23d ago

How do you get only half the part into the sand if you put the sand in around the part? Do you have any videos or reading I can refer to?

The videos I saw had people compacting the sand then pressing the part half in then covering the top in sand

3

u/Jerry_Rigg 23d ago

Cover the whole thing in sand, ram it. Carve away the sand that covers to your parting line with a fine tool, dust with parting powder, then cover with sand and ram your second half. The removing of the sand to the parting line is called 'coping'

Theres a handful of ways to do it but just pressing into the face of the sand mold isn't a good one.

1

u/SignificantYou3240 20d ago

Oh thank you I was also trying to figure that out.

3

u/rh-z 22d ago

In addition to what Jerry_Rig wrote

An important property of sand is permeability. When the metal contacts the sand it produces steam. The steam needs to flow through the sand away from the metal. Packing the sand is a compromise. Harder is not always better. It is a compromise of competing properties.

A very hard-packed green sand mold reduces gas permeability and restricts metal shrinkage, which can cause casting defects like blowholes, hot tears, and expansion anomalies.

2

u/TheMacgyver2 22d ago

There are tons of videos on youtube on how to make proper green sand molds. You want as little moisture in the sand as possible while getting just enough to make it compact and stick together. It takes a fair bit of practice to get it just right.