Calculating Compression Tonnage for Round Molds

Forgive me, I calculated the area of a circle wrong! :) He makes sense now. My miscalculating led me to believe there were other variables involved.

However, I am still very much interested on good books/resources on hydraulic systems that are used in molding operations.

Elijah Angwah

if you have a 20" round mold that you close and clamp with enough tons to contain that area 3.14 *10*1-*4000 = 628 tons trying to force it open. So you need it to be clamped with 628 tons. It could be bolted shut or a far weaker hydraulic press closes it and heavy latches hold it closed, then you fill it.

You may not need a press that closes with 628 tons?

You then compress the filler into it with 4000 psi and all is well.

First-approximation check for size: Area = pi x radius squared = 314 square inches. Tonnage = pressure x area, so 2 tons per square inch x 314 square inches = 628 tons. You probably need a safety margin; if the object being molded has the 314 square inch area, you probably have sprues or other regions also contributing to the total force you need to contain, so a 650 or 700 ton press is reasonable. Think of the pressure / area / force relationship in terms of hydraulics: the contained pressure is trying to lift the top of the mold, and you're trying to prevent that from happening (and no, it doesn't matter if the parting line is horizontal or vertical for this analysis).

Elijah A grit/resin mix eh? in a round mould, you don't mention how deep the mould is. If this was a long cylinder i.e. like a pllar, then it is a different situation to a short cylinder, i.e. like a 'cake' It looks like you are casting somthing like a 'grinding wheel'?

Have you ever seen an Italian 'drop weight' brick machine? A heavy weight is pulled up by a robust chain drive system, as the chain turns the 'semi-circle' at the top, the hook disengages and down drops the weight......that naturally impacts on the grit/resin mix. Safety devices prevent mishaps. Steady away, you could cast a lot of grinding wheels in a day......just a thought

Elijah

A good book on hydraulics is: "The Lightning Reference Guide"

I had a copy given to me by a fluid powre specialist.

I am quoting a company now on the supply of a tile press. They want a vibrating bed / mould, and a vacume system for sucking the water out of the concrete mix, an ejection system. I'm also going to propose a small pick and place unloader, but I don't think he wants to spend the money.

He wants to press 4" X 30" tiles, but I have no idea of the PSI required. The end product It will in fact be a concrete tile.

Do you think he will need resin for this process?

Good Luck

Keith