how molds are manufactured

I hope this is not fungi / moulds!

Different methods depending on the material and purpose.

You can use sand, Plaster of Paris, Latex, wood etc etc

A mould for a small part can be made by spark eroding the positive sample into the negative mould.

Bigger parts the negative form can be machined with a CNC into the mould block.

Maybe you should narrow it down a bit by informing us of the product and material.

What process are the molds going to be used in? Why do you want to know all of the ways they can be made -- what are your criteria for selection?

Like Hendrik, my first thoughts are "molds for injection molding", and to select a good process for making the mold, more information is needed. Quantity, material, and size are key, but seeing the actual geometry is important too. You'd might be surprised at the number of designs that aren't manufacturable without changes. This is why you sometimes pay experts for their opinion.

basically it was related to injection moulding machines .. thanx for the reply

Basicly the answer is that they are very, very expensive. Got to Detroit Mold Engineering's site for lots of visuals.

You may visit http://plasticmoulds.blogspot.com and post questions. This is a site to enhance the knowledge of beginners in the field of mould making.