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A RAM press uses two-piece molds to mold ceramic items. The negative half of the mold is on the static table and the positive half is on the press. The press drives the positive mold into the clay, forming the ceramic blank. The RAM press can produce complex shapes and has a cycle rate of 1,500 cycles in an eight-hour shift.
A RAM press is a mechanical device used to mold ceramic items using two-piece molds pressed together by a manually, hydraulically or pneumatically operated mechanism. The device consists of a static table mounted below the mobile motorized press. The molds used are in two parts, with the negative half of the mold typically mounted on the static table and the positive half on the press. A charge of deaerated clay is placed in the negative half of the mold and the press is activated. The press then drives the positive mold section into the clay, forcing it to fill the negative half, thus developing an internal shape dictated by the positive mold and an external shape that mirrors the negative mold.
The RAM press has been used to shape ceramic items from tableware to tile since the mid-1940s. Invented by Ohio State University ceramic engineering graduates Keith Blackburn and Richard Steele, the RAM press uses a two-part molding system. A negative female mold half is fixed on the lower table, or stage, part of the press. A positive male die is attached to the movable upper part of the press, which is moved vertically by a ram powered by compressed gas or oil or by a manually operated mechanism. Dowel pins and holes in the two halves of the mold ensure correct alignment during pressing.
When the RAM press is ready for a work cycle, a suitable sized piece of deaerated clay is placed in the female part of the mould. The press is then cycled, forcing the male half of the mold into the cavity formed by the female mold. This action forces the clay to take the shape of a cavity between the male and female molds, thus forming the ceramic blank. At the end of the cycle, the press and male die are lifted and excess material is trimmed off the part, which is then removed from the RAM press.
The quality of the two halves of the mold determines the amount of finish needed after the part is removed from the press. Surface imperfections can be cut from the surface of the piece or removed using a wet sponge depending on their severity. Once the part is finished it can be decorated, glazed and finally fired. The RAM press can be used to produce complex shapes in a variety of sizes. The cycle rate of the press depends on a number of factors, with an average of 1,500 cycles in an eight-hour shift.
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