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Vibrating tables are used in precast concrete formwork for many reasons: vibration increases consolidation, it increases homogeneity in the end product, the concrete is more dense, it eliminates air pockets and surface imperfections, and compressive strength is increased. Once you establish the proper vibration for your mix, the same process will work every time. Many factors can affect the final result of vibration, and operators should experiment to see which methods work best for them. Some of these factors include: whether or not to clamp the product to the table--clamping reduces wear on the mold, but unclamped molds will produce a denser, smoother surface; the amount of energy needed for proper consolidation; the length of vibrating time; the number of vibratory drives; and design of the table deck.