Tell about the principle of using the thimble of the mold

1. The principle of die thimble layout

(1) The layout of thimble should make the ejection force as balanced as possible. The demoulding force required for parts with complex structures is large, and the number of thimble should be increased accordingly.

(2) The thimble should be installed in effective parts, such as bone, column, steps, metal inserts, local thick glue and other structurally complex parts. The thimble on both sides of the bone position and the column position should be arranged as symmetrically as possible. The edge spacing between the thimble and the bone position and the column position is generally D = 1.5mm. In addition, try to ensure that the center line of the thimble on both sides of the column passes through the center of the column.

(3) Avoid setting the thimble across the steps or on the inclined surface. The top surface of the thimble should be as gentle as possible. The thimble should be placed on the structural part where the plastic parts are under better stress.

(4) In deep bone position (depth ≥20mm) or difficult to arrange dome needle, flat thimble should be used. When using a flat thimble, the flat thimble should use inserts as much as possible to facilitate processing.

(5) Avoid sharp steel and thin steel, especially the top surface of the thimble must not touch the front mold surface.

(6) The layout of the thimble should consider the distance between the thimble and the water channel to avoid affecting the processing of the water channel and water leakage.

(7) Consider the ejection function of the ejector pin. In order to exhaust the ejector, the ejector pin should be arranged at the place where vacuum is easily formed.

(8) For plastic parts with appearance requirements, the thimble cannot be arranged on the appearance surface, and other ejection methods should be used.

(9) For transparent plastic parts, the thimble cannot be placed in the part that needs to transmit light.

Second, the principle of selecting the thimble of the mold

(1) Select a larger diameter thimble. That is, when there are enough ejection positions, a larger diameter and size priority ejector should be used.

(2) The specifications of the selected thimble should be as few as possible. When selecting a thimble, the size of the thimble should be adjusted to minimize the size specification, and at the same time, the preferred size series should be selected as much as possible.

(3) The selected thimble should meet the requirements of ejection strength. When ejecting, the thimble must bear greater pressure. In order to avoid the bending deformation of the small thimble, when the diameter of the thimble is less than 2.5mm, the thimble should be selected.

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