Cavity and mould
|Release time:2013-02-28 Source:admin Reads:|
Sides of the part that appear parallel with the direction of draw are typically angled slightly to ease release of the part from the mold. Insufficient draft can cause deformation or damage. The draft required for mold release is primarily dependent on the depth of the plastic seals: the deeper the cavity, the more draft necessary. Shrinkage must also be taken into account when determining the draft required. If the skin is too thin, then the molded part will tend to shrink onto the cores that form them while cooling, and cling to those cores or part may warp, twist, blister or crack when the cavity is pulled away.
Tunnel gates, also known as submarine or mold gates, are located below the parting line or mold surface. An opening is machined into the surface of the mold on the parting line. The molded part is cut from the runner system on ejection from theplastic seals.Ejector pins, also known as knockout pins, are circular pins placed in either half of the mold, which push the finished molded product, or runner system out of a mold. The standard method of cooling is passing a coolant through a series of holes drilled through the mold plates and connected by hoses to form a continuous pathway.
By substituting interchangeable inserts, one mold may make several variations of the same part. More complex parts are formed using more complex molds. These may have sections called slides that move into a cavity perpendicular to the draw direction, to form overhanging part features. When the mold is opened, the slides are pulled away from the plastic seals by using stationary “angle pins” on the stationary mold half. These pins enter a slot in the slides and cause the slides to move backward when the moving half of the mold opens. The part is then ejected and the mold closes. The closing action of the mold causes the slides to move forward along the angle pins.