Design Plastic Injection Molds to Press Specifications

A plastic injection mold designer must consider many factors when designing injection molds, including the press the mold will run in.  Knowing the press specifications is very important in order for the mold to operate properly, and most efficiently during injection molding production.  

Vertical Press Clamping System

The orientation of the clamping system is of course a very important consideration, as this determines whether the mold will open horizontally or vertically.  A vertical molding press is used in over-molding production, also called insert molding because the molten plastic is molded around an object.  An example would be an electrical wiring harness with plastic molded around a portion of it, clamps or even something like knives where the handle is molded around the metal.  

The insert in a vertical molding press can be either steel or even plastic.  A vertical press requires molds for the top and bottom, as a vertical molding press has a rotary table which holds at least two bottom (B) sides of the mold, while the top half (A) half comes down to close on the bottom half molding the part.  

There is usually one top half, and at least two or more bottom sides to the mold, so that when the A side is molding the part on the back of the table, another B side is in front of an operator or a robot loading an insert into the open mold.  Once molded, a robot or operator can unload the over-molded part from the mold, prior to loading new inserts into it.   Constructing molds for a vertical molding press is quite different than for a horizontal molding press, even though the concept is the same.  

Horizontal Molding Press

The most common type of injection molding operation is in a horizontal press, requiring an A side and B side, closing together on a horizontal plane to mold the parts.  When the horizontal mold opens for ejection, parts usually fall into a bin below or are grabbed by a robot and taken to an inspection area.  Most horizontal molding operations do not require an operator at the press, as the vertical over-molding jobs do without automated equipment.   

Horizontal molding presses are very efficient and non-labor intensive, with a top-quality high-performing injection mold, a horizontal molding operation can run for hours in a lights out environment.  

Regardless of whether the mold is for a vertical or horizontal press, the placement of water fittings and hoses is of the utmost importance in designing the tool.  The clamping pressure and press tonnage are also very relevant specifications, in order for the mold designer to calculate the pressure of the molding operation while also considering the material chosen and how it will flow into critical areas.  

Michiana Global Mold has decades of experience designing tools for various plastic injection molding environments, meeting tight tolerances with high performing, precision custom injection molds.  Download a FREE copy of our book “Design Considerations for Different Molds” for more information.

Michiana Global Mold has decades of experience designing and building precision custom injection molds for various industries. Contact us today to speak with one of our knowledgeable engineers for a FREE design consultation on your mold building requirements.  We can custom design molds for your applications, regardless of your molding environment.

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