Both standard injection molding and Reaction Injection Molding (RIM) benefit from the ability to rotate and tilt the mold during or after injection to aid the material flow within the cavity. Excess air inside the mold often prevents the raw material from filling the cavity to an optimum level which can affect the structural integrity of a formed part. To combat this issue for one customer, Beckwood designed a traditional 4-post press capable of ‘tilting’ up to 90 degrees. As material is injected into the press cavity, a rotating base tilts the press, redistributing material into parts of the mold that were previously filled with air.
The tilting function was achieved through the use of hydraulic cylinders, each equipped with independent counterbalance valves and flow controls. The counterbalance valves were used as a safety measure to ensure the tilting occurred in a smooth, controlled manner. The flow controls were used to keep the cylinders in sync, allowing the press to tilt to its 90-degree position in a balanced manner. The PLC control system integrated the tilting motion of the press with the mold injection system, guaranteeing that an appropriate amount of material was fed into the mold’s cavity based on the current press angle.
This uniquely customized hydraulic press resulted in improved part quality and a drastically reduced scrap rate of molded parts.