Meaning
Mechanical tensioning of internal columns prevents the mould plates from bending under high injection pressure. In heavy-duty tools, support pillar preloading involves making the pillars slightly longer than the space they occupy. When the mould is clamped, these pillars are compressed, providing immediate resistance to the forces inside the cavity.
This prevents the plates from bowing, which would cause the part thickness to vary.
Deflection Control
Large moulds often experience plate movement when the resin is injected at high pressure. Support pillar preloading counteracts this by providing a rigid structure that supports the centre of the mould.
Machining Precision
Creating the correct amount of interference requires grinding the pillars to a specific length. If the support pillar preloading is too high, it can bend the plates in the opposite direction and cause leaks. If it is too low, the pillars will not engage until the plate has already started to move.
Load Balancing
Distributing the clamping force across the entire mould base is the goal of the pillar arrangement. By using support pillar preloading, the designer ensures that the centre of the tool is as stiff as the edges. This leads to more uniform part quality and reduces the wear on the guide pins and bushings.
Balanced loading extends the life of the mould base by reducing cyclical fatigue. Technicians verify the pillar height during every major overhaul of the tool.
