Anisotropic Shrinkage Variance in Glass-Filled Polyamide Secondary Tooling Nests
Secondary tooling nests for glass-filled polyamide accommodate anisotropic shrinkage through floating datum pins aligned with transverse contraction vectors.
Shim Pocket
Meaning
Machined feature in a mould base allows for the insertion of thin metal plates to adjust the position or height of a tool component. The presence of a shim pocket simplifies the fine tuning of shut off surfaces and core pins. These recesses are typically located behind the support pillars or under the cavity blocks.
Precise Adjustment
Small variations in part thickness or flash levels are corrected by changing the thickness of the shims. Because the shim pocket is a controlled depth, the toolmaker can swap plates without remachining the entire assembly. This flexibility is essential during the validation stage of a new mould.
It provides a mechanical way to compensate for press deflection.
Maintenance Accessibility
Wear on the parting line often requires the tool to be pulled for refurbishment. Having a shim pocket integrated into the design allows for quick restoration of the original stack heights. Instead of grinding down large surfaces, the technician simply adjusts the shim stack.
This method extends the life of the tool by preserving the primary steel. It also reduces the downtime associated with minor repairs. Standardized shim sizes ensure that replacements are always available in the toolroom.
Tooling Life
Repeated cycles at high clamp forces can compress the internal components of a mould. A shim pocket provides a way to reset these clearances. Regular inspection of the shims ensures the tool stays in balance.