Inline temperature compensation for dimensional metrology of polymer parts in a production environment based on 3D thermomechanical analysis

In the present work a new method for thermal compensation in dimensional metrology of polymer parts in a production environment based on 3D thermomechanical simulations is developed. A fixture for measuring the length dimension of a classical polymer part is placed in a production environment and equipped with sensors in terms of thermocouples for temperature measurements of the part and the fixture and a contact probe for measuring the dimension. A 3D thermomechanical model is developed in ABAQUS, emulating the thermoelastic conditions of the polymer part when placed in the fixture. Knowledge from classical heat transfer and elasticity theory is then applied to derive a more generic, yet simple expression for the compensation from the transient 3D temperature and displacement fields, based on dimensionless values, which makes applicable for a wide range of initial and surrounding conditions found in a production environment. The developed expression is then used for length compensation on 24 samples measured inline ten minutes after production. The results reveals a significant improvement in capturing the transient behavior of the part with a reduced error from 13 μm to 3 μm, applying the developed formula instead of using more classical 1D standard thermal compensation.