A Structured Review and Classification of Demolding Issues and Proven Solutions

The demolding of replicated parts can result in damage to both the replication tooling and finished parts and is a particular problem for the replication of smaller parts which can be quite fragile. Various techniques have been proposed in the literature to solve such problems by reducing the overall demolding force. This paper presents the challenge of demolding replicated parts and reviews the proven solutions from the literature which have been developed. A summary chart of these solutions is presented which may be used to implement plans to solve demolding problems with replicated parts. Such a rationalization of existing knowledge will enable replication tool developers to systematically select and apply proven solutions to solve, and ultimately prevent, demolding problems.

Suspension of water droplets on individual pillars

We report results of extensive experimental and numerical studies on the suspension of water drops deposited on cylindrical pillars having circular and square cross sections and different wettabilities. In the case of circular pillars, the drop contact line is pinned to the whole edge contour until the drop collapses due to the action of gravity. In contrast, on square pillars, the drops are suspended on the four corners and spilling along the vertical walls is observed. We have also studied the ability of the two geometries to sustain drops and found that if we compare pillars with the same characteristic size, the square is more efficient in pinning large volumes, while if we normalize the volumes to pillar areas, the opposite is true.

Anisotropy of water droplets on single rectangular posts

We report results of extensive experimental and numerical studies of the anisotropy of water drops deposited on single rectangular posts of mesoscopic size sculpted on different materials. Drops of different volume deposited on the top face of the posts assume an elongated shape along the post direction. Systematic investigations show that while the angle measured along the direction parallel to the post does not change, the one measured across them increases monotonically with the drop volume. The difference in these two angles is found to be proportional to the contact line eccentricity even for very elongated drops, regardless of the post size and material. Results obtained with the lattice Boltzmann method are consistent with these observations and indicate useful trends on the evolution of the drop shape with the system main parameters. We argue that drops deposited on single posts having a very sharp profile represent an ideal model system to investigate anisotropic wetting.