Geometric analysis of the MDF kerf-bending structure accuracy

Abstract

In digital design, rigid flat materials commonly hinder the fabrication of complex-curved geometries. A fabrication approach based on the socalled bending cut patterns or “kerf-bending” can be used to improve the ability of a material to bend. This bending method relies on a complex mechanical behavior, requiring an accurate evaluation of the resultant surface. By mastering the geometric effects, some adjustments can be made to the project so that the result better approximates the designer’s intentions. This study focused on geometric accuracy of MDF kerfbending, including target-geometry design, cutting, bending, 3D scanning and analysis. It demonstrated that depending on the arc bending radius, the sample with a defined cut pattern may become excessively tensioned, protruding to the outside, or without enough stiffness to conform to an ideal shape. Experiments have validated this methodology and obtained a stable and precise half-cylinder by selecting the most adequate radius range for the material and parameters adopted.

Freeform Shape Fabrication by Kerfing Stiff Materials

“…The remaining flexibility stems from the connecting points of the twist beams, and a slightly higher stress tolerance of our material than the MDF evaluated by [CTJ*20]. For a more in‐depth material analysis, we refer to [CTJ*20] and [LS22].…”

“…In the same context of working with plywood or MDF, [CTJ*20] perform stress tests on bidirectionally kerfed MDF planes via uniaxial and biaxial stretching and out of plane bending, while [LS22] analyze the accuracy of arcs created by one‐directionally kerfed rectangular MDF strips of different dimensions.…”

“…While the maximum density of cuts is only restricted by the fabrication method, an incentive to use the minimum number of kerf cuts is the production time, which can be lowered drastically by reducing the cut density based on the locally required flexibility. Additionally, using too many cuts may result in a very unstable result, while the opposite can lead to the material breaking under the bending stresses, as shown by [LS22]. Since we are working with a laser cutter, the fabrication constraint translates to a minimum distance between cuts, which stems from the risk of material being burnt away entirely.…”