On the build orientation effect in as-printed and as-sintered bending properties of 17-4PH alloy fabricated by metal fused filament fabrication

Purpose The purpose of this paper is to systematically investigate the influence of build orientation on the anisotropic as-printed and as-sintered bending properties of 17-4PH stainless steel fabricated by metal fused filament fabrication (MFFF). Design/methodology/approach The bending properties of 17-4PH alloy fabricated by low-cost additive manufacturing (MFFF) using three build orientations (the Flat, On-edge and Upright orientations) are examined at both as-printed and as-sintered states. Findings Unlike tensile testing where the Flat and On-edge orientations provide similar as-sintered tensile properties, the On-edge orientation produces a significantly higher bending strain with a lower bending strength than the Flat orientation. This arises from the printed layer sliding due to the Poisson's effect, which is only observed in the On-edge orientation together with the alternated layers of highly deformed and shifted voids. The bending properties show that the Upright orientation exhibits the lowest bending properties and limited plasticity due to the layer delamination. Originality/value This study is the first work to study the effect of build orientation on the flexural properties for MFFF. This work gives insight information into anisotropy in flexural mode for MFFF part design.

Effect of polyurethane/polyvinyl alcohol coating on mechanical properties of polyester harness cord

In this article, water-based polyurethane (PU) with different concentrations and partial alcoholysis polyvinyl alcohol (PVA) were used to coat polyester (PET) harness cord in turn. The surface and mechanical properties of harness cord before and after coating were evaluated by performing the tests of dynamic contact angle, morphology observation, bending properties, tensile properties, and wearability. It was found that the surface properties of 1.5% PU-coated harness cord tended to be stable, and the mechanical properties of PU(1.5%)/PVA-coated harness cord were optimal. Compared with PVA-coated harness cord, the wearability of PU(1.5%)/PVA-coated harness cord showed a great increment up to 135.7%. This was because the PU coating effectively improved the interfacial properties between the PVA coating and the hydrophobic PET fibers and enhanced the adhesion of the PVA coating to the PET fibers.

Properties of Plywood Made from Perforated Veneers

The paper is focused on the bending properties of beech plywood made from veneers with perforations. The modification of the plywood was done by the targeted perforations in veneers used. The perforations were rectangular in shape 5 × 30 mm. There was a gap of 10 mm between the perforations (in each direction) and the perforations in the individual rows were shifted by 10 mm relative to each other. Two structures of lightweight plywood were investigated: sheathed (lightweight type 1) with perforated inner layers sheathed with solid veneer and perforated (lightweight type 2) with perforations in each layer. Bending properties were evaluated by three-point bend testing. The results showed decreased bending strength (MOR) as well as decreased modulus of elasticity in bending (MOE) with reduction of weight. Bending strength (MOR) was reduced by 33 to 57% and modulus of elasticity (MOE) by 13 to 43% compared to standard (non-lightweight) plywood. Bendability of lightweight plywood expressed by the minimum bending radius (Rmin) and the coefficient of bendability (koh) point to a slight decrease in bendability by 1 to 35% compared to standard (non-lightweight) plywood. The benefit of the proposed plywood lightweight constructions is weight reduction by 16.5 to 24.4%.