Sustainability assessment of rapid sand mould-making using multi-criteria decision making mapping

Capabilities of Additive Manufacturing (AM) for rapid tooling are well known in recent times. Rapid sand moulds are advantageous over traditional sand moulds in terms of cost, manufacturing time, flexibility, etc. This paper identifies metrics related to mould manufacturing and categorises them into four categories (cost, time, quality and environmental sustainability). A methodology based on the deterministic Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) multi-criteria decision making algorithm is used to map at high-resolution the influence of such categories on to the decision-making space when comparing AM with conventional sand mould making. Results show that AM is almost always clearly advantageous overall (excluding some very limited corner cases) for the examined cas

Investigation of process parameter effect on anisotropic properties of 3D printed sand molds

The development of sand mold three-dimensional printing technologies enables the manufacturing of molds without the use of a physical model. However, the effects of the three-dimensional printing process parameters on the mold permeability and strength are not well known, leading the industries to keep old settings until castings have recurring defects. In the present work, the influence of these parameters was experimentally investigated to understand their effect on the mold strength and permeability. Cylindrical and barshaped test specimens were printed to perform, respectively, permeability and bending strength measurements. Experiments were designed to statistically quantify the individual and combined effect of these process parameters. While the binder quantity only affects the mold strength, increasing the recoater speed leads to both greater permeability and reduced strength due to the reduced sand compaction. Recommendations for optimizing some 3D printer settings are proposed to attain predefined mold properties and minimize the anisotropic behavior of the sand mold in regard to both the orientation and the position in the job box

Damage Assessment of A356 Al Alloy Under Ratcheting–Creep Interaction

The aim of this report was to examine the influence of asymmetric cyclic stress on the ratcheting behavior of A356 Al alloy with special emphasis on its postratcheting creep behavior. A series of A356 alloy specimens were deformed under asymmetrical cyclic loading with different combinations of mean stress and stress amplitude. These tests were carried out up to 2000 cycles. Followed by ratcheting, the specimens were subjected to impression creep tests under varied stresses and temperatures. It is revealed from the ratcheting tests that strain accumulation increases with increasing stress amplitude or mean stress. However, total accumulated ratcheting strain of the investigated alloy was significantly low compared to that reported for some other aluminum alloys. The results of creep tests indicated that predominantly dislocation climb–assisted creep occurred for the alloy. Postratcheted specimens exhibited higher creep rates compared to that of the as-received A356 alloy; this fact was attributed to the work softening of the specimens during the impression creep test. The extent of work softening was minimum in the specimen that accumulated the highest strain during ratcheting, leading to its lowest creep rate