1, Material limitations
Currently mostly appropriate for metal materials such stainless steel, titanium alloys, aluminium alloys, etc., the possible kinds of materials for SLM technology are somewhat limited. SLM technology currently has great restrictions for the use of non-metallic materials. This is mostly related to the unique qualities of SLM moulding technology, whereby some materials are prone to cracking, warping, and other problems during processing, so restricting the range of materials that may be handled. Furthermore, high purity of raw materials is necessary for SLM moulding in order to lessen the impact of contaminants on the moulding process. High-purity materials have somewhat high acquisition costs, which drives manufacturing costs even more.
For some materials with unique qualities or architectures, such composite materials, nanomaterials, etc., SLM moulding technology has quite significant processing difficulties. To attain effective moulding, these unique materials sometimes need processing under certain process conditions. Consequently, process modifications and technical advances grounded on the properties of these unique materials have grown to be a major focus for the advancement of SLM technology.
2, Insufficient mechanical performance
Although SLM technology produces metal parts with high density and superior mechanical performance indicators, such tensile strength than castings, and can even reach the level of forgings, their mechanical qualities still have flaws. The features of SLM moulding process could cause variations in the density of the parts in several directions, therefore producing uneven mechanical properties. Certain parts of the workpiece may contain pores and unmelted powder throughout the manufacturing process due to the features of the powder and the energy distribution of the laser beam, which can influence the density and mechanical qualities.
Furthermore, the thermal strain produced by fast melting and cooling during SLM moulding could cause part deformation or fracture. Furthermore influencing the mechanical characteristics of the component could be the residual tension inside it, thereby lowering corrosion resistance and fatigue strength. The mechanical qualities of the parts may vary depending on elements like SLM moulding process parameters, powder materials, and post-treatment; examples of such variations are hardness, tensile strength, and compressive strength. The fluctuations in this mechanical performance could restrict the use of SLM technology in some high-precision or high dependability applications.
3, Processing accuracy issues
Since SLM technology has quite low dimensional accuracy, reaching the micrometre level is challenging. This is mostly stemming from the difficulties in precisely managing the melting, solidification, and shrinkage of metal powder during the moulding process, therefore producing unstable dimensions of the moulded pieces. Usually, post-processing like grinding, polishing, etc. is necessary to raise the dimensional accuracy of moulded parts. These processing techniques, meantime, might influence the mechanical qualities and surface quality of the moulded parts.
Furthermore crucial for SLM moulding process machining accuracy is its quite high surface roughness. Control of the surface roughness at a low level is challenging in metal powder due to their complex melting, flow, and solidification processes throughout the forming process. In the following use of moulded parts, poor surface roughness could cause stress concentration, corrosion, and other problems. Thus, a major difficulty confronting the development of SLM technology is how to lower surface roughness and increase the surface quality of moulded parts by optimising process parameters and post-processing procedures in the SLM moulding process.
4, Low production efficiency
Longer moulding time and worse production efficiency follow from layer by layer material stacking required by the SLM moulding method. SLM moulding techniques have less production efficiency, more manufacturing cycles, and more expenses than conventional subtractive manufacturing techniques. Furthermore complicated in structure and expensive in maintenance is SLM moulding machinery. Equipment breakdown could cause extended downtime, so influencing production progress, raising maintenance costs, and so generating production risks.
Furthermore restricting SLM technology's production efficiency are the available moulding materials. distinct materials have distinct processing parameters and performance criteria, which demand optimisation and adjustment for every material, therefore extending production time and cost. Thus, one of the main problems that has to be resolved in the evolution of SLM technology is how to raise production efficiency of SLM technology and lower manufacturing expenses.
5, High cost
Three key reflections of the high cost of SLM technology are those related to equipment purchase cost, raw material cost, and maintenance cost. The manufacturing cost of the equipment is somewhat significant in SLM moulding operations since high-precision lasers and scanning systems are used there. Concurrently, the SLM moulding process lacks economies of scale and calls for a quite small number of equipment, which drives even more increases in equipment acquisition prices.
Usually composed of powdered metals, SLM moulding uses raw materials with somewhat significant preparation and processing expenses. The low usage rate of raw materials makes it unable to recycle the residual powder, therefore adding to the raw material costs. Furthermore, frequent maintenance and upkeep of the SLM moulding process equipment guarantees their normal performance and service lifetime. The great complexity of the technology causes the maintenance and upkeep expenses to be somewhat costly.
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