The materials available in engineering are many and very diverse. They are basically distinguished by their chemical composition, their state (solid, liquid or gas) and their internal structure.
In this case we will focus on solids because they are the most used in the design of machines and components, mainly due to their ability to perform structural functions.
The selection of materials for the different parts or components is a fundamental part and the success of our design will largely depend on doing it correctly.
Below we will list and briefly detail the main factors to take into account:
– Function and life cycle of the component: The first thing to bear in mind is that the material must meet the demands to which the piece is going to be subjected. We must attend to its physical characteristics and properties:
- Density: relationship between the mass and the volume of the material, fundamental because it will define the weight, among other aspects.
- Mechanical properties: behavior of the material against external agents (elasticity, plasticity, malleability, ductility, hardness, toughness and brittleness)
- Thermal properties: determine the behavior of materials against heat or ambient temperature (specific heat, thermal expansion, heat capacity, thermal conduction, specific temperatures…)
- Electrical properties: behavior when electric current passes through it (conductivity, resistivity, magnetic properties, dielectric properties…)
- Optical properties: they are those that are revealed when light falls on them (transmissivity, absorptivity, reflectivity…)
– Manufacturing and/or shaping processes: It is important to take into account the processes by which we are going to work the starting material. Although initially it meets the required properties, we must pay attention to the fact that after these processes they may undergo variations that reduce or enhance them. We must also choose a material for which the means of transformation are within our reach and have reasonable costs.
– Cost and supply: It will be essential to take into account that the chosen material adapts to our budget and that the supply conditions are favorable to us. We can find equivalent materials and we must then assess the best value for money and also make sure that we are going to obtain the material within the necessary period.
– Finishes and other sensory aspects: The finish we want to give to the product or machine will also condition the choice of material. If possible, this factor will be less decisive than the previous ones, but every day the importance given to user perception is greater. We will find materials with more or less attractive colors and textures, with greater or lesser ease of performing finishing operations, the possibility of painted or lacquered finishes, a greater or lesser sensation of solidity, better or worse touch, etc.
– Recycling and environmental impact: Perhaps the conditioning factor that is currently gaining the most weight. The environmental sensitivity of both people and companies is on the rise and that is why materials with less environmental impact are sought both in obtaining them and in their transformation, prioritizing those that generate less waste and that can be recycled at the end of their life. its useful life.
At Probotec we want to contribute our grain of sand to achieve a more sustainable industry and world and for this we have the ISO 14001 certification whose objective is to control environmental aspects, reduce impacts and ensure legal compliance in environmental matters. We have drawn up environmental management procedures for all waste generated directly or indirectly and we require all our suppliers to properly manage it.
– Other possible conditions: As each project is a world, different conditions may arise, even greater than the previous ones. A couple of examples may be the degree of innovation (depending on the possibility of researching and experimenting with new materials) or the machine’s work environment (different degrees of humidity or salinity and exposure to extreme temperatures).
Alfredo Blanco Veiga, Department of Mechanical Design PROBOTEC.