As with everything, having multiple choices is usually a good thing. But for an upcoming CNC processing project, it is very difficult and expensive to choose too many options without a clear goal. Therefore, we analyzed six factors that should be considered before processing hard metals or soft metals.
Mechanical properties of metal:
Let's start with mechanical properties, which are measured by the properties of materials when different forces are applied. The main mechanical properties of metal to be considered are:
L Strength (hard metal)
L Ductility (soft metal)
L Elasticity (hard metals tend to be more elastic than soft metals)
L Hardness (hard metal)
L Density (density varies from soft to hard)
L Magnetic (steel)
L Fracture toughness (all metals have the highest range of fracture toughness, but the range from soft to hard is the hardest)
L Damping (hard metals often have less damping capacity)
If any of the above attributes are important to your project, we recommend that you conduct some research to obtain an actual attribute rating for each material. Check our materials page for a comprehensive list of all our metals and link to a detailed data sheet.
1. Wear and fatigue properties of metals
Environment loop: There are many resources for environment loop testing. In most cases, materials are placed in a controlled environment and tested for high and low temperature, high and low humidity, thermal cycling and thermal shock.
Generally, if you are machining a part to achieve prototype fit and function, you do not need to worry about material wear. If you need to ensure that the strength or parts can withstand extreme temperature and other environmental performance tests, the selection of materials will be very important. Let's break down the most important fatigue properties.
Fatigue strength and toughness: This is the stress that the material can withstand under a specific number of cycles. These changes have been extensively studied to help select the appropriate materials to meet your end use requirements. In fact, according to the research on this subject, "it is estimated that about 90% of the failures in metals are caused by fatigue." Failures occur quickly and without warning, so we usually measure fatigue strength by average ratio. When selecting materials, if you know that the part will withstand multiple stress cycles, it is recommended to evaluate the fatigue strength level.
Environment loop: There are many resources for environment loop testing. Most materials are tested in low humidity, low temperature and high temperature environments.
--High temperature resistant metals: titanium and stainless steel.
--Metals capable of withstanding extremely cold temperatures and maintaining toughness at low temperatures: copper and aluminum.
Creep resistance: Creep resistance is defined as the ability of a material to resist "creep". Creep is the tendency of solid materials to deform over a long period of time due to exposure to high levels of stress. It should be noted that the creep resistance may exceed the standard stress limit of the material because it will last for a long time. Creep is particularly important for use cases that may be exposed to high temperatures, such as aerospace applications or spacecraft. The creep resistance of metals is controlled by their alloy composition and melting temperature. Nickel, titanium and stainless steel have the highest creep resistance to metals. The melting temperature of aluminum is often very low, and it is not recommended for aerospace applications.
2. Corrosion (oxidation) resistance of metal
Metal corrosion is the result of chemical reaction between metal and surrounding environment, which is degradation or oxidation. There are many reasons for metal corrosion. It is worth noting that all metals will corrode. Pure iron usually corrodes quickly, but stainless steel combines iron with other alloys and corrodes slowly. If you are worried about corrosion, stainless steel is a good metal choice.
Another alternative to stainless steel is anodized aluminum. This method helps to reduce corrosion and is a very durable surface treatment. As anodizing is an ancillary service, it may increase the project lead time, so it may not make sense to your project requirements.
3. Thermal properties of metal
We've been exposed to it a little bit, but metals react very differently under hot pressure. Metals can expand, melt and conduct electricity. List a few changes we will explore. Let's decompose metals and their thermal properties in the following table.