Hard Metals vs. Soft Metals for turn-milling CNC Machining

turn-milling CNC Machining

Like all things, having multiple choices is usually a good thing. But having too many options without a clear objective for an upcoming COMPUTER NUMERICAL CONTROL machining project can be overwhelming and costly so we broke down the top six factors you should consider before settling between a hard or soft metal for machining.

Mechanical Properties for Alloys

Let’s start with mechanical properties, which are measured by the performance of the material when different forces are applied.

The top key mechanical properties intended for metal to consider will be:
Elasticity (hard metals tend to be more elastic than soft metals)
Hardness (hard metals)
Strength (hard metals)
Ductility (soft metals)
Density (ranges vary going from soft to hard based on the density scale )
Magnetic (steel)
Damping (hard metals tend to have small damping capacities)
Fracture toughness (all metals have the highest range of fracture toughness, but it ranges from soft to hard being the toughest)
If any of the above houses are important to your project, all of us recommend doing some research to get actual property ratings per materials. Check out our materials page to get a comprehensive list of all our alloys with links to detailed data sheets.

Wear and Fatigue Houses for Precious metals

Typically, if you are machining a part for prototype fit and function you won’t need to worry about the wear of a material. Your choice of material will be very important ,In cases where you need guaranteed strength or perhaps for the part to stand the test of environmental real estate like extreme temperatures. Let’s break down the most important fatigue properties to consider.

Fatigue power and toughness: This is the stress to which the materials can be subjected for a specific number of cycles. These variations have been studied extensively to aid in the appropriate selection of materials to meet your end- use requirements. Indeed, according to research on this topic, “ Exhaustion is estimated to be responsible for approximately 90% of all metallic failures. ” Failure occurs rapidly and without warning therefore we all typically measure in exhaustion strength by ratio averages. When choosing the material, we recommend evaluating the fatigue-strength rating if you know the component will be under numerous stress cycles.
–Metals that can withstand high temps: titanium and stainless steel.
Environmental cycling: There are many resources for environmental cycling testing. Most of the time components are placed in a controlled environment and tested against high and low temperatures, high and low humidity, thermal cycling, and thermal shock .
–Metals that may endure extremely cold temperatures and remain ductile in low temperature ranges: copper and aluminum.
Creep resistance is defined as a components ability to resist “creep” which refers to the tendency of a solid materials to deform over a long period of time due to exposure to high levels of stress. It’s important to note that creep resistance can happen beyond the standard tension limits of the material because it happens over a longer period of time. Creep becomes especially vital you use cases that have the potential contact with elevated temperatures.Thinking aerospace applications or spacecraft,Creep level of resistance for precious metals is usually managed by their alloy composition as well as their melting temperature. Nickel, titanium, and stainless steels possess the highest creep resistance for metals. Aluminum tends to have very low melting temperatures and not recommended for aerospace make use of instances.

Corrosion (Oxidation) Resistance in Metals

Corrosion on alloys is deterioration or oxidation as a result of chemical reactions between it and the surrounding environment. There are numerous reasons for metallic corrosion and it’s worth noting all metals can corrode. Pure iron typically corrodes very quickly, but stainless, which combines iron and other alloys, is very slow to corrode. Stainless steel is a great option for a steel in case you are worried about corrosion.

Another alternative to stainless steel would be anodizing aluminium. This method helps reduce corrosion and is definitely a very durable finish. Since anodizing can be a secondary service, it will likely add lead time to assembling your project, so this might not make sense for your project needs.

Manufacturability of Metals

When it comes to manufacturability, each supplier or manufacturing partner probably has a different set of requirements based on their capabilities. If you discover your part cannot be machined and you have little flexibility in your part design, you might need to change manufacturing methods to 3D printing, which offers unique solutions in metal and plastics. The good news is if you have decided to machine the component and upload pertaining to quote, we all at Protolabs offer almost instant design for manufacturability (DFM) feedback with every quotation. Within the quote analysis, you’re able to access an interactive three-dimensional image of your part design, which allows you to review your component geometry and assess any potential style issues such as wall thickness, narrow pockets, tolerances, threading, and hole-making.

Thermal Properties in Metals

We touched on it a little already, but precious metals react extremely differently when put below thermal pressure. Metal may expand, melt, and conduct to mention a few changes.

Cost of Metals

Last up on our set of important elements to check prior to choosing your materials is usually cost. It probably comes as no surprise to you, but if you have more property requirements or perhaps needs, then it’s likely you will be paying more for that material. Aluminum is an affordable machining materials if you can trade off some of the additional features we talked about above. If trade-offs are not an option, we recommend referring to the DFM to optimize your part design and style, saving you time and money regardless of the material selection.

There is a lot to unpack here, but we hope you feel a little more knowledgeable about the trade-offs among hard and soft metals once it’s time for you to start your next engineering project. If you still have questions, all of us suggest reaching out to our highly experienced engineering team meant for input.

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