What is a Metal Alloy?
June 11, 2022
What is a Metal Alloy?
You’ve likely heard of the term alloy, but what exactly does that mean? Metal alloys are used everywhere. From the tiny screws that hold eyeglasses together, to the frame of a skyscraper. Parts of the phone or computer you’re reading this on are metal alloys.
Most of the metal parts and structures you see are metal alloys.
In simple terms, a metal alloy is a specific mixture of metallic and nonmetallic elements. The elements used to make the alloy are melted down into a liquid, mixed together, and then cooled to resolidify. This process is sometimes called alloyization.
Why are metal alloys used?
You’re probably familiar with most of the metallic elements in the periodic table. Metals like aluminum, iron, copper, gold, and titanium are naturally occurring elements. You might be surprised to learn that the majority of the elements are classified as metals.
Not every element is naturally occurring, but for the ones that are, you can dig them up from the ground, and process them into metal bars or plates.
Alloys are used because in most cases, a pure, single metallic element isn’t ideal for parts or building structures.
Adding other metal or nonmetal elements improves specific properties of the alloy. The strength, durability, color, flexibility, machinability, and corrosion resistance can all be significantly improved.
For example, adding a small amount of lead or sulfur to alloys improves the machinability of metals. And adding carbon increases hardness, but decreases machinability.
Because the percentages of the elements used in alloys can be easily adjustable, there are 100s of different alloys–each having specific pros and cons.
What are the most common metal alloys?
Metal alloys usually have a base metal that makes up the majority of the composition. In addition to the base element, there are common additions. You’ll see numbers that are used to identify the different alloys, like 303 stainless steel, or 2011 aluminum.
Here are a few of the common metal alloys used in precision machining.
Stainless steel alloys
Stainless steel is one of the most commonly used alloys. Stainless steel alloys have an iron base, usually around 25-35%. Another 20-30% of chromium and nickel are added to the iron to improve corrosion resistance and prevent the metal from rusting.
The remainder of stainless steel alloys are made up of 7-10 other elements. Stainless steel alloys can contain smaller amounts of sulfur, silicon, copper, carbon, nitrogen, and manganese. These elements can make the alloy harder or softer, improve machinability, and increase the corrosion resistance.
Steel alloys
Steel is another commonly used metal alloy that’s incredibly diverse. Steel alloys are made with 95-99% iron. Surprisingly, pure iron isn’t useful for parts or building materials because it’s soft and brittle. It’s easily bent and malleable, until other elements are added to create a steel alloy.
Adding a small amount of carbon to the iron makes it hard, and usable for durable parts and building materials. But, adding too much carbon makes the alloy more difficult to machine. To improve machinability, elements like sulfur and lead are added.
Aluminum alloys
Pure aluminum is a great material, but it lacks strength and durability needed to make usable parts. To increase the tensile strength, zinc and manganese are added to aluminum alloys. Chromium can also be added to increase the corrosion resistance of the aluminum parts.
Most aluminum alloys are 85-95% aluminum. This keeps the benefits that aluminum offers–mainly the excellent strength-to-weight ratio.
Copper alloys
Copper is one of the best conductors of electricity and heat. So, pure copper (99%+) is used for electrical wiring. But, copper is soft and flexible, so copper alloys are used for parts that need more strength and durability.
Copper has a wide variety of alloys that include different copper alloys, brass, and bronze. Free machining copper is 97-99% copper, and small amounts of lead, beryllium, cobalt, and/or tellurium.
Brass alloys are a combination of copper, zinc, and lead. The zinc adds hardness and durability to the parts.
Bronze alloys are a mixture of copper and tin. Bronze is even harder than brass alloys, so it’s used when more durability is needed.
Learn about the difference between copper, brass, and bronze.
Nickel alloys
Nickel is a metal that’s added in smaller amounts to stainless steel alloys. Nickel offers some of the best corrosion resistance. It’s also more expensive than most other metals. Nickel based alloys are often considered super alloys, because of the high corrosion resistance and strength.
Monel is a nickel-copper alloy that contains around 65% nickel and 30% copper.
Inconel is a nickel-chromium alloy that’s roughly 70% nickel, 15% chromium, and 8% iron.
Hastelloy is a nickel-chromium-molybdenum alloy. It contains 55-60% nickel, 15% chromium, and 15% molybdenum.
Those are some of the most common metal alloys used for precision machined parts. But, the properties of the alloy can be changed by adding 0.2% of a certain element. This makes the combinations and applications of different alloys limitless.
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Laser Engraving vs CNC Engraving: How Should You Mark Your Metal Parts?
June 18, 2022
Laser Engraving vs CNC Engraving: How Should You Mark Your Metal Parts?
After they’re machined and cleaned, many parts are engraved or marked. Engraving is commonly used to identify the metal alloy of the part, track part lot numbers, or add specific part numbers.
For example, a stainless steel component might be engraved with:
SS303
#002
That would indicate to people that the part is made of 303 stainless steel, and is the second lot of parts.
Anything can be engraved on metal parts, but it is a secondary process that happens after machining, so it adds to the manufacturing time and costs. You only want to engrave information that’s necessary.
The two most common ways to engrave metal parts are laser engraving, and CNC engraving. The same general principles apply, but they are two different machines, and mark the parts differently. In some cases, laser engraving is better, and other times CNC engraving is best.
We’ll explain how each process works, and what its recommended use cases are.
Quick comparison
The biggest difference between laser engraving and CNC engraving is the actual engraving process. They both achieve similar results.
A laser engraver uses a high-power laser to heat and vaporize a tiny amount of material off the surface of a part. Because there’s no contact, the part generally doesn’t need to be fixed.
A CNC engraver uses a sharp cutting tool that touches the surface of the part to remove material. This process usually engraves a single part at a time, and the part is secured in a vice.
How does laser engraving work?
The first laser engraving machine was purchased over 40 years ago, in 1978. Since then, the technology has improved drastically, and laser engravers are more accessible. Laser engravers use heat to burn and permanently mark a surface.
They can be used to create artwork on a piece of wood, glass, or metal. The machine works similarly to a CNC machine. You use a computer program to upload the image and text you want engraved, hit go, and the laser moves around, etching your design onto the surface.
Different settings can be adjusted depending on the material you’re engraving and increase or decrease the intensity of the laser marking. If you want a more prominent marking, the speed can be slowed down, so the laser burns the material for longer.
Setting up the laser engraver can take some time, and you might need to make adjustments if the marking isn’t clear enough. It can also be challenging to mark a curved or uneven surface. But, once you get the right settings right, laser engraving is a quick process. And a tray of 100+ parts can be set in the engraver to be marked simultaneously.
Laser engraving is used for simple part numbers, and more complex engravings like a barcode or QR code.
How does CNC engraving work?
A CNC engraver setup is more like a drill press. There is a sharp, pointy cutting tool that’s dragged across the part surface to mark the surface of the part. The engraver is connected to a computer program where the marking details are entered.
Generally, this engraving process is used specifically for hard metal parts.
The parts are held in a vice attached to the engraving table while the cutting tool moves around to mark the part or lot numbers. Unlike a laser engraver, a CNC engraver usually works on one part at a time. The engraving takes a few seconds, and then the cutting tool resets and is ready for the next part. Because the parts need to be switched out one by one, this engraving requires more human attention.
CNC engraving is commonly used in the automotive, aerospace, healthcare, and oil and gas industries. It’s used to add simple numbers to parts, and not ideal for more complex engravings.
Pros and cons of each method
These part marking processes are similar, but they both have specific pros and cons.
Pros and cons of laser engraving
Pros and cons of CNC engraving
Engraving parts is a common secondary process. Both laser engraving and CNC engraving are great ways to add important numbers and markings to your parts. Reach out to our team to learn more about our secondary manufacturing operations.
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