January 19, 2025
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 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.
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.
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.
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.
These part marking processes are similar, but they both have specific pros and cons.
Different materials and surface finishes can affect the final appearance and durability of your part marking.
For aluminum parts, laser engraving creates a dark gray or black mark that stands out well against the light surface. However, on stainless steel, laser marking typically produces a lighter, white-colored mark due to the oxide layer that forms. This contrast difference is important to consider when choosing your marking method.
Surface finish also plays a crucial role in marking visibility. On bead-blasted or matte surfaces, both laser and CNC engraving provide excellent visibility. However, for highly polished surfaces, CNC engraving often provides better long-term visibility since it physically cuts into the material rather than relying on surface changes.
For parts that will be exposed to harsh environments or frequent handling, CNC engraving is often preferred due to its deeper marking depth. This is particularly important for parts used in industrial environments where oil, chemicals, or abrasive materials might be present. Laser marking, while more superficial, is often sufficient for parts in controlled environments or those requiring detailed marking like QR codes.
When choosing between laser and CNC engraving, production volume and timeline can significantly impact which method is more cost-effective. For large batches of parts that need the same marking, laser engraving often provides faster turnaround since multiple parts can be marked simultaneously. A tray of 100 parts can be laser marked in roughly the same time it takes to CNC engrave 10-15 parts individually.
The durability of your part marking depends on both the marking method and the part's end-use environment. CNC engraved markings typically last the lifetime of the part since they're physically cut into the material, making them ideal for parts that undergo frequent handling or exposure to chemicals and cleaning processes. This is particularly important for traceability markings that need to remain readable throughout the part's lifecycle. Laser markings, while extremely precise, can be more susceptible to wear on certain materials, especially in high-abrasion environments.
Labor and handling costs vary between the two methods.
Laser engraving requires more initial setup time to dial in the correct settings, but once set up, it requires minimal operator intervention. CNC engraving needs an operator to load and unload each part, but the setup process is typically straightforward. For ongoing production runs, this difference in labor requirements can affect both turnaround time and final cost.
The location of your part marking can significantly impact both the marking process and long-term readability.
For cylindrical parts like shafts or pins, the flat end faces typically provide the best surface for clear, consistent marking. If end faces aren't accessible, marks can be placed on the cylindrical surface, though this may require special fixturing for CNC engraving.
For flat parts, marking is best placed on the largest flat surface away from edges and critical features. This ensures optimal visibility and reduces the risk of marking interference with part function. When parts have multiple machined surfaces, consider placing marks on a non-critical surface that won't affect fit or function.
Recessed areas often provide natural protection for markings but can be more challenging to access, particularly for CNC engraving. These locations work well for laser marking since the process doesn't require physical contact. Conversely, raised bosses or pads can be specifically designed into parts to provide ideal marking surfaces, especially for parts that need frequent marking inspection.
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. This can help with inventory management and tracking parts.
Reach out to our team to learn more about our secondary manufacturing operations.