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Things to note when adding text and letters to a part

Blog sharing 2019-07-02

There are many reasons why you might want to add text to a part. For self-assembling furniture, text may be required to explain how one part is inserted into another. For electronic components, the text can provide important safety instructions required by law. Other components simply display the company's name and logo for branding.

Although there are many reasons to add text, there are many ways to add it. Depending on the manufacturing process and the materials used, text and letters can be engraved, embossed, screen printed, rubbed... the possibilities are manifold.

But putting the text in one part is not always as easy as it seems. Each method of adding text has its specific benefits, but it also has its own specific rules to ensure it works.

Over the years, we have used various methods to add text to various parts. Therefore, we will list some guidelines for incorporating words, letters and numbers into your parts and prototypes.

CNC machining

You can use CNC milling machines to add letters to machined parts (metal or plastic). However, there are some rules to follow in doing so.

When adding text to a precision CNC machining design, the first thing to consider is whether the text should be engraved (cut into the surface of the part) or embossed (extended from the surface).

While embossed text is sometimes easier to read, it is often best to use engraved text because it requires less material to be removed from the workpiece, thus saving time and money.

CNC cutting tools can only be so detailed, so choosing the right font and text size is critical. The font should be Sans-Serif (no decorative tip that is difficult to cut) and must be at least 20 pounds in size. Soft metals may slightly shrink the text.

CNC text prompts:

Engraving text is easier than embossing

Sans-Serif font

Size 20+

Depth approximately 0.3 mm

Injection molding

When using plastic injection molding to make plastic parts, the rules for adding text are slightly different.

Since the injection molded parts are basically opposite to the metal molds they are processed, the rules for engraving/embossing are reversed. For molded parts, embossed text is preferred because it is easier to engrave the metal mold using a CNC milling cutter. (due to the reasons explained in the CNC machining section.)

Unfortunately, the raised text on molded plastic parts poses a risk. Since the text is above the surface of the part, it can be easily wiped off by wear. For this reason, it's helpful to add a simple border around the text to protect the letters.

Molding text prompts:

Embossed text is easier than engraving

Increased border protection

Lifting from the surface of the part ~0.2 mm


Post processing

Embossing and engraving text have significant benefits. For example, it can be added during the manufacturing phase (for example, using a CNC milling machine) and does not require its own separate process. Second, it ensures a certain degree of persistence: fonts that are physically raised or lowered generally last longer than letters made using ink. Such text can also prevent unauthorized copying of parts because printed text can be easily erased or painted on top, while embossed and engraved text cannot.

However, in many cases it is not possible to add text using manufacturing machinery. The text may need to be much smaller, or the Serif font may be needed to match the company's brand. Or the part itself may be too clumsy to be carved or embossed

In this case, there are other options. Instead of adding text to the manufacturing process, we can add text after the product is manufactured. There are several different ways to do this, all of which offer special benefits.

At 3ERP, we offer the following surface treatment options for adding text, symbols and logos:

screen printing

Pad printing


Laser engraving

While adding text as a surface treatment adds an extra stage to production, it can be more cost effective in some cases.