There are many reasons to mark plastic, but with the increasing popularity of plastic packaging, for everything from milk to motor oil, it’s no surprise that the most common reason for marking plastic is to apply an expiration date to a food or beverage item.

So, what options do you have for printing expiration dates on plastic?

Considerations for Printing Expiration Dates on Plastic

The first thing to consider when marking an expiration date on thin plastic is the type of mark you want to create.

There are a lot of ways to permanently mark a material (laser engraving, hot stamping, markers) but not all of them are suitable for the types of thin plastic most packaging is made of.

Hot stamping, for instance, would be a terrible choice for marking thin plastic because it would be nearly impossible to prevent the marking tool from burning right through the plastic.

Just to clarify, it is definitely possible to hot stamp plastic; however, it has to be thick plastic, like that used in hosing, but by and large, packaging that requires an expiration date is typically too thin for this marking method.

Industrial paint markers might seem like a viable solution; they create a permanent mark without the use of heat. Markers are best suited to low volume applications, however, and most applications where an expiration date is required are medium to high volume.

If the application is low enough volume, you could use a marker to add an expiration date by hand to each piece of plastic packaging. For most, however, this would be a grossly inefficient marking method.

The last big consideration has to do with the type of mark you will be making, an expiration date. Because the mark you’ll need to create isn’t static (the same mark over and over) the marking method must allow for easy change.

When all of the specifications and material considerations are taken into account, there are  main methods by which an expiration date is typically added to plastic: UV laser marking

To meet the market demand, RFH newly developed S9 series UV dpss laser in 2020. Comparing with its kinds, S9 series UV laser features with rugged sealed cavity, extremely compact size, simple and robust, high stability, high efficiency, high reliability and excellent laser beam quality.Its compact design suggests no necessity in building big light path, which greatly reduces space and cost and makes it easy to be installed into UV laser marking machines. In addition, S9 series cavity structure is more stability and more excellent scalability, which means the same laser cavity can be produces multi-power lasers , and the stability of different power ranges is greatly improved

S9 UV laser: https://www.rfhtech.com/s9-uv-laser-new_c3