Laser marking of thermoplastic
This technical brochure
provides detailed information on laser marking.
A number of different effects occur when a laser
hits a thermoplastic material, and some of these
effects are not completely understood. What
is evident is that the interaction between the
laser and the thermoplastic compound depends
on a number of factors, and the results of the
interaction differ. For example, grey PA66 without
fillers may be possible to mark, but self-extinguishing
PA66 may be impossible to mark.
In order for a thermoplastic to be possible
to mark by laser, the material must absorb energy
from the laser beam and consequently change
colour (or exhibit a similar effect). Such absorption
may occur naturally with the sole polymer or
may require the addition of pigments and/or
Most thermoplastic compounds that are not pigmented
(in their original colour) cannot be marked
with a laser or can be marked only slightly
because they do not absorb laser light (the
wavelength of a standard Nd:YAG laser is 1064
Thermoplastics without fillers or pigments (natural
thermoplastics) can be divided into three general
categories according to their ability to be
1. Thermoplastics that
adequately absorb laser energy and consequently
carbonise, which results in a noticeable darkening
of the area where the laser hits. Examples
of these materials include PES and PSU.
2. Thermoplastics which
absorb laser energy erratically and carbonise
in an irregular way, which results in marks
that are not uniform (i.e., discontinuous
marking). Examples of these materials include
PS, SAN and ABS.
This group also comprises
styrene resins and polyesters (PET and PBT).If
a suitable pigment or special additives are
incorporated, these materials can be marked
more uniformly, and high-quality marking can
In both these groups, optimisation of a pigment/additive
mix for a dark background can result in a mark
whose light colour approaches white.
with low or negligible absorption.
This group includes PA,
POM, PP, PE and PPS. In their original,
uncoloured state, these materials cannot be
marked by laser. However, a mark with a light
colour approaching white can be obtained by
adding a dark pigment. When certain of these
thermoplastics are pigmented with light colours,
lightly coloured marking results, and darkly
coloured marking can be obtained by incorporating
Laser marking may be strongly influenced
by the addition of fillers, reinforcers, special
additives, self-extinguishing additives and
other additives. Contrary to what one might
think, the presence of fibreglass reduces the
ability to be marked only slightly. Due to their
intrinsic colour, some types of fillers or self-extinguishing
additives may reduce the ability to be marked
by laser. On the other hand, the additives in
certain self extinguishing systems may improve
the contrast of laser marking.
Laser Marking on Thermoplastics Compounds
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LATI Industria Termoplastici S.p.A.
Via F. Baracca, 7 21040
Vedano Olona (VA) - Italy
Tel. : +390332409111 - Fax: +390332409307