Plexiglass cracking is not just a cosmetic problem. It weakens the material and the cracks begin to “creep” even more, especially if there is a load. As a result, the leaf may burst at the most inopportune moment. The company Elektroplast, which sells plexiglass parts (they are https://pkf-elektroplast.com.ua/p1671662607-orgsteklo-akril-kuski.html), explained why this happens and how to prevent the appearance of microcracks when working with PMMA.

Internal stresses of the material

Plexiglas remains in ultimate stresses, especially during extruded glass production. This is the result of uneven cooling and hardening of the polymer after molding.

During mechanical or thermal treatment, these stresses can be redistributed, leading to crack formation. Cast plexiglass is less prone to such problems due to the uniformity of its structure.

temperature fluctuations

Sharp changes in temperature (e.g. during sharp laser cutting, heating or cooling) cause local expansion and contraction of the material. If Plexiglas is cooled quickly after heating, it leads to the formation of microcracks that spread over time.

Effects of chemicals

Some chemicals, such as alcohols, acetone, dichloroethane, and even some adhesives, react with plexiglass, causing it to crack. This is especially noticeable where the material is subjected to mechanical or heat treatment, since such areas already contain micro-damages.

Mechanical damage and thickeners are emphasized

During processing (cutting, drilling, engraving), microscopic defects appear in the material, which can become foci of cracks. This is especially true for parts with sharp corners or thin walls.

What should we do?

To prevent the formation of cracks, the manufacturer Elektroplast recommends the following:

1. For processing and operation in difficult conditions, it is preferable to choose cast plexiglass. It has higher resistance to cracking due to its homogeneous structure and low internal stresses.
2. To reduce internal stresses, the plexiglass workpiece can be heated to a temperature of 100-120 °C and held at this temperature for several hours and then cooled slowly. This prevents the formation of cracks during subsequent processing or operation.
3. Before using adhesives, solvents or varnishes, it is necessary to check their effect on a test sample. For bonding, it is recommended to use cyanoacrylate or UV-curable adhesives that minimally affect the structure of the material.
4. When working with a laser, it is important to avoid excessive local heating of the material. The optimal cutting and engraving parameters (power, speed, pulse frequency) should be selected experimentally.

To avoid cracks in parts of complex shape, it is recommended to round the corners, drill holes in places where high levels of load are expected, and grind the edges after cutting.