Welcome back to the NCA Ltd blog where we share into our latest developments, projects and insights from our plastic engineering company. As often occurs in discussions with clients, we provide a comprehensive overview of our services and solutions to meet the demands of each project. Part of our commitment to providing the highest quality of product and service within our manufacturing capability is to offer our own tailor made solutions to the needs of each client. In today’s blog we discuss a question and topic that arises often, the annealing or normalising of acrylic and what this process means for your project.
Firstly, what is annealing or normalising of acrylic? Normalising and annealing of acrylic are another way to refer to the process of heat treatment that is applied to the acrylic. It is a vital part of the process which ensures that the high tolerance loads are maintained during the machining, binding and polishing of acrylic which prevents cracking and crazing. Crazing refers to the phenomenon that produces a network of fine cracks on the surface of a material, for example in a glaze layer. Crazing frequently precedes fracture in some glassy thermoplastic polymers. As it only takes place under tensile stress, the plane of the crazing corresponds to the stress direction
Normalising and annealing are both two parts of the a process that work in tandem to produce the finished result. Firstly, normalising gives the plastic a uniform structure which gives assurances as to the plastic’s mechanical properties. Annealing is the second part of the process which changes the microstructure and properties of the plastic. Reducing internal stresses and hardness, annealing ensures better mechanical and thermal properties.
Heat treating also can help to eliminate internal stresses for better mechanical and thermal properties. Without this important process, it is almost impossible to produce accurate plastic components to precise tolerances.
Our expertise within the fabrication of plastics allows our team to heat treat plastics to the highest of standards required for your project which can be adjusted depending on the properties of the plastic such as its thickness, applications and the properties of the plastics themselves.
The most cost effective process to heat treat plastics is through either casting or extrusion. However, both processes can cause materials to be highly stressed and create a surface skin which can pull and distort components during and after the manufacturing processes. In order to avoid such issues and prolong the lifespan of the finished components, NCA Ltd hear treat our machined component parts thus preventing both internal stress and the formation of a surface skin.
The impact of heat treatment on materials such as acrylic (PMMA) can cause material shrinkage of around 2% and 4%. This is a result of the material relaxing and releasing the internal stresses that have developed during the casting or extrusion processes.
At NCA Ltd we work closely with each client to develop components that not only can be produced on budget and on time, but also give a reliable and long performance with minimal stresses. Designed and fabricated to the requirements of each project, we seek to offer long term solutions to your challenges. For more information on any of our acrylic engineering services and to request a quotation, contact 01928 79020 or via firstname.lastname@example.org