The constructional requirements of the designed furniture are as follows: simplicity of the concept, rational selection of materials, satisfactory stiffness, stability and strength of the system, proper realisation of joints and technology of machining. The simplicity of the concept of a furniture piece, and its individual elements, joints and mechanisms affect the performance characteristics of the product and the technical and economic indicators of production. The choice of the type of materials, including their physical and mechanical parameters, depends on both the durability and reliability of the product, as well as the material absorbence of the production process. The designer-constructor, in the process of developing a new project, should not only focus on integrating the aesthetic, functional and technological requirements, but must also determine the usable strength of the product by choosing relevant cross sections of the elements, the dimensions of joints, types of connections and methods of connecting various materials, which will ensure failure-free work throughout the entire period of exploitation.
At the design and construction stage of a furniture piece, an analytical or numerical examination is also necessary for the strength of the construction under static and dynamic load, at a changing position of operational forces and at different support schemes of the tested system. The conditions of work of multifunctional, mobile and transformed furniture should especially be simulated in theoretical calculations. On the basis of these calculations, the durability of movable parts of furniture must be evaluated, such as doors, inserts, drawers, containers, flaps, as well as the permissible carrying capacity for shelves, partitions, frames, racks, hanger rods, as well as the global stiffness of the product and its individual elements, which permanent deformation may worsen the aesthetics of the piece of furniture.
A numerical optimisation of the construction may also turn out to be useful. By building functions of the aim related to achieving the minimum own cost value of production, at the permitted usable strength of the product, satisfactory dimensions of transverse cross sections of elements and joints are quickly found, which guarantee minimal wearing of materials and production forces at a maximum reliability of the construction.
The technology requirements are mainly related to the nature of production (unit, discrete, serial and mass) and a technological process that is possible to complete. In preparing a product for mass or serial production, requirements related to maximum use of existing resources of the company should be taken into account. In particular, the dimensions of elements are optimised and unified, adjusting them to maximum performance during the cutting of boards, veneering, sawing, sanding, etc. Operations are standardised in order to reduce the number of changes and prolong production cycles. Furniture for discrete production is designed in a different way. Production plans are created only for registered orders of customers; therefore, their number is known and highly atomised in terms of constructional and technological diversity. In the case of furniture produced in such a way, most attention during designing is devoted to finding a rational compromise between form, function, construction and technology. Therefore, it should be noted that even with a large diversity of products, elements can be unified which are not significant for the client, but important structurally or technologically. Only products designed and manufactured for individual customer orders, in micro – and small enterprises, provide designers with considerable freedom and constructors and technologists with greater flexibility to meet these visions, without any damages to the durability of the construction or safety of the user.
