Decision Support System for Designing with Polymer Materials – Current Challenges and Future Expectations - Efficient Decision Support Systems: Practice and Challenges from Current to Future - page 499

CAMPUS does not offer the designer the prices of the candidates and as we will be able to
notice in this chapter the material cost is important and is checked numerous times during
the polymer selection and design process. Another way of finding the most appropriate
material is to investigate the polar charts, which allow the comparison of polymers for
multiple selection criteria (Elsevier ed., 2010). The properties of each candidate are
designated on n-scales, which radiate from a central origin yet the points on scales are
joined to form the closed polygon. It is welcomed to define the minimum properties'
values of the future product and to create its polygon so the possible candidates are only
those, which enclose the product's polygon.
Sometimes during product design the requirements does not meet with existing materials or
material production processes irrespective of designer's knowledge, experiences and effort.
Consequentially, the project is postponed until new special designed material is developed
to satisfy the design. It has to be subjected that this involves additional time and finances to
support the project and that it is usually only justifiable for special products at high
technology performance.
5. Plastic product design process
Design process is not always alike in all enterprises however the basic phases stay the same.
While progressing through the task clarification, conceptual, embodiment and detail design
phase engineer has to make numerous decisions not only about product design but also
about manufacturing, assembly, maintenance, and its impact to the environment. Plastic
product design is very distinguished (Alber et al., 2007) from conventional design with
common materials like metal and ceramics as the plastics could offer better characteristics
for noticeable lower costs. Some of the advantages mentioned before in Section 3 are of
major importance. Therefore, material selection is one of key decisions, especially when the
designer has to choose between approx. 120.000 different plastic materials (Ashby, 2005;
Ashby & Johnson, 2005). It is of great importance as it influences technical and economical
aspect of the product. To support this idea, a diagram of new product development process
is described and illustrated in Fig.1. It also indicates where in the described development
process, the previously selected material could be modified.
After 3D computer model of potential product is finished, a preliminary plastic material
selection is set considering technical parameters, product type (product's purpose, exposure
to the high temperatures, etc.), customer's requirements and wishes, fashion trend, special
restrictions (product's contact with food, toys, etc.) and material costs. At this stage, first
strain/stress analyses and casing simulations could be performed. Some severe material
changes could be done according to results and usage of reinforcement fibres is discussed.
Production process selection is next engineer's decision directly connected to plastic
material selection as he or she has to consider products type, its size and precision, wall
thickness, tolerances, surface roughness and even a size of production series. In case the
manufacturer wants to use particular production machines or the series is large and the
chosen polymer could be produced only with the production process suitable for small
series, the need for material change is present again. Next phase is tool design, followed by
detail casting simulation. Due to the results, some parameters like strain, elasticity, fibre
reinforcement or thermal resistivity may have to be adjusted. Furthermore, additional
analyses and simulations are fired to approve or to disprove the last selected plastic. Final
step before sealed approval is calculation and costs appraisement.