‘cost per part’ [11]. It is the main goal of a mould designer to
minimize this figure. When energy efficiency is introduced as a new
sub-goal, related KPI’s might include:
Energy required for producing a plastic part,
Overall number of parts to be produced with the mould,
Wasted energy, due to residual cooling time, per part
Effort and time required for designing the mould,
Effort, energy and resources for mould manufacturing,
Expected life-time of the mould, and
Effort and energy required for mould change.
The estimated number of parts to be produced with the mould can
be considered as key constraint when carrying out a cost benefit
analysis. The impact of costs as well as energy related
consequences, having in mind an overall optimum, are conflicting
with the discrete optimum of a single mould. The mould designer
must not forget about the basic constraints with respect to part
quality and required productivity.
The research work had to take into account that most injection
moulds are designed inpidually as these are unique or produced in
very small number of units. There are general similarities, but due to
the complex engineering of cooling systems inside a mould, one
cannot easily reuse existing design solutions for similar products. In
automotive industry for example, the OEM is accumulating
thousands of different CAD-based mould designs for different types,
variants as well as prototype parts. It is a challenge to reuse this
knowledge. Regarding energy efficiency in injection moulding, only
little knowledge is available so far. Peças et al. for example
assessed the difference in environmental impact between different
manufacturing methods for moulds with low production volumes
[12]. For larger production volumes they discovered the
environmental impact of the mould manufacturing phase becoming
insignificant in comparison to the use stage of the mould [13].
Our work is accompanied by a case study in the automotive
industry, where injection moulds are designed, built and used in
production for medium to large quantities. Hence, main challenge
addressed was to elaborate an approach to capitalise the available
engineering knowledge and gather new knowledge about energy
flows as well as energy efficiency in the use phase of injection
moulds. This is e.g. identification of correlations between design
alternatives and their impact on energy efficiency in production. This
paper presents feedback from the use phase of moulds that can be
exploited for design of new moulds.
2.3 Analysis of Injection Mould Design Impact
For being able to assess an impact on energy efficiency, there is the
need to analyse the existing mould design with respect to the
required quality, effort, energy and costs. These requirements have
to be put in relation to the necessary energy to produce a part. The
existing design knowledge base had to be analysed to find out what
relevant information could be useful for the mould designers and / or
process engineers considering aspects of energy efficiency in
production phase. The idea was to set-up a knowledge repository to
continuously collect information and provide a possibility for
evaluation accordingly. Thiede, Spiering and Kohlitz showed that
structuring energy information of injection moulding processes in
sub-phases is beneficial to analyse the influence of energy
efficiency measures due to the dynamic behaviour of electricity
demand [14]. This approach is pursued in this paper. The work was
structured in the following main phases:
1. Structure the injection mould design procedure in main tasks, 注塑模具设计英文文献及中文翻译(3):http://www.751com.cn/fanyi/lunwen_18373.html