| Date | November 2020 | Marks available | 3 | Reference code | 20N.2.SL.TZ0.1 |
| Level | SL | Paper | 2 | Time zone | no time zone |
| Command term | Explain | Question number | 1 | Adapted from | N/A |
Question
Figure 1 shows design for environment software that can be used to analyse the environmental impact of a component using life cycle analysis (LCA).
The software generates a sustainability report, see Figure 2. This can be used by designers and manufacturers to make informed choices regarding the environmental impact of the component.
Design for environment software can be used to calculate the energy consumed if the component was made from different materials. The pie charts in Figure 3 show the energy consumed by ABS and aluminium at the pre-production, production, distribution and disposal stages of the product life cycle for the component. The unit of measurement of energy is megajoules (MJ).
State one reason why the product was designed to only last two years.
Outline one reason why using injection moulding has resulted in a low estimated material unit cost.
Outline how finite element analysis (FEA) could be used to further develop the process during the component’s manufacture by injection moulding.
Outline why solid modelling rather than surface modelling would have been used in the computer-aided design (CAD) development of the component designed in Figure 1.
Outline one possible impact on the sustainability report in Figure 2 if the material of the component is changed from a thermoplastic to a thermosetting plastic.
Explain one waste mitigation strategy the designer could use to reduce the percentage of ABS sent to landfill at the end of the product’s life.
List one reason why the design for environment software does not generate a result for energy consumed at the utilization stage of the product lifecycle.
Calculate the embodied energy of the component if it is made from ABS. Give your answer to one decimal point and show your workings.
Outline why the energy consumed at the pre-production stage is greater for aluminium than for ABS.
Explain how end-of-pipe technologies can reduce the environmental impact of manufacturing.
Markscheme
planned obsolescence;
allows for new technologies to be introduced;
allows for continued sales;
allows for improved safety in later generations;
Award [1] for stating one reason why the product was designed to only last two years.
less material is wasted (through errors);
by re-introducing excess plastic/high accuracy/consistency;
injection moulding is suitable for shaping plastic material;
ABS is an inexpensive material;
high volume/high speed/continuous flow/24/7/ method of production;
takes advantage of economies of scale;
Award [1] for identifying a reason why the use of injection moulding has resulted in a low estimated material unit cost and [1] for a development of that reason up to [2 max].
FEA is used in the calculation/simulation of unknown factors of flow/thermal/stress analysis;
to optimize the mould/change the thickness (of the material/wall);
Award [1] for identifying a reason why FEA could be used to further develop the process during the component’s manufacture by injection moulding and [1] for a development of that reason up to [2 max].
solid models contain data regarding mass/volume;
this data is required for virtual prototyping/FEA/design for the environment software to generate accurate results;
solid models provide a complete set of data allowing the product to be realized/tested/virtually prototyped/undergo FEA;
surface models contain no data about wall thickness/interior (components) of the part;
Award [1] for identifying a reason why solid modelling rather than surface modelling would have been used in the CAD development of the component designed in Figure 1 and [1] for a development of that reason up to [2 max].
increases landfill/reduces recycling rate;
as thermoset plastics are difficult to recycle (due to their stronger bonds);
increases duration of use;
as thermoset plastics are generally harder/stronger/more heat/creep resistant than thermoplastics;
changes the manufacturing process (to compression moulding);
as thermoset plastics are more difficult to injection mould;
Award [1] for identifying one possible impact on the sustainability report in Figure 2 if the material of the component is changed from a thermoplastic to a thermosetting plastic and [1] for a development of that impact up to [2 max].
recycle;
material labelling the component;
which allows for easy material sorting/separation;
dematerialization;
reduction of volume of material/ABS used in each component;
which reduces processing/energy/waste;
Award [1] for identifying a waste mitigation strategy the designer could use to reduce the percentage of ABS sent to landfill at end of the products life and [1] for each subsequent development of that strategy up to [3 max].
the component does not consume energy during utilization;
the software cannot predict/know how often/how long/the way in which the product is used;
Award [1] for listing a reason why the design for environment software does not generate a result for energy consumed at the utilization stage of the product lifecycle up to [1 max].
a)
or
b)
MJ;
Award [1] for a correct answer.
Award [1] for the correct workings.
Embodied energy refers to either:
a) total energy consumed throughout the lifecycle of a product (cradle-to-grave)
or
b) total energy consumed in production (cradle-to-[factory]gate).
The unit MJ must be included to award the second mark.
aluminium requires mining/extraction from ore/bauxite;
which is energy-intensive;
Award [1] for identifying why the energy consumed at the pre-production stage is greater for aluminium than for ABS and [1] for an appropriate development up to [2 max].
Do not award a mark for only stating mining/extraction. Response must also include a reference to ore/bauxite.
end-of-pipe technologies reduce pollutants/waste at the end of a process;
by using filters;
to prevent contamination of soil/air/water;
Award [1] for how each distinct point is an explanation of how end-of-pipe technologies can reduce the environmental impact of manufacturing up to [3 max].
Do not accept 'reduces environmental impact'.
Examiners report
Straightforward, but not all candidates identified why the product was only designed to last for 2 years.
A good range of answers were provided but many only obtained one mark.
Many candidates demonstrated a limited understanding of FEA.
Many candidates only provided a simple or generic understanding of solid and surface modelling and struggled to articulate their answers in response to the question.
Quite straightforward, well answered. Many candidates achieved at least one mark.
A fair question and a good discriminator, as identifying the strategy was easy for most candidates, however very few elaborated correctly on the recycle cluster, achieving no subsequent marks. A good number of those who identified dematerialisation also achieved the second mark, but not the third. A number of students cited incentives such as returning the product for a refund, but this would be unlikely for a product of this type and it is not a waste mitigation strategy.
A very easy question, well answered. Most candidates identified that the product does not consume energy during utilization or that the software could not predict how the product would be used.
A straightforward question with most candidates able to complete the calculation from the data provided and being awarded two marks.
A fair question but only a few candidates explained that aluminium needs to be extracted from ore/bauxite.
A straightforward question that allowed a range of marks for candidates who understood the concept and utilisation of end of pipe technologies. Many candidates were able to achieve 1-2 marks but very few achieved 3.
