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noted that the parts built in this method are predominant in one direction – the
direction in which the extrusion head has deposited the material. Due to this, the
strength of the part is affected and the adhesive strength between the layers is
reduced which is considerably better in case of continuous filaments. The tensile
strength of the part is drastically reduced due to the rater orientation and the
occurrence of air gap. When shapes with thin walls and curvature are involved, the
filament discontinuation causes the part to be of poor strength and may also lead to
failure over a period of time. Fig 1.11 shows that printing with very thin layers gives a
smooth finish.
These are some common problems associated with fused deposition modelling the
properties which the parts suffer from. To improve this there has been a lot of
research and development in this area of rapid prototyping in a bid to improve the
deposition techniques and also on the range of materials which can be used with this
type of prototyping.
1.4 Literature Review
There are a lot of important factors affecting the quality of parts produced by this
method of rapid prototyping but the most important are mainly the speed of
deposition, layer thickness and the width of the road. Speed and the road width
contribute nearly sixteen percent each at ninety nine percent level of significance
[6a]. Layer thickness plays a much important role being effective in the range of
Forty Nine and Fifty Two percent at Ninety five percent level of significance without
pooling and ninety nine percent level of significance with pooling respectively.
Type of materials used in FDM play a very important part as they are the one‟s who
decide the final use-ability of the part. There have been quite a lot of experiments
with different materials in FDM to explore which material suits best and for which
purpose. ABS polymer is quite often used a standard material for RP processes, but
conventional ABS polymers in filamentary form are known to be of low strength and
hardness. In an experiment by Fan Li et al [7] to overcome this, ABS was modified
by adding different property modifiers including short glass fiber, plasticizer,
compatiblizer. It was found that glass fiber could significantly improve the strength of
the ABS filament but it came with a reduction of handelability and flexibility. These
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