|
Comparison of Types of Mold Flow Analysis |
|
|
|
|
Wednesday, 13 April 2005 |
Currently there are three main types of plastic flow analysis: Midplane, Fusion(Dual Domain™) and True 3D. During a long period Midplane was a
monopolist on this market.
But it is not a perfect solution. This
method has two main disadvantages: rather labour-intensive process of
models preparation for analysis and problems with implementation of this method for thick-walled models. As result now we have three methods to analyse the injection moulds processes. Another two, Fusion and True 3D was invented to solve lacks of Midplane method.
The Fusion or Dual Domain method is a modified Midplane method. This
method uses flow analysis on two sides of model (internal and external surfaces) with special “joining” technology instead of middle surface of the plastic part and reduce seriously time required for models preparation. As a result this makes possible to carry out more calculations for the same model on various design stages of the detail and of the mould. But it is not a free bonus. The model for Fusion method has more than double amount of elements to achieve the same quality with the Midplane model. So the calculation time longer than for Midplane method. This is especially important for cases which requires several calculation with various parameters, injection points etc. Also this method complicates research of a model with various thickness of the main shell or other parts of model. As this requires modification of the initial CAD model instead of modification only value of thickness for Midplane model. And there is other more serious problem.
The Fusion method takes away the control over process how the system
interprets thickness on model. It is especially unpleasant and is
fraught with mistakes at the analysis of difficult models with
complex transitions between parts of model with essentially changing
of thickness.
The True 3D is most precise. This method allows most precisely reflects features of a model and can analyse the processes impossible with the previous methods, for example jetting. Only this method is fully adequate for analysing of thick-walled models. But... But this method demands incredible amount of elements. More than 1 million of elements is absolutely normal for such analysis. For example 30000 elements it is a big Midplane model. Even with multiprocessor computers True 3D analysis lasted several times longer than Midplane or Fusion. As a result this method is not widely used nowadays. On estimation by Moldflow Corporation less than 5% of moulded parts analysed using this method.
I have tried to estimate current position of Midplane, Fusion and True
3D methods by four most important criteria with a 100-ball scale.
Please see a table below, higher is better.
By my estimation Midplane and Fusion have very close results. I thing
this balance will remains during at last next 2-4 years. Fusion
method will be used for fast analysis especially on the earlier
stages of design mainly from simple to medium complexity models.
Midplane models will be used for more precise final analysis from
simple to complex models and for exceptionally thin-walled models.
True 3D, this is another case. This method is waiting time when the
computer industry will be able to offer adequate calculation speed
for reasonable cost. It will gradually increase the popularity
together with growth of processors productivity but it will be rather smooth process. Currently I have applied double score for “ Area of effective implementation ” than real 5% because in some cases it is the only solution on the market and it is limited not to a method itself but by external reasons.
Dipl. Eng. Igor Jogla
Moldflow and Dual Domain are trademarks or registered trademarks of Moldflow Corporation.
|
