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Product category: Simulation, modelling and validation software
News Release from: Simpoe Mold | Subject: Simpoe-Mold
Edited by the Engineeringtalk Editorial Team on 30 January 2007

Simulation software allows rheological
analysis

Simpoe-Mold allows designers to streamline the construction of automative parts.

Precious wood on the side facing the interior in combination with robust plastics High optical and technical requirements perfectly combined in one moulded component

Looking at the cover for the gear stick in the centre console of the new C-Class, you will see an impressive example for the knowhow of HS Formtechnik from the Swabian town of Fichtenberg.

Heiner Sigmund, Technical Director of HS Formtechnik, presents a cover from the centre console of the C-Class.

The composite part, made from thin wood and PC/ABS plastics, was manufactured for Behr, supplier of the automotive industry.

"The part is very sophisticated".

"When it comes down to it, it has to be accurate to a five hundredth and it needs to be able to withstand assembling and disassembling up to ten times" explains Sigmund.

Due to these requirements the part had to undergo a preliminary rheological analysis, which was carried out with the simulation tool Simpoe-Mold of the French Simpoe Group.

The results of the computation formed the basis for the further development of the injection moulding tool.

First, the Catia data sent by the customer is imported and converted for the application of Simpoe-Mold.

Next, the constructors simulate the filling process.

At this stage, they will also determine the optimum position of the gates, check the position of weld lines and search for potential air traps.

Another important point is the calculation of the expected cycle time.

"That is the factor which costs money", says Sigmund.

The next step is the analysis of the distribution system.

The choice is between a hot and a cold channel system.

On the hot channel the injector is situated close to the part to be moulded so that waste is kept to a minimum.

However, the regulation of a hot channel is more complicated and causes additional heat input on the inside of the tool.

The cold channel is less prone to failure, but produces more waste.

On the basis of the results of the simulation and the technical requirements for the cover of the centre console the constructors chose a hot channel.

Another important issue is the thermal regulation of the tool.

"The trick is to maintain as even a temperature as possible all over the component part and to deflect the heat as quickly as possible from the tool", notes Sigmund.

In practice, that means that areas of the moulded part, which have become too hot, have to be actively cooled.

For this purpose, a thermal regulation system is applied, which will take critical areas into account and dispose of them thermally.

The goal is to minimise the cooling time and thus the manufacturing cost per moulded part.

This is not the end of the simulation, however.

One of the main problems in the manufacturing of plastics moulding is warpage occurring after manufacture.

Warpage can be due to temperature distribution, fibre orientation or geometry.

With Simpoe-Mold the estimated extent of warpage and the reasons for it can be determined.

That way, constructors can take preliminary measures to minimise warpage.

Sigmund allowed two days in total for the simulation, including the assessment of the process parameters and computing times.

The simulation gives the customer an idea of the problems which may occur in the manufacturing process of the formed part.

In close cooperation with the customer, HS-Formtechnik will then suggest solutions and develop optimisations.

According to Sigmund's experience, the value of the simulation also lies in the transparent presentation of the results and the common basis for discussion created thereby.

Sigmund estimates that it will take approximately three weeks in total from supplying the first Catia data to the final approval for the construction of the tool.

Another 12 weeks will be taken up by construction and manufacture of the tool.

The simulation will not reduce the time required for manufacturing the injection mould tool.

"But in the end the difference shows in quality".

"For one thing, the formed part is manufactured in minimal cycle time and with minimal warpage", Sigmund explains.

"For another thing, adjustments on the tool are largely unnecessary, so that additional time and money are saved here".

According to Sigmund, in the case of the formed part for the cover the result of the simulation matched reality by 90%.

"Some minor adjustments were required, but the supplied parts for the zero series were already fit for assembly and testing".

"You do basically ask yourself the question 'Should I get myself a simulation tool?'" Sigmund says.

"The acquisition cost and the additional time required for the execution of the simulation are inhibiting factors".

"Especially since the cost for the execution of the simulation are not usually borne by the customer".

"I am offering the customer additional certainty; he can look at the simulation before manufacture of the tool and examine critical points".

"Thus, necessary adjustments are recognised at an early stage", explains Sigmund.

"For another thing, the know-how provided gives the customer extra time and improved quality".

"That gives HS-Formtechnik a competitive edge and higher customer loyalty".

A research project funded by the European Union confirms this experience and the economic advantage provided by the usage of simulation software.

According to the study, development costs, for instance, can be lowered by up to 25%.

Therefore, constructors at HS-Formtechnik have been working with simulation tools for plastic injection moulding since 2002.

Cadmould was used at first.

The customers' rising expectations then rendered a search for a more advanced tool necessary.

Apart from short computing times, the availability of future-oriented 3D-functionality was especially important.

The decision was made in favour of Simpoe-Mold, which in Germany is distributed by Men at Work.

For Frank Hornung, Managing Director of Men at Work, this is not particularly surprising: "Simpoe-Mold appeals through easy handling with a clear structure and is therefore very user-friendly".

"Apart from that it is just very cost-effective".

"The software costs between Eur5000 for the newcomer package (including filling and distribution computation) and Eur25,000 for the full package (filling, cooling, warpage).

"From a technical point of view Simpoe-Mold has a lot to offer: apart from the common computations of thin and large parts surfaces, the software allows 3D computation (plain solid parts)".

"Of course, a computation for sequential injection moulding is possible, too".

"This process lends itself for instance to jobs which require the number of weld lines to be kept to a minimum".

"As companies often receive external data, the integrated repair programme Simpoe-Mesh is extremely useful", explains Hornung.

"It helps to quickly identify and eliminate imperfections".

"Another important factor is the comprehensive material data base with up to date material descriptions of all common plastics.

"Heiner Sigmund is very happy with the software and the service".

"The cooperation is optimal with regard to both the technical know-how and flexibility", the CEO notes.

"There is only one thing left to be desired: In the case of the cover discussed plastic is sprayed on wood".

"The wooden inlay serves as an isolator and due to its stiffness influences the part's tendency to warp".

"At the moment, these two factors can only be taken into consideration inadequately".

"There is still room for improvement in that respect, and according to Frank Hornung they are busy working on it".

"Apart from the usage of Simpoe-Mold software for classic injection moulding, the application is becoming more and more interesting and important in the area of two-component tools as well as tools with metal inlays".

"Especially in the insert moulding of thin conductor paths it is advantageous for us to know the pressure distribution in those areas, so that we can take appropriate measures against warpage of the conductor paths", Sigmund explains.

With the simulation software the processing chain was completely closed at HS Formtechnik .

The company provides everything, from consultation, planning and development of the construction and toolmaking to part manufacture (plastic injection moulding) and assembly.

Sigmund comments: "When a customer places an order, he receives the plastic part at the end of it, complete with manufacture and assembly".

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