In-depth analysis improves injection moulding

Moldflow Plastics Advisers Version 7.0 has powerful new analysis capabilities to allow users to simulate more phases of the injection moulding process and further optimise part and mould designs.

Since its launch in 1997, Moldflow Plastics Advisers (MPA) design-for-manufacturability software has revolutionised the way that plastics part and mould designers optimise their part and mould designs.

Unlike Moldflow Plastics Insight (MPI) software, which provides a complete suite of modules for simulating the most comprehensive range of manufacturing processes encountered in thermoplastics and thermoset injection moulding across a broad range of geometry types, MPA products provide first-pass analysis tools best used in the earliest stages of part and mould design.

MPA products have been designed for the "casual analyst," who is typically someone for whom running injection moulding simulations is not the primary job.

It will answer basic questions such as "Will the part fill?" and "Where are the weld lines?".

As a result, MPA tools are used extensively by part and mould designers, mould makers, industrial designers, design consultants and even by advanced CAE analysts, who use MPA results to determine which applications require the more in-depth analyses available in MPI modules.

Over the years, the capabilities of MPA software have expanded from being able to analyse only the part geometry to being able to analyse complete, multi-cavity mould layouts, including hot or cold runner systems and family moulds.

The results available from MPA analyses have also grown to include pressures, temperatures, sink marks, cooling quality and gate location.

Now, newly launched Moldflow Plastics Advisers Version 7.0 offers two new addon modules - Performance Adviser and Cooling Circuit Adviser.

Aimed at the mid-range user, they will provide powerful new analysis capabilities to allow users to simulate more phases of the injection moulding process and further optimise their part and mould designs.

Additional enhancements are also included which allow users to better select materials, design more efficient moulds, collaborate with plastics CAE experts and increase productivity.

The enhancements included in MPA 7.0 will help the mid-range user reduce the need to rely on shop floor technicians or past project experience to solve critical issues associated with part and mould designs, and instead employ the MPA technology to address these issues before their design goes into production.

At the heart of MPA 7.0 is Moldflow's patented dual domain technology, which allows users to work directly with 3D solid CAD models without the need to create a finite element mesh analysis model.

This saves anywhere from hours to days to weeks in model preparation time, meaning more part and mould designs can be evaluated more thoroughly.

In addition, MPA is easy to learn and use and does not require extensive training or plastics processing expertise.

MPA 7.0 is upward compatible, so that users can upgrade to Moldflow Plastics Insight (MPI), Moldflow's complete suite of high-end analysis modules, or link to Moldflow Manufacturing Solutions (MMS) products.

Performance Adviser is used to simulate the packing phase of the injection moulding process, the results of which allow users to minimise undesirable part shrinkage.

A warpage adviser is also included, which indicates if a part is likely to warp or deform beyond acceptable levels.

A packing analysis can be used to optimise the second stage of the injection moulding process to achieve the right balance between part quality, part cost, and cycle time.

Users can set up and evaluate packing profiles to determine the optimal packing pressure and duration of packing.

From the analysis, the user can review the volumetric shrinkage, cycle time, and the average temperature across the part.

The new MPA 7.0 Warpage Indicator is a traffic-light plot (analogous to the confidence-of-fill plot) that highlights the areas where part warpage exceeds a user-specified, acceptable warpage level relative to a user-specified reference plane.

Users can investigate further for additional information on the source of warpage and obtain recommendations to fix the problem.

Users evaluate whether changes made to the part or mould design or to the material or process conditions will bring the part warpage to within acceptable levels.

Undetected, warpage can become an extremely costly problem to fix once a mould is in a production environment.

The warpage module of MPA 7.0 has been evaluated by Materialise where it has correctly predicted the warpage on a part in the company's Rapidfit Rapid Fixturing and Measuring system, essentially a checking jig for large stereolithography parts.

Rapidfit comprises a large steel base plate measuring about 2 x 1m with a lot of holes drilled in it.

At the bottom is a foot made of Durethan BKV 30 H2 from Bayer which screws into the baseplate and supports the pillar above it.

It is a rectangular part about 50 x 25mm and warpage is critical because it needs to bolt flat to the base plate.

A small misalignment at the bottom, magnified into a large misalignment at the top would render the system ineffective.

The Cooling Circuit Adviser is used to simulate the cooling phase of the injection moulding process so that users can optimise their mould designs for uniform cooling and minimum cycle times.

Mould designers can now quickly design and evaluate their cooling circuit layouts to achieve uniform cooling with a minimum cycle time.

Regular cooling channels, baffles, bubblers, and hoses all can be modelled and evaluated.

From the analysis, users obtain the part temperature and cooling time.

The part temperature plot is useful in identifying hot spots and non-uniform cooling regions.

The designer can then consider part and mould changes to address these problems.

The cooling time plot is useful in identifying regions which are taking a longer than average time to cool, thereby affecting the overall cycle time.

In addition, the analysis provides several results related to the cooling circuits, including Reynolds number, flow rate, pressure, and temperature, all of which can help the designer to maximise the efficiency of the cooling system.

In addition to the two new addon modules, MPA 7.0 includes some other significant new features and enhancements: New optimisation tools include a material/process adviser and a mould runner system adviser that will help customers quickly identify the right materials and the most efficient way to deliver melted plastic through an injection mould.

Users can now optimise the material selection process by evaluating several materials and identifying the material that has the largest processing window for their part design.

The user begins by selecting any number of materials, and then launches the Moulding Window Analysis.

The software compares each material's processing window and ranks the materials in the order of most suitable (largest processing window) to least suitable (smallest processing window).

Mould designers using Moldflow Mold Adviser will benefit from the runner system adviser, which extends the gate optimisation tool (introduced in MPA 6.0) to automatically size sprue, runner, and gate components of the runner system.

An optimised runner system helps to reduce scrap, improve productivity, and reduce production costs.

By automating the runner system design process, mould designers will have one less issue to address regarding their mould design.

While designing the runner system, the user can mark portions of (or the entire) runner system for auto-sizing.

The program calculates best dimensions for each marked segment of the runner system and automatically updates the model with these calculated dimensions.

The designer can review the changes made and obtain feedback on the reason(s) for the change in the dimension.

The novel Connect to Consultants Tool is a utility to facilitate communication between MPA users and a plastics simulation consultant.

For MPA users who need advice on an existing project or determine they need more in-depth analyses, the "connect to consultants" tool in MPA 7.0 provides a fast and easy way to collaborate with an expert MPI user, slashing significant time from product development cycles.

This powerful tool is simple to set up and operate.

To begin with, the user specifies the e-mail address of the expert/consultant inside the software.

From this point on, the expert/ consultant can be notified via e-mail when a specific issue arises.

The notification can be triggered either manually or automatically.

In manual mode, the MPA user initiates the call to the expert/consultant.

When doing this, the user can choose to provide the model and/or a report to facilitate the expert/consultant to quickly comprehend the issue and provide a response.

In automatic mode, the expert/consultant can set up criteria that will trigger the automatic notification of a problem.

The criteria can be specific to the current model or based on historical trends in results.

The latter option allows potential problems to be detected even before they arise.

The Connect to Consultants tool will nurture a mentoring relationship between the MPA user and the designated expert/consultant in the organisation and ensure the successful application of the technology.

In the long run, it can also turn a novice MPA user into a more informed user.

Customer-driven enhancements include new runner system modelling tools to allow users to increase productivity and a new plastic material orientation result plot to give further insight to the behaviour of the melted plastic as it flows through a mould.

The Material Skin Orientation Plot displays the orientation of polymer molecules on the skin (surface) of the part at the end of filling.

This plot assists in determining a qualitative estimate of the part strength, especially in the vicinity of weld lines.

Uniform orientation leads to better surface quality, while differential skin orientation potentially causes differential shrinkage and part warpage.

Part and mould designers can evaluate alternative gating strategies to reduce differential orientation.

Moldflow Mold Adviser users can also take advantage of new modelling tools that allow them to translate, rotate, and mirror portions of the complete runner system.

Previously, these tools were limited to part geometry only.

These much-requested tools allow mould designers to quickly and efficiently design runner systems, thereby increasing overall productivity.

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