Part designers using Autodesk Inventor® or Autodesk Inventor® LT software have the option to use the new Autodesk® Moldflow® Adviser Design plug-in (formally Project Krypton from Autodesk Labs) to evaluate their plastic part designs directly within the native CAD environment. Part designers can evaluate manufacturing feasibility, cost efficiency and environmental impact concurrently with product development as the design evolves.
This plug-in highlights potential design problems directly on the CAD model and provides immediate feedback on design manufacturability, cost efficiency, and the environmental impact of the plastic material. Fill patterns, undercuts, poor draft angles, weld lines, and sink marks are represented on the model, and these are updated almost instantly as design parameters are altered in the model.
These capabilities allow designers to react quickly to address identified issues and optimize their designs.
You may not be the Moldflow user in your company, but you can still use this utility to perform some preliminary checks in Inventor before the Moldflow users get their hands on the model.
In order the install the Moldflow Adviser Design add-in for Autodesk Inventor, the following criteria are assumed:
- You are on subscription
- You have a Network License of Autodesk Moldflow available
- You have one of the following CAD packages: Inventor 2012 – 32 and 64 bit, Inventor 2012 LT – 32 and 64 bit, or Pro/E Wildfire 3.0-5.0 32 and 64 bit.
To access the installer for the utility, visit the Autodesk Subscription site and locate the product enhancements section. You may need your contract manager to perform this download in order to obtain the files.
During the installation process, Autodesk will ask about the network license manager and server locations. If you cannot locate a Moldflow license server, the installation will not be able to continue.
Shown below are the available FlexLM feature codes allowed for the Adviser utility.
There are several modeling features and techniques in Autodesk Inventor just for plastic part modeling.
A couple years ago, specially designed modeling tools known as the Plastic Features were added. These features include such gems as Lip, Boss, Rest, Grill, Snap Fit, and Rule Fillet. The Rib command was also recently overhauled to better work with plastic features.
Perhaps the largest increase in capability for plastics over the last couple years has been the inclusion of the Multi-Body Part commands, which allow a user to build a single part is if it were an assembly.
After modeling is completed in this file, the individual solid bodies can be broken out into their own respective parts with use of the Make Components or Make Part commands. Autodesk Moldflow Adviser Design does not support multi-bodied parts so this step has to take place before part analysis can begin.
Material Selection is also quite important for the Adviser to work. If no material is preselected (Default) the Adviser will use polypropylene. If a non-plastic material such as aluminum is chosen, then the Adviser will automatically disable itself.
Moldflow Design Widget
The on-screen advisor tool requires some interface and customization adjustments in order to fully utilize the utility. These adjustments include turning on additional menus and configuring the settings for each of the plastic indicators.
For information about an indicator click on the icon and a pop-up dialog with two tabs is displayed. The Alert Pop-Up tab outlines any parameters that need attention. Several individual parameters have sub-menus that help visualize or rectify the problem.
The Information Pop-Up tab shows how each parameter contributes to the indicator value.
The warning alerts can also be switched to view the individual indicator element graphs by selecting the blue information button in the indicator flyout.
In order to see what the resultant calculators predicted for the part, use the Finished Part View in any of the indicators to launch a previewed render of the part, including potential sink marks in the material.
This preview dramatically improves visual understanding, conveying potential changes to the design criteria, or showcasing potential flaws in manufacturing of the part.
The menu for the advisor add-in allows for the user to activate two on-screen toolbars as well as configure the rules for cost efficiency, manufacturability, and plastic material impact.
The Injector toolbar allows the user to move the initial injector for a part and either add or remove additional plastic injectors for the material. The addition of the injectors will change the animation of the fill.
The animation toolbar controls the on screen animation of the plastic filling preview process. This process actually uses multi-threading capabilities of your system to increase the speed and analysis of the preview.
The loop option allows the animation to play over in repeat during visible inspection. The elapsed time of the animation below is approximately three seconds.
Each setting for the three indicators can be controlled here. Rule inclusion can also be selected for each heading. For instance, if draft angle was not a concern to the user, the calculations and subsequent warnings can be disabled from the widget.
Simple selection for which portion of the screen the indicators will reside.
Manufacturability is the combination of wall thickness, undercuts, draft angle, weld lines, sink marks, and filling of the part. A weighted combination of these factors results in the rating in the indicator.
Remember that the settings for all of these factors can be adjusted in the advisor rules.
Ideally, a plastic part should have an even wall thickness across the entire part. Otherwise, quality problems can occur.
Molten plastic will prefer to flow through thick sections of the mold. Excessively thin areas could have problems filling or may fill at a slower rate than thicker areas. Problems of short shots, underflow, and possibly weld lines can result from variation in part wall thickness.
Excessively thick areas will take longer to cool, which can lead to the part deforming as the molten plastic solidifies as well as longer manufacturing cycle times. Excessively thin areas require a higher injection pressure to fill the mold cavity, increasing the possibility of unfilled sections of the part.
The wall thickness element examines the part thickness and its variation to highlight regions that could cause molding problems.
An undercut is a design feature that interferes with the ejection of a molded part from the mold. An undercut can include features such as holes or bosses that are not aligned with the direction of ejection, threaded sections, and snap fingers.
The snap finger shown above has an undercut surface highlighted in red.
This part could not be produced without the inclusion of moving parts within the mold to ensure the part could be ejected. This will add to the cost of the mold.
A draft angle is a slight taper added to assist in the ejection of the molded part from the mold. Surfaces that lie parallel to the direction of the part ejection will cause difficulties in production.
The amount of draft added will depend on the material to be used and the surface finish of the part.
Highly polished surfaces often have a draft angle of 1.5o while heavily textured leather-like surfaces can require a draft of 6o to 8o.
A weld line on plastic parts can cause structural problems and/or be visually unacceptable.
A weld line is created when two or more flow paths meet during the filling process. Weld lines can be caused by material flowing around holes or part inserts, multiple injection gates, or variable wall thicknesses, where different localized fill rates can cause separate flow fronts. If the different flow fronts have cooled before meeting, they will not interfuse well and can cause a weakness in the molded part. A line, notch, and/or color change can appear. This is undesirable in highly visual areas of the part.
It may not be possible to remove weld lines from the part. Changing the injection location, modifying local part thickness, changing the selected material, and/or modifying processing parameters such as injector speed and mold temperature could move the location or minimize visual impact of the weld line.
Sink marks result from localized shrinkage of the material at thick sections of the part.
A plastic part solidifies from the outside surface to the center of the part. On cooling, sections of the part that are thicker than the surrounding area can have a small reservoir of molten material in the center of the part. As this reservoir solidifies, it shrinks, drawing the surface inwards to form a sink mark.
Sink marks appear as depressions on the surface of an injection molded part. These depressions are typically very small; however, they are often highly visible because they reflect light in different directions to the rest of the part. The visibility of a sink mark is dependent on the color and surface texture of the part.
Where possible, change the part design to minimize thick sections. Manufacturing parameters can be adjusted to reduce or possibly eliminate sink marks.
The Filling result can be used as an indicator of the probability of plastic filling a region within the cavity under conventional injection molding conditions.
Manufacturability is the combination of mold cost, material cost, and production cost. A weighted combination of these factors results in the rating in the indicator.
The Costing efficiency indicator is based on a single cavity mold. The proper assessment of a multi-cavity mold should be done with specialized software such as the full Autodesk Moldflow Adviser product.
The size of the part and the relative cost of the selected material combine to determine the material cost.
The mold cost is determined by the size and complexity of a part along with the number and position of injection locations.
The size of the part when measured in the Z direction.
Part's projected area
The area of the part when projected onto the X-Y plane.
Geometric features of the plastic part such as the extent of undercuts and the number and location of injection locations contribute to the cost of manufacturing the metal mold.
The time it takes to manufacture a part and the associated costs are represented in the Production Cost element. Because plastic injection molded parts can have a large range of size and complexity, the Production Cost indicator is based on a single-cavity mold of average size and complexity.
Plastic Material Impact
Manufacturability is the combination of carbon footprint, recyclability, embodied water, and embodied energy. A weighted combination of these factors results in the rating in the indicator.
Publicly available data is the basis for the Plastic Material Impact indicator result. Autodesk’s prime data source is Plastics Europe http://www.plasticseurope.org.
The amount of carbon dioxide produced when making the raw material needed to manufacture this part, multiplied by the weight of the part.
The recyclability of a material is a measure of the percentage of the material that is recovered as scrap and subsequently reprocessed into useful products.
The embodied energy is the total energy required in the making of a part. Typically 70-90 percent of this energy is associated with manufacturing the raw material. Value is multiplied by weight.
Embodied water is a measure of the amount of water required to produce the selected material. Value is multiplied by weight.
The use of this tool can aid in the process of creating not only cost effective parts, but also parts that are more sustainable in design. Even if your company only pays lip service to these ideas, they do become an increasing important part of design choice and public awareness for your products.
By starting the selection process early on, the lead time due to rework and failed prototypes is reduced in your process making your work more cost effective and sustainable as well.
Just remember to turn it off when not in use to save on computational time in Inventor.
Mark Flayler is an application engineer with IMAGINiT Technologies, specializing in manufacturing environments. He has implemented Autodesk manufacturing products within several industries including the blow/injection molding, automotive, and custom machinery markets. Mark has extensive experience and a comprehensive understanding of the
technical, practical business, and human dimensions of implementation. When not providing training, support and implementation, he writes the IMAGINiT Manufacturing Blog
and takes an active role in the manufacturing community. Mark is an ATC certified instructor, and is PSE and ATC certified in AutoCAD, AutoCAD Mechanical, AutoCAD Electrical, Autodesk Data Management, and Autodesk Inventor.