Written by our Technical Simulation Manager – Håkan Fransson, through Altair.
Historically, foundries have used too high of casting temperatures during high pressure die casting simulations. Many foundries believe there is a minimal temperature drop (~ 20 degrees) from the melting furnace to the filling of the part. Running a simulation with too high of a casting temperature will result in an incorrect simulation of the cold flow and a different temperature gradient which will cause the porosity prediction to be slightly off. This can result in cold joints, cracks on the surface of the casting, or increased porosity.
In a test on thermocouples conducted in a furnace with a melt temperature of 700 degrees, it was found that the temperature drop from the furnace to the exit of the filling chamber (where the ingate system starts) is actually more than 100 degrees. This has also been proven in several other independent tests, one of which was project managed by the Swedish Foundry Association. Running an HPD chamber filling simulation will solve this problem and provide a better understanding of the real values in the process. This, along with a few other simulation tools and tricks, will provide faster, easier and more accurate castings.
HPD Chamber Filling – Taking into Account the First Filling Phase
With new innovations in simulation software, engineers can take the correct temperatures into account and simulate the whole process of high pressure die casting. Running a complete simulation gives more accurate settings of different phases by setting it by millimeter movement of the piston in the chamber. This allows the testing of different phases and start points for optimization as well as the ability to account for the air in the chamber that could be encapsulated into the melt during the filling of the first phase and then create gas porosities in the casting.
Speeding up Simulation of the Filling Chamber
It is not necessary to have the same mesh resolution for both the chamber and the part. In this example, a 6 mm mesh was used when filling the chamber, a 4 mm mesh from the exit of the chamber to the casting cavity, 2 mm mesh for the remaining fill, then 1 mm when the calculation of solidification should take place.
Since larger meshes produce faster calculations, a switch from 2 mm to 6 mm during the first phase can significantly decrease simulation time. It’s best to spend all your time and effort on the part of interest, which is typically the quality of the casting.
Enabling Gas Calculations with Gas Bubble Movement
By saving time with quicker simulations, there is time to take into account calculations of mold gas and backpressure for more accurate mold filling simulations. Some things to consider;
– View of gas bubble movement in the cavity
– Gas porosities can be predicted – position and size
– Test various vent positions in order to remove gas porosities
Simulation of Cold Flows
Cold flow simulation innovations now accurately simulate how low of speeds filling can be performed at and how thin section walls can be without losing integrity. Such innovations allow engineers to explore the limits of different materials and processes as well as find workarounds that can stretch these limits.
3rd Phase Shrinkage Prediction
Using piston movement in the chamber, a pressure curve can be setup in the last stages of the filling process. It is best to use pressure equal to the 3rd phase feeding pressure set on the machine. This innovation makes the feeding/porosity process more realistic and accurate.
New innovations in casting process simulation of high pressure die casting makes it possible to simulate the complete high pressure die casting process without spending a lot of time setting up the simulation, running it, and analyzing the results. Faster speeds enable the possibility to add more details in the simulation like gas calculations and filling of the first phase. The culmination of these innovations give more accurate results.
ATAS MetStar 9.1 – Streamlined & easier to use
Some news in this release are:
• Enhanced communication with external devices
(i.e. spectrometer, inoculation machines, wire feeders and charging devices)
• Higher precision for analysis of hypereutectic alloys
• More adaptable to suit a specific metallurgical process
• Easier to use than ever before
Curious for more? Click here.
As a NovaCast Christmas tradition instead of sending Greetings cards, we have donated money to the Swedish Cancer Society to show our support to affected families. We hope our contribution will help more families spend a lot of Christmas’ for years to come.
We wish our partners and customers a Merry Christmas and a Happy New Year!
Thank you to all of you who stopped by our booth at Fundiexpo in Queretaro, Mexico. See you next time!
Thank you everyone who attended our user meeting in Malmö!
Vi söker nu en driven och affärsinriktad ledare, som vill anta utmaningen att föra NovaCast Systems till nästa nivå i företagets utveckling. Läs mer här.
Today, NovaCast Systems is launching the most user friendly metallurgical process control system on the market, ATAS MetStar 9.0.
Each one that has foundry experience knows the day-to-day challenges of achieving the same quality of the melt between the charges. The expectations from the customers are high both on casting quality and precision in delivery, for a competitive price. Foundries have to use all their know-how and handicraft experience to meet the requirements and still they are struggling with too big variations in the production process.
ATAS MetStar is the metallurgical process control system that helps the foundries stabilize their quality through an optimized production process. Per-Eric Persson, Product Manager explains; “-The system returns important data of each sample of the melt, the unique fingerprint, and the operator/the metallurgist on the shop floor has the possibility to correct possible negative variations before the actual castings are done.” He continues, “- Our system helps the foundries to cast only the castings needed which involves key cost-savings for the foundries.”
In this version of ATAS MetStar a new Good Guys’ Index (GGI) is available. It shows how successful the operators are to minimize the foundry’s environmental footprint. The GGI value takes, for example, melting and holding time in the electrical furnace and addition of new materials into account.
Camilla Sjögren, Marketing Manager, clarifies “- GGI is a value that visualizes how taking control of the production process not only leads to less variations, stable quality and reduced scrap rate, the foundries also gain environmental advantages like less energy consumption and less material usage. We want to create an active awareness; you can make big changes with small steps. You see, green business is good business. For everyone.”
What to know more? Send us a message!
Today NovaCast is launching the fastest casting simulation software ever, NovaFlow&Solid 6.0.
Today NovaCast Systems is launching the casting simulation software NovaFlow&Solid 6.0 with a revolutionary adaptive Multi mesh technique and a Good Guys’ Index (GGI).
With the adaptive Multi mesh technique the simulation time is reduced by 50 %. “-With the new technique you use the mesh resolution needed for different parts of a simulation” explains Håkan Fransson, Product Manager for NovaFlow&Solid. “-The timesaving comes from switching mesh in the simulation and during filling in several steps. Where the sections are thick-walled you use a bigger mesh resolution and for sensitive areas you use a finer mesh.” He continues; “-Now there is no excuse for not using simulation. Shortening simulation time is crucial for the foundries to be able to optimize all their castings.”
Simulation software is an important tool for the foundry industry. It is used to simulate an actual casting and analyze the result to detect weaknesses during flow filling and solidification. The detected errors such as porosity, stresses and gas entrapment are corrected already in the simulation phase. When the results from the simulation analysis are in line with quality requirements the piece is going into production.
The Good Guys’ Index compares optimized simulations and visualizes the financial and environmental impact, such as energy consumption and CO2 emission. Camilla Sjögren, Marketing Manager at NovaCast clarifies “-This is an important step towards NovaCast’s vision. With our systems the foundries secure their quality, at the same time as they are guided towards reducing their environmental footprint. You see, green business is good business. For everyone.”
NovaFlow&Solid 6.0 is an innovative casting process simulation tool using FVM (Finite Volume Mesh Technology). It visualizes the consequences of a specific gating and feeding system and simulates mold filling and solidification. It simulates most commercial casting methods and can use all types of mold and core materials.
For more information, please contact:
Håkan Fransson, CEO/Product Manager NovaFlow&Solid, +46 709 24 58 20
Camilla Sjögren, Marketing Manager +46 709 24 58 21
Would you like to learn more about optimizing the thickness of investment castings for the aerospace industry?
Altair is hosting a free webinar where they will highlight the functionality and potentials using NovaFlow&Solid, specifically for investment casting manufacturing and development of aerospace castings.
Register your participation by clicking here.
ATAS MetStar 9.1 – Streamlined & easier to use Some news in this release...
As a NovaCast Christmas tradition instead of sending Greetings cards, we have donated money...