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Education: What is Casting and Molding Simulation?

2024-01-03

Education: What is Casting and Molding Simulation?

模流, 模流軟體, 模流分析, Mold flow analysis, Mold Simulation, 金型シミュレーション, 鋳造シミュレーション,

In modern society, everyday electronic consumer products such as smartphones, essential laptops for work, and vehicles on the road, all rely on a significant number of metal components. But do you know what kind of technology is used to manufacture these metal parts?

In this discussion, we will delve into two closely related metal processing technologies crucial to human civilization – “Casting” and “Molding simulation”. We hope this will help you gain a better understanding of casting and molding simulation.

 

What is Casting?

Since the discovery of the malleability of metals, humanity has been studying related processing technologies, evolving alongside human society to the present day. Among the common processing technologies used in modern manufacturing processes, such as Machining (NC, Numerical Control machining; CNC, Computerized Numerical Control), Stamping, Forging, etc., there is another processing technique known as Casting.

Casting is one of the ancient and longstanding metal processing technologies that has been used throughout human development, with origins dating back to around 3200 BC in Mesopotamia, where bronze artifacts were crafted. This technique takes advantage of the property that metals become liquid when heated to their melting point. Molten metal is poured into molds, and after cooling, it solidifies into the desired shape.

In modern casting technology, there is a broad classification based on the mold material used, distinguishing between “Expendable mold casting” and “Non-expendable mold casting”.

  • Expendable Mold Casting

    Expendable mold casting involves creating molds using materials such as sand, resin, plaster, wax, etc., to meet temporary and short-term needs. However, these materials lack durability, making them unsuitable for repeated use. In expendable mold casting, the materials used for molds are often named based on the casting technique.

    • Sand Casting
      Sand casting utilizes the properties of sand, including its plasticity, cohesiveness, and refractory nature. The process involves covering a model with sand, applying pressure to shape intricate details, and then casting molten metal. After production is complete, the used sand can be recovered and reused.
    • Plaster Mold Casting
      Plaster mold casting is a technique that involves covering a model with plaster specially formulated with specific ingredients. The plaster solidifies to obtain the product’s shape, and molten metal is then poured into the plaster mold for casting. After production is complete, the plaster mold is rendered unusable due to burning from the molten metal’s influence. However, it can be recovered and reused through crushing processes.
    • Shell Mold Casting
      Shell mold casting utilizes the same concept as sand casting, with the key difference being the addition of an adhesive to the casting sand. After shaping the sand to the desired form, it is heated to solidify before being used for casting along with other molds. Upon completion of production, the adhesive disintegrates at high temperatures, reverting the sand to its original state. However, proper treatment is necessary for reuse due to impurities introduced during the process.
    • Lost-wax Casting
      In contrast to the aforementioned casting techniques, the wax used in lost-wax casting is not reusable. The process involves creating a prototype with wax, covering its surface with materials such as plaster or resin, allowing it to dry and solidify, and then placing it in a kiln for sintering. As the wax melts away at high temperatures during heating, molten metal is poured into the resulting void, creating the cast product.
  • Non-expendable Mold Casting

    In contrast to expendable mold casting mentioned earlier, non-expendable mold casting involves creating molds with special alloys capable of withstanding high temperatures and pressures. These molds are used for long-term and semi-permanent production needs. Due to the durability of the molds, the products manufactured exhibit repeatability and closely resemble the original mold’s shape, making this method highly suitable for mass production or component manufacturing. Non-expendable mold casting is named based on the technology used.

    • Permanent Mold Casting
      Permanent mold casting utilizes molds made from materials resistant to high temperatures and metal fatigue. Techniques associated with this casting method include Gravity Casting and Low-pressure Casting, both of which leverage durable molds for the casting process.
    • Die Casting
      Also known as pressure die casting, die casting is a technique that involves injecting molten metal into precision molds at high speeds and pressures, allowing for the rapid formation of products in a short period. Related die casting technologies include Hot-chamber die casting and Cold-chamber die casting.
    • Semi-solid Metal Casting
      Semi-solid metal casting utilizes a slurry state where both liquid and solid phases coexist, taking advantage of the semi-solidified or semi-molten condition of the metal for the die casting process. Related technologies include Rheocasting, which involves transitioning from a liquid to a solid-liquid coexistence state, and Thixocasting, which transitions from a solid to a solid-liquid coexistence state.
    • Centrifugal Casting
      Centrifugal casting involves pouring molten metal into a rotating mold, utilizing the characteristics of the liquid and centrifugal force to fill the mold with molten metal. This technique is not limited to metals and can also be applied to liquidizable and dissolveable building and industrial materials such as glass and concrete.


What is Casting simulation (Molding simulation)?

In the past, during product development in casting, it was challenging to observe the actual flow and solidification conditions inside molds. Consequently, it was necessary to produce prototypes before mass production to evaluate aspects such as the adequacy of mold design, sufficient strength, and fulfillment of design objectives. However, this method incurred significant costs and had long lead times.

With the advancement of computer technology and casting techniques, related technologies in Computer-Aided Engineering (CAE) have developed. Eventually, it became possible to simulate the flow and solidification of molten materials inside molds. This advancement allows for the consideration and validation of mold designs before production. This technology is known as Molding simulation, which can be further divided into Injection molding simulation for resin materials and Casting simulation for metal materials, depending on the materials used.

  • How is Molding Simulation Applied?

    Molding simulation is applied in both Injection molding for resin materials and Casting for metal materials. In most cases, it is used for simulating and verifying the molding of molds and products. In the actual manufacturing process, molding simulation is typically applied between the design and fabrication of molds, as illustrated in the diagram below. If molding simulation is effectively utilized, engineers can eliminate design uncertainties before mold fabrication, analyze the causes of problems in the product, and use the results as a basis for improvement.

    電腦輔助工程, 电脑辅助工程, CAE, Computer Aided Engineering, コンピューター支援設計,

  • Defects Analyzable by Molding Simulation?

    Regarding the defects that molding simulation can analyze, it can typically simulate and analyze defects caused by factors such as flow, solidification, and temperature. However, the specific functionality and accuracy of modules may vary depending on the development technology of the manufacturer and the concept of the software. For example, in casting simulation, defects like misrun, metal wave, hot cracking, soldering, air entrapment, blowhole, shrinkage cavity, and others can be analyzed.

  • Effects of Molding Simulation?

    Molding simulation brings about several benefits, as summarized below:

    • Cost Reduction
      Introducing molding simulation into the manufacturing process allows for simulation and analysis of issues and defects before production and when problems arise. It also enables the verification of improvement proposals. Once the proposed improvements are confirmed, actual mold enhancements can be implemented. This significantly reduces costs compared to traditional manufacturing processes.
    • Quality Improvement
      Molding simulation, by simulating issues and defects, allows the application of analysis results to mold design, leading to the improvement and enhancement of the quality of both the mold and the product.
    • Reduced Development Time
      The development process is often the most time-consuming aspect of the product manufacturing process. With molding simulation using CAE technology, simulations and verifications can be conducted before actual manufacturing, substantially reducing the time required for testing and validation.
    • Environmental Impact Reduction
      The development process involves significant material and cost expenses for mold production and prototype manufacturing, leading to the generation of substantial industrial waste during the manufacturing process. For instance, mold release agents used to facilitate smooth removal of products from molds can result in the production of waste gas and oil through evaporation and degradation during heating. Analyzing and verifying these processes through molding simulation can effectively reduce industrial waste and minimize environmental impact.
    • Optimization of Manufacturing Process
      Summarizing the aforementioned effects, introducing molding simulation into the manufacturing process enables low-cost verification of product design, continuous improvement of quality through testing and simulation of proposed enhancements, and optimization of the manufacturing process using a large dataset generated from verification tests. This allows for the most efficient product development, leading to the optimization of the entire manufacturing process.

  • Limitations of Molding Simulation?

    Certainly, molding simulation allows for the analysis of issues and defects, bringing about various effects as mentioned earlier. However, strictly speaking, the analytical results obtained from molding simulation are experimental data obtained under ideal conditions. If the set manufacturing conditions differ from the actual environment when using molding simulation, the results obtained are prone to deviations, making it challenging to apply them to improvement proposals for mold design.

    Typically, molding simulation allows for the configuration of basic manufacturing conditions such as the temperature of the mold and molten material, injection speed and position of the plunger rod, injection and pressure intensification pressures, and so on. However, there are various factors in the manufacturing environment that can influence the actual manufacturing conditions. Examples include the maintenance status of the machine, environmental conditions within the factory, and the experience of on-site operators.

Manufacturers and Products for Molding Simulation

  • Injection Molding

    Autodesk’s Moldflow (USA), Dassault Systèmes S.A.’s SolidWorks (France), CoreTech System Co.’s Moldex3D (Taiwan), Toray Engineering D Solutions Co., Ltd.’s Timon Mold Designer (Japan) …and more.

  • Casting

    Hitachi Industry & Control Solutions, Ltd.’s Adstefan (Japan), ESI Group’s Procast (France), QUALICA Inc.’s Jscast (Japan), TOYOTA Systems Corporation’s Topcast (Japan), Flow Science, Inc.’s Flow-3D (USA)
    AnyCasting Software co.,ltd.’s Anycasting (South Korea), Novacast’s NovaFlow&Solid (Sweden) …and more.

     

 

With the explanations above, I hope you have gained a broad understanding of casting and molding simulation. In the next section, I will provide a more detailed introduction to the applications of molding simulation.

Until then, see you next time.

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