If you are a design engineer and you are designing an aluminum object or component through die casting, then it could be overwhelming knowing that there are several factors to consider during this stage. Keep in mind that one of the most important steps in manufacturing die-cast products is perfecting the design process. In this way, you can achieve an efficient and successful outcome.
Fortunately, expert designers have extensive knowledge when it comes to designing quality aluminum die-casting products. Here, we are going to explore how to design a product to obtain an effective and efficient manufacturing process.
We are also going to give you some of the important considerations for designing an object or component through die casting.
Design for Manufacturing
In the field of engineering, the term, Design for Manufacturing (DFM) is commonly used. The aim of this process is to make production more cost-effective and simpler. DFM is more involved in the processes used and the manufacturing techniques.
One of the major benefits of DFM is that any issues with the production techniques can be detected and fixed earlier during the design phase. This is ideal since any problems during this stage are less expensive to fix compared to when they are known after or during the production stage.
Using DFM methods can result in reduced manufacturing costs while retaining excellent quality. The following are some of the objectives that should be accomplished during the optimization of aluminum die-cast production.
- Guarantee that the object or component can be extracted easily from the die.
- As much as possible try to use fewer casting materials.
- Reduce the amount spent during the solidification for a casting.
- Guarantee that the final component or object can perform as required.
- Try to minimize the secondary operations needed.
To meet these production optimization objectives, the following factors should be considered during the design stage.
One of the most common and unavoidable circumstances in aluminum die casting is shrinkage. This can happen frequently in most castings.
As the melting temperature changes to room temperature, the molten metal will gradually cool down. When this happens, sometimes the cast has the tendency to shrink down towards the middle part.
Although this can help in ejecting the casting from the outer walls of the die, unfortunately, at the same time, it could also restrict any interior protrusions on the mold. During these circumstances, ejection might be challenging. When this happens, a draft can be used in reducing the shrinkage, making the ejection of the cast much easier.
Typically, a die is divided into two halves. One is static, while the other is movable. They will be bound together so that mold can be formed, and the molten metal can be poured into it.
The parting line refers to the intersection where the two halves will meet. Choosing where the parting line should be placed is one of the important things to consider during the design process. This is because this can greatly affect the other design specifications.
Also, take note that the area where the parting line is located is also the area where the flash, a die-casting defect, will appear. A secondary process will be required to remove the flash. That is why it is important that it should be designed in such a way that it can be easily accessed by the trimming machinery.
When it comes to die-casting, a draft refers to the minimal taper found on the sides of the mold for easy removal of the casting. Most often a taper can be seen in other types of molds.
For instance, in baking pans that are used for bread and muffins. All cast surfaces should include this draft for easier removal. If not, then it will be difficult to remove the cast and could likely damage it.
The measurement of the draft will differ throughout the design. There should only be a small draft on the outside walls since the cast will shrink away. On the other hand, a larger draft is needed in the holes and the interior walls since the metal will shrink around them.
Wall thickness must be carefully considered to ensure a successful outcome, minimal material waste, and fast production. If the wall is extremely thin, then it could prevent the smooth flow of the molten metal; hence, the metal could harden before the mold is fully filled.
Also, thin walls could be prone to warping when there is a need for post-mold machining forces. While extremely thick walls could mean there is a waste of casting material, at the same time, the solidification times will also increase.
As much as possible, the wall thickness should be the same. In this way, the molten metal can flow smoothly. This is necessary if you want to have an efficient solidification process that guarantees superior strength and reduces potential defects. If it is essential to have variations in thickness, then the transition should be done gradually rather than making is suddenly.
Radii and Fillets
These two elements refer to the curved junctures found between the two cast surfaces that can result in a sharp edge. The main difference between radii and fillets is that radii can be seen on the outer edges while the fillets can be found on the interior edges.
Radii and fillets have rounded edges and are crucial in the die-casting design since they allow the metal to flow smoothly when removed.
Sharp corners can result in instability of the metal flow, which can potentially weaken the cast component. With the use of radii, trimming sharp edges and corners will no longer be needed during the secondary process.
This refers to the protruding aspects of cast objects that are usually used for mounting points or as standoffs. For instance, a boss can be included in a doorknob.
It is important to incorporate bosses in your design since it can eliminate boring operations as part of the secondary process. Keep in mind that extreme changes in wall thickness can lead to unequal shrinkage and sinking, creating a negative impact on the integrity and appearance of the product.
That is why it is important that bosses should be designed in such a way that there is uniformity in wall thickness.
To maintain a uniform wall thickness, a hole in the middle of the boss can be added. Another alternative would be to add abundant fillets in the area where the boss is connected to the remaining parts of the cast.
This can allow a smooth flow of molten metal. To increase its strength, there should be an accurate draft angle on the bosses and ribs as well.
This refers to the small bridges of metal that can be included between walls to improve their strength without the need for more metal. This can also allow the molten metal to reach all parts of the die by adding more flow pathways.
As you have observed, designing an aluminum die cast can be very challenging. The aspects that we mentioned above are just some of the important things to consider during the design stage.
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