Die casting is a vital manufacturing process that most industries cannot evade. It involves the production of huge volumes of metals by the application of modern-day technologies and proven methodologies.
However, it is important to note that as much as die casting is a lifesaver to most industries, every step of the process affects the quality of the final product.
Now, you might want to know what is die casting draft angle and why you should care about it, right? Lucky for you – we have all the details you need, from what it basically means to its importance and contribution to the production of quality metal parts. Stick around to learn more!
Die Casting Draft Angle – A Jargon-Free Definition
As the name suggests, a draft angle is an angle or, in other words, a slope that is integrated in the vertical direction of the walls of the die casting mold in order to facilitate easy injection of the cast from the die cavity.
The draft angle is essential on the surfaces responsible for the direction of the die. Without the presence of a draft angle, the part is likely to peel off due to excess friction or, even worse, cause the metal formed to get stuck on the mold. When this happens, forcing it out through pressure may result in further damage, leading to additional costs.
So, is it possible for you to design a die-casting draft without any unwanted expenses? Let’s discuss it below, along with the notable benefits of including the right draft angle.
The Remarkable Benefits of Considering Draft Angle in Die Casting
Easier Part Ejection
Die casting involves injecting molten metal into a mold cavity and allowing the metal part to form through solidification. After the metal cools and solidifies into a metal part, it must be removed (ejected) from the mold.
Now, if the manufacturer fails to incorporate draft angles on the surfaces or perhaps makes incorrect calculations, removing the part from the mold becomes challenging. Using force to remove the metal only causes strips, dents, and even damage. However, including draft angles provides a slight taper, which allows the casting to be removed without causing damage or sticking.
Extends Die Casting Tooling Life
Die-casting tooling is typically the mold through which the molten metal is injected. Now, the mold can be used repeatedly to produce similar metal parts; however, if you neglect the drafting angle in die casting, you will end up with overhanging walls, which may get stuck, resulting in tool wear as you use force to remove the parts.
Drafting angles help reduce friction when the metal is being ejected. This implies that the more it’s easy for you to remove the metal, the fewer chances there are for tool damage. Thus, you can expect your die-casting tool to serve you longer.
Improved Surface Finish
Without draft angles in die casting, there is a high possibility that the metal part will have imperfections like dents, strips, drag marks, and scratches. However, with accurate draft angles, the metal part will be removed from the mold cleanly and smoothly, resulting in high-quality parts.
The advantage of improved surface finish extends further. As the manufacturer, you can also reduce the cost incurred when perfecting the surface finish. This means you won’t need surface finishing methods to correct imperfections.
How to Design a Die Casting Draft?
The draft angle in die-casting calculations varies greatly on the basis of the following factors:
- Type of metal
- The type of surface
- The thickness of the Wall
Let us discuss all in detail.
Type of Metal
Before you start designing, you have first to understand the material properties of the alloy you are using. The drafting angles used on Aluminum alloys may not be the same as those used on Zinc. You have to consider aspects like thermal expansion and contraction rates.
For example, Zinc has a shrinkage rate of 0.7%, which is easily compensated for in the tool design. Aluminum, on the other hand, has a higher shrinkage, and engineers mostly will incorporate +- 1-2 of draft angle to accommodate the abrasive nature of the metal.
Type of Metal Surface
Generally, a draft angle of 1.5-2 degrees facilitates easy ejection of parts. For textured parts, ensure that you use a draft angle of 2.53 degrees, and for vertical surfaces, use at least 0.5 degrees. If you are dealing with metal on a metal molding component, a drafting angle of 3 degrees will serve you well.
The Wall Thickness
Again, if your mold walls are too thick, it will affect the filling, resulting in hard ejection. So consider demolding the problem. These problems are usually common and can result in multiple losses if not careful. Therefore, you must pay attention to the setting of the draft angle and the calculation of the demoulding force of medium-moving fixed mold.
Now that you have seen how drafting angles in die casting is essential, you can proceed to your manufacturing process. However, if you are still new to the manufacturing world, it is recommended that you request a professional die casting supplier. At Sunrise Metal, we have specialists who have experience in correctly calculating draft angles, whether on aluminum alloys or zinc alloys; you can expect quality products from us. Don’t risk a chance to produce low-quality parts; contact us today and let us partner with you.