A lot of industries benefit from using components and products made using the die casting process. Die casting is the process of manufacturing that creates well-defined, smooth, textured surface metal parts and products. If you are here to know more information about die-casting, you are in the right place. Here at SEI Castings, we will be sharing with you an article to discuss design tips to consider for die casting.

Die casting uses cold or hot chamber manufacturing techniques that use high pressures, which forces and inject molten metal parts into a steel die that can be reused many times with speeds ranging up to 60-100 miles per hour. A clamp will hold the die in place during the injection, cooling, and solidifying stage of the metal. It is a fast and sustainable process that is capable of producing metal parts of the same size and shape.

Die casting is a manufacturing process that uses durable non-ferrous metals. The most commonly used ones are aluminum, magnesium, and zinc. The type of metal used for the die casting manufacturing process will determine whether they will use the cold chamber or hot chamber method for the metal to be injected into the steel die. 

Most manufacturers for various industries prefer using die casting to other manufacturing processes because it can create metal parts and products quicker and with high precision. Die casting parts have plenty of uses which included automotive parts, appliances, enclosures, heat sinks, office equipment, machinery, sporting goods, toys, etc. 

Die casting also allows for the manufacturing of metal components and parts that have fine details such as lettering, smooth-textured surfaces, and other unique features without requiring any other additional process. It is a process that can maintain close tolerances that do not require machining, therefore, making it a suitable choice for low-volume products as well. It is quite a versatile process because you can create high-volume and low-volume product orders. 

Recently there have been plenty of innovations in the technology of manufacturing and material science which has effectively eliminated a lot of old designs presumptions and process challenges. The improvements and advances have helped with the creation of new specifications for necessary design elements which include dimensional control, draft, and flatness.

Here are some tips on how to design the part or product economically and efficiently.

Parting lines for die-cast parts and products 

When planning the die casting design, you must decide on the type of parting line that will split the component and produce a contact surface between two or more parts. The designer will place the line depending on the shape and tolerance of the different surfaces. They can try a broken parting line or a straight parting line. Opting to use a straight parting line is the least expensive option when you take into account the tooling costs. 

When choosing what parting line to choose for the die casting part, make sure to consider the following factors. 

Customer’s part or product requirements

When manufacturing custom die casting parts for a client, it can be a challenging job to decide which parting line to choose. You must consider their tolerance requirements because parting line surfaces tend to have a lower quality than other surfaces. 

Die costs

When creating die-cast components, using a straight parting line can help reduce the cost of tooling. However, there are cases where it is cheaper to opt for a broken parting line because adding features in the component will need side die pulls, which can be more expensive than stepping the parting line. 

Machining

Most components and products produced during manufacturing may require additional processes such as post-production machining. Surface areas that have critical tolerance or finishing requirement must be strategically placed on the opposite side of the parting line.

Make sure that the area beside the parting line does not have an important cosmetic requirement specified by the client because the vents and gates that will be placed on the line will be visible. This part will also require additional processing to get rid of the excess material from the casting. 

Metal flow

The filling process will depend on the placement of the gate inlet. The inlet must be positioned in the parting line as it will determine if the casting fills correctly with the molten metal. The die casting process uses high pressure, so the injecting mechanism will press the molten metal into the casting to prevent the component from shrinking during the solidification process. 

What are the other factors to consider when determining the parting line placement?

Cores

The placement of the cores (forms the holes in the component) will control the placement of the parting line. So, as a designer, you must consider the placement of the core as well as the size of diameter, and length of the core of each hole required for the casting. 

Ejector pins

Also known as knockout pins. The parting line placement will affect the amount of force necessary to knock out or remove the component during pressure die-casting. You must avoid undercuts whenever necessary, especially when it is aligned to the parting line. You may also have to use additional machining to the die components. 

During the design process of die casting, metal flow is one of the aspects that must be considered. If the mold or die does not fill up correctly, then it can produce components that have defects. For example, visible surface flow lines and air pockets can cause porosity in the interior of the component.

You must also need to check the ejector pins if they can eject the casting from the die correctly. The pins must be designed to create a minimal number of residual pin marks on the casting’s surface. The ejector pins will prevent the component from bending. 

The ejector pin marks produce depressed or raised indentations of about .381 millimeters. The size of the ejector pin marks may differ depending on the casting size. Keep in mind that you should use raised ejector pin marks for effective manufacturability. 

Flash formation

The parting line of two die halves is where the flash formation can occur. It is an extension of metal that can form on the casting or when two die parts cast a feature. The seam of a metal can also occur during the regular operation of the ejector pins. The flash formation can be prevented early on during the design phase.

You must also figure out the amount of metal that must be removed during the removal process. These issues should be dealt with early on in the design phase so that you can prevent any problems as well as improve your company’s cost savings for the overall production process. 

Creating draft for die casting components 

The designer of casting components must create a draft prior to the start of the manufacturing process. The draft is the taper or slope allocated to the cores and other parts of the cavity of the die. This is responsible for preventing the casting from becoming trapped in the mold or tool during the casting’s ejection, therefore, making it easier to open the die and eject the casting from the die.

The introduction of drafts must be done early on and should be started from the parting line. The draft position, whether on an inside wall, hole, or outside wall must have different calculations. The difference in the shrinkage can help determine the right calculations for the amount of draft. 

Outside wall placement will need the least amount of drafts since the casting is prone to shrink away from the die steel forming outside its surface. On the other hand, untapped holes will need the most draft, since the casting may shrink during the solidification process so it can exert great force on the die steel and may form the interior surface of the hole. The inside wall may also undergo shrinkage on the die steel as it creates the surface of the inside wall of the casting. 

A die that is easy to open and eject the component will produce a component more concise for flatness and will have a high-quality surface.

Wall thickness 

Die castings are known for having thin-walled structures that do not have strict rules for the minimum and maximum wall thickness. It is important to create and design uniform walls all around the component, especially the areas where variations can occur. This will make sure the metal flow will be smooth during filling and can also reduce distortions that can occur due to cooling and shrinkage. 

A good mold filling will manufacture parts that have fewer defects and excellent properties. The casting must be designed correctly, so the entire mold fills before solidification occurs. The inability to fill the whole mold can cause cold shuts or poor surface finish in the casting. You can decrease the possibility of cold shuts without sharp or unnecessary corners which can obstruct the melt flow in the mold by using radii. 

If you are interested to know more about SEI Castings’ die casting services, you can contact us through this contact form. You can also request for custom die casting quote. Please let us know if you have any questions or inquiries.

SEI Castings currently offers standard and custom die-cast products using non-ferrous metals like aluminum and zinc. We can customize your orders according to your preferred specifications. If you want to order die cast products from us, please call us at 408-374-1031. Our company is located at 66 First Street #4 Gilroy, CA 95020. Make sure to choose a reputable company like SEI Castings for all your standard and custom die cast products’ needs.