Die-casting mold – How To Design A Die-Casting Mold

In modern manufacturing industries where molten alloys are fashioned into intricate metal parts through die-casting services. The die-casting mold stands as a central element in the process. This mold facilitates the mass production of metal parts, with its attributes directly impacting the final product design. 

A complete understanding of the die-casting mold process will facilitate you in designing and selecting the appropriate mold for your die-casting needs. Let’s understand the important aspects of die-casting mold, its designs, types, and advantages.

What is die-casting mold?

The die-casting entails the mold cavity which structures the dimensions and contours of casting. The molten metal alloy is injected into the molds under high pressure; afterward, mold specifications will ensure the results. They are extensively used in various industries for instance aerospace, consumer goods, automotive and electronics etc.  

The strength-to-weight ratio, rapid cycle times, consistent surfaces, and shape adaptability are the advantages that make die casting an idolized manufacturing method. 

What is aluminum mold die-casting?

Aluminum die-casting molds or dies are diligent for the manufacturing of aluminum parts. These molds have a higher melting temperature and strength than aluminium or else there will be technical damage during the casting process. The aluminum die-casting molds are relatively expensive.

Die-cast Aluminum mold

What is High-pressure die-casting mold?

In High-pressure die casting (HPDC) mold, high speed, and pressure are the key features. In this process, the molten metal is poured into the casting machine’s pressure chamber. The cavity of die casting mold gets quickly filled and molten metal hardened due to high pressure (up to 20 MPa). The preliminary filling speed is between (0.5~70) m/s. A quantity of high-quality casts can be produced in a short period using high-pressure die-casting molds. It is highly economical and cost-effective when it comes to die-casting projects.

Stages involved in designing die-casting molds:

There are a few meticulous steps in creating a die-casting mold design are outlined below.

1- Design and specification:

The engineers contemplate the final product and create detailed designs with its typical specifications. This includes comprehension of tolerance, geometry, and complexity of the final component. The involvement of CAD formats plays an important part in 3D model creation that binds with industrial standards and intended product requirements.

2- Tooling and mold base preparation:

After design finalization, there comes the second process of tooling and mold base preparation. The mold components such as the mold core and die cavity are carefully crafted by experienced toolmakers by harnessing the high-grade materials competent enough to tolerate high pressure and temperature.

3-  Mold assembly and finishing:

It is the central process of die-casting mold design which encompasses careful aligning, securing, and fitting of multiple parts altogether. This detailed stage ensures precise cooling and venting to integrate slides and pins that ease final part ejection. Surface treatments and finishing treatments are appropriate to prevent corrosion, prolong durability, and smooth operationality.     

4- Testing and validation:

It is imperative to meticulously test the mold before putting it into full-scale production. To analyze mold’s quality, integrity, and functionality, multiple trials are regulated. After testing there might be some more fine tunings and adjustments needed to improve the consistency of the mold.   

5-  Production and maintenance:

Now the mold is ready for stationing in the production process after thorough testing and validation. Once the mold is fitted the molten metal is fed under high pressure into a mold cavity. After solidification, the produced component qualities are checked. The operationability and longevity of the mold are at the hands of routine maintenance which indirectly preserves the quality of manufactured components.  

Die-casting mold parts:

There are multiple parts of die-casting mold with different specifications and functions. The chief parts of the die-casting molding are cited below:

Cover Die: The cover die inholds a shot hole for cold chamber or sprue for hot chamber machines. The basic purpose of a cover die is, to allowances of molten metal into the die.  

Ejector Pin: In die-casting machines, the ejector pins allow the removal of die-casted components. They should be correctly positioned to regulate the consistent removal.

Runner: It allows or maintains the molten metal flow from the nozzle to the cavity. The pressure is adjusted with the change in viscosity. When there is less thickness, the pressure is increased, and vice versa.

Sprue: The sprue bridges the injection unit of the molding machine to the mold cavity. It plays a significant role in injection molding where it allows the removal of excessive material.

Cavity Insert: Cavity inserts are usually manufactured from steel. It shapes the exterior of the die-casting components. It is the mold’s external part and is movable.

Ejector Plate: Ejector plate drives the ejection pins during casting removal. All the pins are moved with the same force and retracted after ejecting for the next shot preparation.  

The above-mentioned are the typical die-casting mold parts. Despite that, some custom molds such as china die-cast molds contain additional components as well according to the design requirement.

Metals used in preparation of die-cast molds:

Certain metals are commonly used in die-casting mold preparation. The specific

Properties and applications are discussed below;

Table: Different metals for preparing die-cast molds and their specifications & applications

Sr. No Metals Specification Applications
1. Aluminum Al-Si alloys, good thermal conductivity, low melting point Automotive parts, aerospace components
2. Steel Tool steel, high hardness, wear resistance Die casting, injection molding
3. Copper High thermal conductivity, excellent machinability Die-casting, jewellery-making
4. Zinc High fluidity, low melting point Automotive parts, electronic housings
5. Magnesium Lightweight, good strength-to-weight ratio Automotive, aerospace components

Different types of die-casting molds:

Depending upon the purpose there are four types of die-casting molds. These are;

Production dyes: 

As the name indicates, the production dyes are employed for large-scale production. The material used for manufacturing these dyes is durable and of high quality to prolong the shelf life. Therefore, its initial tooling cost is much higher but compensated for long-term use.

Prototyping dyes:

The function and tooling process is like production dyes, although the simplified features and machining minimize the tooling cost. The prototyping approaches are 3D printed parts, gravity casting, and machine hog outs. The produced prototype will not be good and efficient as compared to the production dyes. Prototyping dyes can be a good option when it comes to small production needs.

Unit dyes:

These dyes are only used for die-casting smaller machinery parts and are much cost effective. They are very handy due to the function of removable dies known as die inserts which can be easily replaced for different part manufacturing. Unit dyes are typically appropriated for parts requiring maximum efficiency and control.

Trim dyes:  

Trim dyes are used in finishing of die casting components for instance removing risers, sprue, flash, and runners. It comes in handy when there are high production volumes. Moreover, sometimes they require hydraulic operated cams for deceptively removing flashes. Whereas, hand de-flashing is the alternative where there is a complexion in part geometry.   

Maintenance techniques of die-casting mold:

The working efficiency and lifespan of the die-cast molds can be increased by appropriate maintenance. Mostly these molds or dyes are expensive so they should be handled carefully. Below listed are some considerations that you should follow:

Mold clean up: It is imperative to remove the residues, dust, and debris from the mold occasionally. You can use compressed air, wire brush, and mild solvent to clean the mold. 

Inspect for damages: The mold should be observed for cracks, wear or tear. In case of damage, the mold should be repaired on an immediate basis to halt further damage.  

Mold lubrications: Formal lubrication of the mold is necessary for smooth functionality. The lubricant should be smeared evenly and thinly.  

Worn parts substitution: Certain parts of the die-casting molds wore out faster due to repeated use. The replacement of these parts should be done to avoid deteriorating the final quality of the product.

Monitoring mold temperature: The characteristics of the final products indirectly depend upon the mold temperature during die casting. The absolute temperature of the casting material can be maintained through heater or cooling channels.   

Advantages of die-casting molds:

Die-casting mold has plenty of benefits, although it requires certain expertise in its design. A few of the merits are discussed below.

  • Efficient part configuration.
  • Hundreds to thousands of parts can be produced from a single mold.
  • High dimensional accuracy.
  • Can bear high temperature and pressure.
  • Speedy and uniform solidification and cooling.
  • Less production cost for large-scale production.
  • Due to high pressure, proper fluid filling.
  • Parts produced entail high tolerance.
  • Prime finishing quality of the produced component.

Conclusion:

In conclusion, molds are the principal constituents of the die casting process. In designing a die-casting mold, each stage demands diligent evaluation, consideration, and management to guarantee superior quality die-casting mold manufacturing. Additionally, the appropriate maintenance of die-casting molds will ensure shelf life and work efficiency. It allows the manufacturing of intricate parts with repeatability and accuracy. 

With the significant demand for corrosion-free, lightweight, and strong parts, the die-casting mold is extensively serving multiple industries including aerospace, automotive, medical, and electronics.