Die casting is a manufacturing process for creating metal parts often used in many industries such as automobiles, models, appliances, and more. But why? Why do these industries use die casting instead of other methods? This blog post will answer a part of this question: how accurate and precise diecasting is?
Diecasting is accurate because it has the capability to produce products that have thinner walls, closer dimensions, and smoother surfaces. Furthermore, it can generate complicated geometries and shapes that are impossible or difficult to produce on regular metallurgy techniques. Lastly, diecasting is capable of large-scale production due to its high precision.
This blog post will talk about how accurate diecasting is, what are the features and technologies that make it accurate, and the pros and cons of diecasting.
Is diecasting accurate?
Die casting is a metal casting procedure where molten metal is poured into a mold and cooled.
Using this technology, you may make precision metal pieces with a flawless polish.
Diecasting is ideal for mass production products because of its capacity to generate detailed and accurate parts.
Die castings are produced from non-ferrous metals like zinc, aluminum, copper, lead, magnesium, tin, and pewter.
Die casting can be done in two ways: hot chambering and cold chambering.
The particular metal and component define the processing method. For example, aluminum, brass, and copper alloys have high melting points and are good fits for cold chamber techniques.
Zinc, lead, and magnesium alloys are the only metals used in hot chamber die casting.
Compared to plastic molding, die casting generates more stable and long-lasting items because of their higher strength and closer tolerances.
In addition, diecast components are more heat resistant and have better electrical characteristics than other types of metal castings.
With die casting, you get thinner walls, closer dimensions, and smoother surfaces than with sand casting.
Labor costs per cast are reduced as a result of speedier production times. Finishing costs are also reduced.
For the same reasons that die casting has advantages over permanent molding, it also has advantages over sand casting.
Instead of forging, die casting creates more complicated shapes with tighter tolerances, thinner walls, and less expensive in the final stages of finishing. Forging does not provide the option of cast coring holes.
The advantages of die casting over traditional metal stamping include creating more complicated shapes with more flexibility in section thickness.
As a result, assembly time can be shortened by using a single casting instead of numerous stampings.
As opposed to screw machines, die casting generates geometries that are impossible or difficult to produce from bar or tube stock while maintaining tolerances without tooling changes.
Moreover, die casting saves time and money because it eliminates scrap and wastage.
For a comparison between diecasting and regular casting, feel free to check this blog post: Casting vs. Diecasting.
Why is diecasting accurate?
Diecasting is accurate because of the technology involved in the process, such as its geometric features such as parting lines, filet radii, ribs, and holes. Furthermore, it has a variety of techniques that can be used, such as gravity diecasting and vacuum-assisted diecasting.
Below, I explained each of these geometric features and techniques used that make diecasting accurate.
Geometric features of Diecasting
The geometry employed in the die casting process determines how well a part fills and cools.
In addition, the metal used in the process determines the grain structure and stress level. The following are some geometric features used in the die casting process:
The drafting refers to an angle that is dependent on the wall and surface type.
It also depends on the depth of the surface and the type of metal used. The angle is determined using a mathematical formula.
Filet radii strengthen a component by redistributing stress concentration at sharp internal corners over the larger volume of the filet, reducing weak areas.
That keeps cracks from developing during straightening.
The parting line determines the inside and outside surfaces of the die and which side of the die is the ejector and which is the cover.
Bosses serve as mounting points and standoffs, and they are intended to keep regular wall thicknesses to terminate post-casting machining.
Ribs in diecasting aids in filling all regions of the die casting with molten metal. These offer a route for molten metal and make ejection easier and faster.
Holes and windows
Holes and windows need the most drafting because they connect with the surface of the die, causing erection harder and perhaps blocking the smooth flow of molten metal.
Variants to Diecasting
Next are Variants in the diecasting process that helps them produce items with accuracy and precision.
The variations detailed below were formulated to overcome defects, mistakes, deformities, and other problems encountered during die casting procedures.
Pore free diecasting
The die cavity is filled with oxygen before injecting or pouring molten metal.
When the heated metal goes to the cavity, oxygen interacts with it, preventing gas bubbles and removing trapped gas pores.
It is an abbreviation for accurate, reliable, and dense. It incorporates steady fill and directional solidification to produce short cycle durations.
Thermal analysis, flow and fill modeling, heat-treatable castings, and indirect squeezing are all part of this process. When the shot is partially formed, double pistons increase the pressure.
In gravity-assisted diecasting, molten metal enters straight into a permanent die, causing turbulence, oxidation, and foaming.
The die can be usually oriented, horizontally, or slanted. As a result, the parts are of excellent quality, strength, mechanical properties, and sturdiness.
Investment casting, also known as lost wax casting, is a labor-intensive method that involves forming the mold from a wax prototype immersed in liquid ceramic.
The wax melts when the pottery solidifies. The ceramic cavity is filled with molten metal and the ceramic mold is torn out and the metal casting is taken away after it has solidified.
Vacuum-assisted high pressure diecasting.
The die is housed in an airtight container. The molten metal is drawn into the die cavity by pressure, where it hardens and is ejected.
In a semi-solid or slurry state, semi-solid metal is spun, poured, and driven under pressure into the mold cavity via a short sleeve.
The parts are characterized by superb surface finishes, close dimensional tolerances, and a fine microstructure.
Low pressure diecasting
The chamber containing the molten metal is located beneath the die. It is pumped into the die chamber through an intake port. The pressure is kept at a constant level until molten metal solidifies.
What are the advantages and disadvantages of die casting?
The main advantage of diecasting is its accuracy. Diecasts are very precise and accurate due to numerous technologies employed in the process. That means it can recreate any design with the smallest details with ease. However, the main disadvantage of diecasting is its price since the process requires a specialized machine.
Advantages of Diecasting:
- Diecasting’s dimensional precision is brilliant. Dimensional accuracy is usually 0.1 mm for the first 2.5 cm and 0.02 mm for each extra cm.
- Diecasting produces surface finishes ranging from 1 to 25 μm.
- Diecasting molds are capable of producing 200 to 300 products per hour. It may reach thousands of components with tiny parts.
- Diecasting can recreate any design with the smallest details using thin walls and structures.
- Threaded inserts, bearings, and add-ons are simple to incorporate with diecasts.
- Diecasting offers tensile strengths of the parts are 60,000 psi or 415 MPa.
- Diecasting can employ hydraulic and pneumatic devices to increase efficiency and save costs.
- Diecasting produces intricate pieces with extremely close tolerances.
Disadvantages of Diecasting:
- When compared to other casting processes, die casting is pretty expensive. It requires the use of a specialized casting machine, which is both expensive to purchase and maintain. Manufacturing businesses can save money by casting in zinc, however, die casting is still a costly casting method.
- Die casting also has weight requirements that the castings must meet. A typical casting, for example, may require a weight ranging from 1 ounce to 15 pounds. If the casting weighs more or less, it has a flaw.
What’s next? The main disadvantage of diecasting is its price because it requires a specialized machine. However, the question remains, how much is diecasting, particularly the machine and ingots? You can find the answer in my other blog post here: Is diecasting cheap or expensive?