When someone asks me “what is draft angle?” or “why do I need a draft angle on my aluminum die casting part?” The technical answer is, all aluminum die castings require a draft angle on the walls of die cast parts perpendicular to the parting plane or parallel to the slide interfaces. Since I have selling die cast parts for over 10 years, I find simple answers and provide simple calculations for my customers. What does that mean to the typical engineer (any engineer other than tooling or mechanical) or professional buyer?
I try to give examples that most people can relate to, because most people do not have a need to concern themselves with how things are made, only what is made, and will it be what they need. I ask, “Have you ever noticed on a cupcake the bottom diameter is smaller that the top diameter?” or “Have you noticed that a cake pan has sides that slope in toward the middle of the pan?” That would be an extreme example of a draft angle. Aluminum die castings would stick inside the die casting tool, molds, or die casting die if there was not enough draft angle in the tool and part. The typical draft angle for an aluminum die casting part is two degrees per side. The calculation for that is simple if a person is familiar with die casting production part design, but is not familiar to most people.
There are many forms of Die Casting Porosity, many are caused by these die casting variables:
a. Metal Temperatures and Mold Temperatures.
b. Material Cleanliness.
c. Die Casting Mold Design.
d. Die Casting Part Design.
e. Die Casting Machine Pressures.
f. Die Casting Machine Shot Speed.
g. Die Casting Spray or Die Casting Mold Release.
h. Other forms of porosity can be from “shrinkage” or wall thickness.
What is Die Casting Porosity? In order for you to know what die casting porosity is, you need to know the die casting basics. The most common form of Die Casting Porosity is a kind of factory defect in which die cast parts contain small pockets of void space and air within the metal, causing it to become porous. Porosity in Die Casting is the air trapped by the metal inside the die casting parts. To know more, a basic knowledge of the die casting process is necessary. Die casting is a process wherein a particular amount of molten metal is put inside a shot cylinder, then it is applied (plunged) with great force with a piston so as to force the metal into a die cast mold or die cast die. During this “plunging process”, air inside the cylinder is forced along with the metal into the die casting mold. It is a very fluid turbulent process. The air forced into the mold with the metal and the metal already inside the mold is forced out of the mold through a series of gates, vents and overflows.
After this, the metal is left to cool down and harden or freeze inside the mold. The metal is then removed as a die cast part. The same process is repeated over again.
Die casting companies use metals which are non-ferrous, or do not contain Iron, as this is the highest factor for oxidation and rusting. Several examples of non-ferrous metals include zinc, aluminum, lead, magnesium, tin and copper. Sunrise Metal only uses aluminum.
In the worst case, porosity in die casting parts, weakens die casting parts, if the voids or pockets are very large. Porosity typically matters most in pressure tight die casting parts. When the air escapes through a die casting part, it is typically caused by porosity.
Employees of Sunrise Metal are POROSITY EXPERTS in die casting parts that need to be free of porosity.
First, a steel mold capable of producing tens of thousands of castings in rapid succession must be made in at least two sections to permit removal of castings. These sections are mounted securely in a machine and are arranged so that one is stationary (fixed die half) while the other is moveable (injector die half). To begin the casting cycle, the two die halves are clamped tightly together by the die casting machine. Molten metal is injected into the die cavity where it solidifies quickly. The die halves are drawn apart and the casting is ejected. Die casting dies can be simple or complex, having moveable slides, cores, or other sections depending on the complexity of the casting.
The complete cycle of the die casting process is by far the fastest known for producing precise non-ferrous metal parts. This is in marked contrast to sand casting which requires a new sand mold for each casting. While the permanent mold process uses iron or steel molds instead of sand, it is considerably slower, and not as precise as die casting.
The aluminum die casting process makes component parts, decorative trim, and finished products. The die casting process used by Sunrise Metal offers many features, advantages and benefits to those who specify this manufacturing process.
* The die casting process provides complex metallic shapes within closer tolerances than any other mass production processes.
* Die castings are processed at very high rates of production. Near net shape is archived so little or no machining is required.
* Parts produced using the die casting process can be produced with thinner walls than those obtainable by other casting methods.
* Parts produced using the die casting process are much stronger than plastic injection moldings with the same dimensions.
* Parts produced using the die casting process are durable, dimensionally stable, and have the strength, feel, and appearance of quality.
* Die casting dies can produce tens of thousands of identical castings within specified tolerances before additional tooling may be required.
* In parts produced using the die casting process, aluminum castings can be painted with a minimum of surface preparation.
* Parts produced using the die casting process can be produced with surfaces simulating a wide variety of textures.
* Parts produced using the die casting process, “as cast”, are smoother than virtually all other forms of casting.
Holes in parts produced using the die casting process can be cored into a variety of shapes, and made to tap drill sizes.
* External threads on parts produced using the die casting process can be readily die cast.
* Parts produced using the die casting process provide integral fastening elements, such as bosses and studs, which can result in assembly economies.
* Inserts of other metals and some non-metals can be die cast in place with high pullout strength.
* There are different aluminum alloys for different uses.
* Corrosion resistance of parts produced using the die casting process rates from good to high.
* Die castings are monolithic. They combine many functions in one complex shaped part.
* Strength is that of the material, not that of the threads, welds, etc.
* Compare Die Casting Alloys, this chart describes the similarities of the various die casting metals.
Tooling: Dies and Molds for Die Casting
Die cast tooling called insert die, die casting dies, or die casting molds, comes in one part each cycle. Sunrise Metal only uses cold chamber die casting machine tooling styles, sizes, and values. Die cast tooling comes in single cavities (one part each cycle) or multiple cavities (more than es or molds for aluminum die cast parts).
Die cast tooling comes in various forms:
1) Die Cast Tooling Inserts
2) Prototype Die Cast Tooling Inserts
3) Unit Die Tooling
4) Complete Class “A” Die Cast Die or Mold Tooling
5) Die Cast Family Mold Tooling
6) Trim Dies for Die Cast Parts
Our In-House Die Cast Tooling Capabiities include:
a. Die casting dies.
b. Die casting molds.
c. Die casting inserts.
d. Die cast tooling modifications.
e. Die cast tooling repairs.
f. Diecast tooling and trim die manufacture.
Die casting is a manufacturing process for producing accurately dimensioned, sharply defined, smooth or textured-surface metal parts. It is accomplished by forcing molten metal under high pressure into reusable metal dies. The process is often described as the shortest distance between raw material and finished photo. The term, “die casting,” is also used to describe the finished part. The term “gravity die casting” refers to castings made in metal molds under a gravity head. It is known as permanent mold casting in the U.S.A. and Canada. What we call “die casting” here is know as “pressure die casting” in Europe.
Bringing Designs to Life With more than 10 years’ experience, Sunrise Metal has been dedicated to providing one-stop aluminum manufacturing solutions, integrated superior rapid prototyping, tooling and die casting, along with CNC machining and surface finishing through state of the art machinery and processes . We bring your designs to life one stop here at Sunrise Metal with quality and reliability by professional and fast way.
If you got any questions, please do not hesitate to send us a message. We reply within 24 hours.