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Heat treatment is the controlled process of heating and cooling materials to improve their properties, properties and strength. Most metals and alloys are heat treated in one way or another, and the understanding and science of heat treatment has evolved over the past 100 to 125 years. The importance of heat treatment is evident in many products in the automotive, aerospace, construction, agriculture, mining and consumer goods industries, all of which use heat treatment to improve the properties of materials, especially steel.
Heat treatment adds about $15 billion in value to metal products each year, about 80 percent of which is steel.
Heat treatment is a manufacturing process in which a material (usually a metal or alloy) is altered by cycles of heating and cooling under complex thermal boundary conditions and a wide temperature range. Heat treatment defines the quality of the product in terms of microstructure, mechanical properties, residual stress and dimensional accuracy [3].
Heat Treatment Basics
The heat treatment process can be used for ferrous metals such as cast iron, AHSS, stainless steel and other alloy steels, as well as non-ferrous metals such as aluminum, magnesium, titanium, copper or brass [2].
The heat treatment process requires the following three main steps [2]:
Heating materials to specific temperatures (ranging up to 2400 °F / 1316 °C)
Soak or hold at a specific temperature for a period of time (ranging from a few seconds to over 60 hours)
Cool at an appropriate rate according to the prescribed method. Materials can be cooled quickly, slowly (in a furnace), or quenched (using water, brine, oil, polymer solutions, salt, or gas).
What is Precision casting?
Investment casting, also known as investment casting, is a lost wax casting process widely used to produce ferrous and non-ferrous metal parts. Unlike other casting processes, precision casting produces net shape parts with excellent surface finish and dimensional accuracy. This manufacturing process is ideal for applications with relatively low volumes (100 to 10,000 pieces) or rapidly changing product designs.
Through precision casting, we can cast nearly 200 alloys. These metals range from ferrous metals (stainless steel, tool steel, carbon steel and ductile iron) to non-ferrous metals (aluminum, copper and brass). When casting in vacuum, super alloys can also be used. The only process that matches the breadth of this material is machining, but it cannot produce the complex geometries that precision casting can provide.
Because precision casting uses consumable molds and ceramic housings, it is ideal for complex and detailed part designs. The process makes complex parts that are difficult, if not impossible, to machine, forge or cast. Examples include internal passages and ports in valve bodies, curved vanes in impellers, and internal cooling passages in turbine blades. A key obstacle to prototyping and short-run production is injection mold time and cost. Every precision casting requires a wax pattern, which is injection molded. As design complexity increases, tools often become too expensive and time-consuming to make prototyping and low-volume production practical.
The benefits of precision casting
Precision casting and sand casting
Sand casting is a casting process in which a casting cavity is formed by sand, and the sand shell produces a rough shape. Usually the tolerance of sand casting is CT8-CT9, and the surface finish is around Ra250. Therefore, for sand cast products, rough surfaces may require more machining operations than investment castings.
Precision casting creates the desired shape with a ceramic shell and can produce a product with a better surface finish. We can meet tight tolerances CT5-6 as precisely as possible, reducing net shape and possibly avoiding further processing.
Precision Casting and Machining
For some products with simple shapes and simple shapes, we can choose precision casting or machining. Machining is the process of machining a part directly from bar to final size. This will cause a lot of waste of raw materials, which will increase the production cost. In addition, if the quantity is large, single-piece production increases the production time, thus delaying the delivery time.
Precision casting makes the product expensive for further processing. CFS Foundry has both a foundry and a machine shop. We can provide machined precision castings at the best price, while allowing our customers to receive a product that performs well, ready to use.
Precision casting and precision forging
Precision forging is a metal forming process in which hot or cold metal bars are pressed directly into shape. In order to withstand high pressure, there are high requirements on the material of the forging die. The commonly used material for forging dies is tool die, and its cost is quite high. The high cost of tooling makes the precision forging process less competitive than precision casting. Precision forging also has regional control over the shape of the product.
In contrast, precision casting requires less mold cost and has no restrictions on the size of the product. This makes our company available for all metal products.
Precision Casting and Metal Fabrication
Metal fabrication is the process of cutting and bending sheet metal into different shapes and thicknesses and welding them together to form a product. This will cost more labor costs and production time.
Precision casting can greatly reduce production time by connecting multiple wax patterns to a gate or system.
For more than half a century, Ermak has been mastering and perfecting the art of sand casting. Sand casting is a common method for producing non-ferrous alloy castings. The process was invented over 6,000 years ago and continues to be modernized. There are three types of sand for casting: wet sand, water glass or water glass or sodium silicate and resin sand.
Sand Casting Sand TypesSand Casting Sand Types
1. Green Sand
Green sand castings are formed using a sand mold formed from green sand, which contains water and an organic binding compound, also known as clay. The term "green sand" means that the sand does not "set," "green," or "unset" when the metal is poured into the mold. Because sand can be reused, casting sand from wet sand is simple and inexpensive. The downside is that sand is a soft mold and can collapse or shift during casting.
2. Water glass or sodium silicate
Sodium silicate can be used to make sand castings. This process is beneficial in sand casting where cavities are required. Carbon dioxide can be rapidly changed from liquid to solid by passing carbon dioxide through sodium silicate. This results in dehydration of the sodium silicate. Sodium silicate must be mixed with other materials in order to remove the core during product decomposition. If the mixture is not correct, the core will get stuck inside the casting.
3. Resin sand
The modeling material of resin sand casting is a mixture of quartz sand and resin sand. When resin sand is mixed and heated, it hardens into a strong, smooth mold. Stronger molds produce fewer defective castings, but are more expensive and slower to produce. Resin sand molds take longer to make because each must be mixed and fired individually.
Investment casting is also known as investment casting or lost wax casting. The process dates back more than 5,000 years and has been used to make small pieces for centuries. Today, this type of casting is seen as the future by many industries looking for lightweight and complex components.
In an investment foundry, it all starts with the production of a wax model or pattern, which is created in the shape of the desired part. However, when time is short, 3D printing can also be used to make models, allowing for quicker rapid prototyping castings. Wax molds are usually made by infusing wax into metal tools or dyes. These patterns are attached to the wax tree, also known as gates, and are used in the mold making process.
The wax model is then dipped or dropped into a liquid ceramic grout, and fine sand or plaster is then applied to the damp surface. Let the mold dry and repeat the process several times, resulting in a layered ceramic mold.
Before pouring the metal into the mold. The wax is removed using a flash furnace, which melts and burns the wax away. The mold is then preheated to a specific temperature to prevent the liquid metal from solidifying before the entire mold is filled.
The alloy is melted in a ceramic crucible using a process called induction and resistance melting. When the alloy reaches its specified temperature, it is poured into a mold and allowed to cool. Once the casing material removed from the metal is cooled, this is usually done using a hammer or high pressure water jet. The part is removed from the gate, and the gate is removed from the part. The surface can then be finished using belt grinding or polishing.
The process produces complex, high-precision parts with excellent as-cast surface finishes, often reducing or even eliminating machining requirements. This is often the only way parts can be manufactured economically.
Advantages of investment casting
This method is ideal for making small complex geometries with complex features from one mold.
Investment casting is widely used. Because you can combine multiple wax patterns to create a unique mold, you can configure parts that cannot be made with machines or tools, making it a valuable alternative to weldments.
Dimensional accuracy and finish are other advantages of this casting method. The casters form a ceramic shell around an even pattern that leaves no parting lines because only one mold makes the casting, not two. The result is a smooth finish with an average finish of about 125 microns, but post-processing smoothing can achieve a finer finish if necessary.
Other advantages of investment casting include:
Reusable material: Design engineers can reuse melted wax for another pattern. Because of the strength of the mold, they can also reuse the mold.
Tight tolerances: Investment casting has a tolerance of 0.003 inches, which is tighter than most casting processes such as die casting.
Design Capability: Investment casting allows design engineers to incorporate identifying marks such as numbers, logos and product IDs into castings.
Disadvantages of investment casting
Despite its beneficial properties, lost wax casting does have its drawbacks. The biggest downside is the size limit. Since few design engineers can use this technique to produce large parts, it may not be the best option for customers who need to manufacture bulky assemblies.
This process is best suited for casting small complex parts. Parts over 75 lbs are better suited for other casting methods.
Investment casting shells are also limited in size and depth. They cannot be smaller than 1.6 mm or deeper than 1.5 times the diameter. If your casting design requires a core and cannot meet these requirements, you may need to seek other processes.
This technique is more complex than other casting processes and requires extensive preparation work and specialized equipment. Therefore, the upfront cost of investment casting may be higher than sand casting or die casting, but the unit production cost will decrease as the order increases.