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  • What is a Foundry
    Jun 23, 2022
    Human beings left the Stone Age behind roughly 4,000 years ago when the Bronze Age began, although some foundries go back even further. The team at Cast Technologies takes great pride in coming from a long line of skilled craftsmen that reaches back to the ancient world. We are today using processes based on the same principles as those used by our ancient ancestors to radically change and modernize the world. While people might think of things like electricity, the printing press and computers as the building blocks of the contemporary world, the truth is our way of life rests to a very large degree on the work of foundries: Automotive, air travel and energy production are just three industries that heavily depend on cast items. You depend on multiple cast items every day of your life. Naturally, modern foundries bear little resemblance to the primitive technologies that man invented to make weapons and tools from simple bronze alloys, but the ideas are much the same: Melt a mixture of metals together and pour the liquid into some kind of mold. Making a bronze spearhead uses much the same technology still used for making parts for a power generator. The ancients made things like weapons and plows, allowing them to put aside their more primitive stone tools. Today, foundries make an almost infinite number of items we rely on in modern life, including car engines, pipes, chains, aircraft parts, tools and many other metal components. Of course, foundries today aren’t limited to bronze, but can cast countless metal alloys depending on the characteristics required by the finished item.    How Has Foundry Technology Changed? Foundries have evolved considerably, thanks to advances in technology and the science of metallurgy. Initially, charcoal fires were used to power little furnaces hot enough to melt metal, but now gas or electric heat are used to power more advanced furnaces.  Early foundries were a dangerous work environment, but modernization and mechanization have made them much less hazardous. For example, pouring molten metals into molds via a robot or other automated equipment is much safer than pouring by hand using a ladle.  Another change in foundries involves the methods used to placing the molten metals into molds. Traditional gravity pours are still used, but there are other methods available now, including vacuum or pressurized gas pours.   A Simple Explanation of the Foundry Process Imagine you are living a few thousand years ago and you wanted to cast a simple item, such as a flat disk, in metal. The easiest method would be something called sand casting. You might start by carving something called a pattern from wood. Once you had your desired shape just as you wanted it, you could sink it into a sandpit and then — very carefully! — you would remove your wooden model from the sand. Done right, this would leave a perfect impression of your wooden model in the sand.  Next, you would prepare your metal according to the characteristics you wanted your finished item to have. Perhaps you’d follow the ancient recipe of one part tin to nine parts copper. You’d need a small furnace, a clay melting pot and of course a hot charcoal fire for melting. Yes, primitive charcoal-fired furnaces can indeed get hot enough to melt copper and tin together, although it’s much easier to achieve the necessary temperatures in a modern foundry. Once your metals had melted together, you’d carefully pour your mixture into the sand cavity and let the metal cool. Finally, you’d remove the solidified metal disk from the sand. If all went well, you’d have a perfect metal copy of your wooden disk. Now let’s imagine you wanted to make a more complex casting. You might want to make your item in two different sections, a top and bottom. This is called a split pattern, and the upper section is called the cope, while the bottom section is called the drag.  Even more complex designs can be made using something called a core. The core is inserted into the mold to create a hollow area.  Now imagine you needed your item to have a smoother finish. You could smooth it out by sanding or grinding. Today, you might sandblast the surface, sand it or machine it smooth with a grinder. This same general process is used in making everything from the simplest tiny items, such as jewelry, to the most complex and large parts weighing hundreds of pounds, such as wind turbine blades. After the item comes out of the mold, further processes may be used if necessary. Cast Technologies has an on-site machine shop to add the finishing touches to any component.
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  • Advantages and Disadvantages of Casting Pattern Classes Types
    Jun 23, 2022
    The table shows the advantages and disadvantages of the different classes of pattern equipment used by sand casting process.   Pattern Type Advantages Disadvantages Wood Loose Low cost to produce. Use to produce plastic patterns. Easily modified. Not suitable for production batches unless converted into plastic before becoming worn. Tend to become inaccurate and to produce poor surface finish. Hardwood Inexpensive for small-batch production. Can be used as masters for plastic patterns. Fairly easily modified but expensive if multiple impressions involved. Fair wearing properties. With care, will remain reasonably accurate over fairly long periods. Not suitable for high-volume production. Plastic Inexpensive to produce. Urethane technology provides good wearing properties and accuracy. Easily modified depending upon the materials used. Suitable for high-volume production patterns with the same dimensional tolerances as metal patterns. Urethane technology has reduced many of the disadvantages of early plastic pattern materials. Metal Excellent wearing properties. High standard of accuracy and stability. Suitable for high-volume production and shell molding. CAD/CAM improvements are greatly reducing cost and lead time requirements. Costly. Difficult to modify. Equipment is less adaptable for movement from one foundry to another.
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  • Casting Competition: Sand Castings vs. Permanent Mold Castings
    Jul 22, 2022
    Sand castings or permanent mold castings? Since we offer both casting processes here at Hengchang Foundry, we often get posed this question. What is the difference between these two casting processes and which one is better suited for your application? Let’s clear up the casting confusion with a cursory overview. Sand Castings: A one-time sand mold is produced, which may contain one or more impressions of the part. Molten metal is poured into the sand mold, then following solidification and cooling, the sand is broken away and the casting is removed. In most cases, the sand is recycled and reused. So when is sand casting the appropriate method? When the production is suited for low and high volumes, the process is driven by material and mechanical casting property requirements, only moderate surface finishes and dimensional tolerances are needed, low tooling costs are needed, and when size and configurations dictate that the part can only be made as a sand casting. There are additional considerations that may have to be taken into account, and it is recommended that the user consult with the foundry prior to finalizing part design. Permanent Mold Castings: Unlike a sand casting, the mold is made from cast iron or steel, allowing for one or more cavities depending on the geometry of the part. The process is best suited for mid to higher volumes, when the part configuration dictates this type of casting, or the process is best suited for the application of the casting. The molds are in, most cases, fully CNC machined with the parting surfaces aligned with a locking system that provides good repeatable casting dimension conditions. When compared to sand castings, permanent mold castings have improved surface finishes, less machining allowances required, and closer net shaped profiles which are made possible by the metal mold configurations. Unlike sand castings, however, permanent mold castings are limited in size and the tooling proves to be more expensive (though part price tends to be lower!). Again, consult with a foundry to determine the right process for your needs! Do you better understand the difference between sand castings and permanent mold castings? Have you decided which is better for your specific applications? See our website for more information on.
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  • Investment Casting vs. Sand Casting — What’s the Difference?
    Jul 22, 2022
    Several casting methods exist for producing the machine parts required for industrial manufacturing processes, including sand and investment casting . Here, we will explore some key similarities and differences between the two.  Sand Casting Process  Metalworkers widely use sand casting technology because it is suitable for casting steel, iron, brass, and most nonferrous alloys—as well as for final products that weigh anywhere from less than a pound to thousands of pounds. The sand casting process begins with creating a sand mold. In a traditional foundry, after making the desired pattern or model of the final product from hardwood, urethane, or foam, sand is compacted around it to form the mold. In order to maintain its shape, the sand is initially treated with a bonding agent known as binder, which improves adhesion between its particles. The pattern is then removed by splitting the sand mold apart into two or more sections. These sections are then bound to receive the molten metal through a delivery system referred to as the gating system. After the metal sufficiently cools and solidifies, the final product is recovered by removing the sand through a shake-out process. Advantages of Sand Casting  Some key benefits of sand casting are outlined below: Low operational costs Can cast ferrous and nonferrous materials Suitable for casting large parts Relatively easy to change the design of the mold Fast lead time  Investment Casting Process Also known as lost wax casting, investment casting technology is reliable for complex and detailed components. Metalworkers use it to create a final product with a near-net shape, leading to lesser material, machining, and labor costs compared to other forms of metal casting.  The investment casting method begins with molding wax into the desired cast and coating it with refractory material, such as ceramic. Applying heat melts out the wax, leaving an empty shell with the void to be filled shaped in the geometry desired. Molten metal is then introduced into this pre-heated shell. As soon as it suitably cools and solidifies, it is recovered by shattering the shell.  Advantages of Investment Casting  Some major advantages of employing investment casting include: Capable of casting ferrous and nonferrous materials  High levels of accuracy  Can cast thin-walled products with complex designs  Smooth surface finishing  Lesser need for extra machining and finishing   Investment Casting vs. Sand Casting Comparison Both investment and sand casting have experienced significant improvements over the years—geared at minimizing the quantity of metal used and reducing extensive finishing and machining requirements. Although they are similar in some ways, some notable differences exist between them.  Similarities A few similarities between both casting methods include: They can both cast ferrous and nonferrous materials  Metalworkers shatter the molds to recover the finished product in both methods They both require a molten metal delivery system   Differences There are some fundamental differences between investment and sand casting, including: Casting time Quality of appearance Materials Design Dimensional tolerance Range of products Mass production   Casting Time The molding cycle for sand casting is short, while the investment casting process takes longer. Quality of Appearance The final product from sand casting is usually rough depending on the sand used. Other defects include clip sand, sand wash, and gas holes. Meanwhile, products from investment casting are significantly smoother. Materials Materials needed for investment casting, such as paraffin wax, sodium silicate, etc., cost more than those required for sand casting (sand, binder, etc.). Sand casting is relatively cheaper. Design Metalworkers can achieve more complex designs with investment casting, while sand casting may require extra tapering and machining to achieve the desired geometry. Sand casting patterns are more cost effective and require much less time to modify than the tooling required to manufacture investment castings, if design changes are required during a production run. Dimensional Tolerance With the high dimensional tolerance of investment casting (CT 4-6), finished parts can have thin walls, while finished parts from sand casting have a minimum wall thickness of 3 to 5mm because of their lower-dimensional tolerance (CT 10-13). Range of Products The adaptability of sand casting is broad, and as a result, it can be used for a wide range of castings, including ductile iron, grey iron, steel, aluminum, etc. Although investment casting can be used for other metallurgies, they are generally suitable for steel castings. Mass Production  Since investment casting can ensure consistency, it is suitable for mass production. Sand casting, however, cannot promise such consistency. Hence, mass-producing finished parts are more challenging using sand casting methods. Which Method Is Right For You? Knowing the appropriate method requires you to put some factors into perspective. Different materials are well suited for different products. Therefore, you must know the materials suitable for your product since it can help you determine the better-suited casting method. You must also consider the possibility of mass production and that each casting method requires different cycle times to inform your decision. Additionally, the overall casting cost must be considered. Ultimately, it is up to you to select the method which overall casting benefits for your project or application.  
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