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About the patterns of Sand Casting

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Sand casting involves various processes that include patterns, sprues and runners, casting allowance and design selection. Out of these processes, patterns find immense importance as it is the deciding factor of the final appearance of the finished product. While casting, molten metal is poured into a mold cavity fabricated from sand ( synthetic and natural). Herein, the cavity is developed by using a pattern, a replica of the real part, made from wood or metal. It is an aggregate kept in box called flask. Further, a sand shaped body, core is inserted inside the mold that develops the internal features of the part like internal passages or holes. Desired shapes can be formed by placing the cores into cavity. Core also decides the volume or location in a casting where metal will not pour into. The write-up below will surely help you to get the clear picture of the patterns:

What is pattern?

A pattern is an exact replica of the object that is required to be casted, and is utilized to form cavity in which molten material will pured in during the casting process. There are basically three types of patterns namely;

Master Pattern: It is the primary design that are used for actual production.

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Production Pattern: From which the original castings are produced.

Permanent Pattern: It is the master pattern that is utilized as final or permanent pattern to reproduce production pattern.

Patterns of Sand Casting

In sand casting, patterns used are made out of metal, wood, plastic, and so forth. These patterns meet the specific standard of construction, that also assure durability and dimensional accuracy. Sometimes, according to the demand, an original item can also be adapted to used as a pattern.

Making of Patterns

Making of patterns is known as pattern-making or styled pattern-making. This work is also related to tool and die making or mold making incorporating the refinement of woodworking. Pattern makers learn this skill through apprenticeships and trade schools over many years of practice. Pattern-making also requires the supervision and guidance of engineers. The processes involved in the pattern making include certain allowances such as:

Contraction Allowances

Pattern requires appropriate allowance for shrinkage wherein there exact value depends on the alloy being casted and the precise sand casting method followed. The linear shrinkage can be up to 2.5% though enlarged sizes can also be witnessed sometimes.

Draft Allowances

There is scope for draft allowance, which means that while pulling out the casting from the sand, edges can be tapered up to 1 and 3 degrees.

Sprues, Gates, Risers, Cores, and Chills

Placement of Sprues, gates, risers, cores, and chills are also decided by the foundry designers in respect to the pattern.

Demand

Patterns are widely required for sand casting of metals including production of ductile iron, gray iron, and steel casting. The precise process and pattern equipment is decided by the order punctualities as well as casting design.

Sand casting is the widely used process that can develop minimum as one and maximum as a million copies. Herein, patterns will remain the vital part of its process.

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The problems with iron foundries in China

The iron foundries are also known as iron casting workshops, which manufacture iron and steel castings. Many overseas buyers and purchasers always try to find the suitable iron foundries in China, so they can buy good iron castings from them. However, they do not know there are many problems with those foundries.

As my years experiences in Dandong Ruiding Foundry, I sort the iron foundries in China to four types. The first type: Large foundries. These foundries own over three automatic molding lines, and can produce over 10000 tons iron castings per year. The second type: Middle foundries. These foundries own one or two automatic molding lines, and other casting processes, such as resin sand, manual green sand etc. The annual production is from 3000 tons to 10000 tons. The third type: Small foundries. These foundries do not have automatic molding lines, but have some molding machines or just manual green sand casting process. The fourth type: specific foundries. These foundries just produce one or two specific products.

What are the problems with these foundries?

As for the large foundries, since they have many auto molding lines, so their production efficiency is very high, and the casting quality is very good. The problems are they can not make large castings, or heavy castings because of the size limitation of the sand boxes. In addition, they can not make some castings with special dimensional or structures requirements. Moreover, they are not willing to accept small orders. Therefore, most of these foundries will only produce the automobile parts.

As for the middle foundries, since they have automatic molding lines, and have other casting processes. They can meet many different demand. The problems are their technical abilities are limited, and their production costs are high. Why? These foundries were developed from traditional casting workshops, so they just start to use automatic molding line, therefore, their old engineers can not reach the new technical level. In one word, their old engineers did not know how to use the automatic molding lines. They are staying in the studying stage. At the same time, these foundries have to feed many engineers and administrative staff since they have many different workshops, and each workshop has different production processes. So, they production costs are higher than small foundries. According to the opinion of Mr. Galen Wang from Dandong Foundry, these foundries will develop into large foundries or small foundries in the future. The middle foundries are not a long-time stable stage.

As for the small foundries, since they just have manual casting process, so they can do it very well. They can control their production and administrative costs very low, and their prices are very competitive. The problems with small foundries are their production efficiency is limited. Since all castings are made by hand. They have no ability to complete large orders. Moreover, their quality is not stable. Therefore, they can just accept small orders, and produce the iron castings with low requirements.

As for the specific foundries, they only produce one or two types of castings. Such as some foundries only produce ductile iron pipes. Some just produce various pipe fittings. Some just produce very large castings, and some just produce stove parts. These foundries own the related equipments and rich experiences for their products, so they can make them very well. Their problems are they can not make other types of castings. Their engineers and workers are not willing to make other products because of higher defective rate and lower output.

All in all, I believe these problems are not the exclusive in China. All foundries in the world will face the same problems. I wrote this article to advise the buyers and purchasers how to choose the suitable foundries in China. There are many good foundries in China, who are maximizing their strengths, and trying to avoiding their problems.

This article was originally written by Mr. Galen Wang from Dandong Ruiding Founding Co. Ltd.

Information about Cast Iron and Its Benefits

Cast iron known as gray iron and it is one of the famous ferrous alloys for iron and metal industry. In cast iron carbon ( c) and silicon (s) are the main element with the amount of 2.1 to 4 wt% and 1 to 3 wt% respectively. Also you can mix Cr, Ni, Mo and Cu according to your requirement.

In India many Investment casting foundry used different ferrous metals such as carbon steel, alloy steel, stainless steel, cast iron for castings which formally known as ferrous castings. But they mostly prefer cast iron with its different compositions including white cast iron, gray cast iron, malleable cast iron, ductile iron etc. See below some basic description for above compositions.

White Cast Iron

White cast iron contains lower silicon and metastable phase cementite, Fe3C rather than graphite. It offers hardness with the rate of toughness. Generally white cast iron classified as cermet. Cast iron is used for structural components manufacturing for good hardness with low cost. Also it used for manufacturing or industrial parts such as slurry pumps, shell liners and lifter bars in ball mills and grinding mills, and the teeth of a backhoe’s digging bucket.

Grey Cast Iron

These types of cast iron characterize by its graphitic microstructure and its widely used cast iron based on weight. Cast iron having 2.5 to 4.0% carbon, 1 to 3% silicon so it’s pure iron also contain less tensile strength and shock resistance than ductile iron or malleable iron and its compressive strength is low then carbon steel. Many casting foundries used gray cast iron to manufacturing some general engineering components such as protective cover, cover, oil pan, hand wheels, frame, floor, hammer, small handle, machine base, frame, box, knife, bed, bearing seat, table, wheels, cover, pump, valve, pipe, flywheel, motor blocks.

Malleable Cast Iron

Its properties are same as mild steel property and it is heat treated iron with carbon alloy which solidifies with graphite free structures means carbon is present in the cemnetite form (Fe3C). This type of cast irons contains different chemical element composition such as carbon, silicon, manganese, sulfur, phosphorus etc. Also it possesses considerable ductility and toughness

All of the above cast iron compositions are widely used for making high quality and higher resistive part for industries. Also auto parts manufacturers in India widely used cast iron for making higher strength and corrosion free automotive parts with help of auto component castings

ductile iron & gray iron castings foundry in the USA. Mabry Castings LTD, www.mabrycastings.com

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AC Refrigeration Compressors, Industrial Fans and Blowers, Packaged Chilling Units, Graded Castings, Ice Machines, HVACR Systems

The advancements in chemistry and science in the 19th century have added pace to the developments in the field of Heating Ventilation Air Conditioning and Refrigeration. Due to this technical breakthrough in HVACR field, a large number of air conditioning, air handling and refrigeration products have emerged in the market for various comfort and process applications. When it comes to the manufacturers of these HVACR products there are many but none can match the pioneer, ACCEL India. With four decades of experience in HVACR industry, ACCEL is an ISO 9001: 2000 certified organization that leads the race for manufacturing air handling, air conditioning and refrigeration equipment.

Air conditioning and Refrigeration equipment:
The equipments used for cooling purposes or temperature reduction purposes generally fall under the category of air conditioning and refrigeration. The refrigeration compressors and air conditioning compressors are the heart of the air conditioning and refrigeration equipments that provide air conditioning, heat pumping and refrigeration for large-scale facilities and equipment by compressing low-pressure, low-volume gas into high-pressure and high-temperature gas. Providing the ultimate benefits of high co-efficient of performance and low power consumption, our single stage air conditioning and refrigeration compressors are the compact and vibration free compressors used for comfort cooling, cold storage and marine and mobile applications. Our two stage air conditioning and refrigeration compressors fall under the category of low power consuming compressors for low temperature applications below -45 degrees like fisheries and dairies. Assembled on a compact rugged base frame, our preassembled factory tested chillers, condensers, compressors and motors are fully protected by reliable calibrated safety devices. Fitted with SMC compressors, our packaged chilling units or brine chilling units are the complete factory assembled units for central air conditioning, marine air conditioning and process cooling in chemical, pharmaceutical, textile industries. Our plate ice machines and flake ice machines are self contained and self sufficient plate ice makers that are available in capacities ranging from 5 to 300 tons.

Industrial fans and blowers:
Industrial fans and blowers are machines to provide a large flow of air or gas to various processes of many industries. This is achieved by rotating a number of blades connected to a hub and shaft. Our air screw fans, tube axial fans, vane axial fans, axial flow fans, bifurcator fans and roof ventilator fans constitute the best range of industrial fans for hot gas applications. ID fan, FD fan, coal mill fan, ESP fan, cooler fan, air slide blower, cool vent fan, nose cooling fan, bag filter fan, exhaust fan and supply fan constitute our dynamic list for centrifugal fans and blowers for dust loading applications.

Graded castings:
Castings are the finished objects generally made by pouring liquid metals into molds to be casted into desired shapes used in different applications in various industries. Equipped with world-class technologies, ACCEL foundry division produces various graded castings for various in-house and outside customer requirements. Our Spheroidal Graphite iron castings are the ductile iron castings with installed capacity of 2000 tonnes per annum used for various industrial purposes. Grey iron is generally brown colored iron which owes its color to the presence of graphite in it. The castings made of grey iron are available with us in grades of 25 and other standard grades for pharmaceutical and other industries. We also manufacture various types of alloy castings tailored as per customer requirements for the best use in machine tools, compressors, pumps and valves.

HVACR systems:
HVACR stands for Heating Ventilation Air Conditioning and Refrigeration. Having expertise in HVACR projects, we excel in designing various air conditioning and refrigeration plants meeting the material specifications as per naval standards & grades. Our highly qualified engineers and technicians with vast experience in erection, commissioning and testing are capable of designing industry’s best marine AC & R systems for marine air conditioning and refrigeration applications.

For all types of HVACR systems, air conditioning and air handling equipments visit http://www.accelindia.com.

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Ductile Iron Application

The scope of ductile iron application can be divided into four fields: First, pressure pipes and fittings. Second, the automobile industry. Third, agriculture, road and construction applications. Fourth, general engineering.

1. Pressure pipes and fittings

Ductile iron pipe has been used to transport water and other liquids, which testifies to the ball better than gray cast iron pipe. Because cast iron has excellent strength and toughness. These physical characteristics make the pipeline withstand the high operating pressure, and can withstand the excavation near pipelines and municipal construction and transportation requirements.

2. Automotive applications

The automotive industry is the second largest ductile iron casting application fields. Ductile iron has been used in cars in the three main areas: first, the car engine parts, second, gears and bushings, third, suspension, brakes and steering. Almost all crankshafts of the Ford Motor Company have been manufactured by ductile iron. Most of the worldwide cars are fitted with ductile iron crankshaft, instead of forged steel crankshaft.

3. Agriculture, road and construction applications

Modern agriculture requires a reliable and long service life of agricultural machinery. The entire agricultural industry are widely using ductile iron castings including tractor parts, plows, brackets, clamps and pulleys. For other types of agricultural machinery including bulldozers, moved into machines, cranes and compressors, ductile iron castings in these areas have a very wide range of applications.

4. General engineering applications

The machine tool industry is using the excellent engineering performance of the ductile iron to design complex machine parts. Ductile iron has high tensile strength and yield strength, and good mechanical processing properties, thus allowing production of lighter castings to keep a good rigidity. Similarly, the strength and toughness of ductile iron has made it to be widely used in all kinds of hand tools such as wrenches, clamps and gauges etc.

Paper manufacturing industry is using the high strength and high elastic modulus of ductile iron. These properties can reduce the weight of the pressure drum and drying drum.

Therefore, ductile iron castings have been widely used in many industrial areas worldwide. With the continuous development of metal founding, the application of ductile iron must be wider in the future.

This article was from Dandong Foundry Blog.

Do you ever mind how ductile pipes are made which we often see them in underground drainage’s. Watch this video.
Video Rating: 5 / 5

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