When it comes to manufacturing gear blanks, centrifugal casting holds several advantages over other methods.
The process involves pouring molten metal into a rapidly spinning mold cavity. The force produced by the mold’s spinning forces the material to conform to the shape of the mold. Additionally, extreme pressures that form within the casting device drive material contaminants to the center of the casting, allowing them to be easily removed in future finishing operations.
Advantages of the Centrifugal Casting Process
There are a number of advantages to using centrifugal casting for the manufacture of cylindrical and circular parts, such as:
Greater strength. The greater strength of parts produced using centrifugal casting is a result of higher density grain structures. As the process allows for more control over directional solidification, the grain structure is more uniform and its mechanical properties are almost equal in all directions. This higher structural density increases the life span of the component and allows for higher stress tolerances. Another factor that contributes to the enhanced part strength is higher product purity, which eliminates internal porosity and improves structural uniformity.
Increased product purity. During the casting process, the spinning of the mold places extreme pressures on the molten material. This pressure causes lighter contaminants and impurities to separate from the denser metal. These impurities gather in the bore of the component, minimizing the risk of formation of weak points or areas of porosity within the metal structure. The machining process following casting removes these impurities, leaving a highly pure end-product.
Better production cost-efficiency. Increased product purity also affects production cost-efficiency. As impurities gather at the interior surface of the part and are machined out, there is a reduction in the number of defective parts and rejects. The lack of porosity produced through the centrifugal casting process also allows manufacturers to use less metal and produce less material waste. In addition, faster setup and shorter production cycle times lead to improved production cost-efficiency.
Limitations of Centrifugal Casting
Although centrifugal casting offers several manufacturing advantages, the process is limited in its production capabilities. Some of the limitations of centrifugal casting include:
Size. To avoid the creation of a parabola at the bottom of the casting—which increases machining time—the height-to-diameter ratio used in vertical casting is 2:1. This requirement limits the size of the produced part. In some cases, horizontal casting provides the solution to these limitations.
Internal diameters. Designs with smaller internal diameters also pose a challenge for centrifugal casting operations. The purity and strength advantages of centrifugal casting decrease as the inside diameters of the components decreases. The issue stems from the higher RPMs required to produce the necessary G forces to form the cast product. Although these speeds are possible, there are significant safety issues related to operating at higher RPMs.
Shape. The centrifugal casting process only provides production advantages to parts with a cylindrical geometric shape. Although other mold shapes are possible, the loss of the structural and purity benefits and the additional cost of the unique die and post-processing operations make its use impractical outside of producing cylindrical shapes.
Additional Casting Services From Accurate Specialties
At Accurate Specialties, we offer a broad range of casting capabilities. In addition to centrifugal casting, we provide:
Spin casting. This type of casting allows for the production of parts with high material purity and consistent weight and density. Additionally, when used for the manufacture of bronze gear blanks, the process creates stronger bonds between the gear tooth and hub.
Chilled casting. This casting method produces cast products with tight grain structures and outstanding uniformity. These properties result from pouring molten bronze into an aluminum or steel mold, which is at a significantly lower temperature, producing a rapid cooling or “freezing” effect.
Continuous casting. Continuous is cost-effective for large volumes of simple parts. It produces parts with favorable mechanical properties, even distribution of alloy agents, and better machinability, friction, and wear properties. The process involves pouring molten bronze alloys through a graphite mold, cooling them into 12-foot bars, and cutting them into “pucks” for further formation.
Bronze Centrifugal Casting Solutions From Accurate Specialties
For the manufacture of cylindrical and circular parts, centrifugal casting offers several advantages, including greater part strength, higher product purity, and better cost-effectiveness.
At Accurate Specialties, we utilize several casting methods—including centrifugal casting—to produce high-quality bronze gear blanks for our customers. Our solid bronze gear blanks are available in diameters ranging from 1–50 inches.
To achieve greater uniformity and a finer grain structure in gear blanks, Accurate Specialties Inc. uses a special form of bronze alloy casting known as chill casting. This process allows us to produce gear blanks that require less machining and are therefore more cost effective for our customers.
Our world-class manufacturing capacity allows us to produce chill-cast bronze gear blanks in all shapes and sizes according to our clients’ design specifications. Along with producing near–net-shaped gear blanks, we incorporate precision CNC machining services for keyway cutting, and we also provide our customers with ready-to-hob gear blanks.
What Is Chill Casting?
When chill casting, workers pour molten alloys into a steel or aluminum die base. Because the die base is significantly cooler than the poured metal, the alloy rapidly “freezes,” chilling from the outside inward. Referred to as directional cooling, this process results in a finer grain structure and exceptional uniformity in the finished product.
Metalworkers most commonly use chill casting to form nonferrous billets and ingots. In these applications, this process yields several advantages over sand casting:
Direct chill casting allows you to retain the mold after use
Chill-cast materials solidify much faster than those created using other means
Chill casting produces a tighter material structure in the finished product, resulting in products that are less porous, more accurate, and of higher quality than those created via other methods
Accurate Specialties uses chill casting to produce bronze gear blanks that incorporate these benefits. Most often, this method is applied to non-symetrical shapes such as sector gears. These advantages reduce product costs, shorten turnaround times, and reduce machining.
Gear Blank Manufacturing
Workers prepare gears for machining by starting with a gear blank, usually a turned casting or forging.
Forging uses thermal and mechanical forces to alter the shape of solid material into the desired conformations. The metallurgical and crystallization processes that occur during heating and forming strengthen or temper the metal, making it stronger and less porous. Steel and steel alloys are among the most common materials used in this process.
On the other hand, casting refers to the process by which workers pour molten material into die bases and allow it to harden into the desired shape. This process enables the production of components that are large, intricately detailed, complicated in design, or otherwise unsuited for forging. Casting also allows metalworkers to use a larger range of alloy choices, and finished products tend to require less tooling.
Accurate Specialties produces a range of solid bronze and composite worm gear blanks for North American markets. We’ve focused on developing top-quality bronze gear blanks for the last 25 years, and our products have gone on to see uses in a wide range of industries.
At Accurate Specialties, we can:
Produce gear blanks from 1” to 50” in diameter
Cast pour weights of up to 6,000 lbs.
Use our in-depth knowledge of the broad range of bronze alloys that we stock to find the perfect metal for your needs
Perfect designs and metal compositions in our state-of-the-art materials lab
Perform a wide range of CNC machining processes
We produce industry-leading centrifugal-cast, chill-cast, and spuncast composite gear blanks, and we’ve also perfected the design of continuous cast bar blanks and shafts. Accurate Specialties provides components for a wide variety of applications in industries including:
What Can Accurate Specialties Do for You?
We produce top-of-the-line chill-cast gear blanks for the industrial sector. Our high-precision capabilities allow us to produce near–net-shape gear blanks that require less machining than those built with other processes, cutting down your overall costs. In addition, we use CNC machining to produce the highest-quality finish, and we employ keyway cutting to provide you with ready-to-hob gear blanks that meet the unparalleled precision and repeatability your products need.
Accurate Specialties is the leading manufacturer of spuncast composite gear blanks. Our spuncast gears deliver the durability and strength of bronze gears while cutting material costs via the use of steel or cast-iron center hubs. Our process and material choices offer the high level of quality and performance you expect at a much lower price point. Our spuncast composite gears are well-suited for use in most any relevant application.
Choosing Accurate Specialties for Spuncast Composite Gear Blanks
As a top manufacturer of spuncast composite gear blanks, we have learned how to make our solutions cost-effective. Our cast iron or steel center hubs we utilize are more affordable than crafting a full bronze gear blank, and without the need for spacers, our composite gears cut the need for added assembly processes. In addition, we receive a bulk discount on materials due to the high volumes of spuncast composite gear blanks that we fabricate, and these savings are passed on to our clients.
We also offer quick turnaround times for your composite gear orders. Components can be completed in as little as one week. Accurate Specialties utilizes integrated manufacturing processes to offer the manufacturing flexibility our customers demand. We guarantee the integrity of all materials, and our strict quality management process ensures a high quality end product.
Industries & Applications
Accurate Specialties’ spuncast composite gear blanks are well-suited for use in most any industry where gear blanks are used. They are relied upon in critical applications across industries such as:
We offer spuncast composite gear blanks in a range of sizes to meet the demands of most power transmission applications. We also produce bronze gear blanks that are centrifugal cast or chill cast, with a range of common and specialty alloys available.
Our gear blanks are used in the following power transmission applications:
Center point irrigation systems
Milling and manufacturing equipment
Screw conveyors and augers
CAT scanner positioning systems
Solar panel positioning systems
Our spuncast composite gear blanks can handle demanding loads placed upon them by precision machine tools while delivering sheer resistance in environments where backlash is minimal. Our gear blanks are designed for dependable operation, and made from heavy-duty materials.
You will find our gear blanks in the following machine tool applications:
Machine tool components
Rotary tables for machine tools
Indexing tables for machine tools
Our gear blanks are utilized in various marine applications, and may be customized to meet your specific design requirements.
Marine applications that have utilized our gear blanks include:
Cable & wench systems
Our spuncast composite gear blanks deliver superior reliability for the automotive industry. Components may be manufactured to meet exact specifications and are made in a variety of sizes to suit the varying needs of the automotive sector.
You can find our gear blanks in the following automotive applications:
Gear-drive power transmissions
Gear Blanks for All Industries
Accurate Specialties is an industry leader in the manufacture of reliable spuncast composite gear blanks across the above applications and many more. Request a quote today to learn how our gear blanks deliver superior performance and savings in your application.
A worm gear is a mechanical arrangement consisting of a spiral-threaded shaft butted against a toothed wheel, resembling a standard spur gear. The threaded shaft, also known as a worm, acts as the driving element, imparting motion to the wheel as the rotational power from the worm is transferred in a 90o plane.
Worm gears are typically used for their high gear reduction ratios. It is common for standard worm gears to achieve reduction ratios ranging from 20:1 up to 300:1. This attribute makes worm gears ideal for applications that require reduced rotational speeds or significantly increased torque. By comparison, it would take multiple conventional gearsets to achieve the same levels of reduction.
Worm gears also have another useful characteristic—they possess a natural self-locking feature by design. The worm can easily turn the gear wheel, but the gear wheel cannot turn the worm, thus preventing reverse movement.
How to Make Bronze
Bronze is one of the most commonly used alloys for worm gears due to the material’s desirable mechanical properties. The term “bronze” covers many copper alloys, though the final product ultimately depends on the other material contained within the alloy. For example, using nickel creates copper-nickel alloys, or using zinc creates brass. Bronze, on the other hand, is most often created by creating a copper alloy with tin or aluminum.
At Accurate Specialties, we utilize a variety of alloys to meet our client’s specific requirements. Typically, for worm gears, we recommend tin bronze (C91700) and aluminum bronze (C95400 and C95500) due to their relatively high strength, and superior fatigue, friction, and wear resistance.
The process of making bronze involves first heating the copper element to a specified temperature. Once the copper reaches a molten state, predetermined amounts of alloying compounds (such as aluminum or tin) are added to the molten copper. The molten alloy mix is then poured into bronze casting dies for the gear components and allowed to cool.
Typical Bronze Worm Gear Applications
The high torque output of worm gears makes them suitable for heavily loaded machinery. Some of the most common applications for worm gears include:
Movable bridge components
The controlled and powerful motion of worm gears are ideal for inducing movements in large and heavy bridge structures.
Elevators, lifts, packaging equipment, and conveyors
Worm gears are used to provide the torque needed to transport heavy loads from one point to another. The non-reversible properties of this gear also act as a secondary safety braking system.
Heavy-duty construction equipment and trucks
Heavy vehicles often use a worm gear differential for additional power. Depending on the action of the vehicle, different amounts of torque may need to be delivered to each wheel. Worm gears are used to provide the necessary torque that governs each wheel’s performance.
At Accurate Specialties Inc., we provide custom worm gear manufacturing services for numerous applications in almost any industry. Our technical team will work with you to help determine the best alloy for your unique specifications.
If you would like to learn more about how to make bronze, bronze worm gears, or any of our other products and services, feel free to contact us or request a quote.
The techniques used to mold and shape metals have evolved significantly over the centuries. Forging, sand casting (static casting), and rolled and welded procedures are just some of the traditional methods used to manufacture metal parts and components. However, there are many applications where these fabrication methods are either unsuitable or inefficient.
The centrifugal casting process can produce components with intricate geometries at a lower cost and with reduced machining requirements in comparison to other commonly used casting methods. The process entails pouring molten metal into the center of a rotating mold. The centrifugal force induced by the rotation pushes the molten metal against the inner wall of the mold to create the intended shape. The molding dies can be oriented horizontally (horizontal centrifugal casting) or vertically (vertical centrifugal casting).
When to Rely on Centrifugal Casting
Centrifugal casting has traditionally been used to manufacture hollow shapes with specified thicknesses in the instance where the end product requires the most dense “best” material on the OD of the product. Due to its mode of operation, centrifugal casting is most suitable for components with axisymmetric geometries (i. e., shapes that are symmetric about a given axis). One benefit of centrifugal casting is reduction in instances of retained air pockets or porosity in the finished product.
Because centrifugal casting is done with a predetermined mold size and controlled via electronic means, it is best suited to applications that require high accuracy. Products with precise dimensions and weight can be manufactured to tight tolerances by controlling the casting process with computerized controls.
Although most commonly associated with molten metals, there are centrifugal casting advantages when used with virtually any material that can be melted into a pourable slurry, including concrete, glass, ceramic, and plastics.
The Vertical Centrifugal Casting Process
The vertical centrifugal casting process consists of several stages. At the beginning, the molten metal is poured into a vertically oriented preheated rotating die. The centrifugal forces in the vertical spinning mold then cause the molten metal to spread horizontally and vertically along the inner diameter of the mold so that it assumes the specified shape.
As the mold and die spin, the denser elements of the molten metal are pushed toward the outer diameter. In a process known as directional solidification, the mold acts as a cooling surface which solidifies the metal from the outer diameter as it moves towards the bore. This process causes impurities to ‘float’ toward the inner diameter, from which they can be machined away when the casting process is complete.
The result is a final product with superior mechanical properties and a more uniform, fine grain structure. For this reason, vertical centrifugal casting techniques are used to manufacture components in the aviation, aerospace, military, petrochemical, and any other industries that require high-reliability components.
Although vertical and horizontal castings can produce products of similar quality, castings with vertical orientations are more suitable for cylindrical shapes with a diameter several times larger than the depth (or height) of the cast. Rings and bearings are examples of products best suited to vertical centrifugal casting.
Vertical centrifugal casting can also be used to cast non-cylindrical parts such as valves and propellers by using specialty castings. Other products that are commonly produced with vertical centrifugal casting methods include:
Balls for ball valves
Accurate Specialties Inc. is an industry leader in manufacturing centrifugal cast bronze gear blanks. Our vertical centrifugal casting techniques produce gear blanks with high purity, density, and durability. Our state-of-the-art equipment generates pressures up to 60 times the force of gravity to segregate and remove impurities and other unwanted elements from our products. All of our gear blanks are machined with high dimensional accuracy using our advanced 4-axis, CNC-controlled VTC to ensure proper installation and minimization of errors.
At Accurate Specialties Inc., we have developed countless gear blanks for thousands of applications for over 30 years. Our ISO 9001:2015 certified quality systems ensure that each one of our gear blanks and friction materials exceeds industry standards and leaves our facilities in the best possible condition.
To learn more about our centrifugal cast gear blanks or our other services, feel free to contact us.