In this complete guide to metal spinning, we will cover everything you need to know. From understanding what metal spinning is and how it works, the tools and equipment used in the process, types of metal spinning, the most common metals used, and the most popular applications.

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What is Metal Spinning

Metal spinning, also known as spin forming, is a metalworking process that involves the transformation of a flat circular blank or disc-shaped workpiece into axially symmetrical round shapes.

This process typically utilizes a lathe machine with a spinning tool that applies pressure to the workpiece, causing it to flow and take on the desired shape.
It is commonly used in industries such as automotive, aerospace, and lighting to produce items like lampshades, reflectors, and even rocket nose cones.

It offers advantages such as cost-effectiveness, quick turnaround times, and the ability to create complex shapes without the need for additional tooling.

Metal Spinning Equipment

A metal spinning operation requires the use of a metal lathe and a roller, which work together to shape the metal into the desired form.

The lathe is a powerful machinery that spins the workpiece at high speeds around an axis, allowing for precise and controlled shaping. It’s a versatile piece of equipment that can also be used for various other metalworking operations such as cutting, drilling, and sanding.

Metal Lathe Components

The following lathe components work in harmony to ensure accurate and efficient metal spinning operations:

Headstock

The heart of a metal spinning machine is the headstock, which houses the spindle, motor, and drive mechanisms. It ensures support, control, and consistent performance for spinning operations. Modern headstocks offer numerical control and automation features, contributing to the reliability and enhanced capabilities of the process.

Spindle

The spindle, a critical component in metal spinning, holds and rotates the workpiece. It features precision bearings and drive systems, directly impacting the process’s efficiency. CNC machines utilize spindles with programmable speed and torque control, enhancing performance.

Mandrel

The mandrel plays a crucial role in the metal forming process, providing volume and shape to the metal disc. This forming die is designed with the interior shape of the finished part, ensuring that the workpiece is deformed evenly without any wrinkling or warble.

As the workpiece is rapidly spun on the mandrel, it receives support and stability throughout the forming process. Prior to being placed on the mandrel, a metalworking lubricant is applied, which not only facilitates easy removal but also enhances the surface finish of the final product. The combination of precise shaping and lubrication ensures high-quality results in metal forming operations.

Roller

The roller is a crucial component in metal spinning machines, playing a key role in shaping the workpiece. As a rigid tool, it applies localized force known as the partial work zone, where plastic deformation occurs. This force prompts the workpiece to flow over the mandrel, transforming it into the desired shape.

To minimize friction and prevent heat buildup and premature wear, the roller tool incorporates a ball roller that spins throughout the process.

Controlling the roller can be done manually by an operator, but this requires a high level of skill and extensive training to produce flawless parts. CNC machining has gained popularity because of its ability to reduce hazards associated with manual production methods.

Tailstock

The tailstock is a crucial component in the process of metal spinning, as it plays a pivotal role in maintaining workpiece stability and concentricity. This adjustable part is designed to accommodate different workpiece lengths, ensuring accuracy and precision throughout the spinning operation.

CNC machines have changed the craft with their precise tailstocks, providing consistent and reliable spinning operations. With their ability to provide steady support and alignment, tailstocks are essential for achieving optimal results.

Whether in traditional or CNC-based metal spinning, the tailstock remains an indispensable tool for achieving exceptional craftsmanship and superior finished products.

Follower

A follower serves as a pressure pad attached to the end of the tailstock spindle, ensuring that the workpiece remains securely clamped in place. The shape and size of the follower are crucial, as it needs to correspond to the area of the base of the finished part.

By exerting even pressure on the workpiece, the follower helps maintain stability and prevents any unwanted movement during spinning. This allows for precise shaping and forming of metal into various intricate designs and functional components.

Lathe Bed

The lathe bed is the backbone of spinning processes, providing essential support for the headstock, tailstock, and carriage. It plays a vital role in ensuring precision and stability during metal shaping.

The rigidity and dimensional accuracy of the lathe bed are crucial for achieving high-quality results. Its sturdy construction and precise alignment allow for smooth and consistent movement of the workpiece, minimizing errors and ensuring optimal performance.

Without a reliable lathe bed, the entire spinning process would be compromised, making it an indispensable foundation for any metal spinning operation.

Metal Spinning Types

Conventional metal spinning involves shaping sheet metal over a mandrel. Shear spinning utilizes axial strokes, offering dimensional accuracy and high tensile strength. The sine law determines wall thickness, diameter, and tailstock roller position for precision forming. Hot spinning uses heat to shape metals quickly, while tube spinning forms a metal tube into the final shape, commonly used in manufacturing tank heads.

Let’s take a closer look at each type of operation:

Conventional Spinning

Conventional metal spinning involves the manual or CNC shaping of metal parts by craftsmen or machinery. It produces shapes like cones, domes, flanges, and hemispheres with careful control of parameters such as speed, thickness, and diameter. Unique techniques and expertise are found in Europe, China, and North America.

Shear Spinning

Shear spinning, also referred to as shear forming, delivers exceptional precision and dimensional accuracy when shaping metal components. This process is ideal for soft metals, expensive materials, and intricate shapes with grain structures. Additionally, single pass shear spinning reduces project cycle time, providing a cost-effective solution.

The Sine Law

Mathematical calculations for precise wall thickness and diameter adjustments are provided by the sine law in metal spinning. CNC lathe machines ensure accuracy, while tailstock rollers and followers govern metal shape consistency. The use of the sine law dates back to the Middle Ages, marking a significant advancement in metal spinning.

Hot Spinning

Shaping metal parts with steam power, heat, and high-speed spinning, hot spinning yields precise dimensions, grain structures, and enhanced mechanical properties. Commonly used for copper, brass, and other metals, it enables rapid formation of complex shapes with a high level of precision.

Tube Spinning

Shaping metal tubes into complex forms for pressure vessels and tank heads, tube spinning ensures precision with a wide range of metals. The process demands precise control over thickness, diameter, and tailstock roller position, automatable through CNC technology for consistent results.

Adjustments

Adjusting parameters like speed, thickness, and diameter is essential for precise metal shaping. Tailstock roller, follower, and workpiece adjustments are made to ensure consistency. CNC metal spinning automates adjustments, enhancing efficiency and accuracy. Precision metal spinning involves machinery and process adjustments for optimal results.

Most Common Metals Used

Aluminum, a lightweight metal, is commonly utilized in metal spinning for parts with a high strength-to-weight ratio. Steel, valued for its durability and strength, is widely employed for various industrial applications.

Aluminum

Aluminum, a widely used NLP term in metal spinning, offers versatility and malleability. It is one of the most common types materials due to its lightweight nature and corrosion resistance.

Steel

Steel in metal spinning offers exceptional strength and durability, making it ideal for industrial applications. It is one of the most common types of materials, alongside aluminum and stainless steel.

Stainless Steel

Stainless steel’s corrosion resistance makes it ideal for metal spinning, especially in aerospace and automotive industries. It offers durability and a polished finish, and the spinning process involves high-speed spinning and precision forming, producing complex shapes with precise dimensions.

Carbon Steel

Known for its high tensile strength and toughness, carbon steel spinning involves forming it into domes, flanges, and cones. This process is widely used in manufacturing tank heads and fittings, offering dimensional accuracy and maintaining mechanical properties. With metal spinning, carbon steel can be formed into various shapes and thicknesses.

Brass

Brass spinning, popular for decorative and functional metal parts, allows production of complex shapes and fittings. Commonly used in architecture and art, brass spinning offers excellent dimensional accuracy and smooth surface finish through precise axial strokes and forming parameters.

Bronze

Bronze spinning’s corrosion and wear resistance make it a popular choice. This process forms hemispheres and cones with precision, ideal for ornamental pieces. Complex shapes with high accuracy and unique grain structures are achieved in bronze spinning, showcasing its mechanical properties.

Hastelloy

Known for its high-temperature and oxidation resistance, Hastelloy spinning demands precision in forming complex shapes. Widely used in aerospace and chemical industries, it ensures excellent dimensional accuracy and consistent wall thickness while maintaining mechanical properties and high strength.

Titanium

Titanium spinning is known for its exceptional strength-to-weight ratio and resistance to corrosion. It is widely used in aerospace, medical, and marine applications. The process involves precision forming of cones and domes, requiring expertise due to the use of expensive materials.

Most Popular Applications

Metal spinning finds extensive use in creating precision hemispheres and cones, along with applications like Venturi in aerospace and automotive industries. This process enables the precise forming of complex shapes and dimensions, making it valuable for producing specialized parts across various sectors.

Hemispheres

Formed with high precision and manual spinning, metal spinning hemispheres offer consistent wall thickness and complex shapes. The process involves CNC metal spinning, creating parts for various industrial applications, utilizing expertise in high-precision fabrication.

Cones

Precision forming and high-speed spinning processes shape metal spinning cones, offering dimensional accuracy. These cones exhibit high tensile strength and complex shapes, essential for industrial applications, requiring expertise in forming various thicknesses and dimensions.

Venturi

Precision forming is crucial in Venturi, a metal spinning application presenting high dimensional accuracy. Expertise is required for complex shapes, widely used in aerospace and industrial flow control systems. The process demands skilled precision and forming parameters, making it essential in various applications.

Parabola

The metal spinning process enables precise creation of parabolic shapes, commonly used in aerospace and manufacturing due to their strength and durability. This process ensures dimensional accuracy, and CNC technology efficiently produces parabolic metal parts.

Cylinders

Ideal for creating cylindrical shapes with high precision, metal spinning offers outstanding tensile strength in the resulting parts. It allows for varying wall thicknesses and seamless production of complex shapes using CNC technology. The cylinders produced exhibit superior mechanical properties.

Hopper Lids and Bases

Efficiently producing industrial hopper lids and bases, metal spinning ensures precise dimensional specifications and exceptional strength. CNC technology enables cost-effective production in various materials.

Tank Heads

Tank heads, widely manufactured through metal spinning, offer high dimensional accuracy and excellent tensile strength. CNC technology allows for the production of complex tank head designs, catering to diverse industrial requirements. This process ensures structural integrity and versatility in tank head creation.

The Future of Metal Spinning

Continuing to be pivotal in modern manufacturing across diverse industries, the metal spinning process undergoes constant development, emphasizing precision, automation, and adaptability. As technology evolves, so does metal spinning, promising further advancements in precision, efficiency, and material versatility.

Metal Spinning: Types, Applications, Advantages and More

Chapter 1: Understanding Metal Spinning

Metal spinning, also known as spin forming, is a specialized metalworking technique that molds a flat, circular blank or disc into symmetrical round formations. This transformation is achieved through the application of a roller that exerts lateral force against the disc's surface while it spins at high speed on its axis, supported by a mandrel. The mandrel not only stabilizes the workpiece but also determines its final configuration.

Through metal spinning, a sheet of circular metal is contorted into diverse shapes without any material being removed. During this reshaping, tensile and compressive forces are applied to the disc blank over a mandrel. Certain spinning techniques may result in the thinning of the original metal sheet, but such variations are managed with precision to satisfy specific end-product criteria.

Metal spinning is one of humanity's most ancient metalworking techniques, skillfully merging artistic expression and technical knowledge with a lineage extending back to Egyptian times. Through the ages, it has transitioned from a purely manual endeavor to a refined industrial method that includes computer numeric control (CNC) technology.

Even with technological advancements, traditional manual metal spinning remains crucial for crafting products of precise detail and exceptional quality. Gaining proficiency in this method requires significant apprenticeship and distinctive expertise, underscoring the craftsmanship involved.

As a historical reshaping practice, metal spinning’s origins can be traced to ancient Egyptian pottery forming, originally employing a hand-driven potter’s wheel since BC. While initially used for wood and clay, the technique was adapted by 25 BC for crafting circular iron shields.

During the medieval era, metal spinning became prevalent for making items such as vases, tea kettles, and trophies. These objects were created using a wooden spinning lathe with manual rotational input by an assistant, highlighting the enduring significance and adaptability of this ancient technique across different periods.

Chapter 2: What is Metal Spinning Machinery?

Metal spinning machinery, often referred to as spinning lathes or flow forming machines, is a type of precision metalworking equipment designed to form and shape metal blanks into round and hollow cylindrical parts, cones, and complex contours. Used in a variety of industries—including aerospace, automotive, lighting, and industrial manufacturing—these machines utilize a rotating lathe and a hardened roller to apply localized pressure, shaping metals such as aluminum, stainless steel, copper, brass, and titanium with accuracy and efficiency.

A typical metal spinning operation employs advanced technology to deliver high repeatability and surface quality, while still retaining flexibility for custom metal forming. The lathe is the primary machinery in this process, mounting and rapidly spinning the workpiece around its axis. Aside from spinning applications, this versatile equipment is also capable of other metalworking functions, such as precision cutting, CNC drilling, and abrasive sanding. For metal spinning specifically, a custom mandrel forms the inner profile, while the coordinated movement of other components results in intricate spun shapes and precise tolerances. Major components of a metal spinning lathe include:

Mandrel

The mandrel, functioning as a form die or spinning mold, determines the geometry of the final spun metal part. As a critical tool in metal shaping, it provides full support and accurate profile definition, ensuring the metal disc conforms tightly during the entire spinning process. Mandrels are specially designed to minimize workpiece wrinkling and deformation, making them essential for achieving precision-engineered results.

Prior to mounting, the metal blank—often pre-lubricated with high-performance grease or wax—is carefully positioned on the mandrel. This lubrication is key for reducing friction during high-speed rotation, improving both material flow and the visual surface finish of the finished component.

Mandrel construction materials are selected based on application requirements. Industry standards favor hardened steel or aircraft-grade aluminum for high-volume production and tooling longevity. For prototypes or low-run jobs, cost-effective mandrels made from engineering plastics or hardwoods can be suitable. Regardless of material, durability and structural integrity are vital, as mandrels must resist deformation under strong radial pressure from the roller tool.

Roller

The roller, also referred to as a spinning tool or forming roller, is meticulously engineered to apply sequential, localized force to the workpiece over the mandrel’s contour, creating controlled plastic deformation. Modern rollers often feature ball bearings for smoother operation, reduced heat, and minimized tool wear—critical factors when working with harder metals such as stainless steel or Inconel alloys.

Roller adjustments are finely tuned to balance pressure and speed, essential for producing uniform wall thickness and intricate metal contours. Although manual operation by a skilled technician enables creative custom forming, the increasing prevalence of CNC-controlled metal spinning machines allows for highly repeatable, near-flawless results in both prototype and mass production environments.

CNC and advanced automation in metal spinning have opened new possibilities for complex geometries, reduced labor costs, and efficient material utilization. This technology is favored for manufacturing components like satellite dishes, pressure vessels, cookware, lighting fixtures, and automotive wheels—all requiring impeccable surface finishes and structural strength.

A distinct advantage of metal spinning is that relatively lower forming force is needed compared to traditional stamping or deep drawing. This allows effective forming of heavy-gauge, high-tensile metals into large diameters without the excessive energy demand found in press forming. As a result, the process is both cost- and energy-efficient.

The work zone in metal spinning features synchronized movement—combining part rotation and roller advance—to create a signature spiral or helical flow. This generates seamless and high-strength spun parts, with a slight twist or spiral that also enhances structural integrity.

Tailstock

The tailstock assembly, installed opposite the headstock, maintains axial alignment and provides robust support for the workpiece against the mandrel during rapid spinning or flow forming. Precision adjustment mechanisms enable consistent pressure to clamp the part securely, a crucial element for accuracy during high-speed or heavy-gauge metal spinning.

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Follower

The follower, or pressure pad, is a tailor-made component attached to the tailstock spindle. Designed to match the base of each spun part, it evenly distributes holding force, preventing slip and ensuring that the metal blank conforms precisely to the mandrel during rotation. High-quality followers contribute to surface finish consistency and repeatability—critical for demanding industrial applications.

Spindle

The main drive spindle in the headstock serves as the axis for both the mandrel and workpiece, delivering rotational energy throughout the forming process. Tailstock assemblies often feature a synchronized spindle that holds the follower, ensuring full axial support and precise movement control. Direct-drive and belt-drive spindles are chosen based on application speed and torque requirements.

Headstock

The headstock is a heavy-duty structural housing that contains the powertrain, including motors and gears for variable speed control, high-torque operation, and precision spindle alignment. It supports and stabilizes the entire assembly during high-speed rotation—key for safety and dimensional accuracy in both manual and CNC spinning operations.

Lathe Bed

Serving as the engineering foundation for all primary components, the lathe bed is manufactured for rigidity and vibration damping. It ensures that the headstock, tailstock, and tool rests remain in perfect alignment while withstanding high operational loads. An accurately machined and robust bed boosts both process consistency and equipment longevity.

Computer Numerical Control (CNC) Metal Spinning

CNC metal spinning is a state-of-the-art evolution in metal fabrication. By integrating computer-aided design (CAD) and automated control systems, CNC metal spinning lathes offer exceptional precision, replicability, and process monitoring for both thin and thick metal sheets. The operator loads a blank on the CNC lathe and secures it using a hydraulic or mechanical pressure pad, programmed with detailed geometries and production sequences.

Upon activation, the CNC spinning machine executes the programmed tool paths, controlling spindle speed, roller pressure, and feed rates to manufacture intricate contours and high-precision components. CNC-controlled lathes are renowned for producing parts with minimal setup time, superior dimensional consistency—often within 0.001 inches (0.01 mm)—and outstanding mechanical properties such as improved tensile strength and fine-grained surface finishes.

Embraced by industries demanding low- to high-volume production, CNC metal spinning is a go-to solution for aerospace components, lighting reflectors, gas cylinders, and custom-engineered industrial products. Automation reduces operator error, cuts production costs, and delivers the flexibility to quickly switch between product runs, meeting the strict demands of today’s manufacturing marketplace.

Playback Numerical Control (PNC) Metal Spinning

Playback Numerical Control (PNC) metal spinning bridges manual craftsmanship and automated production. In this process, a skilled operator uses a joystick or pendant to manually control the roller during the first production run, shaping the metal into the desired geometry under real-time observation. Every movement is recorded by the system's control software.

After the initial part is successfully formed, the PNC system stores and plays back the recorded motions, allowing for rapid and repeatable production of complex parts. Program refinement—such as optimizing roller feed rates, correcting geometry deviations, or integrating enhanced safety protocols—ensures production accuracy and reduces scrap rates.

PNC metal spinning is especially valued for high-volume production environments where consistency, quick changeover, and process reliability are paramount. Applications include serial manufacturing of commercial lighting components, HVAC ducting, and pressure vessel ends, where the demand for precision and consistent quality is essential.

Advantages of Modern Metal Spinning Machinery

Today's metal spinning machines deliver several competitive advantages versus traditional forming methods. Metal spinning supports rapid prototyping, lean manufacturing, and just-in-time production, making it a preferred technique for custom and contract manufacturers. The process reduces material waste, lowers tooling costs, and allows for complex shapes that might be challenging or cost-prohibitive with deep drawing or stamping. High-precision spun parts offer superior strength-to-weight ratios, tight tolerances, and smooth finishes—attributes essential for advanced engineering and demanding industrial standards.

How to Select the Right Metal Spinning Equipment

Choosing between manual, CNC, or PNC metal spinning machines depends on your production needs, material type, part geometry, and volume requirements. When evaluating machinery, consider spindle power, lathe bed rigidity, maximum blank size, available controls, tooling compatibility, automated material handling, and after-sales support. Partnering with a reputable metal spinning equipment manufacturer or service provider ensures optimal machine performance, long-term durability, and high-quality spun metal components tailored to your application.

Related Services and Market Applications

Besides core metal spinning processes, specialized services such as custom metal spinning, CNC prototyping, post-spinning heat treatment, and advanced surface finishing greatly extend the capabilities of metal spinning shops. The process serves diverse markets, including defense, consumer products, energy, architectural lighting, and experimental design. For a deeper dive into customized spun parts or requesting quotes, explore our metal spinning services or connect with experienced metal spinning manufacturers through our trusted directory.

Chapter 3: What Are the Top Metal Spinning Machines?

In the United States and Canada, manufacturers and metalworking professionals have access to a broad selection of metal spinning machines designed to meet the growing demands of precision metal fabrication. These advanced machines are essential to modern manufacturing, playing a pivotal role in the cost-effective and efficient production of metal spun components used across a wide variety of industries. Metal spinning technology supports sectors such as aerospace, automotive, HVAC, electronics, lighting, defense, and more. By enabling the streamlined creation of high-quality, complex shapes from aluminum, stainless steel, copper, and specialty alloys, metal spinning equipment continues to drive technological progress and economic growth throughout North America.

Below, we highlight several of the industry-leading metal spinning machine models—from CNC-equipped automated solutions to robust manual units—and discuss their core features, advantages, and ideal applications to help you identify the best fit for your metal forming or sheet metal fabrication needs.

Leifeld PNC350-800 (Manufacturer: Leifeld Metal Spinning AG)

The Leifeld PNC350-800 is a renowned CNC metal spinning machine engineered for advanced automation, high accuracy, and consistent reliability. Equipped with a sophisticated CNC control system, this equipment streamlines programmable setups, reducing changeover times and increasing productivity for both low and high-volume production runs. Its large working diameter accommodates the fabrication of complex or oversized components ideal for the aerospace and automotive industries. The PNC350-800 excels in producing seamless metal parts such as wheel rims, gas cylinders, pressure vessels, and other precision-engineered assemblies that require repeatable results and minimal material waste.

MJC Engineering E-400 (Manufacturer: MJC Engineering & Technology, Inc.)

The MJC Engineering E-400 stands out as a highly capable CNC metal spinning lathe known for both operator-friendly programming and robust mechanical construction. Designed to handle demanding tasks in heavy-gauge spinning, the E-400 incorporates advanced features like automated tool path optimization and real-time quality monitoring, providing exceptional performance for metalworking shops focused on accuracy, cycle time improvement, and longevity. Its adaptability extends to producing a variety of high-precision cylindrical and conical parts for industries including renewable energy, medical devices, and industrial machinery manufacturing.

Baileigh R-M10 (Manufacturer: Baileigh Industrial, Inc.)

The Baileigh R-M10 represents a durable and cost-effective choice among manual metal spinning machines, catering to small-scale manufacturers, prototyping shops, and metalworking hobbyists. While it lacks automation features found in CNC spinning machines, its simple, user-intuitive design ensures ease of use and straightforward maintenance. The R-M10 is favored for shaping small metal blanks and fabricating custom parts, such as lamp reflectors, decorative items, or rapid prototypes, in environments where flexibility and budget constraints are a priority.

PNC-CNC Metal Spinning Machine Series (Manufacturer: PNC Engineering)

The PNC-CNC Metal Spinning Machine Series encompasses a diverse portfolio of CNC-controlled units designed to address a wide range of spin forming specifications. These machines are engineered for superior precision in metal forming operations, featuring high-torque spindles, programmable forming rollers, and advanced user interfaces for intuitive operation. Their exceptional build quality and scalability make them a go-to solution for businesses aiming to automate and optimize metal spinning production lines—from small parts to large, complex shapes—serving industries such as HVAC, lighting, electronics, and industrial equipment manufacturing.

LNSpin LS-250 (Manufacturer: LNS America, Inc.)

The LNSpin LS-250 is an advanced, automatic metal spinning machine ideal for high-volume manufacturing environments. Featuring state-of-the-art automation—such as robotic loading/unloading and integrated cycle monitoring—the LS-250 offers unmatched efficiency and operator safety by minimizing manual labor and expediting production turnaround. Its flexible programming and robust design enable seamless adaptation to new part geometries, supporting rapid changeovers and continuous 24/7 operation, making it an optimal solution for large-scale production of spun metal components in sectors like commercial lighting, HVAC, and consumer appliance manufacturing.

As the global landscape for metal spinning equipment continues to evolve, new models and innovative features are regularly introduced. When selecting a metal spinning machine for your business, it’s essential to evaluate current manufacturer offerings, assess core features (including material compatibility, programmable automation, forming capacity, safety systems, and total cost of ownership), and determine which model aligns best with your specific production volumes and application requirements. For buyers seeking the best value and futureproofing, researching after-sales support, software upgrade capabilities, and local supplier availability may provide a valuable edge in operational efficiency and competitiveness. Learn more about how to choose the right metal spinning equipment.

Leading Manufacturers and Suppliers

Chapter 4: What are the different types of metal spinning?

Spinning is categorized as compressive draw forming due to the radial, tensile, and compressive stresses that affect the metal flow within the localized roller work zone and nearby regions. Tensile stresses arise when the roller makes contact with the workpiece, increasing with the axial feed of the roller, which causes volumetric displacement in a plane radial to the mandrel.

As the metal volume decreases towards the center, compressive stresses form between the metal volumes. These stresses contribute to increased thickness at the open end and may lead to buckling and wrinkling. Adjustments in the direction of the feed can help mitigate these issues.

Conventional Metal Spinning

In conventional spinning, the roller directs the workpiece over the mandrel's contour, maintaining a constant material thickness throughout the process. After shaping, the workpiece's depth increases while its diameter decreases. This method is regarded as the most basic form of metal spinning and involves less complex tooling and machinery.

Shear Spinning

In shear spinning, the rollers apply a downward force as the workpiece is shaped over the mandrel's contour. This process results in a final part with a reduced material thickness compared to the original blank, while maintaining a constant diameter. The depth of the workpiece increases, and the increased compressive forces enhance the part's mechanical properties, such as strength and hardness.

Shear spinning demands a more robust tooling design and precise machining to ensure dimensional accuracy and a good surface finish. The process creates significant friction and wear on both the workpiece and mandrel, necessitating the use of coolant to manage the heat generated.

The Sine Law

The thickness of the final material in a shear spinning process is theoretically governed by the Sine Law. According to this law, the final thickness of the part is calculated by multiplying the original thickness of the flat metal sheet by the sine of the semi-apex angle of the cone. This principle is applicable when the part has a conical profile achieved through a single-pass shear spinning process. The metal that remains perpendicular to the spinning axis will retain its initial thickness.

Hot Spinning

Hot spinning involves heating the workpiece to forging temperatures using a heating torch, which is applied while the workpiece is pressed over the mandrel. This technique is employed when the material exhibits low ductility and malleability or if the metal sheet is excessively thick and hard to deform at room temperature. Cold spinning, performed at ambient temperatures, is suitable for a wide range of metals.

During hot spinning, the metal is deformed in its plastic state, which allows for substantial deformation and refinement of the grain structure, enhancing physical properties such as strength. However, the process leads to rapid oxidation of the heated metal, making it harder to control and more costly overall.

Tube Spinning

Tube spinning is a variant of shear spinning designed to elongate and reduce the wall thickness of hollow cylindrical tubes. The process begins with the tube being mounted and secured on the mandrel. The elongation is achieved by drawing the tube over the mandrel's length using three or more rollers positioned equidistantly around the tube. The axial flow of the material follows the direction of the roller movement.

Tube spinning can be carried out externally or internally relative to the mandrel. In external tube spinning, the tube is stretched over the mandrel's outer surface. Conversely, in internal tube spinning, the tube is spun and elongated inside a hollow mandrel.

This method is effective for creating tubes with varying diameters, provided that wall thickness is not a critical factor. Similar to shear spinning, tube spinning demands a complex tooling design and enhances the mechanical properties of the tube.

Adjustments

To achieve the desired thickness and finish of the workpiece, adjustments can be made to various parameters, including RPM, roller shape and diameter, pressure, attack angle, and feed rates. In some cases, a second pass may be required to reduce the outside diameter near the edge of the workpiece.

Adjusting the edge of the workpiece can be challenging, as it may result in edges that need trimming or become excessively sharp. Careful adjustments are necessary, as each pass of the roller can make the material increasingly brittle and prone to spring back from the tool.

Necking and expanding are additional techniques used in metal spinning. Necking involves the gradual reduction of the diameter in a specific section of the part, while expanding refers to the increase in diameter in a particular section.

After metal spinning, two common post-processes are planishing and trimming. Planishing is used to smooth out wrinkles and marks left by the tool on the finished part. This step involves using a planishing tool to apply force while the workpiece is spun at a slower RPM. Trimming involves cutting away any excess material from the edges of the finished part to achieve the desired shape and dimensions.

Chapter 5: What metals are commonly used in metal spinning?

Metal spinning is versatile and can be used with various types of metals. If a metal can be processed by metal stamping, it can also be spun. Additionally, some metals that are challenging to form through stamping can be successfully shaped by spinning. However, metal spinning lathes typically operate at pressures up to 15,000 psi, which limits their ability to deform metals such as carbon steel and tool steel.

Aluminum

Aluminum is a favored material for metal spinning due to its excellent strength-to-weight ratio, ductility, and malleability. These properties make it a preferred choice in the metal spinning industry. Aluminum is widely used because of its high resistance to corrosion and chemicals, as well as its thermal stability. It serves as a cost-effective and lightweight alternative to steel.

Commonly used aluminum alloys for metal spinning include , , , , , and .

Spun aluminum parts can be found in a variety of applications, including cooking utensils, kitchenware, drums, funnels, decorative elements, electronic device components, appliances, and furniture.

Steel

Steel, an alloy primarily composed of iron and carbon along with other elements, exhibits varying properties based on its specific composition and the manufacturing methods used. These properties influence its workability and performance during metal spinning.

Stainless Steel

Stainless steel, defined by its chromium content of at least 10.5%, along with additional elements like nickel, molybdenum, and manganese, is renowned for its superior resistance to chemicals and corrosion. It offers exceptional strength, toughness, and rigidity, which are preserved even under high pressures and temperatures.

Carbon Steel

Carbon steel primarily consists of iron and up to 2% carbon. This composition enhances strength and rigidity but also increases brittleness, reducing malleability and ductility. The higher carbon content diminishes corrosion and chemical resistance, though carbon steel remains a cost-effective choice.

Carbon steel is categorized into low carbon or mild steel (less than 0.3% carbon), medium carbon steel (0.3 - 0.6% carbon), and high carbon steel (more than 0.6% carbon).

The steel's manufacturing process affects its workability in metal spinning. Hot-rolled steel, processed at temperatures exceeding its recrystallization point, is more ductile and malleable but prone to oxidation, which can weaken it. Cold-rolled steel, rolled at room temperature, is less flexible but maintains strength and is also suitable for metal spinning.

Steel, in its various forms, is ideal for heavy-duty applications and is widely used in automotive, construction, manufacturing, and aerospace sectors. It is commonly employed in the fabrication of pressure vessels, tanks, and processing equipment.

Brass

Brass is an alloy of copper and zinc known for its excellent thermal and electrical conductivity. Its copper content imparts resistance to corrosion, microbial growth, and biofouling. Brass is also valued for its attractive color, ranging from dull yellow to reddish hues, which makes it ideal for decorative applications.

With its good ductility and malleability, brass is highly workable during metal spinning. Common applications for spun brass parts include musical instruments, pipes and fittings, structural elements, furniture, and various electronic devices.

Bronze

Bronze is an alloy primarily composed of copper and tin, with additional elements like manganese and phosphorus. It is known for its distinctive yellowish-brown color and offers higher strength and rigidity compared to brass. Although heavier than brass and stainless steel, bronze maintains many of the beneficial properties of copper, including good weldability.

Parts made from spun bronze are highly durable and exhibit superior strength. Common applications include sculptures, musical instruments, trophies, engine components, and structural elements. However, bronze is less malleable and harder than brass.

Hastelloy

Hastelloy is a specialized metal alloy composed of nickel, chromium, and molybdenum. Renowned for its superior resistance to chemicals, oxidation, and corrosion, this alloy is frequently employed in demanding environments. It is commonly used for manufacturing tank heads in pressure vessels found in oil refineries, power generation facilities, and chemical plants, as well as in various automotive and aerospace components. With its impressive strength and durability, Hastelloy performs exceptionally well under high temperatures and pressures.

Titanium

Titanium is a metal known for its excellent strength-to-weight ratio and resistance to chemicals and corrosion. It's both lightweight and flexible, which makes it ideal for metal spinning applications. Despite these advantages, titanium is quite costly and less commonly used for spinning compared to other metals.

Chapter 6: What are the applications of metal spinning?

Metal spinning is an effective technique for producing concentric and symmetric parts in low to medium production volumes, especially when the expense of metal stamping dies is too high. For larger production runs, metal stamping becomes more cost-efficient and faster compared to metal spinning.

Certain metal shapes are too intricate for metal stamping to handle efficiently and are best created through metal spinning due to their unique design requirements.

Hemispheres

Metal hemispheres are versatile components used in a variety of applications, including lighting fixtures, reflectors, mixing bowls, satellite dishes, tank heads, covers, caps, and domes. They can feature either straight or curved walls and are crafted from materials such as cold rolled steel, stainless steel (grades 304 and 316), aluminum, copper, and brass.

Cones

Funnel shapes, hopper designs, and cone-shaped pendants.

Venturi

Venturi tubes used in dust collectors, fans, blowers, and air scrubbers.

Parabola

Bells, antenna reflectors, satellite dishes, lighting fixtures, and supports for columns and stands.

Cylinders

Tubes, vessel and tank casings, gas containers, and canisters.

Hopper Lids and Bases

Hopper lids and bases are crafted through hand spinning to handle different materials. These components are made from premium aluminum, spun and trimmed to meet specific customer requirements. Occasionally, additional processing is needed, such as incorporating holes and slots.

Tank Heads

Metal spinning is a fabrication technique used to manufacture tank heads for pressure vessels, storage tanks, and various process equipment. Given that these vessels often endure high pressures and challenging conditions, the goal is to produce seamless, robust, and resilient tank heads through metal spinning. This process demands meticulous control to meet stringent regulations regarding dimensions, strength, and material composition.

Typical shapes of tank heads include:

• Flanged only
• Dished only
• Flanged and dished
• Hemispherical
• High crown
• Torispherical
• 2:1 Semi-Elliptical

Chapter 7: What are the advantages and disadvantages of metal spinning?

The benefits of the metal spinning process include:

• Spun parts have greater reliability. Metal spinning produces seamless parts that are durable enough to withstand high internal pressures and external forces. The seams are weak spots in finished parts; they reduce strength and integrity. Metal spinning also refines the grain structure of the metal; this results in improved mechanical properties such as increased tensile strength, toughness, and hardness. This advantage allows lighter material to withstand the same pressure or external load for an application where lightweight and heavy-duty material is required.
• Metal spinning has simpler, easier to maintain, and more cost-effective tooling than stamping, casting, forging, and hydroforming processes. Soft and inexpensive tooling can be used for low production demands or one-time production. However, large-scale production requires harder and more rigid tooling. Tooling for the metal spinning process takes less set-up time.
• Making minor alterations on the final part is a lot easier and is quickly performed with metal spinning, especially if the change is a reduction of the part size. It only takes an adjustment of the tooling. Making alterations on the final part is expensive in other metalworking and casting processes.
• Metal spinning produces relatively smaller amounts of material wastes.

The drawbacks and constraints of the metal spinning process are as follows:

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• Metal spinning has longer processing times than other forming and casting processes. It is usually limited to small to medium production demands. Large-scale production consumes more time.
• Part consistency is difficult to maintain. In manual operations, part consistency and quality depend on the skill level of the operator.
• Metal spinning is limited to the production of axially symmetric shapes such as cones, parabolas, and hemispheres.
• Metal spinning has a small room for errors during production. Once defects (e.g., cracks, dents) are induced in the workpiece, it is difficult to repair as part quality and reliability are an expense. Therefore, defective parts must be scrapped.
• There are a lot of safety risks associated with manual spinning due to fast-moving parts. Make sure that the workpiece is tightly clamped between the tailstock and the mandrel before it is spun, as the workpiece may be thrown during the operation. Strong presence of mind must also be practiced during operation.

Conclusion

• Metal spinning is a metalworking process that involves the application of force by a roller in order for the workpiece, which is spinning at high speeds, to conform to the contour of the mandrel. Metal spinning transforms a flat or preformed metal sheet into an axially symmetrical figure.
• A lathe machine is adapted for the metal spinning process. The components of a metal spinning lathe are the mandrel, roller, tailstock, headstock, spindle, and follower.
• Conventional metal spinning increases the depth of the workpiece while maintaining its material thickness constant.
• In shear spinning, the material thickness of the workpiece is reduced while maintaining its diameter constant. The depth of the workpiece also increases.
• Hot spinning is used for materials that are difficult to deform at room temperature. It is used when the material has low ductility and malleability.
• Multiple pass spinning is used when producing parts with sharp and complex designs. It also ensures uniform thickness.
• Tube spinning is a form of shear spinning, which elongates hollow, cylindrical tubes.
• Ideal materials for the metal spinning process are metals that can be deformed on a mandrel and lathe or can be metal stamped. Metals commonly formed by metal spinning are aluminum, steel, brass, bronze, Hastelloy, and titanium.
• Metal spinning specializes in creating hemispheres, cones, cylinders, parabolas, and venturis. It is an ideal fabrication process for constructing tank heads.
• Spun parts are seamless; this makes them durable. Metal spinning also improves the mechanical properties of the metal by refining its grain structure.