Because the metal flow in the localised work roller zone and nearby areas is affected by tensile, radial, and compressive stresses, spinning is categorised as compressive draw forming.
In a plane perpendicular to the mandrel, tensile stresses are produced when the roller touches the workpiece. As the axial roller feed increases, these stresses grow, leading to volumetric displacement.
Compressive stresses form between the volumes when the metal's volume decreases towards the centre. Because of these tensions, the open end becomes thicker, and wrinkles and buckling are possible. The feed's direction can make up for this.
Table of Contents
What Is Metal Spinning?
A metal spinner uses a lathe to shape flat discs or sheets of metal, according to the definition of metal spinning. Metals can be bent, shaped, or shaped by hand using mechanical force or tools. Although the method can create objects with intricate curves, it often keeps the wall thickness consistent throughout the object, which is dictated by the initial sheet or disc thickness.
Products made of spun metal have found their way into various industries, serving as ornamental pieces and practical components. Metal spinning is a great way to make prototypes, one-of-a-kind items, and custom metal fabrications in medium to large quantities at a low cost. It can be used by teams to turn metals into marketable art.
Types of Metal Spinning
Conventional Metal Spinning
The workpiece is typically spun conventionally by having the roller push it over the mandrel's shape. The method maintains a constant thickness of the workpiece's material. The workpiece's diameter decreases, and its depth increases after shaping. Because of its relative ease of use, this form of metal spinning is often regarded as the most basic.
Shear Spinning
As the workpiece slides down the mandrel's surface, the rollers provide a downward force, a process known as shear spinning. Compared to its blank form, the final part has a thinner material thickness, but the diameter stays the same. Additionally, the workpiece's depth grows. The workpiece's mechanical qualities, such as its hardness and strength, are improved due to the higher compressive forces.
A more robust tooling design and accurate machining control are necessary for shear spinning because it impacts the part's dimensional accuracy and surface smoothness. It increases wear on the mandrel and friction on the workpiece. Because of the high temperatures produced, coolant is an essential component.
Hot Spinning
Using a heating torch, the workpiece is heated to the forging temperature during hot spinning. While the workpiece is being squeezed over the mandrel, the heating flame is directed towards it. When the material's ductility and malleability are poor, or the metal sheet is too thick to be easily bent at ambient temperature, the hot spinning process is employed. Cold spinning, which involves spinning at room temperature, works with any metal.
In the hot spinning process, the workpiece deforms plastically, improving grain structure and strength.
Yet, oxidation occurs quickly when the metal is heated. The procedure as a whole is more costly and harder to regulate.
Tube Spinning
Tube spinning, a type of shear spinning, lengthens hollow cylindrical tubes while decreasing their wall thickness. Mounting and clamping the tube in the mandrel is the initial step. Three or more rollers, placed equally around the tube, draw it over the mandrel's length. Like the motion of rollers, the axial flow of materials follows a specific direction.
The mandrel's outside and inside can be used to spin tubes. The exterior surface of the mandrel is used to stretch the tube in external tube spinning. A hollow mandrel is used for internal tube spinning, which involves spinning and stretching the tube.
If the wall thickness is not an issue, tube spinning can be utilised to fabricate tubes of different diameters. Improving the mechanical qualities of the tube necessitates a more complex tooling design, similar to shear spinning.
Adjustments
It may be necessary to alter the feeds, pressure, attack angle, roller shape and diameter, RPMs, and the workpiece's thickness and finish. A second pass can be made if the outside diameter needs to be reduced close to the workpiece's edge.
Adjusting the workpiece's edge can be challenging since it might result in either a sharp edge that requires trimming or an uneven edge. Careful execution is required when making changes. As the material is passed over the roller, it becomes harder and brittle, eventually springing back off the tool.
Metal spinning also allows for necking and expanding. The steady reduction of the part's diameter in a specific area is called necking. When a part's diameter segment increases, we say it has expanded.
Metal spinning requires two post-processes: planishing and cutting. As a final stage in metal spinning, planishing eliminates creases and tool marks from the completed product. Now, the workpiece is being ground using a planishing tool spun at a reduced speed. Trimming is the process of removing any surplus material from the edge of a completed product.
Metals Used in Metal Spinning
Metal spinning is a technique that can be applied to any metal. Metal spinning can process any metal that can be created by metal stamping. Metal spinning is a processing method used for metals that cannot be stamped. Besides carbon steel and tool steel, metal spinning may distort any metal because lathes work at 15,000 psi for the process.
Aluminum
Metal spinning is a great use for aluminium because of the metal's abundance, ductility, and malleability, as well as its high strength-to-weight ratio. The metal spun from it is the most common type. Not only is it thermally stable, but it also resists corrosion and chemicals. A lightweight and inexpensive substitute for steel is aluminium.
The following aluminium alloys are ideal for metal spinning: 1503, 6061, 5052, 2024, 7075, and 3003.
Appliances, furniture, decorative pieces, electronics, drums, funnels, and cooking utensils are just a few examples of the many uses for spun aluminium.
Steel
Steel is a metal that combines several elements, including iron, carbon, and others. Steel's composition and production process determines its qualities, including its workability during metal spinning.
Stainless Steel
In addition to nickel, molybdenum, and manganese, stainless steel requires at least 10.5% chromium. Its resistance to chemicals and corrosion is legendary. Its qualities, including great strength, toughness, and stiffness, are preserved even when subjected to extreme heat and pressure.
Carbon Steel
The primary elements of carbon steel are carbon and iron. There is less than 2% carbon. Carbon steel's strength and rigidity come at the cost of its malleability and ductility, as well as its hardness and brittleness. The elevated carbon content reduces its resistance to corrosion and chemicals. Despite this, carbon steel is a good substitute because it is inexpensive.
There are three different carbon steel grades: low carbon (also known as mild steel) with less than 3% carbon, medium carbon (ranging from 0.3% to 0.6%), and high carbon (more than 0.6% carbon).
The steel blank's workability when metal spinning is also affected by its production process. Milling hot-rolled steel takes place at temperatures much over its recrystallisation point.
However, cold-rolled steel is rolled without heating the metal. Hot-rolled steel has better ductility, malleability, and flexibility than cold-rolled steel. Hot rolling steel, on the other hand, weakens the material due to oxidation. However, metal spinning is an appropriate application for both varieties.
When it comes to demanding tasks, any steel will do. The aerospace, automotive, building, and manufacturing sectors frequently use spun steel components. Steel is a common choice of material for processing equipment, tanks, and pressure vessels.
Brass
Zinc and copper are the main elements in brass. Because of its copper, it is very conductive electrically and thermally and resistant to biofouling, microbes, and corrosion. Its attractive appearance and subtle yellowish-to-reddish hue make it an ideal decorative material.
The ductility and malleability of brass are excellent. Metal spinning produces a product with exceptional workability. Many common household items use spun brass components, including pipes and fittings, furniture, musical instruments, and electrical gadgets.
Bronze
Copper, phosphorus, manganese, and tin make up the alloy known as bronze. Its striking yellowish-brown colouration serves as a distinguishing feature. It is stiffer and stronger than brass. Its weight is higher than that of stainless steel and brass. Other brass-like qualities often associated with copper are also present. Additionally, it is easily welded.
Many things, like sculptures, musical instruments, engine parts, awards, and structural components, are made using spun bronze because of their durability and increased strength. In contrast to brass, though, it is less malleable and tougher.
Hastelloy
Among the elements that make up Hastelloy are chromium, nickel, and molybdenum. This unique alloy has gained immense popularity thanks to its remarkable resistance to chemicals, oxidation, and corrosion. Parts made of spun hastelloy find extensive application as pressure vessel tank heads in chemical and power plants, oil refineries, chemical manufacturing sites, and automotive and aerospace machinery. Hastelloy is strong and durable because to its heat and pressure resistance.
Titanium
Titanium is remarkable for its resistance to corrosion and chemicals, as well as its high strength-to-weight ratio. In addition to being a good material for metal spinning, it is lightweight, pliable, and soft. Titanium is less spun than other metals and is extremely costly.
Suggestions to Improve the Performance of Your Metal Spinning Design
Define Object Function
You risk squandering time and resources while spinning if you need more clarity on your design. The procedure suits designs with sharp corners because metal can only be spun on semi-circular or circular geometries. After the end aim is settled upon, a plan can be devised to use the accuracy and adaptability offered by metal spinning.
Pick Your Material
Metal spinning may be done with many different types of metals, but to get the most out of it and to avoid wasting any, you need to use the right materials for the job. The final product will vary greatly between metals according to the desired thickness.
Even a little alteration in the part's thickness or diameter can render it useless for your technical endeavour. Furthermore, the spinning process might cause some metals to become more stiff than others. For the greatest outcomes, it's important to know which metal is ideal for your project and to use a material that fits your demands well.
Consider Material Thickness
The thickness of your object's sidewalls can vary by as much as 25% and depends on the metal you select and the object's sidewall height. The force exerted by the mandrel on the unfinished metal must be carefully considered.
It would help if you prevented sharp corners in the final product because a greater corner radius is easier to work with and stronger than tighter ones. For optimal results, ensure the created end object radius is at least two or three times the material thickness. Although the corner radius can be 30% different from the metal thickness, it can be equal in other instances. As with the initial metal blank, the bottom's thickness will be constant.
Cost Factors
For low-volume projects, many metal-forming technologies are too expensive or time-consuming. However, metal-spinning prototypes and short runs shine. When you examine various sizes and tolerances in your design, a cost-benefit analysis can help you find ways to save money. Lead times may be shortened due to the rapidity of metal spinning in part creation, but planning for precise and rapid manufacturing is critical.
Metal spinning allows for the creation of smaller, more precise, typically stronger parts than those generated using other methods. By bringing the metal's grain structures into a more favourable alignment for your application, spinning can potentially enhance the raw material's qualities. In some situations, metal spinning may be a more economical alternative to other metal-forming techniques for making prototypes and one-off items.
Conclusion
Metal spinning is a process that uses a lathe to shape flat discs or sheets of metal, creating intricate curves and maintaining consistent wall thickness throughout the object. It has various applications in industries, such as ornamental pieces and practical components. There are three types of metal spinning: conventional, shear, hot, and tube spinning.
Conventional metal spinning involves pushing the workpiece over the mandrel's shape, maintaining a constant thickness. Shear spinning involves sliding the workpiece down the mandrel's surface, providing a downward force, improving the material's hardness and strength. Hot spinning uses a heating torch to heat the workpiece to the forging temperature, while tube spinning lengthens hollow cylindrical tubes while decreasing their wall thickness.
Adjustments to feeds, pressure, attack angle, roller shape and diameter, RPMs, and the workpiece's thickness and finish may be necessary. Necking and expanding are also possible. Metal spinning requires two post-processes: planishing and cutting.
Metals used in metal spinning include aluminum, steel, and stainless steel. Aluminum is ideal for metal spinning due to its abundance, ductility, malleability, high strength-to-weight ratio, and thermal stability. Steel is a lightweight and inexpensive substitute for aluminum, with alloys like 1503, 6061, 5052, 2024, 7075, and 3003 ideal.
In summary, metal spinning is a versatile and cost-effective method for shaping various metals, including aluminum, steel, and stainless steel.
Steel is a metal composed of iron, carbon, and other elements. Its composition and production process determine its qualities, including workability during metal spinning. Stainless steel requires at least 10.5% chromium for resistance to chemicals and corrosion. Carbon steel has less than 2% carbon and is strong but has malleability, ductility, hardness, and brittleness. There are three grades of carbon steel: low, medium, and high.
The steel blank's workability during metal spinning is affected by its production process. Milling hot-rolled steel takes place at temperatures much over its recrystallisation point, while cold-rolled steel is rolled without heating the metal. Hot-rolled steel has better ductility, malleability, and flexibility than cold-rolled steel.
Brass is a popular choice for spinning components in aerospace, automotive, building, and manufacturing sectors. Its ductility and malleability make it ideal for decorative items like pipes, fittings, furniture, musical instruments, and electrical gadgets. Bronze, made up of copper, phosphorus, manganese, and tin, is stiffer and stronger than brass but less malleable and tougher. Hastelloy, made up of chromium, nickel, and molybdenum, is known for its resistance to chemicals, oxidation, and corrosion.
Titanium is a remarkable material for metal spinning due to its resistance to corrosion and chemicals, high strength-to-weight ratio, and lightweight properties. To improve the performance of your metal spinning design, define object function, choose the right material, consider material thickness, and consider cost factors. Metal spinning allows for the creation of smaller, more precise, and typically stronger parts than other methods, potentially enhancing the raw material's qualities.
Content Summary
- Metal spinning, or spin forming, shapes metal into axisymmetrical parts under tensile, radial, and compressive stresses.
- The process involves a roller and mandrel spinning rapidly to shape a flat metal disc or sheet.
- Metal spinning can maintain or reduce the starting metal sheet thickness, depending on the technique.
- Conventional spinning keeps the material thickness consistent, altering the workpiece's diameter and depth.
- Shear spinning thins the material, maintaining diameter but increasing depth, enhancing mechanical properties.
- Hot spinning involves heating the workpiece to forging temperatures, refining grain structure but risking oxidation.
- Tube spinning extends hollow cylindrical tubes, improving mechanical qualities with complex tooling design.
- Adjustments in metal spinning include feeds, pressure, roller shape, and the workpiece's thickness and finish.
- Necking and expanding are techniques for reducing or increasing the diameter of a part's specific area.
- Planishing and cutting are post-processes for smoothing and trimming the spun metal parts.
- Metal spinning can work with any metal, offering versatility in material choice.
- Aluminium is popular for its abundance, ductility, and corrosion resistance, making it ideal for various applications.
- Steel, including stainless and carbon varieties, is used for its strength and durability in different sectors.
- Brass, known for its electrical conductivity and corrosion resistance, is used in decorative and practical components.
- Bronze offers greater strength and corrosion resistance than brass, used in durable and decorative items.
- Hastelloy is chosen for its exceptional chemical and corrosion resistance in harsh environments.
- Titanium is prized for its strength-to-weight ratio and corrosion resistance, though it's less commonly spun due to cost.
- Metal spinning benefits include versatility, cost-effectiveness, efficient material usage, and precision.
- The process supports rapid prototyping, short lead times, and design flexibility, making it suitable for various applications.
- Metal spinning produces durable, strong parts with seamless, high-quality surface finishes.
- Defining the object's function helps tailor the metal spinning process to the design's specific requirements.
- Choosing the right material is crucial for achieving desired outcomes, considering factors like thickness and mechanical properties.
- Material thickness considerations are essential for ensuring the part's strength and functionality.
- Conducting a cost analysis can identify potential savings and optimise the manufacturing process.
- Metal spinning allows for the efficient production of small batches and prototypes, enhancing the raw material's qualities.
- The process is adaptable, supporting the creation of complex shapes and intricate designs.
- Metal spinning's environmental benefits include minimal waste production and the potential use of recycled materials.
- The technique is widely used across industries, including aerospace, automotive, lighting, and decorative arts.
- Innovations in metal spinning continue to expand its applications and improve its efficiency.
- Collaboration between designers, engineers, and metal spinners enhances the quality and creativity of spun metal products.
- Metal spinning's cost efficiency makes it an attractive option for businesses seeking to reduce manufacturing expenses.
- The process's rapid turnaround times help companies meet market demands and project deadlines efficiently.
- Metal spinning's design flexibility enables the realisation of unique and custom metal fabrications.
- The seamless construction of spun parts enhances their performance and aesthetic appeal.
- Metal spinning's durability and strength are critical for applications requiring high-performance components.
- The technique's historical significance enriches its modern applications, blending tradition with innovation.
- Metal spinning's adaptability to different metals allows for a wide range of product designs and applications.
- The process supports sustainability initiatives by maximising material efficiency and minimising waste.
- Metal spinning plays a crucial role in prototyping, allowing for quick testing and iteration of design ideas.
- The technique offers a unique solution for producing high-quality, axisymmetrical metal parts.
- Metal spinning contributes to advancements in manufacturing and design, pushing the boundaries of metal forming.
- The process's precision aids industries requiring reliable and consistent components.
- Metal spinning's environmental benefits align with contemporary sustainability goals.
- The technique allows for the economical production of custom and small-batch items.
- Metal spinning continues to evolve, incorporating new technologies and materials.
- Collaboration with experienced metal spinners can unlock new possibilities in product development.
- Metal spinning's versatility and cost efficiency make it a valuable tool in the manufacturing landscape.
- The technique's ability to produce seamless parts is particularly beneficial for specific applications.
- Understanding the nuances of metal spinning can lead to better product performance and manufacturing outcomes.
- Metal spinning remains a dynamic field, contributing to innovation in product design and manufacturing.
Frequently Asked Questions
Automatic spinning involves specialised machinery that automatically feeds and shapes metal blanks into desired forms without the need for manual intervention during the spinning process.
While both automatic and CNC spinning utilises automated processes, automatic spinning often involves dedicated machines designed for specific spinning tasks, whereas CNC spinning machines can be programmed for various spinning operations.
A wide range of metals can be spun, including aluminium, stainless steel, copper, brass, and various alloys, depending on the application's specific requirements.
Common applications of metal spinning include the manufacturing of kitchenware, lighting fixtures, aerospace components, automotive parts, and architectural elements.
CNC spinning is often preferred for mass production due to its high precision, repeatability, and efficiency in shaping metal blanks into consistent forms at a relatively rapid pace.