Orbital forming is an advanced metal forming technique that serves to shape, join, and assemble materials with precision and durability. This article reviews what orbital forming is, the step-by-step process, various types, as well as the orbital forming chart.
Orbital Forming Process
Orbital forming is a cold forming process that uses localized, incremental plastic deformation to reshape a workpiece. Unlike conventional methods, that apply direct axial force, orbital forming employs a sweeping line of pressure, gradually shaping the material. The rotating tool (die or peen), rotates around the rivet or tenon at a fixed tilt angle, hence, causing the material to collapse and form a desired head. This process is particularly effective for creating low-profile, aesthetically pleasing finishes while maintaining joint articulation
This forming process requires a number of steps, which the following sections discuss in details.
Material Selection and Blank Preparation
The material selection process prioritizes ductile alloys such as aluminium AA6061, titanium Ti-6I-4V, and low-carbon steel. These materials are also common in metal stamping operation because they can undergo plastic deformation without cracking. On selecting the raw material, cut it into a near-net-shape blank, example a cylindrical billet for gears, flat disc for flanges. Then, clean the blank’s surface to remove every contaminant, and apply a lubricant like graphite or PTFE to minimize friction. A perfect example of this process is an aerospace rivet blank, which will be a precision-cut from an aluminium 2117 rod and coating with dry-film lubricant to prevent galling during forming.
Machine and Tooling Setup
Configure the orbital forming machine with two primary components: the upper peen / die tool (tilted at 1–6°) and the lower die (stationary or rotating). The upper tool is typically made of high-speed steel (HSS) or carbide for wear resistance. Next, calibrate the tilt angle on the basis of the part geometry. Generally, smaller angles (1–2°) are for shallow forming and larger angles (4–6°) are for deep draws.
Workpiece Loading and Fixturing
Clamp the blank securely onto the lower die using a hydraulic fixture or vacuum chuck. Precise alignment is critical to ensure the orbital path of the upper tool centres on the workpiece. This is because misalignment can lead to asymmetric deformation or premature tool wear. In automotive applications, a steel constant velocity (CV) joint blank might be fixtured with a hydraulic clamp to prevent slippage during high-speed orbital motion.
Initiation of Orbital Motion
On initiating the machine, the upper die rotates in a predefined orbital path while maintaining its tilt angle. The CNC-controlled actuators or eccentric drive mechanism generate an orbital motion. As the tool orbits, its tilted face creates a sweeping line of contact with the workpiece. Hence, applying localized pressure to a small area (~5-10% of the surface). For example, forming a copper electrical connector might involve a spiral orbital path with a 2 mm radius and 300 RPM rotational speed.
Incremental Deformation and Material Flow
The tool’s orbital motion induces progressive plastic deformation in the workpiece. Metal flow either radially outward (to form flanges or splines) or axially (to thicken walls or upset rivet heads). The incremental loading reduces peak stresses, allowing large deformation with minimal force. Strain rates are carefully controlled to avoid adiabatic heating or cracking. For instance, forming an aluminium gear might require 100 orbital cycles, with each revolution displacing material into the die cavities by 0.1mm.
Continuous Monitoring and Feedback
Sensors embedded in the machine monitor force, temperature, and tool alignment in real time. A closed-loop feedback system adjusts parameters like rotational speed or axial force to compensate for material variability. Then a lubrication system intermittently sprays fresh lubricants to maintain a low-friction interface.
Completion of Forming Cycle
The orbital motion continues until the workpiece reaches its final geometry. The machine automatically retracts the upper die, and the finished part is unloaded. Cycle times vary from seconds (for small fasteners) to minutes (for complex components, such as a medical implant thread which might take 2 minutes with 120 orbital revolutions).
Quality Control and Inspection
Within the quality system frame work, the final step of the orbital forming process involves rigorous quality control and inspection. This includes verifying dimensional tolerance (±0.05mm) using coordinate measuring machines (CMM) and conducting non-destructive testing (NDT) methods. Examples include ultrasonic testing or dye penetrant inspection to identify defects, therefore, ensuring compliance with specified standards and documentation protocols.
Orbital Forming Types
Orbital forming categorization is according to the tool path, application, or specific techniques. Each of the types addresses specific industrial needs, from high-strength aerospace joints to precision medical devices. The following sections highlight some of them.
Orbital Riveting (Orbital Peening)
Orbital riveting is a process ideal for creating strong, aesthetically pleasing rivet heads. It involves using a peen tool to gradually form the rivet shank into a specified head shape, ensuring a secure and visually appealing joint. The low-force nature of orbital riveting minimizes material stress and distortion, therefore, making it suitable for delicate components.
Orbital Staking
Orbital staking employs a sharper tool to peel material away from the substrate. This process forms a lip or flange over the part that it retains, thus, securing it in place. Deploying this method is common when assembling components that require a strong, tamper-resistant joint.
Orbital Flaring
Orbital flaring utilizes an eyelet-type peen tool to form a semi-tubular rivet tenon or eyelet outward. This method secures two or more components together, creating a robust and reliable connection. Orbital flaring is common in applications where a flared end provides additional support and prevents the joint from pulling apart.
Roller Forming
Roller forming employs die rollers to create retention joints, which can be either tubular structures or machined castings and forgings. In radius roller forming, a radius roller die is used for applications where thin-walled tubular forms are curled over.
Impact Riveting
Impact riveting is an assembly process that uses force to permanently fasten two surfaces together. The high-impact nature of the process swells the shank of the rivet, filling the holes in the material layers. It is an ideal process for high shear load joints and high RPM rotating joints.
Orbital Swaging
Orbital swaging compresses rods, tubes, or wires radially to reduce diameter or create profiles. For example, copper tubes are swaged into leak-proof connectors for medical devices.
Orbital Forming Chart
An orbital forming chart is a valuable tool for determining the optimal parameters for a specific application. This chart typically includes information on material types, rivet diameters, forming forces, and cycle times. By consulting the chart, engineers can select the appropriate powerhead and settings to achieve the desired joint strength and appearance. It can also assist in determining powerhead requirements to form a mild steel rivet. Below is a sample of a standard orbital forming chart with some critical parameters for common applications.
| Material Type | Shank Diameter | Tool Force (kN) / Pressure (MPa) | Forming Time (Seconds) | Rotation Speed (RPM) | Final Head Size (mm) |
| Aluminium 6061-T6 | 3-20 | 10-30 kN / 50-150 MPa | 10-30 | 300-500 | 1.5-3 x shank diameter |
| Titanium Ti-6AI-4V | 4-15 | 50-150 kN / 200-400 MPa | 30-90 | 100-200 | 1.2-2 x shank diameter |
| Stainless Steel 316L | 5-25 | 150-500 kN / 400-800 MPa | 60-180 | 50-150 | 1.5-2.5 x shank diameter |
| Copper C11000 | 2-12 | 5-20 kN / 30-100 MPa | 5-20 | 400-600 | 2-3 x shank diameter |
| Low-Carbon Steel (AISI 1018) | 6-25 | 80-300 kN / 200-600 MPa | 20-60 | 150-300 | 1.5-2.5 x shank diameter |
Factors Influencing Orbital Forming Chart Parameters
Several factors influence the parameters listed on an orbital forming chart.
- Material Properties: The material’s hardness, tensile strength, and malleability significantly impact the forming process. Softer materials require less force and shorter cycle times, while harder materials may require higher force and longer cycle times.
- Rivet Dimensions: The diameter and length of the rivet or tenon influence the required forming force and cycle time. Larger rivets necessitate higher forces to achieve proper deformation.
- Desired Head Form: The shape and size of the desired rivet head affect the selection of the peen tool and the forming parameters. Different peen designs are optimized for creating specific head forms, such as flat, round, or conical heads.
- Equipment Capabilities: The capabilities of the orbital forming machine, including its force capacity and speed range, also influence the selection of forming parameters. It’s important to select parameters that are within the machine’s operating limits.
Creating an Effective Orbital Forming Chart
To create an effective orbital forming chart, follow these guidelines.
- Material Testing: First, perform thorough testing on various materials to determine their forming characteristics. This testing should include measuring the force required to achieve different levels of deformation and assessing the resulting joint strength.
- Data Collection: Next, collect data on the relationship between forming parameters (force, speed, cycle time) and the resulting joint quality. This data should be organized in a clear and concise manner, hence, making it easy for engineers to reference.
- Chart Organization: Organize the chart by material type, rivet diameter, and desired head form. Include recommended force ranges, cycle times, as well as peen tool types for each combination of parameters.
- Regular Updates: Review and update the chart regularly to reflect changes in materials, equipment, and also application requirements. Continuous improvement ensures the chart remains accurate and relevant.
Applications of Orbital Forming
Orbital forming serves across a wide range of industries due to its versatility and efficiency, with some examples as follows.
Orbital Forming in the Automotive Industry
In the automotive industry, orbital forming assembles brake linings, hinges, and various interior components. Its ability to join dissimilar materials, such as aluminum to steel, makes it invaluable in vehicle manufacturing.
Electronics
In electronics, this cold-forming process secures components in circuit boards, connectors, and also other electronic devices. The low-force nature of the process prevents damage to sensitive electronic components.
Consumer Goods
In consumer goods, it assembles appliances, hand tools, and furniture. Its aesthetic appeal and ability to create durable joints make it ideal for high-volume manufacturing.
Aerospace
In the aerospace sector, orbital forming is employed to join lightweight, high-strength materials in aircraft structures and engine components. The process’s precision and reliability are critical in ensuring the safety and performance of aircraft.
Orbital Forming at ITD Precision
Enhance your production efficiency with ITD Precision’s advanced orbital forming capabilities. Our automated assembly technologies, including index orbital riveting and also custom-engineered fixtures, ensure precise, durable, and high-quality component assembly. With expertise in various materials and stringent industry standards, we deliver customized solutions tailored to your exact specifications. Whether you need strong, reliable joints for automotive, aerospace, or industrial applications, ITD Precision has the experience and technology to get the job done right. Contact us today to learn how our orbital forming expertise can add value to your next project.
