Impact Riveting uses impact force to permanently fasten components together. The quick process helps to minimize cycle time, increase throughput, and lower operating expenses. The most commonly used rivet for impact riveting is a mild steel semi-tubular rivet. The proper rivet geometry is crucial to meet the joint requirements.
Orbitform’s Lab Technicians have helped numerous customers assemble their parts in our Solution’s Lab and helped determine what fastener best fits their application. With over 30 years of experience, we have developed general guidelines to consider when choosing semi-tubular rivets.
There are three critical diameters to consider when choosing a semi-tubular rivet: head diameter, shank diameter, and end-hole diameter . The pull-out force required for the joint will determine the necessary head diameter. Soft materials will require larger diameter heads with greater surface areas to withstand pull-out forces.
The rivet shank diameter can be determined by comparing it to the thickness of the material stack up . Optimally, the ratio between the shank diameter and part thickness should between 1:1 and 1:3 for metal parts (closer to 1:1 for plastic parts).
Once the shank diameter has been determined, you can design the clearance hole to fit the rivet. This is important because too small of a hole can lead to rivet feeding issue or damage to the rivet or part. Generally, the clearance hole should be .010” to .015” larger than the shank diameter.
The rivet end-hole diameter should be about 70-80% of the shank diameter. Larger percentages mean the wall is thinner, which is easier to form and requires less force. However, this may also decrease the strength of the joint.
Another important consideration is the depth of the hole in the end of the rivet. The average depth is 100-125% of the end-hole diameter. Proper hole depth is necessary to prevent the rollset from hitting the body of the rivet and causing shank swell or rivet deformation.
Shank Length & Rivet Stick Out
The shank length is determined by the part stack up thickness and the required rivet stick-out . This stick-out is also known as clinch allowance and is generally between 50-55% of the shank diameter. If the rivet is too long, the parts may not be fastened together tightly. If the rivet is too short, there may not be enough material to clinch the parts together at all.
Mild steel rivets are the most common rivets used for impact riveting. However, different rivet materials may give very different results. For example, harder materials, such as stainless steel, require more force to form. This may increase the chances of shank swell and must be considered when determining shank length. It is vital to be aware of the hardness of rivets when designing parts and to determine the appropriate assembly equipment.
With over 30 years of manufacturing and assembly experience, our lab technicians and engineers have supported tens of thousands of assembly applications. Call us today for help determining the proper rivet size for your part, and let us assemble samples in our Solution’s Lab to ensure your part meets your requirements.
Posted: 09/12/2018 | by The Orbitform Blog Team | Posted in Impact Riveting
Growing With Purpose
Milford Fastening Company began in 1940 as Milford Rivet & Machine Company and was recognized across the industry for building quality riveting machines, many of which are still in operation today. When Orbitform identified Milford as an acquisition target, company leaders saw an opportunity to gain a brand with significant marketplace recognition that would benefit customers by offering them a full suite of fastening solutions under one roof.
The deal resulted in Orbitform expanding its lineup by adding light and medium-duty impact riveting machines to the existing product categories of orbital, radial and heavy-duty impact fastening capabilities. The company also gained loyal advocates who knew and trusted the Milford brand. This growth elevated Orbitform’s position as a leading one-stop-shop for all riveting applications.Integrating Brand Identities
Upon approval of the acquisition, Orbitform took the first step in integrating Milford into its product line by moving the machine design and manufacturing to Orbitform’s facility in Jackson, Michigan. Rather than absorbing the product line and offering the capability as-is, Orbitform engineers constantly enhance Milford riveters by introducing modern manufacturing techniques, thus reducing the variability of internal components. The initial upgrades allowed new Milford machines to be built without their typical “fit at assembly” process.
Orbitform fastening experts also designed improved safety devices, new tooling configurations and automated rivet feeding systems for the Milford line of riveters. Milford riveters are now available in mechanical and pneumatic models with various upgrades: vibratory and mechanical rivet feeders, enhanced safety features, several operator actuation methods, and optional process monitoring of forces, loads, and deflections.Brand Recognition Education
One of the key challenges in business acquisitions is educating past, current and new customers about changes that will impact them. More than a decade has passed since Orbitform’s procurement of Milford, yet some customers remain unaware of the transition.
There are multiple ways to share the news about major business changes and how they will impact customers, including written and digital communications, advertising, and even alignment of the sales force to ensure all products are being positioned equally. However, internal buy-in must be achieved before a transition will be successfully accepted externally.Continued Legacy Product Support
An important factor to consider during an acquisition is determining how to offer customer service for products already in service. At Orbitform, the knowledgeable Spare Parts and Tooling team became experts on the entire spectrum of Milford products. This allowed the team to serve as an invaluable resource for previous and new customers seeking support, as well as for those who require extensive troubleshooting or replacement parts.
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