Flow Drill Fastening vs. Conventional Screw Connections: Differences & Benefits
Modern designs in mechanical engineering, the automotive industry, and lightweight construction place high demands on joining technologies. In addition to conventional screw connections, an alternative method is increasingly being used: flow drill fastening.
We explain the key differences and show in which applications flow drill fastening has proven particularly effective.
What are the differences between the two methods?
And when is flow drill fastening the better choice?
What Is Flow Drill Fastening?
In flow drill fastening, no thread exists before the joining process. Instead, the thread is created directly in the component during the fastening process.
The flow drill screw is driven into the material at high speed and with controlled feed force. Friction generates heat, causing localized plastic deformation of the material, which is displaced downward. This creates an extruded collar into which the screw is subsequently driven with a form-fit connection.
The entire process – penetration, thread forming, and fastening – takes place in a single operation.
This creates a strong screw connection without the need for pre-drilling or thread cutting.
For a detailed introduction to how flow drill screws work, read our article → Friction drilling: the future of fastening technology?
Why Flow Drill Fastening Offers Advantages over Conventional Screw Connections
Compared directly with conventional screw connections, flow drill fastening offers clear process-related and design-related advantages, particularly in automated manufacturing environments and when joining thin-walled materials.
Unlike conventional screw connections, which require drilling, thread cutting, and additional process steps, flow drill fastening combines the formation of the extruded collar, thread forming, and fastening itself into a single operation.
This not only reduces process complexity but also improves repeatability and overall efficiency.
Key Advantages at a Glance
No pilot hole and no additional thread creation required
Reduced process steps and shorter cycle times
High thread load capacity even in thin-walled materials
No additional fastening elements such as nuts or threaded inserts required
Fastening possible with access from only one side of the component
The technology particularly demonstrates its strengths in automated assembly processes. By combining thread forming and fastening in a continuous process, stable and repeatable joints can be achieved with a high level of process reliability.
This makes flow drill fastening a powerful alternative to conventional screw connections, especially in applications focused on efficiency, automation, and lightweight design.
Conventional Screw Connections
With conventional screw connections, the thread is usually prepared before the fastening process begins.
Typical methods include:
Tapped holes in the component
Use of nuts
Use of threaded inserts
Combination with blind rivet nuts or weld nuts
These joining techniques are well established and versatile. However, they generally require multiple process steps and additional components.
Particularly with thin-walled materials, thread load capacity can be limited, making additional fastening elements necessary.
Direct Comparison of Joining Technologies
| Criteria | Flow Drill Fastening | Conventional Screw Connection |
|---|---|---|
| Pilot hole required | No | Yes |
| Process steps | 1 | Multiple |
| Thread load capacity in thin materials | High | Often limited |
| Additional fastening elements | Not required | Often required |
| Automation capability | Excellent | Good |
| Component accessibility | Single-sided access possible | Often requires access from both sides |
| Cost per joint | Low in series production | Higher due to additional components |
The comparison shows that flow drill fastening offers significant advantages wherever high process speed, automation, and lightweight construction are key priorities.
When Is Flow Drill Fastening the Better Choice?
Flow drill fastening is particularly beneficial when processes must be efficient, repeatable, and implemented with as few production steps as possible.
Typical applications include:
Thin-walled materials such as sheet metal or profiles
Automated high-volume production
Applications with access to the component from only one side
Assembly processes focused on short cycle times
In all of these cases, flow drill fastening offers clear advantages over conventional screw connections.
Typical Applications of Flow Drill Fastening
Today, the technology is used across a wide range of industries.
It is particularly common in applications involving thin-walled metal structures (lightweight construction) or multi-material joints.
Automated Flow Drill Fastening in Industrial Assembly
To ensure reliable flow drill fastening, several process parameters must be precisely coordinated.
These include rotational speed, torque, feed force, and process monitoring.
For this reason, automated production lines use specialized fastening systems that precisely control the entire process.
One example is the ADAPTIVE DFS fastening system. It combines an electronically controlled screwdriving unit with a servo-electric feed axis. The entire fastening process is continuously monitored.
Thanks to adaptive process control, even demanding flow drill fastening applications can be automated with repeatability and high process reliability.
When Is Each Joining Technology the Right Choice?
The choice between flow drill fastening and conventional screw connections depends largely on the specific requirements of the component, the process, and the production environment. Both technologies have their place. The decisive factor is the individual application.
Flow Drill Fastening – Ideal for Automated Processes and Lightweight Construction
Flow drill fastening demonstrates its strengths particularly in modern automated manufacturing environments. It is an excellent choice when processes need to be efficient, repeatable, and implemented with as few production steps as possible.
Typical Applications
Thin-walled materials such as sheet metal or profiles
Multi-material joints, e.g., steel-to-aluminum
High production volumes and automated serial manufacturing
Single-sided access to the component
Focus on short cycle times and reduced process costs
In these applications, flow drill fastening significantly simplifies the assembly process while maintaining high joint quality.
Conventional Screw Connections – Flexible and Universally Applicable
Conventional screw connections offer advantages in applications where maximum flexibility or existing threaded structures are the primary consideration.
Typical Applications
Thick-walled components with existing threads
Applications requiring frequent disassembly and reassembly
Low production volumes or manual assembly processes
Use of standardized fastening elements
In these cases, conventional screw connections stand out for their versatility and ease of use.
Decision Guide at a Glance
When processes need to be automated, fast, and implemented with minimal effort, flow drill fastening offers clear advantages. Especially in lightweight construction and modern manufacturing concepts, it is often the more efficient solution.
Conventional screw connections, on the other hand, remain the right choice for flexible applications, individual assemblies, or existing designs with predefined threads.
In practice, one thing becomes clear: The higher the degree of automation and the greater the demands on efficiency and process reliability, the more flow drill fastening demonstrates its advantages.
Conclusion
Flow drill fastening is a powerful alternative to conventional screw connections, particularly in automated production environments.
By combining thread forming and fastening in a single process step, cycle times can be reduced while creating strong joints even in thin-walled materials.
For industrial applications, specialized fastening systems are available that precisely control the flow drill fastening process and ensure a high level of process reliability.
Automated Flow Drill Fastening with ADAPTIVE DFS
For the automated implementation of flow drill fastening, DEPRAG offers the specialized ADAPTIVE DFS fastening system.
→ Learn more about the ADAPTIVE DFS flow drill fastening system here
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