Chipless thread forming in plastics using thread-forming screws

Direct Screwing in Plastics – Reliable Joints with Reduced Stress

Optimized thread geometries help prevent component damage, reduce critical stress concentrations in the material, and ensure process-reliable fastening across a wide range of plastic applications.

Direct screwing in plastics creates durable screw joints directly in the component, eliminating the need for additional fastening elements. Specifically engineered thread geometries precisely control material flow and enable controlled thread formation. This results in stable clamp loads and consistent installation behavior, supporting repeatable assembly processes. The outcome is an efficient and robust fastening solution for plastic applications.

Direct Screwing in Plastics with a Thread-Forming Screw Installed in a Plastic Component

Our Direct Screwing Solutions for Plastics

baier & michels develops direct screwing concepts specifically engineered for plastics and tailored to the characteristic properties of thermoplastic and thermoset materials.

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Thread Creation without Pre-Cutting Operations

During installation, the required thread is formed directly in the plastic through thread forming, eliminating the need for any chip-producing machining operations. The fastener precisely displaces the material and forms a load-bearing mating thread that is perfectly matched to the screw geometry. This creates accurately fitting contact surfaces without the manufacturing-related tolerances that can occur with pre-cut internal threads. As a result, this principle enables efficient assembly as well as durable and removable joints.

Typical Applications for Our Thread-Forming Screws in Plastics

  • Automotive Industry
  • Electrical Engineering
  • Medical Technology
  • Industrial and Consumer Goods
Wherever cost-effective and reliable fastening technology is required, direct screwing in plastics offers clear advantages.

Circular Thread Profile with Self-Locking Performance Without Additional Locking Elements

Thread Geometry as the Key Factor

b&m thread geometries are deliberately designed to differ from conventional screw concepts. Instead of a 60° flank angle, reduced angles of 30° and 25° are used. This design forms the basis of modern direct screwing systems and improves material engagement while achieving a higher fill level at the thread root. At the same time, screw bosses in injection-molded components can be designed with less material, supporting the implementation of thin-walled component structures. The increased overlap between the thread flanks and the plastic material also ensures reliable load transmission.

Our Direct Screwing Solutions for Plastics

Reliable fastening directly in plastics – engineered for outstanding performance and maximum process reliability.

Optimized direct screwing system for high performance plastics

b&m-PLAST R®

Optimized direct screwing system for high performance plastics

Frequently Asked Questions About Direct Screwing in Plastics (FAQ)

Direct screwing in plastics is a fastening method in which a thread is created directly in the component during screw installation. Separate pre-processing operations such as thread cutting or the use of additional fastening elements are not required. The result is a cost-effective and durable screw joint, particularly suited for the industrial production of plastic components.

In direct screwing applications, the thread is created directly in the material through thread forming. Rather than removing material, the plastic is intentionally displaced and reshaped. A specially designed thread geometry controls material flow and forms a load-bearing mating thread. This creates precise, removable joints with consistent assembly performance.

Thread forming and thread rolling are chipless processes in which the plastic material is reshaped through displacement. In thread forming, the thread is generated directly during screw installation. In contrast, thread cutting removes material, which can lead to stress concentrations or reduced strength in plastic components. For this reason, chipless processes are often the preferred solution for plastic applications.

Direct screwing is suitable for various types of plastics, including:
  • Thermoplastics
  • Thermosets
Depending on material properties—particularly strength, toughness, and glass-fiber content—the thread geometry and joint design can be adapted accordingly. The method is especially well suited for integration into injection-molded components.

Direct screwing in plastics offers both technical and economic advantages:
  • Reduced assembly effort by eliminating additional components such as threaded inserts
  • Efficient processing with short cycle times in mass production
  • Consistent screw-in behavior for repeatable assembly processes
  • Adaptability to different materials and component geometries
  • Support for lightweight designs through material-efficient construction
This makes the process particularly suitable for applications requiring a combination of cost efficiency, component optimization, and reliable performance.

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