Self-tapping screws are those that can form their own threads as they are driven into the material. Plastic requires a specially designed thread profile as tapping screws used with steel can result in residual stresses in the plastic that can degrade the structural integrity of the assembly. Plastic screws give you more flexibility and quickly assemble components with fewer fasteners. When looking into self-tapping screws, the first step is to decide what type of self-tapping screws are best suited for the application. Thread-forming and thread-cutting are the two categories self-tapping screws are classified into. Below is a brief description of each category.
When you are using a thread-forming screw, you will get a very secure fit. Thread-forming screws produce little waste as the plastic that is displaced to create the thread relaxes back into the root of the thread. This attribute is one of the reasons why a thread-forming screw would be chosen over thread-cutting. Thread-forming screws, generally, function best in thermoplastics. This is due to the spring back function of the material to fill voids created by the screw.
These screws actually remove material because they have cutting edges. In general, thread-cutting screws can be used for both thermoplastics and thermosets without issue. Each application can result in a different screw being recommended, so a review of each application should be done. Thread-cutting screws have a smaller flank angle to reduce instillation torque while increasing surface area which results in a higher pullout force.
ecosyn®-plast is a great option for a thread-cutting screw for plastic. These screws are designed differently than tapping screws because they are designed to easily penetrate the material without causing stress to the material. Check out some advantages of ecosyn®-plast:
- Low driving torque and high stripping torque
- High breaking torque and tensile strength of the screw
- Excellent security against vibration
- Low risk for cracking the base material
- No setting of the assembly due to excessive relaxation of the plastic material
If you have questions about self-tapping screws for plastic or need help in deciding on a fastener, contact us at ProvenProductivity@bossard.com. Our experts can help you get the materials you need for a successful project. We are also prepared to provide you with technical advice and we can even provide field-related assembly tests for you in our laboratory to help with application technique.
Self-Tapping Screws for Plastic by Bossard