Special Five-Lobed Thread Profile
The thread cross-section features five raised forming areas, allowing the screw to progressively act on the hole wall at specific contact points rather than subjecting the entire circumference to thread-forming resistance at the same time.
The number, angle, protrusion height, and arrangement of the five lobes should be confirmed according to the original product design.
Forms Internal Threads in a Pilot Hole
When driven into a properly sized pilot hole, the special thread profile can displace or cut into the material and form internal threads that mate with the screw, reducing the need for a separate tapping process.
TYPE-BF screws generally still require a suitable pilot hole unless the product is specifically designed with a drill point or other structure capable of directly penetrating the material.
Helps Reduce Thread-Forming Resistance
The five raised lobes contact the hole wall progressively, reducing the friction that would occur if the entire thread circumference engaged the workpiece simultaneously. This can make thread forming and driving easier to control.
Actual driving torque will still depend on pilot hole size, workpiece material, hardness, screw thread profile, and surface treatment.
Increases Localized Contact Pressure
The five-lobed profile concentrates thread-forming force at several contact points, helping the screw displace or cut into the workpiece material and form matching internal threads.
If the workpiece material is too hard or lacks sufficient ductility, thread wear, screw breakage, or workpiece cracking may occur.
Provides Stable Thread Engagement
Because the internal threads are formed directly by TYPE-BF, the resulting contact surfaces can conform to the thread profile, helping increase engagement and friction between the screw and hole wall.
Actual pull-out strength, prevailing torque, and load capacity should be verified through sample assembly and functional testing.
Provides Auxiliary Anti-Loosening Performance
The special multi-lobed profile can increase localized contact pressure and thread friction, helping reduce the possibility of reverse rotation under general vibration or equipment operating conditions.
The five-lobed thread design should be regarded as an auxiliary anti-loosening feature. Additional locking measures should still be considered for high-vibration, high-load, or safety-critical applications.
Reduces the Need for Pre-Tapping
Once a suitable pilot hole has been prepared, TYPE-BF can form internal threads and fasten the component in the same operation, reducing separate tapping, chip-cleaning, and nut-installation processes.
May Reduce the Need for Nuts and Additional Components
The screw can engage directly with the internal threads formed in the workpiece, making it suitable for one-sided assembly, applications where rear-side nut installation is not possible, or products with limited internal space.
Thread Profile Can Be Adjusted for Different Workpieces
The lobe height, thread pitch, thread angle, lead-in section, and point structure can be adjusted according to the characteristics of metals, die-cast parts, or engineering plastics, allowing the thread design to better match different material hardness and ductility.
Suitable for High-Volume Production and Automated Fastening
TYPE-BF screws with consistent specifications can be used with vibratory bowls, feeding tracks, and automatic screw-fastening equipment, making them suitable for products with demanding assembly cycle times.
For automated fastening, rotational speed, downward force, thread-forming torque, final tightening torque, and stopping position should be properly controlled.
Multiple Head Types and Drive Options Available
Depending on product appearance, installation space, and tooling, TYPE-BF screws can be designed with pan heads, countersunk heads, hex heads, flange heads, and other head types, together with Phillips, Torx, hex socket, or external hex drives.
Customization Based on Drawings and Samples
TYPE-BF screws can be customized according to customer engineering drawings or physical samples, including screw head type, drive recess, thread diameter, thread pitch, five-lobe profile, overall length, point structure, material, hardness, tolerances, heat treatment, and surface treatment.
Common Applications
TYPE-BF screws can be used, depending on thread design and material conditions, in:
- Metal enclosures, cabinets, and sheet metal structures
- Electronic and electrical equipment
- Automotive and motorcycle components
- Aluminum alloy and zinc alloy die-cast parts
- Engineering plastic housings and components
- Home appliances and consumer products
- Telecommunications and information equipment
- Motors, fans, and mechanical components
- Instruments and precision equipment
- Metal furniture and hardware accessories
- One-sided assembly locations or areas where rear-side nut installation is difficult
- Mass-production and automated fastening lines
Key Considerations When Selecting TYPE-BF
Before selection, first confirm whether the term “five-lobe” refers to the thread cross-section, point cutting structure, or another special design. Complete engineering drawings or physical samples should be obtained to avoid selecting the product based on name alone.
Pilot hole size is a critical factor affecting thread-forming quality. If the pilot hole is too small, driving torque may become excessively high, potentially causing drive recess damage, screw breakage, workpiece cracking, or excessive load on fastening equipment. If the pilot hole is too large, thread engagement may be insufficient, resulting in free spinning, thread stripping, or reduced pull-out strength.
If the screw uses a thread-forming process based on material displacement, the workpiece must have sufficient plasticity and ductility. Materials that are too hard, brittle, or too thin may not form complete internal threads.
The screw must be hard enough to form threads in the workpiece while retaining sufficient core toughness. Improper heat treatment may lead to thread wear, insufficient forming capability, or brittle screw fracture.
Fastening tools should be set to appropriate rotational speed, downward force, and shut-off torque. Before mass production, driving torque, tightening torque, failure torque, and pull-out strength should be tested to confirm that the process has an adequate safety margin.
If TYPE-BF screws are intended for repeated assembly and disassembly, the durability of the formed internal threads should be confirmed. Repeated removal may wear or enlarge the internal threads in the workpiece and reduce driving torque during subsequent installation.
For outdoor, humid, corrosive, high-vibration, or high-load environments, screw material, surface treatment, anti-loosening methods, and corrosion risks associated with dissimilar-metal contact should also be evaluated.
