Countersunk Hexalobular Or Torx Serrated Head Screw

Product introduction

This product is a screw with a special shape. It integrates annular anti-loosening serrations on the basis of the plum blossom structure in the countersunk head. After locking, the serrations are embedded in the surface of the workpiece and have excellent vibration resistance. As a typical non-standard screw, it breaks through the limitation of standard parts without serrations and can provide non-standard length, countersunk angle and tooth shape parameters. We support the development of customized non-standard screws, adjusting the thread, tooth height and heat treatment process according to your plate material, thickness and vibration level. It is suitable for applications such as automobiles, electronics, photovoltaics, etc. that require anti-loosening and a smooth surface. The material can be selected from 304/316 stainless steel or alloy steel, and is controlled according to ISO 9001 and IATF 16949 systems.

 

Product design and features

Core structural components: Countersunk head: 90° (or 82°/100° customized) countersunk angle. After installation, the head is completely embedded in the surface of the workpiece to achieve a zero-bulge smoothing effect.

Inner Torx Drive Slot: It adopts ISO 10664 standard plum blossom slot (T type/TX type), which is evenly stressed when driving. The torque transmission efficiency is 30% higher than that of internal hexagonal drive, which greatly reduces the risk of "slip" and "rounding".

Circular saw teeth: There is a circle of radial or concentric saw teeth on the bottom surface of the head. When locking, the saw teeth are pressed into the surface of the connected parts to form a mechanical lock, which effectively resists vibration loosening.

Core Features—Why it is a “specially shaped screw”

Ordinary countersunk head torx screws on the market do not have serrations, but we have integrated anti-loosening serrations on the standard countersunk head torx screws. This makes it impossible to directly find the corresponding model number in the standard fastener manual, so it is a typical special-shaped screw.

 

Specific special features include:

The height, number of teeth, and direction of the saw teeth (clockwise to prevent loosening or counterclockwise to prevent loosening) can be set non-standardly.

The countersunk angle can deviate from the standard (such as making 100° to fit the thin plate countersunk hole)

Plum groove depth can be deepened to withstand higher torque

If the size (such as total length 23.7mm), thread specification (such as M6×0.75 fine thread) or sawtooth shape required by the customer is different from any of the above standard parameters, the product further becomes a non-standard screw. When we design and produce parameters according to the customer's specific working conditions (for example, for galvanized sheets with a thickness of 1.2mm, requiring vibration resistance level ISO 16130 Class B), they are customized non-standard screws.

 

Materials and application areas

SUS304 stainless steel: good corrosion resistance, medium strength, general industrial equipment, electronic shells, furniture

SUS316 stainless steel: resistant to salt spray, acid and alkali (especially chloride ion environment) ships, coastal facilities, chemical pipelines

SCM435 alloy steel (quenched and tempered): hardness HRC38-42, tensile strength ≥1220MPa heavy machinery, automobile chassis, wind power generation

Titanium alloy (customized): ultra-light, non-magnetic, biocompatible medical implants, aerospace, high-end competition equipment

 

Examples of application areas:

Automobile manufacturing: seat frame, dashboard beam, door lock mechanism (requires anti-vibration and smooth surface without scratching)

Electronic and communication equipment: server chassis, 5G base station filter housing (countersunk head does not interfere with PCB board installation)

Household appliances: sheet metal connection of washing machine drum, air conditioner outdoor unit (anti-loosening and beautiful)

Photovoltaic and new energy: inverter housing, energy storage battery module end plate

In any of the above areas, if standard specifications (such as M5×0.8×12mm) cannot meet the mounting hole depth or plate thickness requirements, we can provide non-standard screws. For example: a photovoltaic customer requires a total screw length of 18.5mm, a countersunk angle of 92°, and a sawtooth depth of 0.25mm - this is a typical customized non-standard screw order.

 

Quality control and certification system

Test items and methods

Dimensional accuracy: Use a three-dimensional coordinate measuring instrument to detect the countersunk angle (tolerance ±1°), plum blossom groove depth (±0.05mm), sawtooth height and tooth pitch.

Mechanical properties: Guaranteed load test, wedge load test, hardness test (Vickers or Rockwell).

Anti-loosening performance: Conduct lateral vibration test according to GB/T 10431 or DIN 65151, and record the torque attenuation curve.

Corrosion resistance: salt spray test (304 material ≥ 240h, 316 material ≥ 720h without red rust).

 

Certification qualification

ISO 9001:2015 (whole process quality system)

IATF 16949 (special requirements for the automotive industry, especially applicable to fasteners with anti-loosening functions)

RoHS/REACH (environmental compliance)

Can issue third-party testing reports (SGS/TÜV, etc.)

 

Customized services

We are good at turning a customer's sketch or a usage problem into mass-produced customized non-standard screws. Here are our customizable dimensions:

Custom dimensions:

Size: any total length (such as 13.2mm, 25.7mm), any thread length, non-standard countersunk head diameter (such as Φ13 but the standard is Φ11)

Thread specifications: metric coarse/fine thread, inch UNC/UNF, self-tapping thread (A/B/C type), even left-hand thread

Plum blossom groove models: T6 ~ T60, or non-standard groove depth/groove width (such as TX20 but 0.2mm deeper)

Sawtooth parameters: tooth height 0.1~0.5mm, number of teeth 6~24, radial/concentric/spiral, one-way anti-loosening or two-way anti-loosening

Material and treatment: stainless steel/alloy steel/titanium alloy, surface treatment: passivation/galvanized/nickel plated/Dacromet/Teflon

Additional functions: Engraving/engraving LOGO on the top of the head, pre-coated nylon anti-loosening glue on the threads, guide cone or internal thread hole on the tail.

 

Customization process

Requirement input: Provide drawings, samples or detailed description of working conditions (board material, thickness, vibration frequency, installation tool restrictions, etc.)

DFM analysis: Evaluate whether cold heading is possible (low cost) or requires precision turning (small batches), and provide manufacturability recommendations.

Sample manufacturing: 10-50 pieces of samples delivered within 7-15 days

Installation verification: Customer tests the anti-loosening effect and the matching of the installation process

Mass production: MOQ is generally 5,000-10,000 pieces, and trial production of 3,000 pieces for complex non-standard screws can be negotiated.

 

FAQ

Q: Why are countersunk head torx serrated screws called “specially shaped screws”? Are there no ordinary standard parts?

A: Yes. Standard fasteners such as GB/T 70.3 only define non-serrated countersunk head torx screws. The serrated structure is a modular feature and cannot be purchased on the standard parts shelf. So it is naturally a special shaped screw. If you also need non-standard length or non-standard thread, it becomes a non-standard screw; if it is completely customized according to your drawings, it is a customized non-standard screw.

 

Q: If I just want it to be longer than the standard M4×10mm, such as M4×15mm, is this considered a non-standard screw?

A: Strictly speaking, if M4×15mm is not in the standard length series (for example, the longest Torx screw in the GB series countersunk head is only listed up to 12mm), it is a non-standard screw. But if there is stock or the mold is close, we can supply it at a price close to that of standard parts. Once any two of the length, serration, and countersunk angle deviate from the standard, it is recommended to use a customized non-standard screw process to ensure quality.

 

Q: Can countersunk head torx serrated screws be used on plastic parts? Will it crack the plastic?

A: Special design is required. Standard serrations can be too deep and cause the plastic to crack. For plastic parts, we can provide customized non-standard screws - reducing the serration height to less than 0.1mm, or changing it to a flexible micro-bead structure, while increasing the countersunk angle to 100°-110° to disperse pressure. This is where the value of customization comes into play.

 

Q: How can I verify that the screws I received are indeed anti-loosening?

A: Simple method: tighten the screws to the metal plate to the specified torque, and use a marker to draw an alignment line between the head and the plate. Then tap the side of the screw head lightly with a hammer (simulating vibration), the regular screw will rotate and misalign the lines, while our serrated screws will keep the lines aligned. For more professional verification, request a lateral vibration test report from us.

 

Q: What is the minimum order quantity?

A: - Regular stock specifications: starting from 100 pieces

Non-standard screws (only length/thread non-standard): starting from 3000 pieces

Specially shaped screws (with standard serrations but other standards): from 5000 pieces

Customized non-standard screws (completely according to the drawings, including non-standard serrations, angles, materials): starting from 8,000 pieces, sample order (100-200 pieces) can be negotiated.

 

Q: Does this kind of screw need to be serrated after it is coated with anti-loosening glue?

A: They have different functions: the anti-loosening glue mainly increases thread friction damping, while the serrations provide independent mechanical anti-loosening. In extremely high vibration environments (such as engine attachments), we recommend simultaneous use. If you need a double anti-loosening solution of "gluing + sawtooth", which is also a customized non-standard screw, we can integrate pre-coated glue (such as nylon 11) into the production line.

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