Thin-head, internal Torx K2, K2.5, K3, K4, and K5 plastic self-tapping screws are specially designed for plastic products. They feature a thin head with an internal Torx hole. The following provides detailed information on customizing the Thin-head, Internal Torx K series self-tapping screws.
Thin-head, Internal Torx K series self-tapping screws
Type: Self-tapping screw
Head type: Thin countersunk head
The head thickness is lower than the standard for standard countersunk heads, achieving a better countersunk effect and a smoother appearance in thin-walled plastic parts.
Groove type: Phillips
The PH2 groove (suitable for K4 and below) is preferred. For larger sizes like K4.5 and K5, the PH3 groove can be considered for greater torque.
Thread type: K-type, also a plastic-specific thread. It features a wide thread pitch, high, sharp threads, and a sharper crest angle, making it easier to penetrate plastic without causing internal stress cracking. These screws feature a self-drilling point, typically Type BP or Type C, allowing for quick tapping without pre-drilled pilot holes.
Target Materials: Various engineering plastics and higher-hardness thermoplastics.
II. Core Custom Parameters
These are essential technical specifications and must be clearly marked on the drawing.
Nominal Diameter: K2: 2.0mm, K2.5: 2.5mm, K3: 3.0mm, K4: 4.0mm, K5: 5.0mm. Tolerance: ±0.02mm.
Length: Refers to the total length. Measurement standards must be specified.
Head Diameter: According to the K-series thin-head standard or customer drawing. The countersunk angle must match.
Head Thickness: Less than the national/German standard countersunk head thickness. This is a critical requirement and must be thin to prevent penetration or lifting of the back face in thin-walled components.
Thread Pitch: According to the K-series standard, the large thread pitch is a core feature of K-type screws, providing a strong grip. Material: Carbon steel (1010/1008), a standard choice for low cost.
Surface Treatment: Natural white zinc, basic rust prevention, and a neat appearance. Other finishes, such as environmentally friendly colored zinc and nickel plating, are available, but this will affect the cost.
Mechanical Properties: According to GB/T 3098.5 or ISO 7049 standards, typically ST2.2 or 4.8, with a hardness of HV270-HV400. It is strong enough for connecting plastic parts and resists twisting.
III. Special Technical Requirements (Omitted/Add as needed)
Salt Spray Test Requirements: White zinc surface treatment, neutral salt spray test for at least 48 hours, no white rust, 72 hours, no red rust.
RoHS/REACH Compliance: All materials (screw body, plating) must comply with EU RoHS regulations, and a third-party testing report must be provided.
Packaging: Blister tray/roll packaging/bags + paper box. Requires anti-mixing and scratch protection.
Identification and Traceability: A label will be affixed to the outside of the carton, indicating the product name, specification, quantity, and batch number to facilitate production traceability.
V. Deliverable Requirements
2D Product Drawings: In PDF and DWG formats, including all key dimensions, tolerances, materials, surface treatments, technical standards, and other information.
Samples: Before the first batch of mass production begins, at least 50 samples of each specification must be provided for confirmation (dimensional, appearance, and trial assembly testing).
Test Report: A first-article inspection report will be provided, including full dimensional inspection, salt spray test report, and material report.
Minimum order quantity and delivery time must be clearly defined.
The core of this customization is the combination of a "thin head" and "K-type plastic thread." The thin head solves aesthetic and structural issues in limited spaces and thin-walled designs. The K-type thread ensures quick screwing into plastic materials, high pull-out resistance, and excellent crack resistance.
Therefore, it is not just a simple screw, but an efficient, reliable, and precise connection solution tailored for the modern plastic products industry, especially the consumer electronics and home appliance industries.
