PRODUCT USER GUIDE: Designation of nylon screws

The designation of screws makes it possible to correctly read the characteristics of a screw in a technical document. Understanding it is essential in order to choose the appropriate and compliant plastic screw for an assembly.
We will not address here the many characteristics and specific features related to metal screws (steel, stainless steel, aluminum, bronze, etc.), as Ajile is a recognized expert exclusively in plastic fasteners.

The designation of a plastic screw is made up of:

- the material used to manufacture the screw

- its geometry, most often defined by the screw head shape

- the drive type for the tightening tool

- the thread measurement (diameter and thread pitch)

- the thread length (for countersunk screws, this is the total screw length)

Material: plastic screws

The most commonly used material to manufacture plastic screws is polyamide, whose commercial name is “Nylon®” and symbol “PA” or “PA6.6”.
Polyamide is a lightweight material offering good mechanical strength. It is completely corrosion-resistant and highly resistant to chemical agents. In addition, it is an excellent electrical insulator, which makes nylon screws very attractive for many applications.

Plastic screw heads

Ajile offers for online purchase on www.ajile.biz, within its dedicated plastic fasteners range, a wide choice of geometries and screw heads covering all the needs of private individuals and professionals:

- slotted round head screws (cylindrical), also designated as DIN84

- slotted countersunk head screws, also known as DIN963

- hex head screws, also referred to as DIN933

- plastic headless screws DIN551

- knurled slotted screws, which can be handled by hand or with a flat screwdriver

Additional characteristics may be added to the head shape, such as domed (B), wide domed (BL), and many others, resulting in full designations such as slotted countersunk head screw or slotted round head screw.

The shape of the nylon screw head or the drive is chosen according to the tool used:

- an open-end, tubular or ring wrench for a hex head

- a flat screwdriver for slotted round or countersunk heads, as well as for headless screws

- a Phillips screwdriver for a Phillips drive

- an Allen key for hex socket screws

After the symbol defining the screw head, comes the symbol designating the thread pitch and the thread.

Thread pitch and threading of a nylon screw

In France, the thread pitch used is metric (ISO).
The metric thread is common to screws and plastic nuts. The dimensions of this thread are given in millimeters.
The number following the letter M corresponds to the nominal diameter in millimeters, which is the outer diameter of the thread, as measured for example with a caliper.
M2: thread diameter 2 mm, commonly used in miniaturized electronic, optical or scientific equipment. An M2 hex head screw is tightened using a 3.2 mm wrench.
M2.5: thread diameter 2.5 mm used in modeling or precision electronics. An M2.5 hex head screw is tightened using a 4 mm wrench.
M3: the most commonly used size for printed circuit board fastening. An M3 hex head screw is tightened using a 5.5 mm wrench.
M4 - M5: common sizes for small mechanical assemblies and electrotechnics. An M4 hex head screw uses a 7 mm wrench, an M5 hex head screw an 8 mm wrench.
M6 - M8 - M10 - M12: used for larger assemblies where lightness, electrical insulation or chemical resistance are essential. Food and pharmaceutical industries value them, as do marine professionals for their resistance to seawater. Hex head: respectively 10, 13, 17 and 19 mm wrenches.

The designation of an M3 hex head screw with a length of 8 mm from Ajile is therefore written as follows:

Screw H M3x8: plastic hex head screw, M3 diameter, 5.5 mm wrench, length L:8 mm

Ajile, specialist in plastic fasteners, offers a wide range of nylon screws from M2 to M12. The thread and screw head specific to your needs are available in stock for immediate shipment.

Looking for plastic screws suitable for your assemblies?

At Ajile, discover an extensive range of plastic fasteners including nuts and washers, designed to meet every requirement. Ajile guarantees high-quality products for professional use. For personalized advice, contact our plastic hardware experts.

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