SPECIALITY SCREWS

Simple selection for Industrial Fasteners
In today's manufacturing industry, the selection for the appropriate fastener has become more important than before. Usually the cost of fasteners is insignificant in the overall product cost, however, if incompatible fasteners are being used, they may prove to be more costly to replace them at later stage. At Bijon, our engineers have the expertise to guide you from the product design to manufacturing process. We have designed a simple formula for your selection of the appropriate fastener.

1. Determine the screw application - Machine screw vs. Tapping screw
Machine screws need to be pre-tapped on the hole or through the installation of an insert. This method is adopting the male and female thread basis. The thread type used is usually coarse and fine metric. The tapping screws work opposite from the machine screws. These tapping screws do not require any threaded insert. The selection of the screw is strictly based on the product material used, be it plastic or metal. There is a wide range of machine and tapping screws to suit your fastening applications.

2. Determine the head type - Pan, Countersunk, Truss, Binding and others
The selection of the screw head is critical to product designers. The challenge to use smaller screw head for compact products without compromising on the tightening torques has resulted the introduction of the miniature screws, also known as camera screws.

3. Screw length
For JIS standard, the tolerance of screw depends on the screw diameter and its tolerance range from –0.4 to -0.8mm. The bigger the screw diameter, the bigger the tolerance will be.

4. Material - Carbon steel (SWCH), stainless steel (SUS) or Brass
The mostly commonly used material for industrial fasteners is low carbon steel (SWCH) because Stainless steel and brass materials are usually 2 to 3 times more expensive compared to carbon steel.

5. Plating
The plating for screws is a thin coating of metal known as zinc chromate deposited on the screw surface. The plating for screws is usually coated between 3 to 5 microns to deter corrosion. Nickel, yellow, blue and black zinc chromate is commonly plated for screws. The RoHS has discouraged the use of Hexavalent chromium (CR6) for yellow, black and blue zinc chromate plating. The usage of Trivalent Chromium (CR3) plating is encouraged for environmental reasons.