Fastening sheet metal is a technical process that not only requires expertise, but also the most optimal screws – specifically self-drilling sheet metal screws. These screws feature sharp threaded shanks and tips that pierce easily through solid metal surfaces and other sturdy materials.
Self-drilling sheet metal screws come with pointed drilling tips designed to penetrate metal without the need for pre-drilled pilot holes.
Without the need for pilot holes, self-drilling screws save installation time, eliminates the extra cost for labor and drill bits. This cost-saving feature and additional advantages make them an excellent choice for metal building construction.
Like any hardware, self-drilling sheet metal screws come with various features. But whatever type of self-drilling sheet metal screw you need for your project, it’s best to go for screws that have:
As many tradies know, rusty screws are a real pain to deal with, not to mention an eyesore. Rust significantly reduces the strength of metal structural elements, reducing the thickness, and even leaving holes in components. It is also difficult to contain rust once it starts to spread, which is why self-drilling sheet metal screws with Corrosion-Resistant capabilities are in high demand.
As part of our quality assurance policy, all BDN Fasteners self-drilling screws are sent to SGS for regular Kesternich (7 cycles) and Spray Salt Tests (1000hrs). Going through regular testing demonstrates our commitment to quality and the results prove consistent product quality.
Self-drilling sheet metal screws with proper Corrosion-Resistant surface treatments last longer against the deteriorating effects that occur from weathering. Such exposure can negatively affect the performance of various components and increase the possibility of failure in the long term.
BDN Fasteners self-drilling sheet metal screws come with Class 3 Corrosion-Resistant coating – designed to cope with even the most challenging of environments.
Self-drilling sheet metal screws should also come with accessories that prevent the possibility of rust. BDN Fasteners self-drilling screws come with optional pre-assembled weatherproof washers such as DEKS Dekseal® Trueblue®, 100% weather sealed washers. These washers provide the perfect seal between the screw and sheet metal, are anti-static to reduce the possibility of rust, and come with a 20-year warranty that will outlast the life of most sheets – a must for construction projects.
Classification of Corrosivity of the Atmosphere:
As a manufactuer who specializes in manufacturing screws that adheres to Australian AS3566 Standards, it is only natural to produce screws according to Australian corrosion resistance standards, which is currently categorized into 6 Classes, namely from Class 1 to Class CX. These corrosion classes are categorised based on the corrosivity of atmospheric environments established by the International Standards (ISO) classification system – ISO9223.
| Classification of fastener corrosion resistance and designation of suitable corrosivity categories for fastener use | |||||||
| Atmospheric corrosivity categories | |||||||
| ISO 9223 | C1-Very low | C2-Low | C3-Medium | C4-High | C5-Very high | CX- Extreme | |
| Fastener Corrosion Resistance Classification | Typical or common characteristics of this category. | Indoor, dry, air conditioned | Most areas beyond 50 km from the seas but can be as close as 1 km from seas that are relatively sheltered and quiet. | Coastal areas with low salinity, urban and industrial areas with low pollution, varies significantly with factors such as winds, topography and vegetation | Occurs mainly on the coast. In areas with rough seas and surf, it extends from several hundred metres to 1 km inland | Normally found 50 m to 500 m inland from the shoreline of coasts exposed to surf or very rough seas. | Offshore locations or within 50m of the shoreline of breaking surf or very rough seas, but could possibly extend to 200m under the most severe sea conditions. |
| Aggressive Industrial Areas | |||||||
| Class 1 X | v | NR | NR | NR | NR | NR | |
| Class 2 X | v | NR | NR | NR | NR | NR | |
| Class 3 X | v | v | V | NR | NR | NR | |
| Class 4 X | v | v | V | V | NR | NR | |
| 300 Series Stainless Steel | v | v | v | V | v | V | |
| NR = Not recommended. | |||||||
ISO9223, which focuses on the Classification, determination and estimation of the Corrosion of metals and alloys, and Corrosivity of atmospheres, the scope of which
ISO9223 standard specifies the key factors in the atmospheric corrosion of metals and alloys. These are the temperature-humidity complex, pollution by sulfur dioxide and airborne salinity.
The ISO9223 category and environmental conditions are on the table below. Environmental conditions and category is complex and can be influenced by a wide range of factors. Note that in certain instances, corrosion zones can extend out further to what is stated above.
The objective of classifying and designating corrosion resistance as such, is to provide manufacturers and users with the requirements for the corrosion resistance of self-drilling screws used in the building and construction industries. The Class designations should be used in conjunction with the ISO9223 environmental conditions category in order to choose the right product for its intended use.
Below is table of the how the atmospheric corrosive categories on ISO9223 corresponds to real life environmental conditions, and how BDN Fasteners series products are warranted according to these conditions.
BDN Fasteners are protected by Class 3 and Class 4 corrosion resistant coatings, which significantly increase the lifespan of not only the screws itself, but part of the coating removed during the drill and drive will cover the exposed metal, creating an extra layer of protection around the hole.
It is also important to note that there is always a trade-off between drilling performance and corrosion resistance. The word “coating” is self-explanatory, and since corrosion resistance is directly related to the thickness of the coating, it will affect drilling performance. In short, the thicker the coating, the duller the drilling point, and it is up to the manufacture to make minor tweaks to the drilling point design to find the perfect balance between coating thickness and drill penetrability.
That said the tables above are all general guidelines, and do consult your local BDN Fasteners representative for further advice and verification of the screw class that is most suited for your desired purpose and to cope with the environment.
At BDN Fasteners, we say that your sheet metal is only as long-lasting as the fasteners it is affixed to, which makes all the difference between a good or mediocre project.
BDN Fasteners offer an extensive range of Corrosion-Resistant self-drilling sheet metal screws in various lengths, sizes, and specifications, suitable for a host of applications.
Special features of our self-drilling sheet metal screws include:
As a leading supplier of sheet metal screws in Asia, we maintain strong relationships with dealers, distributors, and project managers, providing the correct fastening solutions for their needs.
For more information and inquiries about our products, contact us today.