General information about types of finishing for fasteners
Fasteners can be Bright steel, Galvanised, Zinc coated, Stainless Steel, Aluminium or Plastic.
These different finishes, coatings or material of fasteners give different levels of protection of resistance to rusting or other special properties to certain applications.
Bright finish is without any form of protection and is the most economical choice, but the fasteners will start to rust long before fasteners that have a protective treatment. Used in applications where no protection is required, for example a one way disposal pallet.
Galvanising, or coating with Zinc, is the best way to prevent fasteners from corroding. The zinc does not protect the steel of the fastener, but is corroded first. The thicker the zinc coating, the longer it will be before the fastener is attacked. The thickest coating is called hot dipped and is applied by dipping the fasteners into a bath of molten zinc.
Galvanised protection is measured in Microns (each Micron is 0.000001 of an metre thick). The thicker the micron coating the better the protection level of the galvanised nails.
Stainless Steel is used when other finishes are not sufficient and need the maximum protection we can offer. For example: stainless steel is ideal for motorway fencing or in applications which are exposed to (salt) water.
A limited range of fasteners are available in Aluminium or Plastic, but they do have some advantages.
Where a timber joint has to be held and later cut, aluminium or plastic fasteners are used, as it is a softer material, reducing the impact on the saw blades and machinery of the joiner/ manufacturer. This material, being softer, cannot be made into long lengths of fastener or be driven into some harder species of timber. However, the lighter properties of aluminium or plastic fasteners are an advantage and aluminium also offer better rust resistance than galvanised nails and plastic doesn't rust at all.
General information about staples:
Staples are generally all the same - simply a formed metal wire bent into a very precise U-shape.
- The part across the top is called the crown.
- The two parts which are parallel and are designed to penetrate into the material are the legs.
- The tip of each leg is called the point.
The Crown is important to determine what tool will drive the staple. Each tool will normally only work with one crown size.
Leg length may vary according to the needs of the application – holding power, thickness of the materials, etc. Each tool will normally drive a range of different lengths.
If the legs are not parallel in the material it is much harder to pull out the staple.
The Points normally come as chisel points, but where very high holding power is required, the points may be divergent points. These are specially cut points which guide the legs in a curve, instead of straight down into the material.
General information about nails:
There are three types of nails:
- Coil nails
- Stick nails
- Finish nails (amongst others brads, pins and T-nails)
The Head is the part of the nail which you would hit with a hammer, or in the case of the pneumatic fastening industry, it is the part that is struck by the driver of the tool. The head can be either Round, Clipped or Off centre.
Round Head Nails have exactly that, a round head. They look just like the loose nails you would find in any hardware store. Round Head nails are are joined together (collated) in coils or in strips (called sticks) so that the tools can be used many times without the need to reload after each nail has been driven.
All Coil Nails are Round Head nails.
Not all Stick Nails are Round Head nails.
Clipped and Offset Headed Nails are always collated in sticks and are designed to allow the shanks of the nails to touch each other when they are collated. In this way it is possible to load more nails into the stick nailers and increase their autonomy.
A Round Head Stick Nailer would typically load 50 nails whilst a Clipped Head Stick Nailer would typically load 75 nails. Of course, the number of nails per load depends on the length of the magazine and the diameter of the nail shanks.
There is very little difference in the holding power of Round Head nails and Clipped Head nails. It is the shank that does most of the holding. The head only comes into play if the shank starts to slip out of the wood (called withdrawal).
The head stops the upper material from separating from the base material and in some cases, where the upper material is less resistant than the base material, the Head could be dragged through the upper material (called pull through). The pull through force for round head and clipped head nails is very similar.
Finish Nails and Brads have heads that are rectangular. They are the same width as the shank, but the breadth of them is greater than the shank. This ensures that their holding power is enhanced, but of course the pull through force is lower than for nails with larger, Round or Clipped Heads.
The heads of the nails can vary in size according to the diameter of the nail shank and the application. If you make a small diameter nail with a large diameter head, it would be more easily broken away from the shank. Increasing the diameter of the head also reduces the number of nails you can have in a Coil or in a Stick. There are some special applications, such as fastening roofing shingles, that require very large diameter heads. These Roofing Nails have a head diameter of 10 mm in order to hold the shingle very firmly and prevent tearing of the shingle when there is a strong wind.
The shank or shaft:
The Nail Shank (also called Shaft) is the part which, does most of the holding. The nail shank is forced between the fibres of the wood and once in place, the fibres press against the shank. This pressure is the reason why it is so difficult to pull a nail out of the wood.
The shank is one of four types: Smooth, Spiral, Ring or Screw.
Smooth shank nails have exactly that: a smooth appearance. Due to their regular form they can be produced at very high speed and are therefore the most economical type of nail. However, their holding power is the lowest of the group. They require less energy to drive them and the air consumption per nail can be lower. Sometimes it is possible to use a smaller tool to drive them.
Spiral shank nails have either a threaded appearance, like a screw, or they can have a helical twist to them. Either way, the purpose of the deformed shank is to increase the force required to remove the nail from the wood. The wood fibres wrap themselves around the deformed section and the difference in diameters that their shape provides makes it much more difficult for the nail to be withdrawn.
Ring shank and Screw shank nails have a series of rings punched into the surface of the shank. Again a difference in the diameter of the shank is produced making it even more difficult to withdraw the nail.
Both Screw shank and Ring shank nails have to be produced at lower speeds and their cost is generally higher than for a smooth shank nail. The air consumption per nail is also higher, and the energy required to drive these nails into hard wood is very much greater.
The advantage of Screw shank and Ring shank nails is of course in the holding power, which is better than Spiral and far superior than Smooth shank.
The point of a nail is much more important than would seem at first glance. There are points for normal applications, points to prevent the wood from breaking and points designed to help bend the nail over after being driven (called clinching).
The standard point for all nails is Chisel point and this is quite sharp and allows easier penetration into the wood.
To reduce the possibility of the wood splitting, there are Blunt Points and Flat Points.
There is also a special point called Clinch Point, in this particular case the shank of the nail is cut diagonally so that when the nail hits a metal plate placed under the wood, it is deflected to one side and can be bent over.