Dowel pins are short solid cylindrical rods used as a fastener to join and locate two or more parts, shafts, hinges, jigs, and fixtures of the machine tool. During the joining of the parts, a dowel pin is inserted through the concentric hole of both parts. Transition and slight interference fit help to press dowel into the holes with moderate pressure. Thus, the friction between the dowel pin and the hole of two parts helps to hold them with each other.
Dowel pin has a chamfer on both sides, which helps for easy insertion of dowel in the holes. Steel dowel pins are commonly using for precision engineering applications. But these are not easy to insert and remove.
During insertion of wooden dowel in the interference fit holes, creates an airtight pressure due to trapped air and glue.
Types of Dowel Pins
Precision Dowel Pin
These are high surfaced finished pins suitable for press-fit or interference fits. These pins have precise tolerance, good surface finishes, and ductility. These are made as per hole size.
Grooved Dowel Pin
Name suggesting that it has a groove on its surface, which allows the pin to rotate in the groove to get better fixing. These are suitable for blind hole application.
Oversized Dowel Pin
It is also known as a repair dowel pin which is 0.001 inches more in size compared to the standard dowel pin. It helps to make the damaged hole wider to fit another pin into it.
Pull-Out Dowel Pin
These are internally threaded dowel pins that allow the screw to get an insert. These pins insert into the hole of any part to fix two parts or remove the dowel pin from the hole. These are more suitable for blind holes.
Stepped Dowel Pin
It having two different diameters. One is acts as a body and the other act as the head.
Standard Dowel Pin
These are the standard ones that can fit into any standard holes. Their dimensions are standardized as per their relevant standard.
Dowel Pin Material
- Aluminum, Brass, Steel, Stainless Steel, and Titanium are common materials of the dowel pin. This material having good ductility and resistance to corrosion properties. Aluminum and brass have good conductive properties.
- Titanium is lighter in weight, and its weight is half of the weight of steel.
- Alloy steel has high tensile strength, resistance to wear and tear.
- Nylon is non-conductive and light in weight. It can absorb vibration and impact.
- Plastic and wood are the two materials using for making dowel pins as per the application. Wooden dowel pins are mostly for wooden work like shipbuilding and timber work
Dowel Pin Size
- D- Outer diameter
- L- Length
Advantages of dowel joint
- It eliminates the use of hardware like screws and nails.
- During assembly, we can simply drill the hole in proportion to the dowel size and insert it to become assembly. It is very secure to use.
- It can be used for various applications. Not only in joining right angle and flat joint but also in the more complex joint.
- Dowel joint having good strength.
Disadvantages of Dowel joint
- Alignment during assembly is quite difficult for the beginners.