Spring pins, commonly known as slotted pins, rolling pins, or tension pins, are hollow press fit fasteners with chamfered ends. They are made of alloy steel, carbon steel, and stainless steel, and have spring like elasticity. They are commonly used as locking devices, positioning points, wear-resistant surfaces, shafts, or conduit for wiring. Spring pin is a widely used wire fastener in various industries. Spring pins fix or fasten two components by compressing into small diameter holes or gaps. They can also be described as hollow press fit fasteners. Heli provides slotted spring pins, which are hollow cylindrical tubes with end-to-end slots for easy installation. Spring pins are also known as rolling pins, open-end pins, tension pins, and C-type pins.

What are the different types of spring pins?
Spring pins are usually divided into two types: slotted and coiled. In the slotted group, there are those with smooth grooves and those with toothed grooves.

Slotted spring pin
The slotted spring pin is a hollow, single turn, molded pin with a parallel straight groove along its entire length. The width of the groove is smaller than the wall thickness of the pin, thereby preventing interlocking or nesting with other pins. Hollow design and grooves endow them with unique self-locking capabilities.
Their manufacturing outer diameter is controlled and slightly larger than the holes to be installed. During installation, the pin will be compressed and continuous pressure will be applied to the host components. The flexibility of slotted pins allows them to be inserted into holes with slightly larger tolerances than solid pins, thereby reducing manufacturing costs.
Direction and pressure
It is important to consider the direction when installing slotted pins, as stress is directly concentrated on the opposite side of the slot.  
After installing the pin into the hole, the slot must remain slightly open to ensure absorption of the applied force. If fully closed, the slotted pin will transfer the load to the main material and may damage the hole or component.
Double installation
To increase shear strength, two slotted pins can be combined to construct a single component consisting of two different slotted pins (one pin inserted into the other pin). It is important to stagger the slots by 180 degrees and it is also recommended to ensure that the hole size is on the higher side of the tolerance.
power
The standard ASME B18.8.2-2000 slotted tension pin is stronger than the standard ASME B18.8.2 coiled pin. The same applies when comparing standard ISO 8752 slotted pins with ISO 8750 rolled pins. In fact, standard slotted tension pins are stronger than low carbon steel solid pins, tapered pins, or slotted pins with similar diameters and can withstand the most demanding applications. The higher strength, multifunctional hole design, and ease of installation make slotted pins the "first choice" for many applications.

Tooth shaped spring pin
The heavy-duty ExpanPin toothed spring pin is hollow like the standard slotted spring pin; However, the grooves on the toothed pin have staggered teeth. These teeth are spaced apart to interlock when the pin is compressed. This alignment helps maintain the roundness of the pin while minimizing lateral movement in a vibrating environment to prevent strikes.
Slotted tooth pins can play a dual role in certain applications, such as when mechanical stops and spring retainers are required. In addition, they can increase shear strength by positioning the slot at an angle between 90 ° and 180 °.
Stoppers and spring fasteners
Double the increase in shear strength
These heavy-duty pins have multiple advantages. They have the following advantages:
The advantage of sturdy pins is that they are lighter in weight and less likely to get stuck during automatic feeding
High seating capacity
Surface coated with light oil, easy to install and disassemble
RoHS compliance
Custom Length Options
Rockwell hardness is 42-50, with high wear resistance and impact resistance

Roll spring pin
A rolled spring pin or spiral pin is a rolled form made of 2-1/4 turns of steel. They come in three styles: light, standard, and heavy, distinguished by material thickness. The rolling design evenly distributes stress across the entire cross-section of the pin and forms a 270 ° surface contact with the main component.
The flexible design of the spiral spring pin can absorb impact and vibration, prevent damage to the mating components, and maintain shear strength regardless of the direction of force. This design also forces the outer edge of the pin to rotate inward during compression. When the pressure is released, the outer edge rotates outward and returns to a stationary state. In high vibration environments, this cycle will repeat countless times.
One unique advantage of these pins is that, due to the presence of coils, they can conform to the shape of non-circular holes. This is particularly useful in applications involving deformation or when the exact shape of the hole is unknown before installation.

Slotting and coiling
Most spring pins are divided into two categories: slotted spring pins and coiled spring pins. Slotted spring pins are the most common. They are hollow cylindrical metal parts with a narrow vertical hole on the side. With this hole, the slotted spring pin can deform and produce a spring like effect.

The rolled spring pin adopts different designs. As the name suggests, they are made of a rolled piece of metal. A thin metal sheet is wrapped in a cylindrical shape several times to form a rolled spring pin.
Corrosion resistant materials
You should choose spring pins made of corrosion-resistant materials. Whether you use them indoors or outdoors, they are inevitably exposed to humid environments. There is always moisture in the air, which is indicated by the surrounding humidity level. High humidity levels indicate excessive moisture. Exposure to this moisture may cause some spring pins to rust or corrode.
Fortunately, the spring pin can be made of corrosion-resistant materials. Some of them are made of aluminum. Aluminum has a high level of corrosion protection. You can also find spring pins made of stainless steel and other corrosion-resistant alloys.

diameter
Whether you prefer slotted spring pins or spiral spring pins, you need to consider their diameter. The diameter of the spring pin must be larger than the hole you want to place it in.
Like traditional compression springs, spring pins work by deforming. When you insert the spring pin into a smaller diameter hole, it will deform. The spring characteristics of these pins enable them to press against the hole wall, thereby securing the parts in place.
When selecting spring pins, make sure their diameter is larger than the hole where you want to place them. If the diameter of the spring pin is smaller than the diameter of the hole, you will not be able to use it. The diameter of the slotted and spiral spring pin must be greater than the diameter of the hole.