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- Head Design Size & Shape
- Shank Mounting Styles
- Head Tip Design
- Other Pin Types & Features
- Materials & Surface Treatments
Locating pins are used for controlled, fine tolerance positioning of a workpiece.
For example, a locating pin is a great solution for a pallet that is moved along one axis, where the drive mechanism is not accurate and stable enough to place it in a position sufficiently accurate to execute a particular process.
But there are a wide range of use cases for locating pins across industries, from electrical vehicle to semiconductor. Which is why locating pins come in a variety of sizes, shapes, and types.
In this guide, we’ll walk through the main features of a locating pin and the different options, including head design, style, shape, mounting styles, and other features.
Head Design Size & Shape
The size of the head, shape of the head, and shape of the nose on a locating pin can vary greatly between applications. There are many ways the head of a locating pin can be designed, so the following sections will help explain how these different sizes and shapes can be used.
Size
One of the most common pins is a stepped pin with either small or large head.
Small Head Design
Large Head Design
Pin Head Diagram
Common Head Shapes: Round and Diamond
The diamond shape is a critical feature that helps with machining inaccuracies and smoother locating operations.
[CLICK HERE FOR MORE INFORMATION ON DIAMOND LOCATING PINS]
When two round head pins are installed onto one plate, the distance between two mounting holes must be precise, and even then, the workpiece will not be placed on the base as easily as it would with the use of a diamond pin.
Round Head Pin
Diamond Head Pin
Alignment Diagram
Looking at the alignment diagram, the round pin is the datum pin that is located on the base and fixed in both X and Y directions. The image in the middle shows a diamond pin that is oriented properly to allow minimal misalignment in the X axis, but prevents the workpiece to move in the Y direction. This way, you eliminate small inaccuracies when it comes to mounting hole distance, and even if it’s manufactured with high precision, the operation will improve since there is less work surface area.
There are other ways of utilizing diamond locating pins. The drawing to the left shows where you need to perfectly align the center of the part, but the angular orientation is not critical.
Other Head Shapes
Triangle
Triangle head pins have qualities in between round and diamond pins. They are more precise due to the increased surface area while allowing for slight misalignment.
Oval
Oval head pins enable positioning for oval or slotted holes machined on a workpiece. Typically used for jigs & fixtures.
NAAMS Style Pins
For NAAMS style pins, additional shapes are offered, including 4-Way and 6-Way.
Shank Mounting Styles
Another primary locating pin feature is the shank. The shank is the part of the pin that is installed in the mounting fixture and does not come into contact with the workpiece. There are several different shank mounting configurations categorized by bottom, side, and top.
Bottom Mounting
Here are the common shank styles used for bottom mounting.
Press Fit Shank
The press fit shank is used when you have access to the bottom of the mounting plate. This way, it can be knocked out when a replacement is needed.
Tapped Shank
Tapped shanks are another bottom mounting option. They are usually paired with a fastener and a counterbored hole on the mounting plate to fix the pin in place.
Threaded Shank
Threaded shanks are another form of mounting to use when the bottom of the mounting plate is accessible. These types of pins can either be threaded directly to the plate or mounted with a nut and washer.
Side Mounting
Since not all designs allow access to the back of the mounting plate, there are other shank designs that are appropriate, including side mounting.
Set Screw Flat
The set screw flat feature allows the pin to be mounted and helps set the orientation of the diamond head.
Shank with Locating Notch
The shank with locating notch feature works the same way as the flat, but while driving the set screw in, you push the back of the head against the mounting surface.
Shank with Circumference Groove
Circumference notch is typically used for pins with a round head, since they do not let you control the orientation.
Top Mounting
Sometimes there is no easy access on the back or the side of the pin mounting plate, and a top mounting shank is used instead.
Counterbore
The clearance hole with the counterbore feature lets you install the pin using a socket head cap screw when you have limited access to the back or side of the mounting plate. The disadvantage of this pin is its size; it cannot be used when small size pins are required due to the size of the mounting socket cap screw.
Flanged Locating Pin
A flange mount pin is another style of front mounted locator. Here, you can see three different styles.
Hexagonal Socket Head & Wrench Hole Head
A hexagonal socket head and wrench hold head are used to tighten the pin in place from the face side.
Head Tip Design
There are several styles of pin head shapes. They serve different purposes and can be utilized in a variety of applications.
Tapered
The lead is usually between 15 to 30 degrees and allows the pin head go into the mating hole even with small misalignment.
Round
Similar to head with lead. This is often used in designs of printed board application. Maximum nose diameter is equal to head diameter.
Rounded Tapered
Similar to head with straight lead, allowing smoother location. You can still enjoy small misalignment while decreasing the stroke in comparison to the round pin.
Radius
Radius tip is common in automotive and welding applications.
Flat
Flat is predominantly used with short stroke applications or where the lead can be incorporated in the hole the pin goes into.
Spherical
Spherical head pins are commonly used to avoid scratching the work piece when locating.
Bullet Nose
Bullet nose pins help prevent binding, especially when using two round pins. These are typically used when locating radially.
Other Locating Pin Types & Features
Have an application that requires a unique locating pin? There are several other types of locating pins used for specific cases. There are also some pins with unique features.
Height Adjustment Pins
Height adjustment pins use the face of the pin to create spacing between the product and the pin’s mounting surface. The face of the pin usually needs to be hardened.
Pins with Shoulder
Pins with shoulders are very popular due to their dual functionality. They provide both XY plane, as well as Z height location.
Stepped Head Pins
Also known as a double pilot pin, stepped head design allows you to position two layers of work pieces as once. They’re used when working with multiple pieces of sheet metal.
Head with Air Vent
It is beneficial to add an air vent, often in the form of a flat running along the side of pin’s head in order to avoid air compression inside the hole, especially when dealing with blind positioning holes.
Eccentric Pins
Eccentric pins can provide additional adjustment when fixing a workpiece. Eccentric pins with pilots provide for easy eccentric adjustments.
Spring Loaded Pins
The tip of spring-loaded pins can compress down into the body of the pin for fine height adjustment.
Other Locating Pin Types
Most locating pins are machined with an undercut feature that allows the workpiece to rest on the base. Sometimes more structural strength is required, and you can design the pin with a radius if the positioning hole can be produced with an appropriate chamfer.
A flat feature on the flange can also be used for orientation of the diamond pin. Please see the example below.
Materials & Surface Treatments
After selecting the overall shape of your pin, the next step is material selection. Different materials and surface treatments have unique traits that would make them favorable for certain applications over others.
These materials and surface treatments can also be used in combination with one another to maximize the benefits a locating pin can provide.
Material Options
Typically, locating pins are manufactured from hardened tool steel such as O1 heat treated to 60-63Rc or from case hardened carbon steel (e.g., 1045 with 45-50Rc).
In some cases, soft 300 series or hardened 400 stainless is used in assemblies where no rust is accepted. Pins made out of soft materials will wear out much faster than harden pins.
Here is an overview of the different types of material options available:
Surface Treatments
There is a variety of coatings that can be used based on your application. In corrosive environments, a hard chrome, Dicoat or TiCN coatings can help extend the life of the pin since they provide non-corrosive and hard layer that can be as hard as 3000 Vickers.
Here is an overview of the different types of available surface treatments:
Insulating Coatings for Welding Applications
A variety of insulating coatings or materials can be used in case of welding applications. Alumina stainless steel coat is one surface treatment that provides great insulation and prevents weld build-up between the work piece and the surface of the pin.
Spot Welding Application
Other Comparison Studies: