Custom Slotted Cylindrical Pin with External Thread High Quality Stainless Steel Grooved Cylindrical Dowel Pin

Descrizione

What is a Cylindrical Pin?

A cylindrical pin is a fundamental and precise mechanical component. It is a solid, straight pin with a constant circular cross-section along its entire length. Unlike tapered pins, it has no chamfer or taper (except for minimal lead-in chamfers on the ends to facilitate insertion). Its primary function is to precisely align, locate, and secure two or more parts together, ensuring they maintain a fixed position relative to each other. They are designed to fit into reamed holes with a tight, slip-to-light press fit, often requiring a hammer or arbor press for installation and removal.

Materials

Cylindrical pins are manufactured from a variety of materials to suit different requirements for strength, corrosion resistance, and environmental conditions.

• Carbon Steel: The most common material, often hardened and tempered to achieve high strength and wear resistance.

• Stainless Steel: (e.g., 303, 304, 316) Used for excellent corrosion resistance and non-magnetic properties, ideal for food, medical, and marine applications.

• Alloy Steel: Used for high-strength applications, frequently coated for corrosion protection.

• Tool Steel: Used in demanding applications like jigs and fixtures for its exceptional hardness and durability.

• Brass and Bronze: Chosen for their good corrosion resistance, electrical conductivity, and non-sparking properties.

• Aluminum: Used where weight reduction is critical.

Surface Treatments

Surface treatments are applied to enhance properties like corrosion resistance, hardness, and appearance.

• Zinc Plating: A very common and cost-effective treatment for good corrosion resistance. It can be clear (blue), yellow (chromate), or black.

• Nickel Plating: Provides a hard, wear-resistant, and decorative finish with good corrosion resistance.

• Chrome Plating: Offers an extremely hard surface with excellent wear and corrosion resistance.

• Black Oxide: Provides mild corrosion resistance and reduces light glare. It is a popular finish for tools.

• Passivation: A chemical process for stainless steel pins that removes free iron from the surface, enhancing its natural corrosion resistance.

• Phosphating: Creates a crystalline phosphate layer that aids in corrosion protection and serves as an excellent base for holding oil.

Specifications

Cylindrical pins are defined by several key dimensional and tolerance specifications, often governed by international standards like ISO 2338 or ANSI B18.8.2.

• Diameter: Ranges from a fraction of a millimeter to over 25 mm. Common sizes include 3mm, 5mm, 6mm, 8mm, 10mm, and 1/4″, 3/8″, 1/2″.

• Length: Varies significantly based on application, from a few millimeters to several hundred millimeters.

• Tolerance: Manufactured to very tight dimensional tolerances (e.g., g6, h6, m6) to ensure a precise fit in reamed holes.

• Hardness: Typically hardened to a range of 50-60 HRC (Rockwell C scale) for steel pins to prevent deformation during installation and use.

Application Fields

Due to their precision and reliability, cylindrical pins are ubiquitous in engineering and manufacturing.

• Precision Alignment: In machine tools, jigs, and fixtures to ensure components are perfectly aligned.

• Locating Components: Precisely positioning gears, pulleys, and levers on shafts.

• Shear Load Transmission: Designed to shear under extreme overload, protecting more expensive components (shear pins).

• Pivots and Hinges: Acting as a axle or pivot point in assemblies.

• Aerospace and Automotive: Used in engines, transmissions, and control systems where precision and reliability are paramount.

An Excellent Case: Aligning a Robotic Arm Gearbox

A leading manufacturer of industrial robotic arms was facing a critical assembly challenge. The primary reduction gearbox, which transfers motion from the high-speed motor to the precise arm joints, required perfect alignment between the hardened steel housing and the main output flange. Any misalignment, even as small as 20 microns, would cause premature bearing wear, gear tooth fatigue, and unacceptable vibration, leading to robotic positioning errors and costly field failures.

The solution was to use two high-precision, hardened, and ground carbon steel cylindrical pins with a m6 tolerance fit. The process was as follows:

1. The gearbox housing and output flange were machined separately.

2. After initial assembly, the two mating holes were reamed together to ensure perfect co-axial alignment.

3. The two cylindrical pins, coated with a black oxide finish for mild corrosion resistance and lubricity, were then pressed into the reamed holes using an arbor press.

This simple yet brilliant application of cylindrical pins ensured that the two critical components were permanently and perfectly located in their exact designed position. The pins carried the entire shear load from the gear train, eliminating any micro-movement between the parts. The result was a dramatic increase in the gearbox’s operational life, a significant reduction in vibration and noise, and the elimination of alignment-related failures. This use case highlights the cylindrical pin’s indispensable role in achieving precision, reliability, and durability in high-performance mechanical systems.