Precision Dowel Pins for Manufacturers: A Comprehensive Guide

Considering Precision Dowel Pins for Your Next Project?

When you’re in the heart of the manufacturing industry, precision is not just a luxury; it’s a necessity. Components like dowel pins may seem small and inconsequential, but in this realm of precision manufacturing, they are paramount to ensuring accurate alignment and fit. Precision dowel pins, in particular, play an indispensable role in guaranteeing accurate alignment and secure fastening in a broad spectrum of applications. But with various tolerances, standards, materials, and sizes available, how do you make the right choice? It is important to know and understand these factors in order to make informed decisions that will meet your expectations & manufacturing needs.

What are Precision Dowel Pins?

At their core, precision dowel pins are simple cylindrical rods. The term “precision” implies that these pins are manufactured to very tight tolerances in order to ensure accurate fit in assemblies. Tolerances refer to the acceptable variation in dimensions from the specified value. The tighter the tolerance, the less variation there is—meaning that their dimensions are incredibly accurate. This precision ensures that dowel pins fit snugly into corresponding holes in two components, ensuring their exact/accurate alignment.

Standards & Tolerances

Several standards are followed in the production of precision dowel pins. The prevalent standard specifications come from the International Organization for Standardization (ISO), the Deutsche Industrie Norm (DIN), the American National Standards Institute (ANSI), and the Military Standard (MS/MIL-SPEC) of the United States. At a minimum, these standards specify the pin shape, and the diameter and length tolerance. These standards might also specify the pin hardness and surface finish. OEM branded dowel pins are handled separately and are addressed later in this blog.

ISO Standard: ISO 2338A & ISO 2338B (for unhardened pins) and ISO 8734 (for hardened pins) are common standards for dowel pins. Under these standards, precision dowel pins can be manufactured to either “M6” or “M5” tolerance classes, with “M6” being the more common of the two.

• For example, an “M6” tolerance for a 5 mm dowel pin might have a diameter tolerance of -0.014 to 0 mm. So, the pin could be anywhere from 4.986 mm to 5 mm in diameter.

DIN Standard: DIN 7 (for unhardened, solid dowel pins) and DIN 6325 & DIN 6325H (hardened, solid dowel pins). Similar to ISO standards, the typical tolerance for precision dowel pins under DIN standards is designated as “M6.” This is the standard fit for dowel pins and ensures a tight fit that might require light pressing or can sometimes be hand-driven depending on the exact material and hole conditions.

• For example, for a 5 mm dowel pin under the DIN 7 or DIN 6325 standard, the typical diameter tolerance might have and upper limit of 5.000 mm & a lower limit of 4.986 mm.

ANSI Standard: ANSI standard for dowel pins is ASME/ANSI B18.8.2. This standard defines sizes and tolerances for standard dowel pins, with the “Standard Series” being the most common.

• For example, for a 1/4 (.25) inch interference fit diameter pin, the diameter tolerance might be +0.0002 to 0.000 inch. So, the pin diameter could be anywhere from 0.2500 inches to 0.2502 inches in diameter.

MIL-SPEC Standard: MIL-SPEC standard for dowel pins, particularly those conforming to MS16555 and MIL-P-21143 have very specific tolerances to ensure reliability and consistency in critical military and aerospace applications.

• The MS16555 specifies a straight headless pin with a radius on one end and a chamfer on the other. The material can be Carbon or Alloy Steel or CRES 410 or 416 Stainless Steel. Available diameters range from 1/16 (.0626-.0628) through 1 inch (1.0003-1.0001). Lengths range from 3/16 to 6 inches long. Standard diameter tolerances are +.0002 over the nominal size.
• The M21143 specifies a a straight headless pin made of CRES 303 Stainless Steel. The Mil-P-21143/1 series has a tolerance up to +.0002 over the nominal size. The M21143/2 series has tolerance of .0002 Under its nominal size.

Material Choices

Different applications may require Precision dowel pins made from different materials. The most common materials in the market include:

• Stainless Steel: Offers corrosion resistance and is suitable for applications exposed to moisture or corrosive substances.
• Alloy Steel: Known for its strength and durability, it’s ideal for heavy-duty applications.
• Brass: Often used when there’s a need to avoid sparking or in applications with lower strength requirements (less common).
• Aluminum: Lightweight and resistant to corrosion, aluminum precision dowel pins are suitable for applications where weight is a concern (less common).

Sizes Available

The diameter of precision dowel pins usually varies from 1/32″ to more than 1″, and their lengths span from 3/16″ to multiple inches. Hence, precision dowel pins come in a wide range of sizes, but certain sizes are more commonly used across various manufacturing applications due to their adaptability and compatibility with standard components. Selecting the appropriate size for your specific application is essential for achieving a snug fit, best performance, cost-effectiveness, and durability.

OEM Branded Precision Dowel Pins

Precision Dowel Pins – OEM branded “Precision” dowel pins are manufactured by precision component brands such as Pic Design, WM Berg, Unicorp and others who have their own technical specifications and are not governed by DIN, ISO or ANSI / ASME standards. They are usually only offered in stainless steel through distributors of precision components.

What to Consider Before Buying

• Tolerance: Precision dowel pins have tight tolerances. Ensure that the pins you buy meet the specific tolerances required for your application.
• Environment: Consider the environment in which the pins will be used. If they’ll be exposed to corrosive substances or high temperatures, material choice becomes crucial.
• Custom Needs: If your application requires non-standard sizes or materials, you might need custom-made precision dowel pins.
• Quantity: Depending on the scale of your manufacturing, you may need precision dowel pins in bulk. Purchasing in larger quantities often results in cost savings!
• Supplier Reputation: Always source your precision dowel pins from reputable suppliers known for their quality and consistency.

Precision Dowel Pins at MF Supply

MF Supply is a WBE/WOSB woman owned business, and a trusted supplier of Functional Equivalents, including precision dowel pins, to OEMs, manufacturers, industry, and government. We are precision dowel pin experts, offering the full catalog of dowel pins in Inch, Metric, Military and OEM branded options in a wide selection of materials, sizes and specifications. As stocking distributors, many precision dowel pins are available and ready to ship today from our national distribution centers.

Browse through the links provided below to find the precision dowel pins that you need:

• Mil-Spec Precision Dowel Pins: The full range of commercial and MIL-SPEC parts (M21143, MS16555, MS9390), including parts that are USA made, DFARS and ROHS compliant.
• Inch Precision Dowel Pins: inch sizes to ASME ANSI B18.8.2 standards in alloy steel, stainless steel 18-8, 316, 400 series and hardened. Domestic and Imported options are available.
• Metric Precision Dowel Pins: Metric sizes including DIN 7, DIN 6325, and ISO 2338 and 8734 in alloy steel, A2 & A4 stainless steel
• Precision Series and OEM branded equivalents to PIC, BERG, both Inch & Metric precision dowel pins including Press-Fit A, B and Slip-Fit C series and all MD series pins in 416 and 303 stainless steel.
• Please send us a Request for Quote for any other dowel pins not listed.
• Custom made parts per print.

Your next step?

If you have additional questions or need help in selecting the right precision dowel pins for your next project, don’t hesitate to reach out to us or send us a quote request. Our team of sourcing experts is always ready to assist you on your journey to manufacturing excellence. “Finding the right screw for you” is our tag line after all!

Book a one-on-one consultation with our President, Robin, to discuss how MF Supply can help you solve your Industrial Sourcing, Fastener, and Safety concerns.

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MF Supply is a WBE/WOSB certified supply chain partner to business, industry and government.  We are sourcing experts and stocking distributors of Hardware, Precision & Mil-Spec Fasteners and Safety supplies.  For more than 50 years, we have been supplying manufacturers in the electronics, industrial, commercial, aerospace and military markets with the full range of fastener products and services.  Our Cage Code is 58QG4 and our registered name is RL Supply Inc dba MF Supply.