Pins
Factory Direct for standard fasteners. Guaranteed quality with qc report and mill cert.Inch/metric available. Quick response with thoughtful service.
Precision Alignment and Positioning Standards
The core function of our “Pins” category is to provide absolute alignment accuracy for mechanical assemblies. Unlike bolts which are designed to hold parts together, a dowel pin is engineered to locate components laterally, ensuring that the relative position between two mating parts remains fixed under shear loads. We stock a comprehensive range of precision dowel pins manufactured to strict DIN and ISO standards. Specifically, our DIN 6325 series features through-hardened steel, ground to an m6 tolerance zone. This specific tolerance ensures a light interference fit, which is critical for jig and fixture building, die casting, and heavy machinery alignment. For applications requiring a different fit or easier assembly, we also supply unhardened pins under the ISO 2338 standard, available in stainless steel for corrosion-prone environments.
Material Composition and Hardening Processes
Durability in a pin is defined by its resistance to deformation and wear. Our steel dowel pin inventory is processed from high-grade alloy steels that undergo rigorous heat treatment. For standard hardened pins, we achieve a surface hardness of 58-62 HRC. This hardness prevents the pin from mushrooming during installation and ensures it does not shear under heavy lateral stress. In contrast, for food processing or medical equipment where hygiene is paramount, we offer stainless steel variants (A1/A2/A4) that resist oxidation. While the focus is often on rigid alignment, this category also encompasses the split pin (cotter pin), which serves a safety function. Typically made from mild steel or stainless steel wire, these pins are designed to be malleable, allowing the tines to be bent back to lock clevis pins or slotted nuts in place, preventing vibration-induced loosening.
Blind Hole Solutions and Extraction Features
Standard parallel pins can be difficult to remove if installed into a blind hole (a hole that does not go all the way through the material). To address this maintenance challenge, Screwtool supplies internal thread cylindrical pins, such as those meeting the ISO 8735 (DIN 7979D) standard. These metric dowel pins feature a tapped hole on one end and an air release flat ground along the side. The air vent allows trapped air to escape during insertion, preventing pneumatic lock, while the internal thread allows a maintenance technician to use a slide hammer or bolt to extract the pin without damaging the workpiece. This design is essential for heavy molds and gearboxes where frequent disassembly is required for servicing. Whether you need a permanent press-fit dowel pin or a removable locating element, our catalog supports both through-hole and blind-hole designs.
Advantages
Strict Tolerance Control for Interference Fits
The defining quality of our precision dowel pins is the consistency of their diameter. A variation of just a few microns can mean the difference between a secure press fit and a loose, failed assembly. We utilize centerless grinding technology to finish our pins to strict tolerance classes, typically m6 for standard interference fits and h6 for sliding fits. This precision ensures that when a machinist reams a hole to the correct size, our steel dowel pin installs with a predictable amount of force and maintains that position indefinitely. This reliability eliminates the “play” or “slop” in mechanical linkages, which is vital for high-speed automation equipment where accumulated tolerances can lead to operational errors.
Integrated Air Release and Chamfer Design
Installing a pin into a tight hole generates hydraulic or pneumatic pressure if the air or lubricant cannot escape. Our DIN 7979D and specifically designed metric dowel pins incorporate a ground flat surface along the longitudinal axis. This “air vent” feature is a critical structural advantage, allowing air to displace as the pin is driven in. Furthermore, the ends of our dowel pins are chamfered or crowned. This geometric detail serves two purposes: it acts as a lead-in to help align the pin with the hole during initial insertion, and it prevents the sharp edge of the hardened pin from shaving material off the hole wall (galling), which would otherwise compromise the fit. These design nuances are what separate professional-grade industrial components from generic hardware.
Versatile Locking and Safety Mechanisms
While dowels handle alignment, safety retention is handled by our split pin selection. These components are manufactured with a precise eyelet and uneven leg lengths to facilitate easy opening. The material selection for our split pins prioritizes ductility without fatigue; the metal can be bent aggressively to lock a castle nut or clevis pin without cracking. This makes them indispensable in high-vibration environments where a nut might back off. By sourcing both the rigid dowel pin for alignment and the ductile split pin for locking from a single supplier, manufacturers can streamline their bill of materials for complex assemblies like automotive suspension systems or agricultural machinery, ensuring every connection point is both aligned and secured.
Use Scenarios
Die Casting and Injection Mold Assembly
A Tool and Die Maker working on a high-pressure aluminum die-casting mold requires components that can withstand extreme thermal cycling and mechanical stress. The maker specifies Screwtool’s DIN 6325 hardened steel dowel pin to align the two halves of the mold core. The hardness of the pin ensures that the repeated opening and closing of the mold does not wear down the locating surfaces, maintaining the dimensional accuracy of the cast parts. For the ejector plate assembly, the maker utilizes our metric dowel pins to guide the movement, relying on the smooth ground surface to minimize friction and prevent seizing at high operating temperatures.
Industrial Gearbox Manufacturing
In the assembly of heavy-duty reduction gearboxes, the precise alignment of the housing halves is critical to ensure the gear shafts run parallel. An Assembly Line Supervisor uses our precision dowel pins to locate the bearing caps and the main casing split line. Once the casing is bolted shut, the dowel pins take the shear load, ensuring the rotating elements remain perfectly aligned. For the output shaft nut, the supervisor installs a split pin through the shaft hole to lock the castle nut in place. This redundant safety measure ensures that even if the gearbox experiences heavy vibration during operation, the main retaining nut cannot loosen, preventing catastrophic failure of the drive train.
Automotive Engine Rebuilding
A Master Mechanic rebuilding a cylinder head relies on precise location to ensure the head gasket seals correctly. The mechanic uses Screwtool’s internal thread dowel pin (DIN 7979D) to align the cylinder head to the engine block. Since these are often blind holes in the cast iron block, the air release flat on the pin prevents the block from cracking due to hydraulic pressure during installation. Later, if the engine needs to be serviced again, the mechanic utilizes the internal thread feature to extract the steel dowel pin easily. This specific pin design is chosen to prevent damage to the engine block deck, which is a costly component to machine or replace.
About Us
Shanghai Screwtool Industrial Co., Ltd. is a dedicated manufacturer and supplier of industrial fasteners, established in 2011 as a subsidiary of the Victor Screw Group. We specialize in providing high-precision components to the global market, bridging the gap between Chinese manufacturing efficiency and international quality standards. Our facility in Lianyungang supports a wide range of production capabilities, from cold heading to precision grinding, allowing us to offer a comprehensive selection of “Pins,” including the hardened dowel pin, flexible split pin, and complex internal thread pins. We serve industries ranging from automotive and mold making to heavy machinery. Unlike simple trading houses, we offer factory-direct benefits including Mill Test Certificates, full traceability, and the ability to manufacture to custom tolerances or drawings. Whether you require a standard DIN/ISO metric part or a specialized locating element, Screwtool delivers consistent quality and professional logistical support.
Call to Action
Contact our engineering team to secure your bulk order of precision pins today!
FAQ
What is the tolerance class of your standard steel dowel pins?
Our standard hardened steel dowel pin (DIN 6325) is manufactured to an m6 tolerance zone, which provides a slight interference fit for precise alignment. We can also supply h6 tolerance (sliding fit) upon request.
How do I remove a dowel pin from a blind hole?
For blind hole applications, we recommend using our DIN 7979D (ISO 8735) dowel pin. These feature an internal thread that allows you to insert a bolt or slide hammer to pull the pin out without damaging the workpiece.
Do you sell unhardened dowel pins?
Yes, we supply unhardened metric dowel pins according to ISO 2338 standards. These are typically available in stainless steel (A1/A2/A4) or unhardened carbon steel, suitable for environments where corrosion resistance is more important than shear strength.
What materials are your split pins available in?
Our split pin (cotter pin) selection is available in Zinc Plated Steel, Stainless Steel (304/316), and Brass, ensuring compatibility with various mating materials and environmental conditions.
What is the lead time for custom pin sizes?
For standard stock items, we ship within 7-10 days. For custom precision dowel pins requiring specific lengths or non-standard diameters, the production lead time is typically 20-30 days depending on the quantity.
