ISO 7379 / DIN 730
Shoulder Bolts
- Precision Shoulder, Stable Pivot Motion.
- Tight Tolerance, Zero Assembly Play.
- Forged Strong, Long Mechanical Life.
Sinsun Shoulder Bolts – Precision Ground Socket Head Screws | ISO 7379 Shoulder Screws & Stripper Bolts for Bearings, Pivot Points & Die Fixtures
Sinsun is a professional shoulder bolts manufacturer and global supplier. We manufacture precision, stainless steel, hex head and stripper shoulder bolts for pivot, automation and mold assembly. Get tight-tolerance shoulder bolt solutions at factory prices.
Get a Quick QouteSinsun Shoulder Bolts Factory | Precision Stainless Steel & Hex Head Shoulder Bolts
We manufacture precision shoulder bolts (shoulder screws / stripper bolts / dowel bolts) in Grade 12.9 alloy steel and A2/A4 stainless steel per ISO 7379. From rotating bearing shafts and pivot joints to die stripper bolts and gate hinges, each Sinsun shoulder bolt delivers tight-tolerance shoulders and reliable performance. Request factory pricing with Mill Test Certificates today.
Get a Quick QouteSinsun Shoulder Bolts | Product Overview & Core Advantages
Shoulder Bolts Shoulder bolts, also known by the term “stripper bolts” or “shoulder screws” in industrial markets worldwide, are special precision fasteners with a smooth cylindrical shoulder between the bolt head and threaded shank. They have different names in different parts of the industry. In Europe they are called boulons à épaulement by engineers, in Spain they are called pernos con hombro by industrial purchasers, and in Asia the mold making industry uses the term jig bolts. Unlike standard bolts, the non-threaded shoulder is a fixed bearing and a positioning journal for free sliding and rotating movement of the mating components.
Sinsun is a professional shoulder bolt manufacturer, with distinct competitive edges over ordinary fastener factories. Most suppliers only produce commercial grade standard shoulder bolts with loose dimensional tolerances. We only classify products into commercial grade and precision grade according to application scenarios, and all high-end models are precision ground. All Sinsun shoulder bolts are manufactured under ISO and DIN industrial standards to ensure ultra-tight tolerance control of shoulder diameter and concentricity, meeting the demands of precision mechanical assembly.
Global mechanical and automation manufacturers often experience operational defects caused by low quality shoulder bolts. These defects include pivot wobble, shoulder surface burrs, thread misalignment and rapid wear during cyclic motion. Integral die forging and secondary precision surface finishing solve these core pain points. Our complete line of stainless steel shoulder bolts, hex head shoulder bolts and stripper shoulder bolts provide low friction, stable positioning performance in long term high frequency movements and vibrations. We also support non-standard size and tolerance customization for specialized automation and mold engineering projects.
Shoulder Bolts Shoulder bolts, also known by the term “stripper bolts” or “shoulder screws” in industrial markets worldwide,
Types of Shoulder Bolts | Sinsun Hot-Selling Full Classification
Browse all high-traffic Sinsun shoulder bolts types, including precision, stainless steel, hex head, stripper and grooved shoulder bolts for diverse industrial pivot and fixing scenarios.
Precision Shoulder Bolts
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Stainless Steel Shoulder Bolts
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Hex Head Shoulder Bolts
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Stripper Bolts
Send inquiry Now| Shoulder Diameter d₂ (mm) | Shoulder Tolerance (mm) | Thread Size | Thread Length C (mm) | Head Diameter d_k (mm) | Head Height k (mm) | Allen Key Size (mm) |
| 4 | 0 | M3 × 0.5 | 9.75 | 7 | 3.5 | 2.5 |
| 5 | 0 | M4 × 0.7 | 10.25 | 8.5 | 4 | 3 |
| 6 | 0 | M5 × 0.8 | 11.25 | 10 | 4.5 | 3 |
| 8 | 0 | M6 × 1.0 | 13.25 | 13 | 5.5 | 4 |
| 10 | 0 | M8 × 1.25 | 13.25 | 16 | 7 | 5 |
| 12 | 0 | M10 × 1.5 | 16.4 | 18 | 9 | 6 |
| 16 | 0 | M12 × 1.75 | 18.4 | 24 | 11 | 8 |
| 20 | 0 | M16 × 2.0 | 22.4 | 30 | 14 | 10 |
| 25 | 0 | M20 × 2.5 | 26.4 | 36 | 17 | 12 |
*Source: ISO 7379 / DIN 730. Shoulder length (L) available from 6mm to 120mm stock, custom lengths to 200mm.*
Imperial ASME B18.3 Socket Shoulder Screws
| Shoulder Diameter (inch) | Shoulder Tolerance (inch) | Thread Size (UNC) | Thread Length D (inch) | Head Diameter E (inch) | Head Height F (inch) | Allen Key Size (inch) |
| 1/4″ | 0 | #10-24 | 3/8″ | 3/8″ | 3/16″ | 1/8″ |
| 5/16″ | 0 | 1/4″-20 | 7/16″ | 7/16″ | 7/32″ | 5/32″ |
| 3/8″ | 0 | 5/16″-18 | 1/2″ | 9/16″ | 1/4″ | 3/16″ |
| 1/2″ | 0 | 3/8″-16 | 5/8″ | 3/4″ | 5/16″ | 1/4″ |
| 5/8″ | 0 | 1/2″-13 | 3/4″ | 7/8″ | 3/8″ | 5/16″ |
| 3/4″ | 0 | 5/8″-11 | 7/8″ | 1″ | 1/2″ | 3/8″ |
| 1″ | 0 | 3/4″-10 | 1″ | 1-5/16″ | 5/8″ | 1/2″ |
- Meta Description: View Sinsun shoulder bolts core technical parameters, including materials, tolerance grades, surface treatments and industrial standards for precision mechanical assembly.
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Product Aliases: Shoulder screws, stripper bolts, pivot bolts, jig shoulder fasteners.
- Main Materials: Carbon steel, alloy steel, 304/316 stainless steel.
Sinsun Shoulder Bolts Core Technical Parameters
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Tolerance Grades
Commercial grade (standard tolerance), Precision grade (tight grinding tolerance).
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Surface Treatment
Black oxide, zinc plating, passivation, plain finish.
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Compliant Standards
ISO 7379, DIN 939, ANSI industrial manufacturing specifications.
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Structural Feature
Smooth cylindrical shoulder, partial thread design, high concentricity.
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Core Performance
Low friction, anti-wear, precise positioning, anti-loose optional structure.
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Custom Service
Support custom shoulder diameter, length, groove position and tolerance
Main Applications of Sinsun Shoulder Bolts
High-traffic application scenarios of Sinsun shoulder bolts, covering automation, mold manufacturing, automotive machinery and precision equipment assembly.
Automation Equipment Assembly
Precision shoulder bolts are the core pivoting and positioning components of robotic arms and robotic production lines. The ultra-smooth shoulder surface guarantees smooth low-friction cyclic rotation and sliding movement. Tight tolerance control eliminates assembly gaps and operational jitter. In automated mechanical systems, these bolts offer high-precision repetitive motion stability.
Stamping Industrial Equipment
Mold stripper shoulder bolts are custom designed for guiding and positioning mold stripper plates. Standardized shoulder sizes for uniform plate parallelism during low- speed stamping & resetting. Exceptional strength alloy material, resistant to frequent impact and extrusion wear. They effectively improve mold operation accuracy and prolong the service life of the die.
Medical & Precision Instrument Equipment
316 stainless shoulder bolts for medical devices, optical instruments and precision test equipment. When used in a clean environment, corrosion-resistant materials prevent contamination by rust. High-precision forming process guarantees zero deformation and precise positioning. They satisfy high-end precision industries’ strict cleanliness and accuracy demands.
Dynamic Vibration-Prone Mechanical Devices
Grooved shoulder bolts with retaining ring construction are suitable for high-vibration industrial equipment and parts that move frequently. The anti-disengagement design, professional in its approach, ensures that bolts do not loosen and parts do not move during cyclic operation.The reliability of the locking system reduces the risk of equipment failures and maintenance costs. In addition, they improve the operational safety of mechanical systems.
Hot FAQ | Sinsun Shoulder Bolts Common Questions
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Q:A shoulder bolt is used to secure two plates of material together？
A shoulder bolt is a precision shaft, pivot point or guide pin. The smooth unthreaded shoulder provides a bearing surface for rotating or sliding components while the threaded end provides clamping. -
Q: Shoulder bolt vs. regular bolt?
A standard bolt is a fully threaded fastener used to clamp components together. A shoulder bolt has a smooth, unthreaded shoulder that is larger in diameter than the thread, to act as a shaft or bearing surface. -
Q: What is a "stripper bolt"?
"Stripper bolt" is a generic name for a shoulder bolt used in stamping dies and injection moulds. The shoulder acts as a guide for the stripper plate as it moves up and down in the press cycle. -
Q: How is a shoulder bolt identified?
Shoulder bolts are specified with shoulder diameter first, then shoulder length. For example, a "10mm x 40mm shoulder bolt" has a shoulder diameter of 10mm and a shoulder length of 40mm, not thread size or overall length. -
Q: What is the best tolerance for a ball bearing shaft?
To mount the inner ring of a ball bearing, choose precision-grade shoulder bolts with a tolerance of +0.000/-0.001″ (imperial) or h8 class (metric). Commercial grade (±0.005") is too loose and the bearing will wobble. -
Q: Can I use a shoulder bolt as a hinge pin for a gate?
Yes, a shoulder bolt is perfect for a heavy gate hinge pin. The thread screws into the gate frame, the unthreaded shoulder passes through the hinge barrel, and the head holds the hinge. Use stainless steel A4-80 to be used on coastal or outdoor doors. -
Q: What material to use for shoulder bolts that get a lot of wear?
For high wear applications such as stripper bolts in stamping dies, use Grade 12.9 alloy steel with nitrided or induction hardened shoulder surface (minimum 55 HRC). Standard industrial pivots are fine with Grade 12.9 as supplied. -
Q: Does a shoulder bolt need a nut?
It depends. If the mating part has a tapped hole, then no nut is required. If the shoulder bolt goes through a clearance hole you will need a nut on the opposite side. Stripper bolts always go into a tapped hole in the die shoe. -
Q: Are stainless steel shoulder bolts as strong as those made of alloy steel?
No. A4-80 (316) stainless has a tensile strength of 800 MPa, whereas Grade 12.9 alloy steel is about 50% stronger at 1,220 MPa. Use alloy steel for high-load applications and coat to protect against corrosion. -
Q: Do you have shoulder bolts with non-standard head drives?
Yes – we can manufacture shoulder bolts with external hex heads, Torx drives (T-series), Phillips, slotted or square drive heads. Minimum order quantities are applicable.
shoulder bolt installation & selection guide – getting it right
Step‑by‑Step Installation of a Shoulder Bolt
01
Choose the right bolt length: The total shoulder length should be equal to the thickness of all rotating components on the shoulder, plus 0.1mm–0.3mm for free rotation. Do not clamp rotating parts between the head and the housing.
02
Prepare the mounting hole There are two options for mounting: The thread is placed into a tapped hole (fixed shoulder bolts) or it passes through a clearance hole with a nut on the backside (through-bolting). Never force the shoulder into a hole that is too small; the shoulder should slide freely into its clearance bore.
Get Samples02
Insert shoulder bolt: Hand-thread the bolt until the shoulder touches the mating component or the head touches the top component.
04
Torque: Use torque wrench on head drive (Allen key or socket). For 12.9 grade bolts, see the torque table below.If you overtighten the shoulder, you may strip the threads or crack the neck of the shoulder.
05
It is important to ensure that the rotating part can rotate freely on the shoulder without any endplay. If it binds, then the shoulder tolerance is either too tight ( premium precision grade ) or the shoulder length is too short . There is too much wobble, or the tolerance on the shoulder is too loose, or the hole diameter is too big.
Get SamplesTorque Reference for Shoulder Bolts (Grade 12.9 Alloy Steel, Lubricated Threads)
| Thread Size | Recommended Torque (N·m) | Recommended Torque (ft‑lbs) | Notes |
| M4 | 2–3 | 1.5–2.2 | Use 2.5mm Allen key |
| M5 | 5–7 | 3.5–5 | |
| M6 | 10–13 | 7–9.5 | |
| M8 | 24–28 | 17–20 | |
| M10 | 48–55 | 35–40 | |
| M12 | 85–95 | 62–70 | Two‑pass tightening recommended (60% then 100%) |
| M16 | 210–230 | 155–170 | |
| M20 | 410–450 | 302–332 | Use torque wrench with calibrated extension |
*These values assume clean, lubricated threads. Reduce torque by 15–20% for dry threads. For stainless steel A4-80 shoulder bolts, reduce torque by 30% to prevent thread galling.*
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