Shoulder screws are one of those interesting fasteners designed for very specific uses that can be classified as a device that “when you really need them, you really need them.” Waltham, Massachusetts shoulder screws, also known as shoulder bolts and stripper bolts, are machine screws with an integral shoulder or journal between the head and thread and are used extensively in industries from aerospace to consumer products because of their versatility and unique attributes when installed.
You’ll find shoulder screws used in a variety of applications and industries, including
- Plastic mold injection
The construction of shoulder screws makes them particularly useful for rotary movement applications, such as shafts for rotating bushings and bearings. Other uses include as guides, axles, and pivot points.
Shoulder screws feature three main sections: head, shoulder, and thread. The head has the largest diameter, the shoulder is described by its diameter and length, and the thread has a major diameter slightly smaller than the shoulder diameter. What makes these screws unique is the mechanical components the shoulders can accommodate. Bearings mounted on shoulders create simple cam followers. Pulleys, gears, and sprockets can rotate at moderate speeds on shoulders. Shoulder-mounted springs can preload components traveling axially along the length of the shoulder.
Shoulder screws can be made from a variety of materials including hardened alloy steel, mild steel, stainless steels, brasses, and plastics. Here are a few of the most common:
- Stainless steels, including:
- 303 – most commonly used, with good corrosion-resistance
- 316 – better corrosion-resistance, good for marine applications
- 17-4 PH – can be heat-treated for greater hardness
- 416 – stronger than 300 series steels
- Alloy steel – the original steel used, common in commercial grade screws
- Mild steel – less expensive than stainless, good for light-duty applications
- Brass – natural lubricity makes it good for sliding and rotating applications, good for light duty
- Plastics – considered commercial grade, plastic screws offer excellent high volume pricing
It’s important to know that you can choose the head type, shoulder length, thread length, and other variables that best fit your application. If necessary, custom shoulder screws can be quickly and inexpensively produced by screw machines for small quantities or cold headers for large quantities. To learn more about options and availabilities, contact the shoulder screw experts at Electronic Fasteners.