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Technical Guide: Miniature Ball Screw Assemblies
Technical Guide: Miniature Ball Screw Assemblies

Technical Guide: Miniature Ball Screw Assemblies

Internal Multi-liner Cylindrical and Flange Nuts for Ball Screw

Ball screw nuts feature an internal return multiliner and are available in cylindrical, externally threaded, and flange nut styles.

Ball screw assemblies expand the PBC Linear screw-driven product line and are engineered and manufactured in the USA to meet growing demand across medical, semiconductor, and automation markets. These compact, high-precision assemblies — offered in metric diameters of 6 mm, 8 mm, and 10 mm with multiple lead and nut style options — deliver efficient, low-friction conversion of rotary to linear motion and are backed by conservative dynamic load ratings and shorter lead times. Designed for tight-space applications, the miniature ball screw line complements traditional lead screw offerings with enhanced performance, flexibility, and reliability for modern OEM systems. Customers may purchase miniature ball screw assemblies (without motors) or peruse our miniature ball screw NEMA motor series.

Discover your ideal ball screw assembly:

Other Related Resources:

Design options to meet your needs

As with lead screws, ball screw assemblies are used to convert rotational motion to linear motion. The main benefits of ball screws are higher efficiency and accuracy, making them ideal for a variety of industrial and automotive applications. They typically include a ball nut, threaded shaft, and a recirculating system that utilizes a continuous movement of balls to transfer forces and propel the nut along the screw. Each ball screw and nut are engineered with gothic arch threads that define the track of the nut and screw thread, offering high rigidity, durability, and duty cycles. PBC Linear offers three nut styles: flanged, externally threaded cylindrical, and cylindrical.

Flanged Ball Nut

Best used when:
You have room for a wider mounting surface and want straightforward bolt-on installation.

Key benefits:

  • Easy to mount with bolt holes in flange
  • Strong, secure attachment
  • Great for general-purpose industrial designs

Cylindrical Ball Nut (Externally Threaded)*

Best used when:
Space is tight and you want the nut to thread directly into a housing.

Key benefits:

  • Compact, space-saving design
  • Clean, round outer profile
  • Ideal for cartridge-style or enclosed assemblies
  • Simplifies integration into cylindrical housings

Cylindrical Ball Nut (No External Threads)

Best used when:
You need a custom mounting solution or clamp-style housing.

Key benefits:

  • Maximum design flexibility
  • Works well in split housings or clamping blocks
  • Good for custom or highly integrated assemblies

Benefits of Ball Screws

Ball screws are used to convert rotational motion into linear motion. They are composed of a threaded shaft, nut and ball bearings. The helical grooves on the shaft match with the internal helical grooves in the nut which is where the ball bearings to roll to create linear movement. The use of ball bearings reduces friction and helps to create a highly efficient system.

Ball screws can offer considerable performance advantages over alternative types of linear motion technology, as listed below:

  • Pneumatic: Ball screws can withstand a higher load with greater precision over pneumatics.
  • Rack & Pinion: Ball screws offer reduced backlash with greater accuracy and precision compared to rack & pinion.
  • Hydraulic: Ball screws achieve greater precision and are generally less expensive than hydraulic systems.
  • Linear Motor: Ball screws can move a heavier load and are generally less expensive than a linear motor.

Roll with Confidence

When bringing products to market, PBC Linear uses a methodical approach to research and development. As with lead screws, customers can be assured that each of our new product introductions has gone through all the necessary testing parameters. We utilize high-end testing equipment such as Keyence optical comparators, Mitutoyo thread form tracers, and custom dynamic lead checkers that analyze up to 15,000 points per meter.

For both our lead screw and ball screws, we use a high-precision, roll-threading process for the most consistent thread forms and high accuracy rate. In addition, we measure and record 100% positional accuracy along the entire travel length of the screw.

Ball Screw Testing

Our miniature metric ball screw product line is currently offered in diameter sizes of 6 mm, 8 mm, and 10 mm, with options for lead length and nut type. Depending on the application, each nut can be acquired in either a flanged or cylindrical configuration.

Dynamic load ratings are an important factor when determining the correct miniature ball screw for an application. PBC Linear will provide conservative dynamic load rating values within this product family, based on 1,000,000 Rev (N). This ensures trusted, reliable performance for those looking to implement miniature ball screws into their systems.

Preload Option -- Ball screws from PBC Linear come standard without preload (backlash clearance held to 0.05 mm MAX). Contact a PBC Linear Application Engineer about reduced backlash options.

Motors – Customers looking for a complete ball screw package can count on PBC Linear for the most appropriate world-class NEMA stepper motors to offer precise positioning and speed control.

Journaling -- Custom journaling of the screw ends and additional support blocks can be requested for unique customer requirements.

Size (Diameter x Lead)
Ball Return Type

6 mm x 1 mm

Internal Multi-liner

6 mm x 2 mm

Internal Multi-liner

8 mm x 1 mm

Internal Multi-liner

8 mm x 2 mm

Internal Multi-liner

8 mm x 2.5 mm

Internal Multi-liner

10 mm x 2 mm

Internal Multi-liner

Ball Screw Internal Multiliner

Ball screw nuts can be purchased in a flange or cylindrical type configuration to meet their respective application. Flange style nuts can often be easier to remove and install in an assembly, provided the assembly can be designed so that the mounting screws or bolts can be easily accessed. Cylindrical nuts allow for a more compact assembly design as there is no flange.

Internal return multiliner nuts are versatile and built to function with shorter leads and lighter loads. Their compact geometry and lighter weight offer a great option for space-saving applications requiring high precision linear motion.

PBC Linear ball screws utilize an internal return multiliner nut. Their compact geometry and lighter weight offer a great option for space-saving applications requiring high precision linear motion.

Ball Screws vs Lead Screws

When it comes to deciding between lead screws and ball screws, each has its own unique advantages within certain industries. The obvious difference is the recirculating balls within ball screw assemblies, which help alleviate the sliding friction that’s associated with lead screw technology. Once you have established the load, accuracy, and lead for your application, consider other factors such as lead accuracy, efficiency, noise, maintenance, and longevity.

Choosing the correct screw-driven technology

When choosing a screw and nut assembly, engineers should consider their application’s core requirements including load, speed, stroke, and accuracy.

Dynamic load ratings for each type and size of screw can be found in either our lead screw or ball screw catalog.

Speed is dictated by lead lengths, with higher leads allowing for quicker movement along the length of the screw.

Stroke is defined by the application, representing the allowable distance traveled along the screw shaft.

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Lead Screw Advantages:

  • Cost less than ball screws.
  • Self-lubricating (Relies on Simplicity technology from PBC Linear).
  • Quieter motion than ball screws.
  • If a lead screw with a short lead is used in a vertical application, the design may not be back-driveable. That can possibly eliminate the need for a separate brake.
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Ball Screw Advantages:

  • More efficient (Requires less torque and smaller motor/drive system).
  • Less friction (Generates less heat).
  • Less frequency of replacement.
  • Can support higher axial nut loads than a lead screw of the same diameter and lead.
  • Higher speed and load capabilities (Not limited by PV).

If you need help deciding on whether to use a lead screw or ball screw for your linear-motion application, contact one of our application engineers today.

Stop waiting and get rolling with American-made** miniature ball screw assemblies from PBC Linear. Our ball screw production process offers shorter lead times, avoiding costly downtimes and delays getting to market! With ball screws from PBC Linear, you can count on our recognized high-precision standards and competitive pricing for a superior value. Standard ball screws ship assembled but are also available unassembled.

What is the lifetime of Ball Screws?

The formula to calculate the service life that 90% of identical, properly lubricated ball screws are expected to reach is:

L10 = (Ca / Fm)3 · 106 (revolutions)

Where:
L10 = service life (revolutions)
Ca = dynamic load rating (N)
Fm = average axial load (N)

Lh = L10 / (nm · 60) (hours)

Where:
Lh = service life (hours)
nm = average rotational speed (rpm)

In applications where vibration or impact loading is present, the life calculations can be adjusted as follows:

L10 = (Ca / (fw · Fm))3 · 106 (revolutions)
Vibration or Impact(fw) Factor
Minor1.0 to 1.2
Low1.2 to 1.5
Moderate1.5 to 2.0
High2.0 to 3.5

I. Average Axial Load Fm for Constant Rotational Speed and Varying Axial Load

Fm = 3√(F13 · p1 / 100 + F23 · p2 / 100 + ... Fn3 · pn / 100)

Where:
F1,2,...n = load per cycle unit (N)
p1,2,...n = cycles (%)

II. Average Rotational Speed nm at Constant Axial Load

nm = n1 · p1 / 100 + n2 · p2 / 100 + ... + nn · pn / 100

Where:
n1,2,...n = rotational speed per cycle unit (rpm)
p1,2,...n = cycles (%)

L10 = (Ca / Fm)3 · 106 (revolutions)
Lh = L10 / (nm · 60) (hours)

III. Average Axial Force and Rotational Speed

When the axial load and the rotational speed vary between different values:

Fm = 3√(F13 · p1 / 100 + F23 · p2 / 100 + ... Fn3 · pn / 100)
nm = n1 · p1 / 100 + n2 · p2 / 100 + ... + nn · pn / 100
PBC Linear provides faster lead times for ball screws

Ball Screws when you need them

Get your complete miniature metric ball screw and nut package that’s out-of-the-box ready to be lubricated and integrated into your next OEM project. We offer shorter lead times, which is accomplished through our ball screw production process and central Midwestern location where we engineer and produce many of our products. We are proud to say that our miniature ball screws are made in America*.

* Cylindrical Ball Nuts (Externally Threaded) are available soon

**Ball screws from PBC Linear are Made in America using both domestic and foreign material sources.

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Source: PBC Linear - “Technical Guide: Miniature Ball Screw Assemblies”
https://pbclinear.com/blogs/blog/introducing-miniature-ball-screw-assemblies
Last updated: February 2026