Choosing Separating Nut: Application Fit and Specification Checks

What Is a Separating Nut?

A Separating Nut is a hold-down and release fastener designed for spacecraft moving-part assemblies. Rather than relying on pyrotechnic charges, the Separating Nut offered by Astralink Science and Technology Co., Ltd. adopts an unlocking mode triggered by memory alloys—a non-initiating explosive mechanism that produces significantly lower shock levels than conventional pyrotechnic releases.

The result is a compact, reusable fastener suitable for deployment sequences where shock sensitivity matters and repeated ground testing is required.

Typical Applications

The memory-alloy Separating Nut is designed to replace conventional compression-and-release hardware on:

• Antenna driving mechanisms — restraining antenna panels or reflectors during launch and releasing them on command
• Laser communication turntables — securing turntable assemblies during ascent and enabling on-orbit unlocking
• Solar wing deployment systems — providing reliable hold-down of solar arrays until the commanded release sequence is initiated

If your mechanism falls into one of these categories and requires low-shock actuation with the ability to test repeatedly on the ground, the Separating Nut is a candidate worth evaluating.

Available Models and Specifications

Three model variants are confirmed. Key specifications are reproduced directly from the product data sheet:

All three variants share the same operating temperature range, unlocking time, reuse count, and supply cycle.

Selection Criteria

1. Locking Force vs. Structural Load

Begin by calculating the maximum preload or hold-down force your mechanism must sustain through launch vibration and acoustic environments. Match that figure to the tight locking force rating:

• 3 kN (M5) — suitable for lighter antennas, small turntable sub-assemblies, or compact appendages
• 8 kN (M8) — mid-range applications where moderate hold-down loads are combined with tighter mass budgets
• 10 kN (M10) — higher-load deployables such as larger solar wings or heavier antenna panels

Do not select a model whose rated locking force falls below your calculated interface load with margin applied.

2. Thread Compatibility

Each variant is built around a defined nut specification (M5, M8, M10). Confirm that the mating bolt thread on your structure matches the variant you select. Changing thread size on an existing interface usually requires a structural redesign of the boss or insert.

3. Envelope and Mass Budget

Envelope dimensions range from Φ29 × 27 mm for the M5 variant up to Φ61 × 38 mm for the M10 variant. Check both the radial and axial clearances on your interface drawing before committing to a model. The corresponding mass increase (60 g → 200 g) should also be budgeted against the subsystem's allocation.

4. Thermal Environment

All three variants are rated for −70 to +70 °C. Verify that your mechanism's worst-case thermal environment—including launch pad soak, eclipse cycling, and storage conditions—stays within this range. Applications whose thermal environment falls outside this band cannot be served by the current product line without further engineering review.

5. Shock Sensitivity Requirements

The memory-alloy actuation principle is explicitly chosen to reduce separation shock compared with pyrotechnic alternatives. If your payload or co-located instruments impose strict shock limits, this is a relevant differentiator. However, exact shock output values are not available in the current confirmed materials; request detailed test data from Astralink Science and Technology Co., Ltd. if shock spectra form part of your qualification criteria.

6. Ground Test and Reuse Requirement

The product is designed for repeated application, with an unlocking impact rating of 20 times. This supports repeated ground deployment testing without hardware replacement after each cycle, which can reduce test campaign cost. If your program requires more than 20 test cycles on a single unit, confirm reuse limits with the supplier.

7. Schedule: Supply Cycle

The confirmed supply cycle for all variants is 3 months. Incorporate this lead time into your procurement schedule and mission timeline. If your integration schedule is tighter, contact the supplier early to discuss options.

Quick Selection Reference

When This Product May Not Apply

• Thermal environments below −70 °C or above +70 °C — no confirmed variant covers this range.
• Locking forces above 10 kN — the current product line tops out at 10 kN; higher-load requirements need a different solution.
• Strict quantified shock spectra requirements
• Schedules requiring delivery in under 3 months — verify feasibility with the supplier before committing.

About Astralink Science and Technology Co., Ltd.

Astralink Science and Technology Co., Ltd. focuses on the research and development of high-performance, low-cost satellites and air-space-ground integrated remote sensing information services. Its main business covers full satellite services, components and parts services, and satellite data. The Separating Nut is part of Astralink's components and parts portfolio, designed to support spacecraft deployment mechanisms in commercial satellite programs.