When Titanium Alloy Meets Magnesium Alloy: How DAOLER® High-Friction Shims Solve the "Loosening" Challenge in Aerospace Connections
In the relentless pursuit of lightweighting in aerospace engineering, the combination of titanium alloy and magnesium alloy is widely regarded as a "golden pair"—titanium alloy delivers high strength, while magnesium alloy offers exceptionally low density. However, this cross-material pairing presents engineers with a formidable challenge during structural joining: fretting displacement at the dissimilar-material interface under shear loading.
When vibration and alternating loads act upon bolted connections, the substantial differences in elastic modulus and coefficients of thermal expansion between titanium and magnesium alloys readily induce micron-scale relative displacement. This not only leads to preload decay and thread loosening, but also triggers severe fretting wear on the magnesium alloy surface, posing a direct threat to the structural integrity of flight vehicles.
How can these two distinctly different materials be made to perform as an integrated whole at the joint?
DAOLER® provides the answer: a 0.19 mm high-friction shim that redefines the reliability of dissimilar-material connections.
Confronting the Three Major Pain Points in Aerospace Fastening
In analyzing the joint conditions between titanium-alloy and magnesium-alloy structural components, the DAOLER® technical team identified the inherent limitations of conventional solutions:
Insufficient friction, shear-induced slippage: Conventional metallic shims typically exhibit a friction coefficient below 0.3 on magnesium alloy surfaces, failing to adequately resist shear loads and resulting in interfacial slip.
Galvanic corrosion risk: The significant electrochemical potential difference between titanium and magnesium, combined with improper shim material selection, accelerates corrosion of the magnesium alloy.
Thermal cycling-induced failure: Spacecraft experience severe temperature fluctuations—from launch vibrations and extreme in-orbit temperatures to ground storage conditions. Ordinary shims lose their locking capability under such thermal cycling.
To address these challenges, DAOLER® developed a customized high-friction shim solution for a mission-critical aerospace structural connection project, with precisely defined parameters responding to stringent technical requirements. DAOLER Diamond Friction Shims.
DAOLER® Aerospace-Grade High-Friction Shims: Four Dimensions of Precision Breakthrough
1. Friction Performance: Static Friction Coefficient ≥ 0.6 – Locking Shear Loads
Under an M8 titanium-alloy bolt preload of 18,000 N, the DAOLER® high-friction shim achieves an exceptional static friction coefficient of ≥ 0.6.
Behind this performance lies the synergistic action of DAOLER®'s proprietary surface micro-texturing technology and specialized coating processes. The precision-engineered micro-serrated surface morphology, acting under bolt preload, establishes a dual locking mechanism of "mechanical interlocking + high friction" at the interfaces with both titanium and magnesium alloys. Even when shear loads approach critical thresholds, no relative displacement occurs at the contact interface, fundamentally eliminating bolt loosening induced by slippage.
2. Thickness Precision: 0.19 mm ± 0.03 mm – 35-Grade Dimensional Control
The contact areas of the four lugs impose stringent dimensional chain requirements on assembly clearances. DAOLER® high-friction shims employ precision rolling and stamping processes to strictly control thickness within 0.19 mm ± 0.03 mm, achieving 35-grade precision standards.
This ultra-thin design not only precisely compensates for assembly tolerances, but also preserves the original load transfer paths of the structure. Functioning as an "invisible guardian," the shim delivers critical anti-loosening performance within an extremely compact envelope, fully satisfying the aerospace industry's dual demands for lightweighting and structural compactness.
3. Extreme Thermal Adaptability: Service at –50 °C to 100 °C, Storage at –100 °C to 55 °C
From ground storage to on-orbit operation, spacecraft endure severe thermal cycling. DAOLER® high-friction shims have successfully passed rigorous validation under both service temperatures (–50 °C to 100 °C) and storage temperatures (–100 °C to 55 °C).
At cryogenic conditions of –50 °C, the shim material exhibits no brittle transition, with friction performance remaining stable. At elevated temperatures up to 100 °C, the coating neither softens nor degrades, maintaining a preload retention rate exceeding 95 %. Leveraging its deep expertise in material thermal stability and surface treatment processes, DAOLER® ensures that the shim performs reliably across the entire extreme temperature spectrum.
4. Dissimilar-Material Compatibility: Protecting Magnesium, Connecting Titanium
To mitigate the potential galvanic corrosion risk between titanium and magnesium alloys, DAOLER® high-friction shims employ a galvanically compatible substrate material combined with an isolating coating. The shim neither galles with titanium nor induces corrosion damage to the magnesium alloy surface.
Furthermore, the shim hardness is meticulously engineered—providing sufficient compressive strength to withstand 18,000 N preload while avoiding indentation or damage to the relatively soft magnesium alloy contact surface. This "rigid-flexible" characteristic positions the shim as an ideal medium for dissimilar-material joining.
Application Value: From Lug Joints to System-Level Reliability
Through the synergistic action of the four technical parameters outlined above, DAOLER® aerospace-grade high-friction shims deliver quantifiable value enhancement for titanium/magnesium alloy structural connections:
Shear-slippage resistance: Across the four lug contact zones, the significantly enhanced frictional force maintains rigid joint rigidity under lateral loading, with zero relative slip.
Bolt loosening prevention: Elimination of preload decay caused by interfacial fretting substantially extends the reliability lifecycle of the joint.
Structural integrity preservation: Avoidance of fretting wear on the magnesium alloy contact surface safeguards the pristine strength and fatigue life of thin-walled magnesium-alloy structures.
Choose DAOLER® – Choose Aerospace-Grade Certainty
In the aerospace domain, joint reliability is directly consequential to mission success. DAOLER® remains steadfast in its "zero-defect" commitment, delivering precision tribological solutions for every connection point.
Whether for the "cross-material joining" of titanium and magnesium alloys, or anti-loosening requirements across other dissimilar-material combinations, DAOLER® high-friction shims stand as a trusted choice for design engineers—backed by rigorous technical specifications and consistent process quality.
Every fastening, engineered to withstand the test of space.
When vibration and alternating loads act upon bolted connections, the substantial differences in elastic modulus and coefficients of thermal expansion between titanium and magnesium alloys readily induce micron-scale relative displacement. This not only leads to preload decay and thread loosening, but also triggers severe fretting wear on the magnesium alloy surface, posing a direct threat to the structural integrity of flight vehicles.
How can these two distinctly different materials be made to perform as an integrated whole at the joint?
DAOLER® provides the answer: a 0.19 mm high-friction shim that redefines the reliability of dissimilar-material connections.
Confronting the Three Major Pain Points in Aerospace Fastening
In analyzing the joint conditions between titanium-alloy and magnesium-alloy structural components, the DAOLER® technical team identified the inherent limitations of conventional solutions:
Insufficient friction, shear-induced slippage: Conventional metallic shims typically exhibit a friction coefficient below 0.3 on magnesium alloy surfaces, failing to adequately resist shear loads and resulting in interfacial slip.
Galvanic corrosion risk: The significant electrochemical potential difference between titanium and magnesium, combined with improper shim material selection, accelerates corrosion of the magnesium alloy.
Thermal cycling-induced failure: Spacecraft experience severe temperature fluctuations—from launch vibrations and extreme in-orbit temperatures to ground storage conditions. Ordinary shims lose their locking capability under such thermal cycling.
To address these challenges, DAOLER® developed a customized high-friction shim solution for a mission-critical aerospace structural connection project, with precisely defined parameters responding to stringent technical requirements. DAOLER Diamond Friction Shims.
DAOLER® Aerospace-Grade High-Friction Shims: Four Dimensions of Precision Breakthrough
1. Friction Performance: Static Friction Coefficient ≥ 0.6 – Locking Shear Loads
Under an M8 titanium-alloy bolt preload of 18,000 N, the DAOLER® high-friction shim achieves an exceptional static friction coefficient of ≥ 0.6.
Behind this performance lies the synergistic action of DAOLER®'s proprietary surface micro-texturing technology and specialized coating processes. The precision-engineered micro-serrated surface morphology, acting under bolt preload, establishes a dual locking mechanism of "mechanical interlocking + high friction" at the interfaces with both titanium and magnesium alloys. Even when shear loads approach critical thresholds, no relative displacement occurs at the contact interface, fundamentally eliminating bolt loosening induced by slippage.
2. Thickness Precision: 0.19 mm ± 0.03 mm – 35-Grade Dimensional Control
The contact areas of the four lugs impose stringent dimensional chain requirements on assembly clearances. DAOLER® high-friction shims employ precision rolling and stamping processes to strictly control thickness within 0.19 mm ± 0.03 mm, achieving 35-grade precision standards.
This ultra-thin design not only precisely compensates for assembly tolerances, but also preserves the original load transfer paths of the structure. Functioning as an "invisible guardian," the shim delivers critical anti-loosening performance within an extremely compact envelope, fully satisfying the aerospace industry's dual demands for lightweighting and structural compactness.
3. Extreme Thermal Adaptability: Service at –50 °C to 100 °C, Storage at –100 °C to 55 °C
From ground storage to on-orbit operation, spacecraft endure severe thermal cycling. DAOLER® high-friction shims have successfully passed rigorous validation under both service temperatures (–50 °C to 100 °C) and storage temperatures (–100 °C to 55 °C).
At cryogenic conditions of –50 °C, the shim material exhibits no brittle transition, with friction performance remaining stable. At elevated temperatures up to 100 °C, the coating neither softens nor degrades, maintaining a preload retention rate exceeding 95 %. Leveraging its deep expertise in material thermal stability and surface treatment processes, DAOLER® ensures that the shim performs reliably across the entire extreme temperature spectrum.
4. Dissimilar-Material Compatibility: Protecting Magnesium, Connecting Titanium
To mitigate the potential galvanic corrosion risk between titanium and magnesium alloys, DAOLER® high-friction shims employ a galvanically compatible substrate material combined with an isolating coating. The shim neither galles with titanium nor induces corrosion damage to the magnesium alloy surface.
Furthermore, the shim hardness is meticulously engineered—providing sufficient compressive strength to withstand 18,000 N preload while avoiding indentation or damage to the relatively soft magnesium alloy contact surface. This "rigid-flexible" characteristic positions the shim as an ideal medium for dissimilar-material joining.
Application Value: From Lug Joints to System-Level Reliability
Through the synergistic action of the four technical parameters outlined above, DAOLER® aerospace-grade high-friction shims deliver quantifiable value enhancement for titanium/magnesium alloy structural connections:
Shear-slippage resistance: Across the four lug contact zones, the significantly enhanced frictional force maintains rigid joint rigidity under lateral loading, with zero relative slip.
Bolt loosening prevention: Elimination of preload decay caused by interfacial fretting substantially extends the reliability lifecycle of the joint.
Structural integrity preservation: Avoidance of fretting wear on the magnesium alloy contact surface safeguards the pristine strength and fatigue life of thin-walled magnesium-alloy structures.
Choose DAOLER® – Choose Aerospace-Grade Certainty
In the aerospace domain, joint reliability is directly consequential to mission success. DAOLER® remains steadfast in its "zero-defect" commitment, delivering precision tribological solutions for every connection point.
Whether for the "cross-material joining" of titanium and magnesium alloys, or anti-loosening requirements across other dissimilar-material combinations, DAOLER® high-friction shims stand as a trusted choice for design engineers—backed by rigorous technical specifications and consistent process quality.
Every fastening, engineered to withstand the test of space.
