Washers

Drastic temperature changes and thermal cycling can cause brutal wear and tear on a variety of fastened assemblies. When tight margins of safety create a near-unobtainable pre-load requirement, securing these assemblies can be challenging. Negative thermal expansion alloys can help solve your tough thermal fastening issues, ensuring a safe and reliable system.

Features

ALLVAR Alloy 30 is a Negative Thermal Expansion (NTE) alloy that:

  • Has a longitudinal Coefficient of Thermal Expansion of -30.0ppm/°C at room temperature.
  • Has a positive CTE in the radial direction (similar in magnitude to Aluminum).
  • Can stabilize the mechanical force on other components. In a fastened assembly, the NTE can compensate for the expansion or contraction miss-match between the bolt and structural components.
  • Exhibits mechanical and material properties similar to other Titanium alloys.
  • Can be machined like many other metals, tolerances of ±0.001” are easily achievable for the most critical applications.
  • Is manufactured into standard size washers and custom thickness spacers.

Value Propositions

  • Enable smaller, lower profile, and lighter structures by eliminating the need for long compliant bolts and flexures.
  • Increase structure longevity by reducing thermal cycling fatigue.

The image to the left demonstrates how pre-load fluctuations stay below ± 200N simply by using an ALLVAR Alloy washer or spacer. Without the ALLVAR Alloy washer or spacer, LAV/Lplate=0, the clamping force is significantly reduced as temperature decreases. With an ALLVAR Alloy washer thickness of 20% of the plate thickness, LAV/Lplate=0.20, there is a near constant load kept across the same temperature range. This is a huge difference from the 50% pre-load reduction with a 120°C temperature change.

NTE Washer and Spacer Products Available

Negative CTE washers and spacers from ALLVAR compensate for the natural expansion and contraction of other materials with variations in temperature. ALLVAR Alloy washers and spacers combat other materials’ thermal displacement to keep constant force loads – whether it’s 80°C or -150°C. Athermalization of fastened assemblies can be achieved by eliminating the thermal changes in clamping force induced by different materials’ CTEs.

WASHER / SPACER STARTER KIT

Kit includes:

  • 12 hours of design and engineering time from ALLVAR engineers
  • Set of washers (quantity depends on size of washers and the application)

Washers available in #2, #4, #6, and #8 sizes. Custom washer and spacer sizes are available.

Nominal Washer size Washer Inside Diameter Washer Outside Diameter Thickness Range Washer Standards ASME B18.24 Part Number Item Number
2
0.094"
0.250"
0.028" - 0.036"
ASME B18.22.1
AEW26X08R000GY0A1
AW30-0002
4
0.125"
0.375"
0.036" - 0.045"
ASME B18.22.1
AEW26X11R000GY0A1
AW30-0004
6
0.156"
0.438"
0.036" - 0.045"
ASME B18.22.1
AEW26X13R000GY0A1
AW30-0006
8
0.188"
0.500"
0.036" - 0.045"
ASME B18.22.1
AEW26X16R000GY0A1
AW30-0008

Knowledge is Power

Our ALLVAR University video series offers a deeper dive into designing with ALLVAR Alloy 30. These specific videos offer more information related to the constant-force load washer application.

Contact Us Today to Revolutionize Your Thermal Performance

Have an application in mind? Please let us know if you have any questions.

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