Guides / Choosing a Supplier

Shipping and Storing Invar Parts Without Losing Dimensional Stability

September 20, 2026

A precision Invar part can be machined, stress relieved and inspected perfectly and still arrive at its destination out of tolerance if it was packaged or handled carelessly in between. Because these parts are specified for their stability, the packaging and shipping step deserves the same attention as the machining process, not an afterthought once the part passes final inspection.

Why handling matters more for Invar

Invar parts are often thin walled, precisely toleranced, or shaped to hold a specific geometric relationship between features, exactly the properties that make careless handling risky. A part that would shrug off a bump in transit if it were a rugged steel bracket can pick up a small permanent deformation, a bent feature or new internal stress if it is a delicate Invar mount, and that stress can manifest as dimensional drift over the following days or weeks, the same mechanism covered in stress relief for Invar machined parts.

The risk is not usually visible damage. A part can look untouched and still measure differently than it did at final inspection, which is why packaging deserves explicit attention rather than assuming standard practices are sufficient.

Packaging for shipping

• Individual cushioning, rather than parts loose in a box or touching each other, prevents contact damage and vibration induced wear during transit.
• Rigid support at non-critical features, not at the tightly toleranced surfaces, so the part is held securely without stressing the dimensions that matter.
• Desiccant or a vapor corrosion inhibitor for uncoated or lightly coated parts, particularly for shipments crossing humid climates or long transit times, since Invar’s corrosion resistance is better than plain steel but well below stainless, a point also covered in surface finish and coating options for machined Invar.
• Clear labeling of fragile or precision features, so anyone handling the package en route treats it appropriately rather than stacking heavier items on top.

Temperature considerations in transit

Invar’s whole purpose is to resist expansion with temperature change, so a reasonable temperature swing during shipping does not itself damage the part dimensionally. The concern is more about condensation: a part shipped from a cold environment into a warm, humid one can develop surface condensation if unpacked immediately, which increases corrosion risk on an uncoated surface. Letting a shipment acclimate to room temperature before unpacking, standard practice for many precision instruments, reduces this risk.

Storage before use

For parts that will sit in inventory before being put into service:

• Store in a dry, indoor, temperature stable environment, avoiding areas with humidity swings or direct exposure to outside air
• Keep parts in their original packaging or an equivalent protective wrap until needed, rather than storing loose on a shelf
• For uncoated parts intended for long term storage, consider a light protective coating or periodic inspection for surface oxidation, especially in humid climates

Inspection after transit

For applications where dimensional stability is critical, such as optical mounts or metrology reference parts, it is worth re-verifying critical dimensions after a shipment, particularly a long transit or one that crossed significant climate differences, before putting the part into service. This is not a sign of distrust in the shop’s original inspection, it is a recognition that transit is a real physical process the part goes through between the shop’s CMM and your assembly line.

If a re-inspection shows a part out of tolerance after shipping when it passed at the shop, that is worth reporting back, since it can indicate either a packaging issue worth fixing for future orders or, less commonly, a stress relief cycle that did not fully relieve the part’s internal stress before it shipped.

What to specify to your shop

• Whether the part requires special packaging beyond a shop’s standard practice
• The destination’s typical climate, if significantly different from the shop’s location
• Whether you need the shop to re-verify dimensions immediately before packaging, as a final check separate from the original inspection

Most shops that regularly ship precision Invar parts internationally have already developed packaging practices suited to the material. Asking about their standard approach before the first order ships is a reasonable question, and one covered in the broader context of how to find a machine shop with real Invar experience.

Send your drawing through our RFQ form, and mention your destination and any special handling requirements. We match you with shops that ship precision low expansion alloy parts internationally as a matter of course.

Frequently asked questions

Keep reading

• Invar Mill Certifications: What a Certified Material Report Should Show
• What to Include on an Invar RFQ: A Drawing Checklist