HUASHENG PRECISION · Updated September 11, 2026
Kovar vs Alloy 42 vs Invar: Specify the Expansion Requirement
Controlled-expansion alloys should be selected against the assembly and its temperature range. Compare the exact material specification and condition before requesting machining or proposing a substitution.
Comparison and drawing review
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| Requirement | What to specify or discuss |
|---|---|
| Kovar | Commonly considered for compatible glass/ceramic sealing systems; the mating material and sealing process must be specified. |
| Alloy 42 | A controlled-expansion alloy used in relevant sealing and electronic applications; use the grade-specific expansion data and product specification. |
| Invar 36 | Considered where low thermal expansion is important; confirm the operating range and required material condition. |
| Any proposed alternative | Compare approved property data over the actual temperature range, supplied form, condition and verification requirements. |
Use the expansion curve for the relevant range
A single coefficient at one temperature does not describe the entire assembly behavior. Tell the supplier the minimum and maximum operating or processing temperatures and identify the material the part must match. Have the design authority approve the selected grade.
Keep material condition in the purchase specification
State the governing specification, stock form and required heat treatment or condition. Confirm whether material documents or additional verification are needed. Free-machining variants and alternate trade names must be checked against the drawing rather than assumed equivalent.
Coordinate machining with downstream sealing
If the part will be plated, heat treated or sealed, specify the sequence and which dimensions apply at each stage. Identify the faces that are functional, the surfaces that need protection and any restrictions on cleaning or handling.
Quote a complete requirement
Send the model and dimensioned drawing, grade, quantity, critical features, final surface condition and inspection scope. We review the machining enquiry against those conditions; material choice and the suitability of a sealing system require the appropriate design approval.
Workshop information
Our company presentation records a 7,000 m² facility in Dongguan, 35 CNC machines and 170 employees. Manufacturing, inspection and any required partner processing are reviewed against the drawing and order requirements.
If a certification or specific document is required, identify its scope before quotation.
Company and equipment informationTechnical references
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