Mycalex 400
Grade · default condition
ISO IEC 60672-3 GM-120
400 = grade 400
Pick the standard moulded lead-borate glass-bonded natural mica for high-frequency insulation, arc resistance and machinability in switches, tube sockets and breaker parts up to 350 °C.
Values for the 400 condition
Other Mycalex tempers and conditions
Mycalex is listed in 3 conditions; see the grade overview at Mycalex.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Grade 410 | Choose the free-machining glass-bonded mica when parts must be turned, milled, drilled and tapped to ±0.02 mm with no post-fire shrinkage; strength is slightly below Grade 400. | — | 40 | 0.1 | 210 HV | 0.65 W/m·K |
Grade 1100 | Use the lead-free synthetic fluorophlogopite mica for RoHS compliance, service near 500 °C or low dielectric loss in RF and vacuum parts; density is lower but cost is higher. | — | 42 | — | — | 0.8 W/m·K |
400DefaultThis page Grade 400 | Pick the standard moulded lead-borate glass-bonded natural mica for high-frequency insulation, arc resistance and machinability in switches, tube sockets and breaker parts up to 350 °C. | — | 45 | 0.1 | 250 HV | 0.7 W/m·K |
What is Mycalex 400?
Mycalex 400 is Mycalex in the 400 grade — pick the standard moulded lead-borate glass-bonded natural mica for high-frequency insulation, arc resistance and machinability in switches, tube sockets and breaker parts up to 350 °C. Mycalex 400 has a tensile strength of 45 MPa (6.53 ksi), weaker than 56% of glass grades. Elongation at break is 0.1% and the elastic modulus is 65 GPa (9.43 Msi). Mycalex 400 has a density of 3.4 g/cm³ (0.123 lb/in³), heavier than 64% of glass grades.
Advantages
- Easy to machine — 75/100, better than 98% of glass grades
- Tough — resists crack growth — 1.3 MPa·√m (1.18 ksi·√in), better than 91% of glass grades
- Ductile — tolerates forming and impact — 0.1%, better than 78% of glass grades
Limitations
- Poor heat conductor — 0.7 W/m·K (0.404 BTU/hr·ft·°F), worse than 95% of glass grades
- Hard to polish — 45/100, worse than 92% of glass grades
Mycalex 400 properties
Typical room-temperature values for Mycalex 400; 16 are specific to this condition. Other listed values are Mycalex reference data and may not represent this condition. Bars are the position among glass grades.
Physical2
Mycalex 400 has a density of 3.4 g/cm³ (0.123 lb/in³), heavier than 64% of glass grades.
Mechanical13
Mycalex 400 has a tensile strength of 45 MPa (6.53 ksi), weaker than 56% of glass grades. Elongation at break is 0.1% and the elastic modulus is 65 GPa (9.43 Msi).
Thermal5
Mycalex 400 is rated for continuous service to 350°C (662 °F). It conducts heat at 0.7 W/m·K (0.404 BTU/hr·ft·°F), worse than 95% of glass grades. Thermal expansion is 11 µm/m·K (6.11 µin/in·°F).
Electrical5
Mycalex 400 is an electrical insulator with a dielectric strength of 15 kV/mm (381 V/mil) and a resistivity of 1×10¹² Ω·m.
Chemical & Environmental2
Corrosion resistance is very good (78/100), better than 53% of glass grades.
Sustainability4
Producing a kilogram of Mycalex 400 takes about 32 MJ of energy and emits 2.2 kg of CO₂ — less than 73% of glass grades. Typical recycled content is 5%.
Manufacturability3
Mycalex 400's machinability is very good (75/100, better than 98% of glass grades).
Common Calculations4
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Mycalex 400
Is Mycalex easy to machine?
Turn, mill, drill and tap directly with carbide or diamond tooling, cutting dry with good chip evacuation. The material is brittle, so use light feeds and full backing support to prevent exit chipping.
Can Mycalex be welded?
Not weldable; assemble with threaded inserts, mechanical clamping or high-temperature inorganic or epoxy adhesive. Metal parts can be embedded during moulding.
Can Mycalex be formed, bent or molded?
Mica powder and glass powder are hot-pressed or compression-moulded to near-net shape at about 600–800 °C; moulded parts show almost no shrinkage and metal terminals can be moulded in place.
What surface finishes work on Mycalex?
Grinding and light polishing are possible, but exposed mica flakes limit the achievable gloss. Surfaces can be cleaned and metallized with fired silver for electrodes; the substrate cannot be anodized or plated.
Mycalex chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| mica (phlogopite / synthetic fluorophlogplaty filler, gives machinability and arc resistance | 50 – 65 | 58 |
| lead borate / borosilicate glass binderlead borate glass in 400/410; lead-free borosilicate in 1100 | ≥ 35 (balance) | — |
Mycalex 400 — frequently asked
What is Mycalex 400 used for?
Mycalex 400 is typically used for RF connector insulators, vacuum tube components, terminal boards and high-voltage insulators. In short: fully machinable inorganic insulator; best high-frequency insulator here; metal inserts moulded in.
What is the tensile strength of Mycalex 400?
Mycalex 400 has a typical tensile strength of 45 MPa (6.53 ksi) — weaker than 56% of glass grades. Strength varies by condition: see the 3 listed tempers.
Is Mycalex 400 easy to machine?
Yes — machinability is rated very good (75/100, better than 98% of glass grades). Turn, mill, drill and tap directly with carbide or diamond tooling, cutting dry with good chip evacuation. The material is brittle, so use light feeds and full backing support to prevent exit chipping.
Can Mycalex 400 be welded?
Not weldable; assemble with threaded inserts, mechanical clamping or high-temperature inorganic or epoxy adhesive. Metal parts can be embedded during moulding.
What surface finishes work on Mycalex 400?
Grinding and light polishing are possible, but exposed mica flakes limit the achievable gloss. Surfaces can be cleaned and metallized with fired silver for electrodes; the substrate cannot be anodized or plated.
Can Mycalex 400 be formed, bent or molded?
Mica powder and glass powder are hot-pressed or compression-moulded to near-net shape at about 600–800 °C; moulded parts show almost no shrinkage and metal terminals can be moulded in place.
What is the maximum service temperature of Mycalex 400?
Mycalex 400 is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- IEC 60672-3 Ceramic and glass insulating materials — Part 3: Specifications for individual materials (Type GM) — IEC (1997)
- Mycalex / Mykroy glass-bonded mica grade data (400, 410, 1100) — Mycalex Ceramics (2023)
- ASM Engineered Materials Handbook Vol. 4 — Ceramics and Glasses — ASM International (1991)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.