For Phillips Countersunk Machine Screw — GB/T 819.1 / ISO 7046 (Series 029), T 819.1 defines dimensions, tolerances and product grades. The sections below describe its scope, what it does NOT cover, and the equivalents across DIN, ISO and ASME.
T 819.1 — Scope
T 819.1 specifies the dimensions and tolerances of phillips countersunk machine screw — gb/t 819.1 / iso 7046 (series 029). Material, property class, surface finish and packaging are governed by separate documents in the same standards family (for example ISO 898-1 for the mechanical property classes of bolts and screws).
Tolerance & Product Grades
T 819.1, alongside the related GB/T 819.1 / ISO 7046 entries on this site, specifies product grades (typically A or B for fine work and C for general engineering) and tolerance classes for the controlling dimensions. Choose the grade against the precision your application requires.
Dimensions Specified by T 819.1
| Size | Pitch (mm) | Length L (mm) | Head diameter dk (mm) | Head height k (mm) | Cross recess | Countersink angle (deg) | Reference standard |
|---|---|---|---|---|---|---|---|
| M3 | 0.5 | 20 | 5.6 | 1.65 | PH1 | 90 | ISO 7046 / GB/T 819 |
| M4 | 0.7 | 25 | 7.5 | 2.2 | PH2 | 90 | ISO 7046 / GB/T 819 |
| M5 | 0.8 | 30 | 9.2 | 2.5 | PH2 | 90 | ISO 7046 / GB/T 819 |
| M6 | 1.0 | 40 | 11.0 | 3.0 | PH3 | 90 | ISO 7046 / GB/T 819 |
| M8 | 1.25 | 50 | 14.5 | 4.0 | PH3 | 90 | ISO 7046 / GB/T 819 |
| M10 | 1.5 | 60 | 18.0 | 5.0 | PH4 | 90 | ISO 7046 / GB/T 819 |
| M12 | 1.75 | 80 | 22.0 | 6.0 | PH4 | 90 | ISO 7046 / GB/T 819 |
| M14 | 2.0 | 80 | 25.0 | 7.0 | PH4 | 90 | ISO 7046 / GB/T 819 |
| M16 | 2.0 | 100 | 29.0 | 8.0 | PH4 | 90 | ISO 7046 / GB/T 819 |
| M18 | 2.5 | 100 | 33.0 | 9.0 | PH4 | 90 | ISO 7046 / GB/T 819 |
| M20 | 2.5 | 120 | 36.5 | 10.0 | PH4 | 90 | ISO 7046 / GB/T 819 |
| M24 | 3.0 | 150 | 43.5 | 12.0 | PH4 | 90 | ISO 7046 / GB/T 819 |
Equivalent Standards
Where direct equivalents exist (ISO ↔ DIN, ISO ↔ ASME), they are listed on the parent Phillips Countersunk Machine Screw — GB/T 819.1 / ISO 7046 (Series 029) page. Always confirm against the dimensions on this page, since some "equivalent" standards differ in tolerances and head geometry.
When to Specify T 819.1
Choose T 819.1 for international engineering work and OEM supply where ISO standards are the contractual reference. It is the default modern specification for phillips countersunk machine screw — gb/t 819.1 / iso 7046 (series 029).