For phillips pan head machine screw, T 818 defines the dimensions, tolerances and product grades. The sections below describe the scope of the document, the properties it deliberately leaves to companion standards, and the equivalent designations across standards bodies.
T 818 — Scope
T 818 specifies the dimensions and tolerances of phillips pan head machine screw — gb/t 818 / iso 7045 (series 033). 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 818, alongside the related GB/T 818 / ISO 7045 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 818
| Size | Pitch (mm) | Length L (mm) | Head diameter dk (mm) | Head height k (mm) | Cross recess | Reference standard |
|---|---|---|---|---|---|---|
| M3 | 0.5 | 20 | 5.6 | 1.8 | PH1 | ISO 7045 / GB/T 818 |
| M4 | 0.7 | 25 | 8.0 | 2.4 | PH2 | ISO 7045 / GB/T 818 |
| M5 | 0.8 | 30 | 9.5 | 3.0 | PH2 | ISO 7045 / GB/T 818 |
| M6 | 1.0 | 40 | 12.0 | 3.6 | PH3 | ISO 7045 / GB/T 818 |
| M8 | 1.25 | 50 | 16.0 | 4.8 | PH3 | ISO 7045 / GB/T 818 |
| M10 | 1.5 | 60 | 20.0 | 6.0 | PH4 | ISO 7045 / GB/T 818 |
Equivalent Standards
Where direct equivalents exist (ISO ↔ DIN, ISO ↔ ASME), they are listed on the parent Phillips Pan Head Machine Screw — GB/T 818 / ISO 7045 (Series 033) page. Always confirm against the dimensions on this page, since some "equivalent" standards differ in tolerances and head geometry.
When to Specify T 818
Choose T 818 for international engineering work and OEM supply where ISO standards are the contractual reference. It is the default modern specification for phillips pan head machine screw — gb/t 818 / iso 7045 (series 033).