CSK Philips Screw
The CSK Philips Screw, short for Countersunk with Washer Face Philips Screw, is a precision fastener featuring a countersunk head with an integrated washer face and a standard Philips drive recess. It is designed to sit flush with or below the surface of the fastened material when installed, ensuring a smooth, low-profile finish.
• Core Features: Equipped with a Philips cross-shaped drive for easy engagement with standard Philips screwdrivers; the washer face enhances load distribution, preventing damage to the workpiece surface.
• Material Options: Available in common materials like 304 stainless steel (for corrosion resistance in indoor/outdoor environments), carbon steel (for high tensile strength in general industrial use), and alloy steel (for heavy-duty applications).
• Surface Treatments: Typically finished with zinc plating (for rust protection), passivation (to boost stainless steel’s corrosion resistance), or black oxide (for aesthetic appeal and mild wear resistance).
• Applications: Widely used in furniture assembly, electronic enclosures, automotive interiors, and consumer appliances where a flat, unobtrusive fastener appearance is required.
| THREAD SIZE | ST2.2 | ST2.9 | ST3.5 | (ST3.9) | ST4.2 | ST4.8 | ST5.5 | ST6.3 | ||
| P | 0.8 | 1.1 | 1.3 | 1.3 | 1.4 | 1.6 | 1.8 | 1.8 | ||
| a | max | 0.8 | 1.1 | 1.3 | 1.3 | 1.4 | 1.6 | 1.8 | 1.8 | |
| dk | nominal=max. | 4.3 | 5.5 | 6.8 | 7.5 | 8.1 | 9.5 | 10.8 | 12.4 | |
| min | 4 | 5.2 | 6.44 | 7.14 | 7.74 | 9.14 | 10.37 | 11.97 | ||
| k | approx | 1.3 | 1.7 | 2.1 | 2.3 | 2.5 | 3 | 3.4 | 3.8 | |
| r | max | 0.8 | 1.1 | 1.4 | 1.5 | 1.6 | 1.9 | 2.1 | 2.4 | |
| Cross recess | No | 1 | 1 | 2 | 2 | 2 | 2 | 3 | 3 | |
| Type H | m | approx | 2.5 | 3 | 4.2 | 4.6 | 4.7 | 5.1 | 6.8 | 7.1 |
| Penetration deptd | min | 1.02 | 1.4 | 1.62 | 2.03 | 2.11 | 2.59 | 2.95 | 3.33 | |
| max | 1.32 | 1.7 | 2.12 | 2.53 | 2.62 | 3.1 | 3.53 | 3.91 | ||
| Type Z | m | approx | 2.4 | 2.9 | 3.9 | 4.1 | 4.3 | 4.7 | 6.2 | 6.7 |
| Penetration deptd | min | 1.1 | 1.48 | 1.6 | 1.85 | 2.05 | 2.64 | 2.72 | 3.38 | |
| max | 1.35 | 1.73 | 2.06 | 2.31 | 2.51 | 3.1 | 3.18 | 3.84 | ||
| y – max. | max | Type C | 2 | 2.6 | 3.2 | 3.5 | 3.7 | 4.3 | 5 | 6 |
| Type F | 1.6 | 2.1 | 2.5 | 2.7 | 2.8 | 3.2 | 3.6 | 3.6 | ||