4-40 x 5/8 18-8 Stainless Steel Flat Head Cap Screw with Nylon Insert is built for a properly cut 82-degree countersink where the head can sit flush or slightly below the surface. A countersunk head bears on the cone rather than a broad underside, so clamp load should not be treated like a full socket head cap screw.

For walk plates, step surfaces, or low-snag equipment panels, confirm countersink geometry, thread engagement, and whether the nylon insert suits the service conditions. For a low-profile head without cutting a countersink, compare 18-8 Button Head Socket Cap Screws with Nylon Insert.

The 18% chromium and 8% nickel austenitic stainless material is commonly selected for general corrosion resistance, clean appearance, and ordinary washdown exposure. Cold Headers can help verify the exact 18-8 flat head nylon-insert configuration before quoting pricing and availability.

Technical Highlights

• Material: 18-8 Stainless Steel
• Thread Size: 4-40
• Length (overall - includes head): 5/8 in.
• Head Style: 82° Countersunk Flat
• Drive Type: Internal Hex
• Locking Feature: Nylon insert providing prevailing torque
• Nylon Insert Diameter (P): 1/16 in.
• Nylon Insert Location (N): 7/64 in. +/-1/2 pitch
• Head Dimensions: ASME B18.3

Call 773-775-7900 or email Sales@coldheaders.com for pricing, availability, or a quote.