4-40 x 2 1/4 18-8 Stainless Steel Flat Head Cap Screw with Nylon Insert should be ordered by total screw length because the head is part of the measurement. Overall-length measurement matters on countersunk joints because the head occupies part of the thickness stack. 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.

This size is often reviewed for washdown covers, processing guards, and inspection doors when stainless material, a flush head, and locking friction are all specified. Where strength matters more than stainless material, Alloy Steel Flat Head Socket Cap Screws with Nylon Insert may be the better route.

Slight magnetism from cold working can be normal for 18-8 stainless, so final material selection should reflect the assembly conditions. For supported flat head cap-screw requests, nylon inserts are installed in-house at the Chicago facility.

Technical Highlights

• Material: 18-8 Stainless Steel
• Thread Size: 4-40
• Length (overall - includes head): 2 1/4 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.