Socket Head Cap Screws
Socket head cap screws are often used in assemblies with counterbored holes. The head height is equal to the nominal diameter. For sizes 1/4″ and larger, the head diameter is equal to one-and-a-half times the nominal diameter.
Nickel Systems maintains an inventory of socket head cap screws in Hastelloy® C276 (Alloy C276) in both inch and metric sizes. Most sizes 1/2″ diameter and larger, are fully threaded. Current inventory in socket head cap screws includes Duplex 2205, A286, Carpenter® 20 (Alloy 20), Nitronic® 60 (Alloy 60), 310 Stainless, 330 Stainless, 17-4 PH, 18-8 Stainless and 316 Stainless.
Flat Socket Cap Screws
Flat socket head cap screws are used when the top of the screw head is to be flush with one of the assembly surfaces. The underside of the screw head and the accompanying hole are countersunk at an 82-degree (includes angle). Flat socket head cap screws are preferred over slotted flat head cap screws if assembly and disassembly are frequent because the drive is less likely to strip with repetitive use.
Button Socket Cap Screws
Button socket cap screws are the fastener of choice if the screw head is outside of the assembly, there are clearance issues and a socket drive is desired. Button sockets are not meant to handle as much stress as a socket head cap screw as the heads have less “beef”.
Square Head Set Screws
Set screws are often used to keep a pulley, gear or similar disc-shaped object attached to a shaft. One advantage of a square head set screw over a socket set screw is that it is externally wrenched. With a socket set screw, grease and dirt may pack into the broach and render it incapable of disassembly.
Various point styles are available on set screws. The choice depends on the application. Point choices include cup, knurled cup, flat, half dog, full dog and cone.
Most of the square head set screws in inventory at Nickel Systems have a cup point. Our shop can readily modify existing parts to provide other point styles. Current inventory includes Hastelloy® (Alloys C276, C22, C2000), Carpenter® 20 (Alloy 20), AL6XN®, Nickel 200, 18-8, 316, 316L and 317L Stainless.
Socket Set Screws
Certain applications require a screw, which is buried completely in a tapped hole in one of the material surfaces. This is a job for a socket set screw.
An important consideration when choosing a socket set screw is how it will interact with the material at the bottom of the hole. If the set screw is to “dig-in”, a point style which features minimal surface area works best. These point styles would include cup, cone or knurled cup. If minimal marring of the surface is required, flat, full dog or half dog would be the point style of choice.
Cup point is the most common style in inventory at Nickel Systems. Socket set screw stock currently includes parts in Hastelloy® C276 (Alloy C276, Alloy 22), Carpenter® 20 (Alloy 20), Duplex 2205, Monel® (Alloy 400, Alloy 405), Inconel® 600 (Alloy 600) and various grades of Stainless (18-8, 316, 317L, 416).