Brass Socket Head Cap Screws

We make brass socket head cap screws with a deep hexagon socket and a plain finish, quoting them from M1 to M10 with lengths made to the drawing. The socket depth is held against the head height, the drive is proved with your key at your torque, and the first article is compared with your sample.

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ISO 9001:2015 · Manufacturing since 1998 · 8,678+ customers · 89 countries and regions

Made to order – there is no stock catalogue. Each part is produced to your drawing, and production starts after drawing review and first-article approval.

What Brass Socket Head Cap Screws Are

Brass socket head cap screws are socket-driven cap screws cut in brass, finished plain so the alloy shows. The part recorded here is quoted from M1 to M10 with lengths made to the drawing.

Cap head. A tall cylindrical head with a flat bearing face and a deep hexagonal socket, the head form that takes the most torque for its diameter.

Brass body. Copper with zinc, free-cutting, non-magnetic, and electrically conductive in a way steel is not.

Deep socket. Enough depth for the key to seat fully, which matters because the material is soft.

Machine thread. A uniform thread for a tapped hole, a nut or an insert.

They are used where the fixing must not rust, must not respond to a magnet, and is expected to look like brass: electrical terminals and busbars, instrument assemblies, decorative hardware, and any joint where a plated steel screw would either corrode or read as the wrong material.

A Deep Socket in a Soft Metal

The socket head cap form puts as much driving depth into the head as the head can hold, and that is exactly what a soft metal needs. An Allen key bears on six short arcs, not on a broad face, so the pressure at each contact is high; if the socket is shallow, the key rides on the top of the arcs where there is least material and the corners yield first.

In brass the sequence is predictable. The hexagon corners deform before the thread strips, because brass is soft and the corners are where the stress concentrates. That means the limit on a brass socket head cap screw is a drive limit, not a strength limit: past a certain torque the part becomes hard to open rather than failing at the joint.

The alloy matters as much as the shape. Brass for fasteners is usually a free-cutting grade with lead or a substitute added to break chips, which machines beautifully and also makes the material less ductile than pure copper alloys. That is why a brass screw drives cleanly and then marks at the socket at a torque that a steel part of the same size would shrug off.

The bearing face contributes in the same direction. A cap head has a flat annulus that spreads the clamp, so the joint reaches its seating load before the socket is worked hard; if the face is not flat, the head loads one side of the socket first and the marks appear on one half of the hexagon only.

Brass also changes the electrical behaviour of the joint. It conducts, it does not form a resistive oxide as quickly as aluminium, and it does not need plating to stay stable indoors. For terminals that is the reason a brass socket head cap screw is used at all: the fixing is part of the current path, and a steel screw would not be.

Sizes, Head and Socket

The recorded range is M1 to M10, with lengths made to the drawing. Custom lengths up to 2,000 mm are subject to the drawing submission and DFM review. The quotation for brass socket head cap screws carries the head diameter and height, the socket size and depth, the thread pitch and the overall length.

Socket depth is the dimension to defend on a brass part. It is limited by head height, and head height is usually set by the standard the drawing follows; where a customer asks for a lower head to save space, the socket comes down with it and the drive gets worse in the material that can least afford it.

Socket size follows the diameter, and on brass the key fit matters more than on steel. A key that is slightly under size works on the corners instead of the flats, and in brass those corners are already the weakest feature of the drive.

Head diameter and bearing face flatness are measured together, because the face is what carries the clamp on a brass part. A face that is not flat points the load at one side of the socket and produces the one-sided wear that reads as a bad batch.

What Brass Socket Head Cap Screws Give and Costs

Four properties decide brass socket head cap screws, and each one carries a cost:

The value is that the fixing behaves like part of the product rather than a fastener screwed onto it. It conducts, it does not attract a magnet, it does not rust, and it can be polished or left to age without a coating to strip.

The cost is strength, and specifically drive strength. The joint can be designed around a lower torque, but the torque has to be stated, because the first person to drive one by feel will take it past the point where the corners survive.

Plain Brass and Other Surface Choices

The recorded finish is plain, so the alloy is the surface. Brass slotted and pan head parts are often left plain for the same reason: the material can be polished, aged or lacquered later without removing a coating first.

Surface Options for Brass Socket Head Cap Screws

Where a plating is applied, the socket is gauged afterwards. A brass part already has a depth margin only as wide as its head, and a coating inside a hexagon changes which key seats and how much of the arc it contacts.

A lacquer is the finish that needs most care, because a heavy coat bridges the socket and the key then cuts through it, leaving a ragged edge that reads as damage on a part whose whole purpose is to look finished.

Where Brass Socket Head Cap Screws Are Used

Three settings where conductivity and appearance are both required:

Why Shi Shi Tong for Brass Socket Head Cap Screws

Four reasons that matter on a soft-metal drive, each tied to something the drawing has to prove:

How Brass Socket Head Cap Screws Are Made

These screws are headed on single-die machines that form the cap head in one stroke, broached with a hexagonal punch, thread rolled on the brass shank, and left plain. The first part of every run is measured on head diameter and height, socket size and depth, thread and length, and driven with the production key.

Broaching a hexagon into brass is easier than into steel and less forgiving of a dull tool. Brass cuts cleanly, so the walls come out sharp and the flats flat, but a slightly worn punch leaves a burr at the top of the socket that a key will not pass, and a punch set too deep leaves thin corners that yield at the first drive. Both are checked on the first article rather than at the end of the run.

Thread rolling on brass is done at a lower force than on steel, with the rolls set to displace rather than squeeze. Over-rolling work-hardens the surface of the thread and makes it brittle at the crest, which shows up as chipped threads after the first assembly rather than as a dimensional error.

Because the parts are left plain, handling is part of the process. Brass tarnishes unevenly where it is touched, so the screws are kept dry, handled with gloves at the final inspection, and packed without loose contact that would rub the socket edges bright.

Inspection: Socket, Head and Thread

What decides whether brass socket head cap screws pass is the socket, the head, the thread and the surface. The inspection agreement covers those, and the criteria come from the drawing.

Socket depth and walls on the projector	Thread and start checked
Hardness against the brass spec	Humidity exposure on the plain surface

Socket depth and across-flats are measured on the projector, together with head height and bearing face flatness, because the four come out of two operations and can each look right on their own. The thread is gauged after rolling, and the length is measured over the head.

The function test is the one that matters most: a sample from every batch is driven with the production key at the agreed torque, opened and closed twice, and the hexagon corners are inspected under magnification. On brass that cycle shows the beginning of corner yield before it becomes visible on the outside of the part.

A sample is also checked for electrical contact where the customer uses the screw in a current path. The contact resistance is measured across the joint before and after the assembly cycle, so a face that is not flat shows as a resistance that changes.

Certificates and Material Documentation

Every batch is traceable to the brass rod it was made from. The alloy and heat number appear on the material certificate supplied with the parts, and the inspection records follow the criteria agreed on the drawing.

ISO 9001:2015	RoHS test report
Registered trademark	Patent: security screw and driver

With each shipment we supply the material certificate, the inspection record for the dimensions on the drawing including the socket depth, and the RoHS report for the alloy. The documents carry the drawing revision and the batch number, so a repeat order of brass socket head cap screws matches the original.

Customers and Projects

More than 8,678 customers in 89 countries and regions have ordered from Shi Shi Tong; 87% of orders come from repeat customers and 56% through referrals. Most projects follow the same route: drawing review, first-article approval, then batches checked against that sample. On brass parts the first article is compared with the customer sample side by side, because tone and socket condition are judged by eye. Buyers visit during the process to review samples.

Buyers and quality engineers visit for sample review, process discussion and supplier audits; the visit is arranged around production so the headers and the broaching station can be seen on the day the parts run.

Customer group visit – sample review	Customer group visit – process discussion	Customer group visit – factory tour
Customer visit – project kick-off	Danish customer – drawing review	Industry exhibition – meeting customers

Related Products and Guides

Technical Guides

Hex Socket Screw Specification Table Socket size and head height against diameter, for the socket head range. Read the guide

Why Brass Screws Rust, and What Actually Stops It What darkens or corrodes on a brass screw, and what a plain finish leaves exposed. Read the guide

Products

Socket Head Cap Screw The same head form in steel. Socket Head Cap Screw	Low Profile Socket Head Screws A cap head with less height in 304. Low Profile Socket Head Screws	Hex Socket Button Head Screw A low domed head with a captive washer. Hex Socket Button Head Screw
Pan Head Socket Screw A socket drive in a rounded pan head. Pan Head Socket Screw	Brass Pan Head Machine Screws The brass family in a pan head. Brass Pan Head Machine Screws	Brass Pan Head Screws Brass with a wider bearing face. Brass Pan Head Screws

Brass Socket Head Cap Screw FAQ

Order Brass Socket Head Cap Screws

How a brass socket screw project runs from drawing to repeat delivery:

Each step is confirmed with you before the next one starts; the drawing revision from the first article is what repeat orders are checked against.