Hex Socket Head Cap Screw, Self Tapping

We make hex socket head cap screws with a self-tapping thread in nickel plated steel, a counterbored cap head and a sharp point, quoting them from M1 to M14. Thread, point, socket and sheet thickness come from your drawing, and the first article is driven into your own sheet.

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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 Hex Socket Head Cap Screws Are

A hex socket head cap screw is a socket screw with a tall cylindrical head, a deep internal hexagon and a full flat bearing face. This item adds a self-tapping thread with a sharp point, so it forms its own thread in the panel instead of running into a tapped hole. It is made in nickel plated carbon steel, quoted from M1 to M14 with Number 858.

Cap head. A cylinder with a flat top and a flat bearing face, made to sit in a counterbore and to be tightened hard.

Hexagon socket. An internal hexagon for a key, sized to the thread.

Self-tapping thread. A coarse thread with a sharp crest that forms its own thread in a drilled or punched hole.

Sharp point. A tapered end that finds the hole and starts the thread on the first turn.

Nickel plated steel. A thin bright barrier deposit over carbon steel.

The Head Is Over-Specified for a Sheet Joint

A cap head exists to take high preload: its height carries a deep socket, and its bearing face seats in a counterbore. A self-tapping thread exists to hold in a sheet, which by definition is thin. Put the two together and the head can take far more than the panel can, so the joint is limited by the sheet and not by the drive.

On a hex socket head cap screw that is not a fault; it is the reason the part exists in certain places. Where a bracket has to be clamped hard onto thin metal and there is access for a key but not for a nut, a cap head with a tapping thread is the only fixing that will do the job. The hexagon gives the torque and the counterbore gives a full bearing face on material that would dimple under a smaller head.

On a hex socket head cap screw the risk is that the socket makes over-driving easy. A hexagon does not cam out, so an operator with a long key can keep turning until the thread strips the sheet, and there is no slip to warn them. On this part the torque limit belongs on the drawing, and the assembly should be done with a setting rather than a hand.

On a hex socket head cap screw the point and the sheet are the other pair to get right. A sharp point needs a hole of the right size to start in; too small and the sheet domes as the point enters, too large and the thread does not form. Because a cap head has no give in it, any doming under the head is permanent and the joint is loose from the start.

Nickel is the finish that suits a general-purpose steel part. It is thin enough not to close the socket, bright enough for visible equipment, and a barrier coating, so a scratch at the socket exposes steel. Where the joint is damp the stainless version of the same geometry is the right part.

Sizes, Socket and Thread

The recorded range is M1 to M14, covering M1, M2, M3, M4, M5, M6, M7, M8, M9, M10 and M14. Custom lengths up to 2,000 mm are subject to DFM review after drawing submission. For a hex socket head cap screw with a tapping thread the quotation carries head diameter and height, socket size and depth, thread size, point form, the sheet thickness and the finish.

On hex socket head cap screws the sheet thickness is part of the specification, not a detail for the customer to work out. A cap head on a 0.8 mm sheet behaves quite differently from the same head on 2 mm, and the pilot hole and the length that works are different too; the first article should be driven into the real material.

Socket depth is set by the head height, and on a cap head there is enough of it. That is the advantage over a lower head: the hexagon is deep enough to take the key properly, so the torque that strips the sheet arrives long after the drive reaches its own limit.

Torque, Tapping and a Counterbore

Three features define this part: the deep socket, the tapping thread and the flat bearing face. The first gives torque, the second removes the need for a nut, and the third spreads the clamp load on a thin panel.

On a hex socket head cap screw the deep socket is what makes the joint possible on thin material. A cap head can develop enough clamp force to close a bracket onto a sheet and hold it there; a pan head of the same thread cannot, because the recess runs out of depth first. Where the joint needs that force, the cap head is the only head that will deliver it.

On a hex socket head cap screw the tapping thread makes it a one-part fixing. There is no nut to drop inside a closed assembly and no insert to install, and the joint holds by the thread that forms in the sheet. The cost is that the sheet is now part of the fastener, and a stripped hole cannot be repaired.

Nickel and the Sheet It Joins

The recorded finish is nickel over carbon steel. On this part the finish matters less than the thread, because the thread is what forms the joint; but nickel is a barrier coating, so a scratch at the socket or a scraped crest exposes steel, and in a damp joint that is where rust begins. It is a finish for dry interiors and visible equipment.

Coating Options for Self Tapping Socket Screws

On hex socket head cap screws the choice between nickel and zinc changes how the part fails. A scraped nickel crest rusts at the scrape; a scraped zinc one is protected by the zinc around it. On a self-tapping screw, where the crest is scraped by definition as the thread forms, that is a real difference rather than a theoretical one.

On hex socket head cap screws for outdoor joints, neither coating is enough. A stainless socket cap screw with a tapping thread is the version that survives, and the thread form and the socket geometry are the same.

Where These Screws Are Used

Three assemblies where a socket cap screw with a tapping thread is the fixing:

Why Shi Shi Tong for Hex Socket Cap Screws

Four reasons that matter on a socket-driven tapping screw, each tied to what the drawing has to prove:

How These Screws Are Manufactured

Shi Shi Tong forms these hex socket cap screws from carbon steel wire on single-die headers that form the cap head and the hexagon in one stroke, rolls the self-tapping thread, forms the sharp point and plates the parts in nickel. The first part of every run is measured on the head and socket, driven into a sheet of the customer thickness and entered into a thread gauge before the batch continues.

On hex socket head cap screws the point is the tooling that decides whether the joint starts. On a cap head screw the head cannot tilt to find the hole, so the point has to enter squarely and start the thread on the first turn; a point that is slightly off centre makes the screw go in crooked, and the head then sits on one edge of the counterbore instead of on its face.

Inspection: Socket, Thread and Point

What decides whether hex socket cap screws pass is the socket, the thread, the point and the plate. The inspection agreement covers those, and the criteria come from the drawing.

Head and socket on the projector	Thread gauged per batch
Hardness checked on the wire	Salt-spray testing of the plate

On hex socket head cap screws the socket is checked across flats and for depth and driven with the production key; the head is checked for diameter, height and face flatness; the thread is gauged per batch and the point for angle. Every first article is driven into a sheet of the customer thickness and the strip torque recorded, because on this part the panel is the weak link.

The plate is checked for thickness and adhesion in the socket and on the bearing face. A salt-spray sample is run where the environment asks for it; the socket is the place that matters, since a rusted socket cannot be driven.

Certificates and Material Documentation

Every shipment of hex socket cap screws is traceable to the wire it was made from and to the plating batch. The grade and heat number are recorded on the material certificate supplied with the parts, and the plating record is kept with the inspection file.

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

With each batch we supply the material certificate, the inspection record for the criteria on the drawing and, where it is listed, the third-party report for the plating. The documents carry the drawing revision and the batch number, so a repeat order is made to the same thread form that was approved.

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 a self-tapping part the first article is driven into the customer’s own sheet, because the joint is the function. Buyers visit during the process to review samples and to see how the parts are formed.

Buyers and quality engineers visit for sample review, process discussion and supplier audits; the visit is arranged around production so the headers and the plating line 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

Long Thin Screws: Drawing and Manufacturing Requirements What to put on the drawing for long, thin parts: datum, shank, thread position and handling. Read the guide

How Long Does It Take to Customize Extra-Long Screws? Where the time goes in a custom long-screw order, from drawing review to first article. Read the guide

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Hex Socket Cap Screw FAQ

Order Hex Socket Cap Screws

How a hex socket cap 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.