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+86 13143444311
Email：sst@szsst88.com
Fax：+0086-755-27322278
Address：Building 9, First Industrial Zone, Tantou Industrial City, Songgang Street, Baoan District, Shenzhen 518105, Guangdong, China
Type:Extra Long Self Tapping Screws
Materials:Steel
Surface treatment:Nickel Plated
Head Type:Cap Head
Drive:Hexagon socket (Allen)
Thread:Self-tapping, half thread
Point:Flat, blunt
Forming:Single Die Heading
Size:M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M14
Number:576
We make extra long self tapping screws in nickel plated carbon steel with a socket cap head, a half thread and a flat point, quoting them from M1 to M14. Socket depth, lengths, point and finish come from your drawing, and the first article is driven with the production key at recorded torque.
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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.
These extra long self tapping screws have a socket cap head, a hexagon drive and a half thread with a flat self-tapping point, in nickel plated carbon steel, quoted from M1 to M14 with Number 576. The length reaches through the joint and the socket supplies the torque the forming thread needs.
Socket cap head. A flat-topped cylinder with an internal hexagon, driven with an Allen key and seated in a counterbore.
Half thread. The plain shank passes the front part and only the last section forms a thread.
Flat self-tapping point. A blunt forming end that starts in a drilled pilot rather than piercing.
Nickel plating. A bright barrier deposit over carbon steel, for visible indoor work.
Extra long self tapping screws with a socket are used where the joint is deep, the far part is soft and the drive has to come from above: panels on spacers, brackets on frames, fittings that cannot be reached with a wrench.
A long self-tapping screw has to form its thread at the far end of a shank that is absorbing torque, and the drive is the part that makes that possible or impossible. A cross recess in that situation cams out as the load rises, and cam-out on a long shank does not just stop the screw: it grinds the recess and leaves a head that cannot be driven at all.
A hexagon socket does not cam out. The key drives on six flats inside the head, so as the torque rises the key stays seated and the load goes into the shank, which is where it has to go. That is why socket cap heads are the usual drive on long forming screws, and why the head is a cylinder rather than a dome.
The hexagon has a practical limit too. On a small cap head the socket is shallow and the key has to be an exact fit; a worn key rounds the corners at the same torque at which a good one would have driven the screw. On these parts the key is part of the tooling, and changing it before it rounds is cheaper than extracting a screw with a damaged socket.
The half thread and the flat point belong to the joint. The plain shank passes the front part so the panel or sleeve is not threaded, and the flat point starts in a pilot and forms the thread without piercing. On a long screw both are necessary: a thread run through the front part would bind, and a sharp point would stall at the tip.
Nickel is the finish over all of it. It is bright and hard, thin enough to keep the socket usable, and it suits a part that is visible at one end and hidden at the other; the barrier nature means a scratch on the head shows, which is the trade for the finish looking like metal rather than like a coating.
The recorded range is M1 to M14, with long lengths made to the drawing. Custom lengths up to 2,000 mm are subject to DFM review after drawing submission. For extra long self tapping screws the quotation carries head diameter and height, socket size and depth, overall length, threaded length, shank diameter and point.
| Item | How it is defined | What we control |
|---|---|---|
| Head | Socket cap head | Head diameter, height and face flatness |
| Socket | Internal hexagon | Across flats, depth and corners |
| Shank | Plain section through the joint | Diameter and length |
| Thread | Self-tapping, half thread | Thread form, length and crest condition |
| Point | Flat, blunt | Point diameter and squareness |
| Material | Carbon steel | Grade and heat number on the certificate |
| Finish | Nickel plated | Thickness and socket fit |
Socket depth is worth naming on the drawing. Two suppliers can both make a cap head to the standard and cut the hexagon to different depths, and the torque the screw will take follows the shallower one.
Threaded length is quoted from the point and plain length from the head. On an extra long screw the plain section is most of the part, and it is what passes the clearance holes of the joint.
Three features define the part: the socket drive, the long shank and the forming thread. The first lets the torque arrive, the second gives the reach, and the third removes the tapped hole.
| Feature | What it gives | What it costs |
|---|---|---|
| Socket drive | Torque without cam-out | Needs the exact key size |
| Long shank | Reaches through a deep joint | Absorbs torque before the thread |
| Flat point | Starts in a pilot without piercing | Needs a drilled hole |
| Half thread | Front part stays unthreaded | Both lengths must be specified |
| Nickel plating | Bright barrier finish indoors | A scratch becomes a rust point |
The socket is the reason the part works at length. Without a drive that holds, a long forming screw is a screw that rounds its head halfway in, and every approach to removing it does more damage than the first attempt.
The cost is the key. A socket cap head is only as good as the key that fits it, and on a long screw the load is high enough that a worn key will show immediately.
The recorded finish is nickel plating over carbon steel. It is a barrier deposit, bright and hard, and on a socket cap head the thinness matters: the socket is shallow, so any coating narrows it and the key that fits an unplated part may not enter a plated one fully.
| Option | How it protects | Effect on socket and thread | Typical use |
|---|---|---|---|
| Nickel plated | Barrier deposit, bright | Socket narrowed; re-checked | Visible indoor assemblies |
| White zinc plated | Sacrificial zinc | Thin build; socket as cut | General indoor work |
| Black oxide | Conversion film, oiled | No measurable build | Internal mechanisms |
| Dacromet | Inorganic zinc-aluminium layer | Thick; can blunt the point | Wet outdoor assemblies |
| Stainless alternative | Passive film, no build | Socket and thread as made | Wet and food service |
Where the joint is wet, stainless is the specification: the socket is the surface that would corrode first and the one nobody can clean, and a rusted socket on a long screw is a part with no removal route.
Where a heavy coating is required for corrosion, it works against the drive. Dacromet in a socket narrows it, and on a forming screw it can blunt the point as well; in those cases the stainless version solves both problems at once.
Three assemblies where extra long self tapping screws with a socket are the fixing:
| Where it sits | The screw passes through a panel and a spacer and forms its own thread in a far part that cannot be tapped. |
| When it goes wrong | A cross-recessed screw cams out under the load, and the head is damaged before the thread forms. |
| Why it happens | The joint is long, the far part is soft, and the drive is a key. |
| What we control | Socket depth checked; first article driven at recorded torque. |
| Where it sits | The screw fixes a bracket at a distance where a wrench cannot reach and the drive has to be from above. |
| When it goes wrong | A long shank twists, and a shallow socket rounds at the torque the joint needs. |
| Why it happens | The joint is structural, the access is from above, and the thread is formed. |
| What we control | Key size and socket checked; first article tightened to joint torque. |
| Where it sits | The screw holds a fitting where the joint is exposed and the head is visible on the outside. |
| When it goes wrong | Nickel corrodes at the socket and the screw cannot be removed. |
| Why it happens | The joint is wet, the head is exposed, and the part is serviced. |
| What we control | Grade and finish checked; first article assembled. |
Four reasons that matter on a long socket-driven forming screw, each tied to what the drawing has to prove:
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Socket and lengths agreed
Socket size and depth, threaded length, plain length, point and finish are agreed as a set, because on extra long self tapping screws the drive has to fit inside the head. Basis: Socket and lengths agreed. |
Headed, threaded, plated in one route
The cap head and hexagon are formed in one strike, the half self-tapping thread rolled and the flat point cut before plating. Basis: One route from wire to plated screw. |
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Socket and point checked
The socket is checked for depth and the point for concentricity, because a point that runs out leads the long shank in at an angle. Basis: Socket and point checked. |
Driving torque recorded
The driving torque into the customer material is recorded from the first article, so a repeat order does not stall at assembly. Basis: Driving torque recorded. |
Shi Shi Tong forms extra long self tapping screws on single-die headers that form the socket cap head and cut the hexagon, draws the long shank, rolls the half self-tapping thread and cuts the flat point before nickel plating. The first part of every run is measured on head, socket, shank diameter, overall length and thread before the batch continues.
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On a long screw the point and the socket are the two ends that decide the part. The point has to be concentric with a shank that is twenty times its diameter long, and the socket has to be deep enough to take the torque that shank will need; both are set at the machine and both are checked on the first part.
What decides whether these screws pass is the socket, the point, the shank and the thread. The inspection agreement covers those, and the criteria come from the drawing.
Head and point on the projector |
Thread form checked |
Hardness checked on the wire |
Coating proved by salt spray |
The socket is checked for across flats and depth, the point for diameter and concentricity, and the shank for diameter along its length. The thread is gauged, and the coating is checked inside the socket.
The first article is driven with the production key at the joint torque and the torque recorded. A long screw that stalls at the driver is one that will stall on the line, and only that test shows it.
Every shipment of extra long self tapping 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 inspection records follow the criteria agreed on the drawing.
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 coating. The documents carry the drawing revision and the batch number, so a repeat order keeps the same socket and thread length.
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 extra long self tapping screws the first article is driven with the production key into the customer material, because the thread and the drive are both proved there. Buyers visit during the process to review samples.
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8,678+
customers served
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87%
of orders from repeat customers
|
56%
of orders through referrals
|
89
countries and regions shipped to
|
Buyers and quality engineers visit for sample review, process discussion and supplier audits; the visit is arranged around production so the headers and the point grinding 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 |
A cross cams out as the load rises, and on a long forming screw that rounds the head before the thread forms. A socket does not cam out.
Yes. The flat point starts in a drilled pilot and forms the thread; without one it will not start cleanly.
The plain shank passes the front part and the thread forms only at the far end, so the front hole is not threaded.
The key was worn or the wrong size. On a long screw the load is high enough that a worn key shows immediately.
It narrows it, so on coated parts the socket is gauged after plating.
Head diameter and height, socket size and depth, overall length, threaded length, shank diameter, point and the finish.
How an extra long self tapping screw project runs from drawing to repeat delivery:
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1
Send the drawing and the material it enters
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→ |
2
Socket, lengths and point agreed
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→ |
3
First article driven with recorded torque
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→ |
4
Batch production and repeat orders
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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.
For a quotation, send the drawing with the head diameter and height, socket size and depth, overall length, threaded length, shank diameter, point and the finish.
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Head diameter
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Socket size
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Overall length
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Threaded length
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Point
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Finish
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Sending a drawing? The form below does not take attachments. Email the PDF, DXF or STEP file to sst@szsst88.com with the part name and quantity in the subject line – the drawing is reviewed and a quotation follows.
+86 13143444311
sst@szsst88.com
