Tel：
+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:Torx Thread Forming Screws
Materials:Steel
Surface treatment:Color Zinc Plated
Head Type:Pan Head
Drive:Torx
Thread:Thread Forming
Point:Blunt
Forming:Single Die Heading
Size:M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M14
Number:525
We make torx thread forming screws in colour zinc plated carbon steel with a trilobular thread that rolls its own thread in a drilled hole and a star socket that carries the driving torque. Thread form, socket, hole diameter and plating come from your drawing, and the first article is driven into your own hole.
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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.
Torx thread forming screws roll their own thread in a drilled hole instead of cutting it, and are driven with a six-lobe star bit. The recorded item is colour zinc plated carbon steel with a pan head, a trilobular thread and a blunt point, quoted from M1 to M14 with Number 525.
Thread forming. A trilobular thread — a rounded triangle rather than a circle — whose lobes press the material of the hole back into a thread. Nothing is cut, so nothing becomes a chip.
Torx drive. Six curved lobes with no internal corner. The bit does not cam out, which is what a forming screw needs: its driving torque climbs steadily and a cross recess would walk out in the middle of it.
Pan head. A low dome on a flat bearing face, wide enough to spread the load and low enough to sit inside its own diameter.
Colour zinc. An electroplated zinc layer with an iridescent passivation. It is sacrificial and thin, so it does not fill the lobes of the thread or the socket.
On torx thread forming screws nothing is cut: a cutting screw removes material: the crest cuts, a chip is made, and the thread in the hole is a groove. A forming screw displaces material: the lobes press the wall outward, and the thread in the hole is a ridge of work-hardened metal that the screw has made. The two look similar from the outside and behave very differently inside the joint.
The first consequence is the chip. In a blind hole, or in an assembly that cannot be cleaned afterwards, a cutting screw leaves material behind — inside a mechanism, behind a board, in a connector. A forming screw leaves none, which is why it is used where a chip is not acceptable rather than where it is merely inconvenient.
The second is the strength of the thread in the material. Forming work-hardens the wall around the ridge and leaves no cut edges to start a crack, so the strip torque is higher than a cutting screw of the same size in the same hole. That is the reason forming screws hold in aluminium and in thin sheet where a cutting screw would strip.
The third is the requirement on the screw. Forming needs a screw materially harder than the part, or the lobes wear instead of pressing. That is why these parts are case hardened, and why the case depth matters: too shallow and the lobes round over on the first panel, too deep and the head snaps instead of forming.
On torx thread forming screws the blunt point and the pan head are the rest of the geometry. The point needs a hole that already exists — drilled, punched or moulded — and the head spreads whatever the formed thread generates. Colour zinc then does the protection, thin enough to leave the lobes as they were cut.
The family is quoted from M1 to M14, with M1, M2, M3, M4, M5, M6, M7, M8, M9, M10 and M14 in the recorded range. Custom lengths up to 2,000 mm are subject to DFM review after drawing submission; on torx thread forming screws the thread form, the hole diameter and the point are quoted together, because the three decide whether a thread is formed at all.
| Item | How it is defined | What we control |
|---|---|---|
| Head | Pan head, flat bearing face | Diameter, height and face flatness |
| Socket | Torx, six lobes | Lobe width and depth, bit tried after plating |
| Thread | Trilobular thread-forming | Lobe height and pitch, checked on the section |
| Hole | Plain drilled hole, not tapped | Diameter agreed with the customer |
| Point | Short taper, blunt tip | Checked on the first article |
| Length | From under the head to the point | Measured on the shop plate |
The hole is quoted on the drawing because on a forming screw it is half the specification. Too small and the driving torque climbs past what the socket and the panel can take; too large and the lobes never touch, so no thread is formed and the screw turns freely. The window is narrow and it moves with the material.
Length is measured from under the head, because that face bears on the part. The thread runs full length, so the useful length is the thread that ends up inside the material, and on a thin panel that is the whole of it.
Three features define this part: the forming thread, the star socket and the colour zinc finish. The first two are a functional pair, because the torque curve of a forming screw is the reason it needs a drive that will not slip.
| Feature | What it gives | What it costs |
|---|---|---|
| Thread forming | No chips, work-hardened thread | Needs a harder screw and the right hole |
| Torx socket | Torque without cam-out | Needs the matching star bit |
| Pan head | Load spread without a washer | Less area than a truss head |
| Colour zinc | Sacrificial, thin, keeps the lobes sharp | Thin; chloride service eats it |
| Blunt point | Starts in a prepared hole | Will not pierce material on its own |
The pairing is not decorative. A forming screw’s driving torque rises as the lobes engage and keeps rising, and a cross recess is designed to cam out rather than carry that climb. A star socket carries it, so the screw either forms the thread or the material fails, which is the outcome the joint design should be aiming at.
The alternative is a cutting screw, which is simpler to specify and cheaper to make, but leaves a chip and a weaker thread in the hole. Where the joint is thin, blind or sealed, the forming screw pays for itself; where it is a through-hole in mild steel with access to clean, the cutting screw is the sensible choice.
The recorded finish is colour zinc with an iridescent passivation, applied after the thread is rolled. It is sacrificial and it is thin, which matters here because the lobes of a forming screw have to press into the hole: a thick coating would blunt them and change the driving torque.
| Finish | How it protects | Effect on lobes and socket | Typical use |
|---|---|---|---|
| Colour zinc | Sacrificial zinc, iridescent passivation | A few microns; lobes keep their edge | General indoor assemblies |
| White zinc | Sacrificial zinc, blue-white passivation | A few microns; re-checked | Where a bright tone is wanted |
| Black zinc | Zinc with dark passivation | A few microns; socket re-checked | Dark visible panels |
| Dacromet | Zinc-aluminium flake layer | Film builds; driving torque re-checked | Outdoor and automotive |
| Stainless alternative | Passive chromium oxide film | None; lobes as formed | Washed and coastal joints |
The coating is consumed where the screw does its work. The lobes rub through the zinc as they form the thread, so after the first installation the working surfaces are bare steel sitting inside a joint where moisture can collect. A colour zinc forming screw protects its head and its unengaged thread far better than it protects the thread that made the joint.
Where the service is wet, that is the argument for a flake coating or a stainless version. A stainless forming screw has its own problem — it must still be harder than the part it goes into, and austenitic grades are softer than the case-hardened steel screws they replace — so the material pair is chosen together rather than one at a time.
Three assemblies where torx thread forming screws are the fixing:
| Where it sits | The screw fixes a component, a terminal block or a board support into a drilled or moulded hole where a metal chip inside the product is not acceptable. |
| When it goes wrong | A cutting screw leaves swarf inside the enclosure, and a cross recess cams out under a powered driver. |
| Why it happens | The assembly is sealed or sensitive, the driver is powered, and the joint repeats. |
| What we control | Thread form and hole checked, socket driven with the production bit. |
| Where it sits | The screw forms its thread in a punched or drilled hole where a tapped hole would add a process and a cutting screw would strip. |
| When it goes wrong | A cutting thread in thin aluminium strips early, and a hole that is a size off either will not form or will not hold. |
| Why it happens | The material is thin or soft, the joint repeats, and the process step matters. |
| What we control | Hole agreed on the customer’s material, driving torque read on the first article. |
| Where it sits | The screw joins a bracket or a module where the joint is made on a line with a powered driver and has to resist vibration afterwards. |
| When it goes wrong | A formed thread resists loosening better than a cut one, but a badly sized hole leaves it with nothing to grip. |
| Why it happens | The volume is high, the driver is powered, and the joint is not serviced. |
| What we control | Thread form checked on the section, hole size and torque agreed with the customer. |
Four reasons that matter on a forming screw with a star drive, each tied to what the drawing has to prove:
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Thread form, hole and socket reviewed together
The lobe height, the hole diameter and the socket are reviewed as one set, so a screw that would strip or a socket that would not carry the driving torque is raised before the die is cut. Basis: Thread form, hole and socket reviewed as one set. |
Heading, rolling and plating in one route
The pan head and the cross are formed in one stroke, the trilobular thread is rolled and the parts are colour zinc plated in the same route. Basis: One route from wire to plated screw. |
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Thread form checked on the section
The lobe height is checked on the section of the first article, and the driving and strip torques are read in the customer’s material. Basis: Torques read in the customer material. |
First article fixes the setting
The first article fixes the wire heat, the die set, the roll and the plating barrel; repeat orders are compared against that record. Basis: First article signed off before the batch is released. |
Shi Shi Tong forms these torx thread forming screws from carbon steel wire on single-die headers that form the pan head and the six-lobe socket in one stroke, rolls the trilobular thread to a blunt point and colour zinc plates the parts. The first part of every run is measured on the head and socket, checked for lobe height and driven into a sample of the customer’s material before the batch continues.
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The trilobular form is set by the roll, and it is checked on a section rather than on the outside. A roll that is slightly worn leaves lobes lower than the drawing, and the screw then forms a shallower thread: it drives easily, holds at first, and strips early. That is a defect the outside diameter never shows.
What decides whether torx thread forming screws pass is the socket, the thread form, the point, the plating and the hardness. The inspection agreement covers those, and the criteria come from the drawing.
Lobe profile on the projector |
Thread checked per batch |
Case and core hardness checked |
Salt-spray testing of the colour zinc plate |
The thread form is checked on the section for lobe height and pitch, and the driving torque is measured in the customer’s material. On a forming screw the two are read together, because the lobes that look right on a section are the ones that produce the torque and the strip value.
Hardness is checked on the case and the core. The lobes have to be hard enough to press steel without rounding, and the core has to be tough enough that the head does not snap when a powered driver reaches its torque — a part that is hard all the way through fails the second test.
Every shipment of torx thread forming 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 material or the plating. The documents carry the drawing revision and the batch number, so the paperwork can be matched to the parts.
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 forming screw the first article is also driven into the customer’s own hole, so the hole and the thread form are proved together. Buyers visit during the process to review samples and to see how the parts are formed.
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8,678+
customers served
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87%
of orders from repeat customers
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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 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 |
Forming rolls the material into a thread and leaves no chip, and the thread in the hole is stronger. Cutting is cheaper and simpler but leaves swarf and a weaker thread.
The driving torque climbs steadily as the lobes engage. A cross recess cams out in the middle of that climb; a star socket carries it.
It depends on the material and on the screw, and it is quoted with the drawing. Too small and the screw strips or the head twists off; too large and no thread forms.
Yes, and better than a cutting screw, because the wall around the formed thread is work-hardened. The hole is agreed on the actual alloy rather than from a table.
A few times in the same hole. Each re-entry re-forms the thread and the strip torque falls.
Socket size, head, thread form and pitch, hole diameter, point form, length and datum, and the case hardness.
How a torx thread forming screw project runs from drawing to repeat delivery:
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1
Send the drawing and the hole detail
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→ |
2
Thread form, socket and hole review
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→ |
3
First article driven into your hole
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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 socket size, the head, the thread form and pitch, the hole diameter, the point form, the length and datum, and the case hardness.
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Socket size
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Head
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Thread form
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Hole diameter
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Point and length
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Case hardness
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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
