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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:Stainless Security Screws
Materials:Stainless Steel
Surface treatment:Plain
Head Type:Flat Head
Drive:Internal Triangle
Thread:Self Tapping
Point:Flat Point
Forming:Single Die Heading
Size:M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M14
Number:668
We make stainless security screws with a countersunk head, an internal triangle socket and a self tapping thread, quoting them from M1 to M14 in passivated A2 or A4. Cone, socket, thread and grade come from your drawing, and the first article is seated in your sheet and turned with your key.
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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.
Stainless security screws are screws finished in bare stainless so they survive weather and washing, with a recess that an ordinary screwdriver will not turn. The recorded item on this page is stainless with a plain finish, a countersunk head and an internal triangle socket, quoted from M1 to M14 with Number 668.
Countersunk head. A cone that seats in the part and leaves the surface unbroken. It centres the screw in the hole and bears on the cone rather than on a face, which is what makes it flush.
Internal triangle socket. A three-sided recess with three flat faces, driven with a triangular key. It takes no common bit, and it seats positively on all three faces rather than tipping on a corner.
Self tapping thread. A coarse thread with a sharp crest that forms its own way into a drilled or punched hole, with a flat point that starts in the hole rather than piercing the material.
Stainless, plain. Passivated and uncoated, so the alloy is the whole of the protection. There is no film to chip at the cone, which is where a flush fixing shows first.
On stainless security screws the countersunk head and the triangular socket are an odd pair until you look at what each can carry. The cone seats in a countersink cut into the part, usually a thin sheet; the sheet around the countersink is deformed and hardened and it is the weakest point in the joint. The socket limits how much torque a hand or a key can apply, and in this pairing the limit is a feature: the drive gives up before the sheet does.
That is the engineering argument for the form. A countersunk head with a full hex socket can be tightened until the sheet around the cone yields and the head sinks, and the joint then cannot be recovered — the countersink is part of the part, not a washer that can be replaced. A triangle socket, driven with a triangular key rather than a wrench, simply cannot deliver that much torque.
On stainless security screws the cone geometry is what makes the flush joint work. The head seats on a matching countersink and centres itself as it is turned, so the screw finds the hole without being guided; the fit between the two angles decides whether the head bears on a surface or on a line.
The socket is formed in the same heading stroke, and its depth is limited by the head height. On a countersunk head the material above the bearing cone is thin, so the socket is shallower than on a pan head of the same thread — another reason the drive suits a low-torque joint.
Plain stainless is passivated after forming. The passivation matters more here than on a coated part, because there is no coating to hide a defect: whatever the cone and the socket look like after passivation is what the customer inspects.
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 stainless security screws the cone angle, the socket size and the thread length are quoted together, because all three decide how the joint closes.
| Item | How it is defined | What we control |
|---|---|---|
| Head | Countersunk cone, flat top | Cone angle, diameter and concentricity |
| Socket | Internal triangle, three faces | Across corners, depth, key tried on the part |
| Thread | Self-tapping, full length | Gauged per batch |
| Point | Short taper, flat tip | Checked on the first article |
| Finish | Plain stainless, passivated | Surface condition and film |
| Length | From the top of the head to the point | Measured on the shop plate |
Cone angle and countersink angle have to match. Ninety degrees is the common case, but a formed countersink in a thin sheet is often a little off, and a head that is a degree out seats on a line: it looks flush and it rocks. The first article is seated in a sample of the customer’s sheet for that reason.
Length is quoted from the top of the head, since the head finishes flush and the top face is the datum that shows. On a thin panel the difference between measuring from the top and from the start of the cone is the head depth, which is the whole engagement.
Three features define stainless security screws: the countersunk head, the triangular socket and the stainless body. The first two are deliberately matched in strength, and the third is what the screw is for.
| Feature | What it gives | What it costs |
|---|---|---|
| Countersunk head | Flush surface, self-centring | Bears on thin sheet; the sheet is the limit |
| Triangle socket | Distinctive access, positive three-face seat | Limited torque; a key is needed for service |
| Self tapping thread | Holds without a nut or tapped hole | Needs the right pilot hole |
| Flat point | Starts in a punched or drilled hole | Will not pierce sheet on its own |
| Plain stainless | No coating to chip at the cone | Galls against stainless; pits in chloride |
The failure this pairing avoids is the sunk countersink. On a plated screw with a hex socket it is easy to drive the head until the sheet around it yields, and once that has happened the countersink no longer matches the cone: the head sits low, the paint cracks around it, and the joint cannot be pulled back. A triangular key makes that outcome require a deliberate effort.
The cost is service access. A triangular key is not in most toolbags, so every technician who opens the joint needs one, and once the screw has been out and back a few times the socket corners are the first thing to wear. Where a joint is opened regularly, an internal triangle is the wrong drive and a machine screw with a standard head is the right one.
Stainless security screws are finished plain and passivated. Nothing is added, so the cone seats exactly as formed and there is no coating to be pushed aside or rubbed off as the head seats.
| Option | How it protects | Effect on cone and socket | Typical use |
|---|---|---|---|
| Stainless A2, plain | Passive chromium oxide film | None; gauged as formed | Outdoor and public fittings |
| Stainless A4, plain | Passive film with molybdenum | None; gauged as formed | Coastal, marine and washdown |
| Zinc plated steel | Sacrificial zinc | A few microns; socket re-checked | Indoor, cost-driven work |
| Black zinc on steel | Sacrificial zinc, dark passivation | A few microns; re-checked | Dark visible panels |
| Dacromet on steel | Zinc-aluminium flake layer | Film builds; socket re-checked | Outdoor steel assemblies |
Stainless has one behaviour that matters in a countersink: it galls. A stainless cone driven into a stainless countersink, particularly in a thin sheet that work-hardens, can seize before the head is seated, and a seized flush head cannot be removed without destroying the countersink. A lubricant on the cone, or a different grade for the sheet, prevents it.
The other limit is chloride. A2 pitting starts at the socket corners and at the thread in a salt-laden joint, and a pit inside a triangle socket is where the key stops seating. Where the service is coastal or chlorinated, the grade is the answer rather than any finish.
Three assemblies where stainless security screws with a countersunk head are the fixing:
| Where it sits | The screw fixes a plate or a panel flush into a sheet where the public has access and the fixing should not be undone casually. |
| When it goes wrong | A standard head is opened with a pocket tool, and a head that stands proud catches clothing and collects damage. |
| Why it happens | The surface is flush, the panel is public, and the fixing is exposed to weather. |
| What we control | Cone angle and socket checked, key confirmed, passivation inspected. |
| Where it sits | The screw holds a panel or a bracket where the joint is washed, the surface must be flat, and access should be restricted. |
| When it goes wrong | A plated screw loses its coating at the cone and stains the panel; a standard drive invites tampering. |
| Why it happens | The environment is wet, the surface is visible, and the fixing is one of many. |
| What we control | Grade confirmed, socket and cone checked, lubricant recommended on assembly. |
| Where it sits | The screw closes a housing or a cover plate on equipment that is serviced by staff with a key and left unattended in between. |
| When it goes wrong | A bright screw or a proud head marks the design, and a commonly available drive makes the cover a target. |
| Why it happens | The housing is exposed, the fixing is serviced, and the surface has to stay clean. |
| What we control | Socket tried with the production key, plating none, thread gauged. |
Four reasons that matter on stainless security screws, each tied to what the drawing has to prove:
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Cone, socket and sheet reviewed together
The cone angle, the socket size and the sheet thickness are reviewed as one set, so a countersink that would yield or a socket that would not take the key is raised before the die is cut. Basis: Cone, socket and sheet reviewed as one set. |
Heading, rolling and passivation in one route
The countersunk head and the triangular socket are formed in one stroke, the thread is rolled and the parts are passivated in the same route. Basis: One route from wire to passivated screw. |
|
Key tried in the formed socket
The socket is checked across corners and for depth and then turned with the production key, because a socket that measures in tolerance can still rock. Basis: First article turned with the production key. |
First article fixes the setting
The first article fixes the wire heat, the socket punch, the roll and the passivation; repeat orders are compared against that record. Basis: First article signed off before the batch is released. |
Shi Shi Tong forms these stainless security screws from stainless wire on single-die headers that cut the countersunk cone and the triangular socket in one stroke, rolls the self tapping thread to a flat point and passivates the parts. The first part of every run is measured on the cone, turned with the production key and driven into a sample of the customer’s sheet before the batch continues.
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The socket punch wears at the three corners, and on a countersunk head there is less material around it than on a pan head, so the wear shows sooner. A worn punch leaves a socket that is wider at the mouth than at the floor: the key sits high, the torque goes into the corners, and the corners are exactly where a flush head has least to spare.
What decides whether stainless security screws pass is the cone, the socket, the thread, the point and the alloy. The inspection agreement covers those, and the criteria come from the drawing.
Cone and socket on the projector |
Thread gauged per batch |
Hardness checked on the formed head |
Salt-spray testing of the stainless grade |
The cone on stainless security screws is checked for angle, diameter and concentricity, and the socket across corners and for depth. Both are then proved in use: the first article is driven into a countersunk sample and turned with the production key, because a cone that measures right can still seat on a line and a socket that measures right can still refuse a key.
Seating is checked with a light behind the head. That is the customer’s acceptance test on a flush joint, and it catches the ring of contact that no dimension on the drawing describes.
The thread is gauged and driven into the customer’s sheet, with driving and strip torque recorded together. On a countersunk self tapping screw the sheet around the countersink has less material than in an unbevelled hole, so the strip torque is lower than the size suggests.
Every shipment of stainless security screws is traceable to the wire it was made from and to the passivation 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 grade or the passivation. 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 stainless security screws the first article is also the point at which the key is agreed, so the customer confirms the tool at the same time as the screw. Buyers visit during the process to review samples and to see how the heads and sockets 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 passivation 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 |
On stainless security screws the recess is an internal triangle: three flat faces driven with a triangular key. It takes no common bit and seats positively on all three faces.
The two limits match. A countersink in thin sheet should not be over-tightened, and a triangular key cannot deliver enough torque to sink it.
It can gall, especially into a stainless part. A lubricant on the cone, or a different grade for the sheet, prevents it; once seized the countersink is usually lost.
With the key, yes, a few times. The socket corners wear first, and a triangular socket has only three of them.
Plain stainless does not rust like steel, but A2 pits in chloride. The pit starts at the socket corners and at the thread.
Cone angle and diameter, socket across corners and depth, thread size and point type, length from the top of the head, and the stainless grade.
How a stainless security screw project runs from drawing to repeat delivery:
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1
Send the drawing and the sheet sample
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→ |
2
Cone, socket and thread review
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→ |
3
First article seated and turned with the key
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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 cone angle and diameter, the socket across corners and depth, the thread size and point type, the length from the top of the head, and the stainless grade.
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Cone angle
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Head diameter
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Across corners
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Socket depth
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Thread and length
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Stainless grade
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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
