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:Pan Head Security Screws
Materials:Stainless Steel
Surface treatment:Plain
Head Type:Pan Head
Drive:Y Recess (Tri-Wing)
Thread:Machine Thread
Point:Blunt
Forming:Single Die Heading
Size:M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M14
Number:417
We make pan head security screws in passivated stainless with a three-lobe Y recess and a machine thread, quoting them from M1 to M14. Recess size, depth, head and thread come from your drawing, and the first article is driven and removed with your own bit.
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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.
Pan head security screws are machine screws with a shallow domed head and a recess that a normal driver cannot turn. On the recorded item the recess is a three-lobe Y, also called a tri-wing, and the thread is a machine thread in stainless. The family is quoted from M1 to M14 with Number 417 and filed under the security screws.
Pan head. A low dome with a wide flat bearing face, so the head spreads load and leaves nothing sharp on the surface.
Y recess. Three lobes arranged around a small triangular centre. A flat or cross driver will not locate in it, and the correct bit is a specific tri-wing size.
Machine thread. A rolled thread for a tapped hole or a nut, ending in a blunt chamfer.
Plain stainless. Passivated and uncoated, so the recess is exactly as cut and the alloy carries the protection.
What pan head security screws depend on is the bit rather than the screw: if the driver is not to hand, the joint does not open, and that is the whole of the design intent.
A security recess is an access-control device, not a strength feature. It stops the person who has a screwdriver and no reason to be there: the curious, the passing hand, the operator who wants to open a cover that is not meant to be opened. It does not stop anyone who has decided to get in, because the bit is available, and a determined person will use a drill. That distinction matters when the part is specified, because it decides how much the security feature is worth.
The Y recess is one of the older forms and it works on unfamiliarity. A flat blade, a cross bit and a hex key all fail to find purchase; the screw stays put while the tool slips. What it does not change is the material around it: a stainless Y recess in a pan head has thin walls and three lobes, and a slipped tool damages it quickly.
That is the cost of the design. On a normal screw a damaged recess is annoying; on a security screw it can be terminal, because the owner may not have the bit either. A product that is sealed with these fasteners has to be planned as a product that is opened once, at the factory or by a service agent with the tool, and the design should say so rather than leave it to the first complaint.
The torque ceiling is lower than a standard drive of the same size. Three lobes do not enclose the bit the way six do, so the engagement is smaller and the recess is more sensitive to a bit that is off-axis or worn. On a stainless pan head that shows up as a recess that rounds at a torque the joint has not yet reached, and there is no second chance to drive it.
So the useful reading of a pan head security screw is: a small, cheap, familiar deterrent on a joint that is assembled once and rarely opened. It is not a lock, and it is not a fastener to specify where the joint has to come apart in service without the tool to hand.
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 pan head security screws the quotation carries head diameter, head height, recess size and the thread, because the recess has to be deep enough to take the bit and the head has to be deep enough to hold the recess.
| Item | How it is defined | What we control |
|---|---|---|
| Head | Pan head, flat face | Head diameter, height and face flatness |
| Recess | Y recess, three lobes | Recess size, depth and lobe shape |
| Thread | Machine thread | Pitch and length, gauged per batch |
| End | Blunt, chamfered | Chamfer cut, not deburred |
| Finish | Plain stainless, passivated | Surface condition and film |
| Length | Under the head | Measured on the shop plate |
Recess depth is the compromise that decides how usable the part is. A shallow recess takes less bit and rounds sooner; a deeper one needs a taller head and more material. On a pan head there is only so much height, so the recess on a small size is short, and the difference between a part that survives assembly and one that does not is often ten or fifteen hundredths of a millimetre.
Length is measured from under the head. Where the joint is sealed by the fastener — a cover, a panel over a gasket — the length decides the compression, and a security screw that bottomed in a blind hole will not seal no matter how right the thread is.
Three features define this part: the Y recess, the pan head and the stainless body. The first deters, the second seats, and the third means the joint can live outdoors while the recess stays as cut.
| Feature | What it gives | What it costs |
|---|---|---|
| Y recess | Stops casual access | Lower torque ceiling than a six-lobe drive |
| Three lobes | Unfamiliar to common tools | Damaged recess has no alternative |
| Pan head | Spread load, low profile | Limited height for the recess |
| Machine thread | Repeatable clamp in a tapped hole | Needs a tapped hole or nut |
| Plain stainless | No coating to wear in the recess | Galls against stainless |
The absence of alternative is the feature that cuts both ways. If the recess survives, the part works exactly as intended and the joint stays closed; if it does not, the assembly enters a repair loop that may involve a drill. That is why the first article of a security part is driven with the customer’s own bit and to the customer’s own torque, and why a bit that is worn is a bigger problem here than on any other screw.
Stainless is the material that makes the trade tolerable. A plated security screw with a chipped recess corrodes where the tool slipped; a plain stainless one has no plate to chip, and the recess that survives the assembly will look the same years later. The one behaviour to plan for is galling on stainless to stainless, which a dry-film lubricant resolves.
The recorded finish is plain, passivated stainless. On a security screw that is worth more than usual: the recess is the only place a tool touches, and a coating would be worn off the lobes at the first assembly, leaving bare steel where water sits and where nobody looks. A passive surface has nothing to wear.
| Option | How it protects | Effect on recess | Typical use |
|---|---|---|---|
| A2 stainless, passivated | Passive chromium oxide film | Recess as cut | Outdoor equipment and panels |
| A4 stainless, passivated | Passive film with molybdenum | Recess as cut | Marine and chemical |
| Steel, zinc plated | Sacrificial zinc | Plate wears at the lobes | Indoor sealed products |
| Steel, black oxide | Conversion film, oiled | No measurable build | Internal mechanisms |
| Aluminium, anodised | Thick oxide layer | Recess dulled by the oxide | Lightweight panels |
Where the product is outdoors, the alloy choice is the whole story. A2 is right for general exposure; A4 is right for coastal and chemical; a zinc-plated steel security screw outdoors is a screw that will need drilling out within a couple of seasons, because the recess is where the coating fails first and the head is where the rusting is least visible.
The surface also affects how much torque the recess can take. A plated recess is a few microns narrower and has a slightly slicker surface; a plain stainless recess bites the bit a little harder and gives better feedback. Neither changes the design, but they change how the first assembly feels, and the customer’s bit should be tried on the surface they will actually receive.
Three assemblies where pan head security screws are the fixing:
| Where it sits | The screw holds a cover, a sign panel or an access plate where the joint is exposed to the public and must not be opened casually. |
| When it goes wrong | A standard recess invites tampering, and a damaged security recess is hard to remove without drilling. |
| Why it happens | The joint is exposed, it is not meant to be opened, and it is stainless. |
| What we control | Recess size and depth checked, first article driven with the customer bit. |
| Where it sits | The screw closes a cabinet whose interior is for authorised access only, where a key or a badge is the real control and the fastener is a deterrent. |
| When it goes wrong | A stripped recess blocks a service visit, and a corroded recess means the cabinet cannot be opened at all. |
| Why it happens | The joint is closed to the public, opened by staff, and often outdoors. |
| What we control | Recess and thread checked, alloy confirmed for the environment. |
| Where it sits | The screw fixes a panel over cash or media, where the fixing slows an opportunistic attempt without being the security system itself. |
| When it goes wrong | A recess damaged at assembly cannot be opened for collection, and the machine is out of service. |
| Why it happens | The joint is high value, it is opened on a schedule, and the tool is held by staff. |
| What we control | First article driven to the service torque, recess inspected under magnification. |
Four reasons that matter on a tamper-resistant fastener, each tied to what the drawing has to prove:
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Recess and torque agreed
The recess size and the assembly torque are confirmed together, because a security recess has a lower torque ceiling than a standard drive and there is no second attempt. Basis: Recess and torque agreed in writing. |
Head, recess and thread in one route
The pan head and the Y recess are formed in the heading stroke, the thread is rolled and the parts are passivated in the same route. Basis: One route from wire to passivated screw. |
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Driven with the customer bit
The first article is driven with the customer’s own tri-wing bit at their torque, because the fit between recess and bit is what the part is judged on. Basis: First article driven with the customer bit. |
First article fixes the setting
The first article fixes the wire, the recess punch 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 pan head security screws from stainless wire on single-die headers that form the pan head and the three-lobe recess in one stroke, rolls the machine thread to a blunt chamfered end and passivates the finished parts. The first part of every run is measured on the head and recess, driven with the production bit and entered into a thread gauge before the batch continues.
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A three-lobe recess is a difficult punch to keep sharp. The lobes are narrow and the tool has to cut three of them from one stroke without leaving a burr at the centre, where the bit bottoms. A punch that is slightly worn leaves lobes that look right from above but do not reach full depth, and a bit in that recess sits high and rounds the top of the lobes at the first turn.
What decides whether pan head security screws pass is the recess, the head, the thread and the alloy. The inspection agreement covers those, and the criteria come from the drawing.
Head and recess on the projector |
Thread gauged per batch |
Hardness checked on the wire |
Salt-spray testing of the grade |
The recess is checked for size, depth and lobe shape and then driven with the production bit; the lobed walls are inspected at magnification, because the failure mode of a security recess is a thin wall that looks acceptable until the first assembly. The head is checked for diameter and face flatness.
The thread is gauged per batch, the alloy is confirmed on the certificate, and the salt-spray sample is run where the customer’s environment asks for it. A security screw that cannot be removed is a service problem, so the batch is judged on removal as well as on insertion: the first article is turned out again with the same bit.
Every shipment of pan head 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 a repeat order is made to the same recess geometry that was approved.
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 security part the first article is driven and removed with the customer’s own bit, because the recess is the function. Buyers visit during the process to review samples and to see how the heads and recesses 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 |
A tri-wing bit of the matching size. A flat or cross driver will not locate, which is the point of the drive.
It deters casual access, not a determined one. The right bit is available, and a drill always works. Treat it as access control, not as a lock.
There is usually no second option, so the part may have to be drilled out. That is why the recess is driven with the customer’s bit at their torque before a batch is released.
Less. Three lobes enclose the bit less than a cross or a six-lobe drive, so the ceiling is lower and the part is less forgiving of a worn bit.
A2 for general outdoor work and A4 for coastal or chemical exposure. A plated steel security screw outdoors usually ends up being drilled out.
Thread size and length, head diameter and height, the recess size and depth, the grade and the torque the assembly will use.
How a pan head security screw project runs from drawing to repeat delivery:
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1
Send the drawing and the bit you will use
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→ |
2
Recess size, depth and torque agreed
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→ |
3
First article driven and removed with your bit
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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 thread size and length, the head diameter and height, the recess size and depth, the assembly torque and the grade.
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Thread size
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Length
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Head diameter
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Recess size
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Recess depth
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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
