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+86 13143444311
Email：sst@szsst88.com
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Address：Building 9, First Industrial Zone, Tantou Industrial City, Songgang Street, Baoan District, Shenzhen 518105, Guangdong, China
Type:Tri Wing Security Screw
Materials:Carbon Steel
Surface treatment:Color Zinc Plated
Head Type:Pan Head
Drive:Tri-Wing
Thread:Half Thread Self Tapping
Point:Blunt
Forming:Single Die Heading
Size:M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M14
Number:380
We make tri wing security screws in carbon steel with a pan head, a slanted Y recess and a half self tapping thread, colour zinc plated and quoted from M1 to M14. Recess dimensions, head, thread and plating come from your drawing, and the first article is turned with the bit your service team uses.
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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.
A tri wing security screw is a screw with a three-winged, slanted Y recess that an ordinary screwdriver cannot turn, used where the maker does not want the fixing opened by whoever has the product. The recorded item on this page is colour zinc plated carbon steel with a pan head and a half self tapping thread, quoted from M1 to M14 with Number 380.
Slanted Y recess. Three wings set out radially, with a slant or an offset that makes a plain three-point bit bind instead of seating. The drive is the shape of the recess, and it is the whole reason the part exists.
Pan head. A low dome on a flat bearing face. It covers the hole, spreads the load and stays inside its own diameter, which is what a row of fixings on a narrow pitch needs.
Half self tapping thread. Thread from the point to a defined position, with a plain shank under the head, ending in a blunt point. The plain length passes the top member of a stack without cutting it.
Colour zinc. Electroplated zinc with a coloured, iridescent passivation. It is sacrificial like any zinc, and the rainbow tone is a visible indicator that the part has been through a passivation bath rather than a plain rinse.
Everything about a tri wing security screw is arranged around the recess. The wings are formed by a punch in the heading stroke, and their depth is limited by the head height: on a pan head there is enough material for a full-depth recess, which is why this drive appears on pan heads rather than on low heads.
The slant is the security feature. A symmetrical three-point recess can be turned with a small tri-point bit that is sold for other devices; a slanted or offset version will not accept that bit squarely, and forcing it deforms the wings. That does not make the screw unopenable — it makes opening it a deliberate act with a deliberate tool, which is what a deterrent is.
The head and the recess are formed together, so the recess sits concentric with the shank. That matters more here than on a cross recess: a tri-wing recess has only three points of contact, so an off-centre recess loads one wing harder than the others and that wing is the one that rounds.
The half thread and the blunt point follow the drawing. In a two-member stack the plain shank passes the top member without cutting into it, and the thread forms or engages in the member below; a blunt point needs a hole that already exists.
Colour zinc goes on after the thread is rolled. It is a few microns thick, so it follows the wings rather than filling them, and it is trivalent rather than the older hexavalent passivation — which is what the RoHS report covers and why the tone is a little less vivid than the classic rainbow.
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 a tri wing security screw the recess size and the head height are quoted with the thread, because the three wings have to fit inside the head.
| Item | How it is defined | What we control |
|---|---|---|
| Head | Pan head, flat bearing face | Diameter, height and face flatness |
| Recess | Slanted Y, three wings | Wing width, depth and slant, bit tried on the part |
| Thread | Self-tapping, half length | Thread length and position from the end |
| Point | Short taper, blunt tip | Checked on the first article |
| Plating | Colour zinc, trivalent passivation | Thickness range and salt-spray sample |
| Length | From under the head to the point | Measured on the shop plate |
The recess is quoted with the bit, not only by name. Two suppliers can both call a recess a tri-wing and differ in wing width, depth and slant; a bit made for one will not seat in the other. Where the customer has an existing driver, the first article is turned with that driver rather than with a drawing.
Length is measured from under the head, because that face bears. On a half thread the thread length is quoted from the point independently, so a screw can be correct overall and still wrong if the thread starts a turn too early and the plain shank no longer clears the top plate.
Three features define this part: the slanted Y recess, the pan head and the half thread. The first is the security feature, the second is the bearing area, and the third is what lets the screw work in a stack.
| Feature | What it gives | What it costs |
|---|---|---|
| Slanted Y recess | Ordinary drivers will not turn it | The right bit is needed for service |
| Three-point contact | Enough torque for a small fixing | Less than a cross; one wing wears first |
| Pan head | Load spread without a washer | Taller than a low head |
| Half thread | Plain shank passes a clearance hole | Thread length must be specified |
| Colour zinc | Sacrificial, iridescent, reassuring | Thin; tone differs from old hexavalent |
The honest limit of the drive is the same as any security recess: the bit is for sale. What the slant does is stop the improvised approach — a flat blade, a Phillips, a small Y bit from another device — and make the person stop and think. That is enough for a product where access should be inconvenient rather than impossible.
The cost lands on service. Every technician who opens the product needs the slanted Y bit, and a worn bit rounds the wings quickly because there are only three of them. Supplying bits with the first order, and standardising the drive across a product line, is the practical answer.
The recorded finish is colour zinc with an iridescent passivation. The zinc is the protection and the colour is the film on top of it: a chromate conversion layer that ranges from yellow through green to violet depending on bath and part orientation.
| Finish | How it protects | Effect on recess and thread | Typical use |
|---|---|---|---|
| Colour zinc | Sacrificial zinc, iridescent passivation | A few microns; recess re-checked | General indoor fixings |
| 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; re-checked | Dark products |
| Dacromet | Zinc-aluminium flake layer | Film builds; recess re-checked | Outdoor and wet service |
| Stainless, plain | Passive chromium oxide film | None; gauged as formed | Washed and coastal joints |
The colour is not a quality grade. A vivid rainbow used to indicate a hexavalent chromate, which is what the RoHS restriction was written to remove; the trivalent process now used gives a softer, less saturated tone, and a customer comparing a current batch with an old sample will see a difference that is compliance rather than decline.
What the colour does show is coverage. A part that was not fully wetted in the passivation bath has a patch of plain zinc, and on a security screw that patch is usually inside the wings or under the head. The sample is inspected for that rather than for how bright it is.
Three assemblies where a tri wing security screw is the fixing:
| Where it sits | The screw closes a housing where the manufacturer wants the case to stay closed in normal use and to be opened only by authorised service. |
| When it goes wrong | A cross recess invites the user with a kitchen drawer of drivers; a stripped tri-wing recess ends the repair. |
| Why it happens | The product is sold to the public, the contents are sensitive, and the case is serviced rarely. |
| What we control | Recess tried with the customer’s bit, thread gauged, plating checked for coverage. |
| Where it sits | The screw holds a panel over a mains connection or a control board where access should be restricted to a technician. |
| When it goes wrong | A standard fixing lets an unqualified owner inside a panel that carries mains voltage. |
| Why it happens | The panel covers live parts, the product is repaired on site, and service has the bit. |
| What we control | Recess depth and wing width checked, bit supplied with the order. |
| Where it sits | The screw closes a coin box, a meter cover or an access plate where casual opening means loss or tampering. |
| When it goes wrong | A commonly available drive makes the cover a target; a brand-specific drive makes it a chore. |
| Why it happens | The contents are valuable, the site is unattended, and the fixing is one of many. |
| What we control | Recess and head checked, plating held, thread form proved on the first article. |
Four reasons that matter on a three-wing drive, each tied to what the drawing has to prove:
|
Recess and bit reviewed together
The wing width, depth and slant are reviewed with the driver the customer will use, so a recess that would not take their bit is raised before the die is cut. Basis: Recess and driver reviewed as one set. |
Heading, rolling and plating in one route
The pan head and the slanted Y recess are formed in one stroke, the half 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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Recess driven with the production bit
The recess is measured for wing width and depth and then turned with the production bit, because a recess that measures in tolerance can still refuse a worn driver. Basis: First article turned with the production bit. |
First article fixes the setting
The first article fixes the wire heat, the recess punch, 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 tri wing security screws from carbon steel wire on single-die headers that upset the pan head and form the slanted Y recess in one stroke, rolls the half thread to a blunt point and colour zinc plates the parts. The first part of every run is measured on the head, turned with the production bit and driven into a sample of the customer’s material before the batch continues.
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The recess punch is the tool that limits the die. Its three wings wear at the tips first, and a worn punch leaves wings that are wider at the mouth than at the floor — a recess that accepts the bit and lets it rock, so the torque goes into the tips instead of the flanks and the wings round off. The recess is checked with the bit on the first article and sampled through the run.
What decides whether tri wing security screws pass is the recess, the head, the thread and the plating. The inspection agreement covers those, and the criteria come from the drawing.
Recess wings and depth on the projector |
Thread gauged after plating |
Hardness testing against the property class |
Salt-spray testing of the colour zinc plate |
The recess is checked on the projector for wing width, depth and the slant angle, and then turned with the production bit. The two checks answer different questions: the dimensions say whether the recess is in tolerance, and the bit says whether it will drive the batch the customer actually receives.
The head is checked for diameter, height and face flatness. On a security screw the head is also the only place the coating can be seen, so the plating is read as a colour sample while the dimensions are taken.
The thread is gauged after plating and the thread start is checked on the half thread. A thread that starts a turn early removes the plain shank and turns a cover that sat flat into one that stands off.
Every shipment of tri wing security 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 security drive the first article is also the point at which the bit 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 recesses are formed.
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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 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 |
Three wings set out in a slanted Y. The slant stops a plain three-point bit seating squarely, so an ordinary driver spins or damages the recess.
It is a deterrent. The bit is available; what the drive does is stop the improvised attempt and make opening the product a deliberate act with the right tool.
The slanted tri-wing bit that matches the recess, not a general tri-point bit. Two suppliers can both call a recess tri-wing and differ in wing width and slant.
No. It will cam out and deform the wings, and once the wings are deformed no bit will work. The damage is not repairable.
It is the standard protective finish for indoor fixings. The iridescent tone is a trivalent passivation, which is the RoHS-compliant version of the old rainbow chromate.
Head diameter and height, recess wing width, depth and slant, thread size and point type, length and datum, material and plating.
How a tri wing security screw project runs from drawing to repeat delivery:
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1
Send the drawing and the bit you drive with
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→ |
2
Recess, head and thread review
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→ |
3
First article turned with the 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 head diameter and height, the recess wing width, depth and slant, the thread size and point type, the length and datum, the material and plating.
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Head diameter
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Head height
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Recess dimensions
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Thread and point
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Length
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Material and plating
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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
