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:Metric Pan Head Torx Machine Screws
Materials:Carbon Steel
Surface treatment:Black Zinc Plated
Head Type:Pan Head
Drive:Torx six-lobe recess (T-size matched to the thread)
Thread:Metric machine thread, rolled 60 degrees, full to the head bearing face
Point:Blunt end with a small chamfer; no taper, no drill point
Forming:Single-die heading, thread rolling, black zinc plating, sorting
Size:M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M14
Number:131
We manufacture metric pan head torx machine screws with a low domed pan head, a six-lobe star recess and a rolled metric thread, in carbon steel with a black zinc finish. Head height, star recess size, thread and length are taken from your drawing.
Watch the factory video·Email sst@szsst88.com
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.
Metric pan head torx machine screws are machine screws with a low domed pan head, a six-lobe star recess and a metric thread, finished in black for dark assemblies. The recorded item on this page is carbon steel with a black zinc plate, a machine thread and a blunt end, quoted from M1 to M14 with Number 131.
Pan head. A low dome over a flat annular bearing face, with a small fillet into the shank and no flange. The ring under the dome is the working surface, and the low profile keeps the head under a cover or inside a counterbore.
Torx recess. Six lobes with straight walls, driven with a matching star bit. The bit seats on six faces, does not wedge like a cross, and transmits more torque into a head that is only a few tenths of a millimetre above its bearing ring.
Metric thread. Diameter and pitch in millimetres — M3 × 0.5, M4 × 0.7, M5 × 0.8 — for a tapped hole or a nut. The pitch is part of the size and does not interchange with a fine pitch of the same diameter.
Black zinc. A zinc plate with a black passivation. The zinc is sacrificial, so a scratch is protected by the metal around it, and the black tone lets the fixing sit quietly on a dark panel.
Machine screw, not self-tapping. The thread is rolled and the end is blunt: it goes into a thread that already exists, and the chamfer lets the first turn enter cleanly.
The pan head and the star recess are formed in one heading stroke, so the recess stays concentric with the shank. That matters more on a pan head than on a taller head: the dome is shallow, the wall around the recess is thin, and a recess formed off centre breaks through on one side.
The recess is cut to the star size that matches the thread. A recess a size small will take the bit only part way and cam out at a fraction of the intended torque; one a size large will not drive the screw at all. On metric pan head torx machine screws the star size is quoted with the thread for that reason.
The thread is rolled and runs to the underside of the head. Rolling work-hardens the flank and leaves a smooth surface that gauges consistently, and it gives the thread the wear resistance a machine screw needs in a joint that is opened more than once.
The end is blunt with a small chamfer. There is no point, because there is nothing to start — the hole is already tapped — and the chamfer is what stops the first thread catching on the lead-in of the hole.
Black zinc is applied after rolling, over the head, the recess and the thread. It adds a few microns, so the thread is gauged in the plated condition and the recess is driven with the production bit afterwards. Neither check is optional on the small sizes.
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; metric pan head torx machine screws are mostly used at the small end, where the pan head keeps a low profile under a cover.
| Item | How it is defined | What we control |
|---|---|---|
| Thread | Metric machine thread, rolled | Gauged per batch after plating |
| Head diameter | About twice the thread diameter | Checked on the projector |
| Head height | Low dome over a flat bearing ring | Measured from the bearing face |
| Recess | Star six-lobe, sized to the thread | Checked with the production bit |
| End | Blunt with a small chamfer | Checked on the first article |
| Length | From under the head to the end | Measured on the shop plate |
The head height is the number that decides whether the screw fits. Pan heads sit lower than a socket cap of the same thread, which is why they are used under covers and in counterbores; but a recess in the panel that is too shallow will still leave the dome proud, and on a dark panel that is immediately visible.
The head diameter is the number that covers the hole. At about twice the thread it covers a normal clearance hole with margin; where the hole has opened up or the panel is soft, the next size up is the honest answer rather than pushing this head.
A pan head and a star drive make a specific kind of sense together: the head is low, the bearing ring is defined, and the drive does not need a tall crown to work in.
| Feature | What it gives | What it costs |
|---|---|---|
| Star recess | High torque, no cam-out, long bit life | Needs the matching star bit |
| Pan head | Defined bearing ring, low profile | No flange, so no extra bearing area |
| Black zinc | Dark tone with sacrificial protection | A few microns; recess and thread re-checked |
| Metric thread | Standard worldwide | Fine and coarse pitches do not interchange |
| Blunt end | Stops at the thread end in a tapped hole | Cannot start in an unthreaded hole |
The drive is what makes the low head practical. A cross recess in a shallow pan head needs depth it does not have, and a bit that lifts marks the dome on the first assembly. A star bit engages on six straight faces and pushes along the axis, so the head can be driven to a seated torque and still look untouched.
The black zinc is a cosmetic and a protective choice at once. It hides the fixing on a dark panel and it protects the steel sacrificially, and unlike a black oxide film it does not expose bare steel when scratched. What it does not do is survive wet service: a black Dacromet or stainless version of the same head is what an outdoor joint needs.
The recorded finish is black zinc plating on carbon steel, applied after the thread is rolled. On a pan head the finish is judged on the dome and on the recess, because those are the two surfaces a customer sees when the fixing is on a panel.
| Finish | How it protects | Effect on thread and recess | Typical use |
|---|---|---|---|
| Black zinc | Sacrificial zinc plus black passivation | A few microns; gauged after | Dark panels, indoor and damp |
| Black oxide | Thin conversion film, oiled | Almost no change | Dry indoor assemblies |
| Blue zinc | Sacrificial zinc, blue-white passivation | A few microns; gauged after | General indoor work |
| Dacromet | Zinc-aluminium flake layer, cured | Thin film; recess re-checked | Outdoor and wet assemblies |
| Stainless (equivalent part) | Alloy provides protection | No coating | Wash-down and coastal work |
The recess is where plating causes a functional problem. Every micron narrows the cross of a star, and on a small pan head the wall around the recess is already thin; a recess that has become tight after plating is harder to drive than a cross would be, because the bit has to seat fully to engage six faces.
The black tone also shows wear. The passivation goes first on the dome as screws are handled and on the recess wings as they are driven, leaving slightly brighter zinc underneath. On metric pan head torx machine screws used on visible panels that is worth saying before a batch is judged, because it is normal wear of a dark finish rather than a coating failure.
Three assemblies where a low dark head with a star drive is the right fixing:
| Where it sits | The screw holds a bracket, a board or a cover inside a black chassis, where the head sits low and the fixing is small. |
| When it goes wrong | A bright head shows through a vent, and a cross recess in a shallow pan head rounds before the joint is tight. |
| Why it happens | The housing is dark, the space is tight, and the fixing is small. |
| What we control | Head height checked against the clearance, recess driven with the production bit after plating. |
| Where it sits | The screw fixes a module, a plate or a rear panel where the head is seen when the case is opened and the tone has to match. |
| When it goes wrong | A head that stands proud fouls a lid, and a glossy head catches the light in a dark interior. |
| Why it happens | The interior is dark, the fixing is repeated, and the assembly is serviced. |
| What we control | Head diameter and tone matched to the sample, thread gauged per batch. |
| Where it sits | The screw holds a bracket or a plate to a tapped hole in a dark frame, where the head is accessible and the joint is opened occasionally. |
| When it goes wrong | A cross recess cams out and marks a finished face, and a loose screw backs out with vibration. |
| Why it happens | The frame is dark, the joint is serviced, and the face is visible. |
| What we control | Recess and head height checked, thread gauged, first article driven at the joint torque. |
Four reasons that matter on a small star-drive pan screw, each tied to what the drawing has to prove:
|
Recess and head height reviewed together
The star size, the head height and the bearing face are reviewed as one set, so a recess that will not fit a shallow head is raised before tooling. Basis: Recess and head height reviewed as one set. |
Head, recess and thread in one route
The pan head and the star recess are formed in one stroke, and the thread is rolled to the underside of the head. Basis: One route from wire to plated screw. |
|
Recess and thread checked after plating
The recess is driven with the production bit and the thread is gauged in the plated condition, because the deposit changes both. Basis: First article checked after plating. |
First article to repeat production
Repeat orders are checked against the first article, which records the drawing revision, wire heat, die set, thread roll and plating. Basis: First article signed off before the batch is released. |
Shi Shi Tong forms these metric pan head torx machine screws on a single-die header that upsets the pan head and the six-lobe recess in one stroke, then rolls the metric thread to a blunt chamfered end. The parts are black zinc plated and sorted. The first part of every run is measured on the head, driven with the production bit and gauged after plating, before the batch continues.
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The star punch is the tool that has to be right at the small sizes. A worn punch leaves lobes that look correct and allow the bit to sit high, and on a shallow pan head a bit that does not seat will mark the dome before it drives anything. The recess is checked by driving rather than by gauging, and the punch is changed on that evidence.
What decides whether metric pan head torx machine screws pass is the head, the recess, the thread, the end and the plating. The inspection agreement covers those, and the criteria come from the drawing.
Head profile on the projector |
Thread gauged after plating |
Hardness testing against the property class |
Salt-spray testing of the black zinc plate |
The recess is checked with the bit and inspected at the lobe corners. A damaged star recess shows as a polished line along one flank rather than as a missing corner, and that line appears before the bit slips — on a dark head it is also the first thing that shows.
The thread is gauged at the plating thickness the batch was run to, not at a bare size. Black zinc on a small metric thread is a meaningful share of the flank, and a batch that passes unplated can fail plated; the gauge is used on the finished part for that reason.
Every shipment of metric pan head torx machine 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 dark small screw the first article is checked with the bit in the recess as well as for tone, because the recess is what fails first and what shows first. Buyers visit during the process to review samples and to see how the heads 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 header 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 |
Machine joints in dark assemblies: brackets, covers and plates in computer, audio and equipment housings, where the head sits low and the fixing is small.
A shallow pan head has little depth for a cross, so the bit lifts and marks the dome. A star bit seats on six faces and drives without cam-out.
From under the head to the end. With a machine thread the whole length is engagement once it is inside the tapped hole.
Not for long. It is a sacrificial finish that gives way in wet service; a Dacromet or stainless version of the same head is the right choice there.
The size that matches the thread, quoted on the drawing. A bit one size small rounds the lobes, and on a dark head the damage shows immediately.
Thread size and pitch, head diameter and height, star recess size, length and datum, material and finish.
How a metric pan head torx machine screw project runs from drawing to repeat delivery:
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1
Send the drawing or sample
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→ |
2
Recess and head height review
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→ |
3
First article driven at joint 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 thread size and pitch, head diameter and height, star recess size, length and datum, material and finish.
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Thread and pitch
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Head diameter and height
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Star recess size
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Length and datum
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Material
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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
