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:Button Torx SEMS screw, carbon steel 12.9, black oxide
Materials:Carbon steel (grade 12.9)
Surface treatment:Black oxide
Head Type:Button head
Drive type:Torx (internal)
Thread:Machine thread
Forming:Multi-station cold heading with captive washer
Number:1476
We manufacture button torx sems screws in carbon steel grade 12.9, black oxide finished, with a low button head, a Torx recess and a flat washer captured by the rolled thread, from M3 to M12. Head height, Torx size, washer fit, thread class and hardness are made to your drawing.
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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 button torx sems screw is a high-strength screw with three features combined: a low button head, a Torx recess, and a flat washer captured under the head by the rolled thread. The washer stays with the screw through kitting and assembly, and the button head keeps the profile low on the joint.
Button head. The button head has a shallow dome and a flat bearing face. It sits lower than a pan head of the same diameter, which matters on high-strength joints where the screw has to stay inside a counterbore or clear a moving part, while the flat face still spreads the clamp load over the washer.
Torx recess. A 12.9 screw is driven to a real torque, and the Torx recess is what carries that torque without camming out. Six flanks, a deep recess and a matching driver keep the recess intact on a screw that will be tightened to the top of its class.
Captive washer and black oxide. The washer is placed on the blank before thread rolling and the first crest locks it on, so no separate washer is handled at the line. Black oxide adds almost no thickness, which keeps the Torx recess and the thread at the dimensions the class needs.
Together these decide how the part behaves on site: the washer is always there, the driver reaches full torque, and the low head fits where a taller screw would not.
The washer is the feature that makes a button torx sems screw different from a plain socket screw. It sits under the button head, clears the thread but not the first rolled crest, and floats enough to align with the joint. A bore that is too tight seizes on the shank; one that is too loose drops the washer in the box.
Head height and Torx size are set together. A lower button head leaves less material over the recess, so the Torx punch is set to leave a full driving section under the dome without breaking through. On a 12.9 screw the head is the part that carries the clamp load, so the height cannot be reduced without checking the bearing face.
The black oxide is applied after heading and thread rolling, and it does not fill the recess. That is why a button torx sems screw can be tightened to its class torque without re-cutting the recess, and why the recess is checked with the matching bit rather than by eye.
Button torx sems screws are quoted from M3 to M12 and up to 200 mm, with length usually held to +/-0.1 mm on the drawing. Where a long version is required, custom lengths up to 2,000 mm are subject to DFM review after drawing submission.
| Item | How it is defined | What we control |
|---|---|---|
| Total length | From the top of the button head to the tip | Datum stated on the drawing; length measured on the shop plate |
| Head diameter and height | The button head and its bearing face | Head diameter and height held to the drawing |
| Washer diameter and thickness | The flat washer captured under the head | Washer O/D, bore and thickness checked on the first article |
| Torx recess size | The recess that takes the T driver | Recess checked with the matching bit |
| Thread class and material | The 12.9 thread that carries the joint | Thread gauged and hardness checked per batch |
Each diameter and length combination is checked against the drawing before a quotation is issued. On a 12.9 button torx sems screw the check also covers the washer bore and freedom, because a captive washer that cannot float will misalign the joint before the torque is reached.
Length is measured from the top of the head, and the thread length is read as a position from the same datum. Head height, recess size and thread class are gauged after black oxide, in the condition the customer assembles.
For a button torx sems screw the drawing fixes six things: thread size and pitch, thread length, total length and its datum, head diameter and height, Torx size, and washer dimensions. A seventh line matters on a 12.9 part: the tightening torque, because the joint is designed around the preload the screw can hold.
| Parameter | Why it matters on a 12.9 SEMS screw | What we control |
|---|---|---|
| Thread start position | It sets how much shank sits under the washer | Start dimension checked on the first article |
| Washer bore | It must clear the thread but not the first crest | Bore and washer freedom checked on the first article |
| Torx size | The driver has to reach class torque without cam-out | Recess checked with the matching Torx bit |
| Tightening torque | 12.9 joints are designed around preload | Recess and thread form checked against the joint |
Black oxide is a conversion coating, not a plated layer. On a 12.9 button torx sems screw that matters because a thick plating on a high-strength thread can cause hydrogen embrittlement, while black oxide changes the surface chemistry with almost no dimensional build-up and no plating bath.
| Finish | How it protects | Effect on thread and recess | Typical use |
|---|---|---|---|
| Black oxide | Conversion coating, minimal thickness | No measurable build-up; recess stays as formed | High-strength joints where black is acceptable |
| Black oxide plus oil | Conversion coating with a light oil film | No dimensional change; oil cleaned before use | Parts stored before assembly |
| Zinc flake (Dacromet) | Zinc-aluminium flake layer | Thin film; recess checked over the coating | High-strength parts in damp service |
| Zinc-nickel | Zinc alloy with higher corrosion resistance | Thicker film; embrittlement risk checked | High-strength parts requiring corrosion resistance |
| Zinc electroplated | Sacrificial zinc layer | Build-up on thread; embrittlement relief required | Lower-strength carbon steel parts |
Salt-spray exposure is agreed per project and written on the drawing; black oxide on its own gives limited protection and is usually specified with oil. For a 12.9 button torx sems screw the finish choice is reviewed with the torque and the environment together, because a coating that protects well but changes the thread fit can still fail the joint.
Packing protects the head and the washer. Screws are packed in layers with the heads up so the oxide is not rubbed through at the head edge, and the label carries the batch, material heat and finish.
Three assembly conditions where a button torx sems screw carries a high preload in a low profile, and what it has to do instead:
Power tools and portable equipment
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Power tools – low-head high-strength joints |
Electric motors and gearmotor frames
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Motors – SEMS screws on cast housings |
Hydraulic power units and pump skids
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Hydraulic units – SEMS screws under vibration |
Four reasons that matter specifically on a button torx sems screw, each tied to what the drawing has to prove:
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Engineering review before tooling
Head height, Torx size, washer bore and thread class are settled before a die is cut, so the first sample is measured against the drawing instead of against a guess. Basis: Drawing or sample reviewed before tooling is released. |
Washer captured on a multi-station header
The screw is headed on a multi-station header, the washer is placed on the blank, and the thread is rolled over it, so the washer cannot come off before assembly. Basis: Captive washer by the thread-rolling step. |
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Torx and washer checked on the part
The Torx recess is checked with the matching bit and the washer for capture and freedom, so the driver reaches torque and the washer still floats. Basis: Recess and washer checked on the first article. |
First article to repeat production
The first article fixes the drawing revision, material heat, washer lot and die set; repeat orders are compared against that record. Basis: First article signed off before the batch is released. |
These button torx sems screws are formed and assembled on a multi-station header. The button head and Torx recess are formed in the die, the washer is placed on the blank, the thread is rolled so the last crest captures the washer, and the parts are black-oxided and gauged. The operator checks the first parts against the drawing before the run is released.
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Between runs the die insert is changed to the drawing head form and Torx size, and the washer lot is checked before it goes into the feeder. The first parts go to the gauges before the run continues, and the setting is recorded so a repeat order can be compared with the approved sample.
What decides whether a button torx sems screw passes is not its appearance: it is the washer staying on and floating, the Torx recess taking the driver at class torque, and the 12.9 thread and hardness matching the drawing. The inspection agreement covers those, and the criteria come from the drawing.
Thread gauging against GO/NO-GO gauges |
Head and washer profile on the optical projector |
Hardness testing of the 12.9 material |
Salt-spray testing of the black oxide |
Each batch is recorded against the drawing revision: head and washer from the first article, the Torx recess checked with the bit, thread gauging per batch, and hardness on the 12.9 material. If a gauge or the washer check fails, the parts back to the last good setting are held and re-checked.
Where the material needs a third-party report, it is specified on the drawing and filed with the batch, so the label and the inspection record carry the same number.
Every button torx sems screw shipment is traceable to the wire it was made from and to the washer lot that went into it. The grade, heat number and standard are recorded on the material certificate, 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 finish. 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. Buyers visit during the process to review samples and to see the forming, thread rolling and finishing steps their parts will go through.
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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, the thread rolling and the black oxide 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 |
It is a screw with a low button head, a Torx recess and a flat washer captured under the head by the rolled thread. The washer stays with the screw, and the button head keeps a low profile on a high-strength joint.
Grade 12.9 is a high-strength quenched and tempered steel that holds a higher preload in the same thread size. The joint is designed around that preload, so the Torx recess and the thread have to carry the torque that comes with it.
The washer is placed on the blank before thread rolling and the last crest stands larger than the washer bore, so the washer floats but cannot come off.
Button torx sems screws are quoted from M3 to M12 and up to 200 mm, usually held to +/-0.1 mm. Where a long version is required, custom lengths up to 2,000 mm are subject to DFM review after drawing submission.
Black oxide changes the surface chemistry with almost no dimensional build-up, so the thread and recess stay as formed. On high-strength screws a thick plating also brings hydrogen embrittlement risk, which black oxide avoids.
Thread size and pitch, thread length, total length and datum, head diameter and height, Torx size, washer diameter, bore and thickness, material grade and hardness, finish, and tightening torque.
How a button torx sems screw project runs from drawing to repeat delivery:
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1
Send the drawing or sample
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2
DFM review and quotation
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3
First article approval
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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 button torx sems screw quotation, send the drawing with thread size and pitch, thread length, total length and datum, head diameter and height, Torx size, washer diameter, bore and thickness, material grade, finish and tightening torque.
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Thread size and pitch
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Thread and total length
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Head diameter and height
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Torx size
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Washer diameter, bore and thickness
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Grade, finish and torque
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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
