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:Big cylinder cap head screw (large-deformation heading)
Materials:Carbon steel
Surface treatment:Black oxide
Head Type:Cap head
Drive type:None (no slot; per drawing)
Thread:Machine thread
Forming:Large-deformation cold heading
Number:1739
We manufacture big cylinder head cap screws in carbon steel with a plain cylindrical head and a thin machine thread, formed by large-deformation heading, black oxidized and made to drawing. Head diameter and fillet, thread class, finish and the fixture used to turn the head are settled before the batch runs.
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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 big cylinder head cap screw is a large-diameter screw with a plain cylindrical head and a machine thread, formed by heading rather than cut from bar. The one on this page is carbon steel, black oxidized, with no slot in the head and a relatively thin thread on a large body.
Large-diameter body. The shank and head are sized for a joint that carries load or fills a large hole, so the wire and the press are bigger than for a standard screw. The head volume is what decides whether the part can be headed at all.
Plain cylindrical head. The head is a smooth cylinder with no slot or socket. It is turned with a strap wrench or a special fixture that grips the head diameter, and the drawing states which method the assembly uses.
Thin thread on a big body. The thread is smaller relative to the head than on a standard cap screw, because the joint is a clamp rather than a structural bolt. The thread is rolled after heading, and its class is read on the finished part.
Together these decide the joint: the head bears on the frame, the thin thread pulls the parts together, and the smooth head gives the assembly a clean face.
This screw is formed from carbon steel wire by large-deformation heading, then thread rolled and black oxidized. The grade comes from the drawing, and the wire heat number stays traceable to the material certificate.
Large-deformation heading upsets a large head from a smaller wire section in one press cycle. The grain flow follows the head and the fillet under it instead of being cut across, which is why a headed big screw is stronger at the head-to-shank transition than a machined one.
The head is a plain cylinder. Its diameter and height are held to the drawing, and the face is left smooth because it is the surface that shows on the frame or the cabinet. There is no recess to form, so the heading die is simpler than a socket tool but the press load is higher.
The thread is rolled after heading. Black oxide is a conversion coating on the carbon steel: it adds no measurable thickness, so the thread and the head keep the dimensions they had before finishing, and the oil film that follows gives the parts their black colour.
Big cylinder head cap screws of this type are quoted from M10 to M24 and in lengths to suit the drawing, with the head measured on the projector and the thread gauged. 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 |
|---|---|---|
| Head diameter | The cylinder that bears on the frame | Measured on the first article and on the projector |
| Head height | The height above the bearing face | Checked against the drawing |
| Head face | The smooth face that shows | Checked for marks and flatness |
| Thread size and length | Machine thread to the drawing | Gauged per batch |
| Fillet under the head | The radius where the shank meets the head | Checked on the projector |
| Total length | From the top of the head to the tip | Datum stated on the drawing; measured on the shop plate |
Each size is quoted against the joint it closes. The head diameter, the bearing face and the thread are reviewed together, because a big head on a thin frame spreads the load while the same head on a small boss may not seat.
Head height is measured from the bearing face, and the total length from the top of the head. The batch is checked on the features the process can drift on: head diameter, fillet and thread class.
The head of a big cylinder head cap screw has no slot and no socket, so the drive is not built into the part. That is a deliberate choice on large screws: a recess big enough for the torque would remove a lot of material from the head, and a smooth cylinder gives a clean face where the screw is visible.
The part is turned with a strap wrench, a split clamp or a special fixture that grips the head diameter. The drawing states the method and the head diameter it grips, and the first article is assembled with the fixture before the batch is released.
The head face and the bearing face are both checked. The face that shows has to be free of press marks, and the bearing face has to be flat enough to seat on the frame without rocking; on a big screw a rock shows as a gap and a loose joint.
The fillet under the head is the other feature that matters. Large-deformation heading leaves a generous grain flow there, and the drawing sets the radius; a sharp corner would concentrate the clamp load at the edge of the head.
This cylinder head cap screw is black oxidized and lightly oiled. The oxide is a conversion layer on the carbon steel, so it does not change the head diameter or the thread, and the black colour is consistent across the batch once the oil film is applied.
| Finish | How it protects | Effect on head and thread | Typical use |
|---|---|---|---|
| Black oxide | Conversion coating, minimal thickness | No measurable build-up | Indoor frames and cabinets |
| Zinc plated | Sacrificial zinc layer | Build-up on thread; gauged after | Indoor parts where rust resistance matters |
| Dacromet flake | Zinc-aluminium flake layer | Thin film; thread checked over coating | Outdoor and wet assemblies |
| Black zinc | Zinc layer with black passivation | Build-up on thread; gauged after | Black parts that need more protection |
| Plain stainless (equivalent part) | Alloy resists corrosion | No coating build-up | Wash-down and marine service |
Salt-spray exposure is agreed per project and written on the drawing. Black oxide on carbon steel is an indoor finish; where the frame is outside or washed down, a zinc or flake coating is specified instead and the thread is gauged after that coating.
Packing protects the head face. Big screws are packed so the heads do not knock against each other, and the label carries the batch, the wire heat and the finish reference.
Three assemblies where big cylinder head cap screws are chosen for the load and the clean head, and what the screw has to do instead:
| Where it sits | The screw pulls a plate or a leg onto a frame, where the head bears on a machined pad and the face is visible. |
| When it goes wrong | A head that is not flat rocks on the pad, and a fillet that is too sharp cracks under the clamp load. |
| Why it happens | The frame is heavy, the joint is tightened once, and the head face is part of the machine’s finish. |
| What we control | Head diameter, face flatness and fillet checked, and the thread gauged per batch. |
| Where it sits | The screw closes a heavy door or a panel where a large head spreads the load and no recess is wanted on the face. |
| When it goes wrong | A head that stands proud catches a door, and a black oxide part that sees condensation rusts at the face. |
| Why it happens | The cabinet is indoors, the screws are visible, and the joint is assembled once. |
| What we control | Head height and face checked, and the finish agreed for the environment. |
| Where it sits | The screw holds a mount or a base plate where the joint sees vibration and the head has to bear evenly. |
| When it goes wrong | A head that does not seat evenly works loose, and a thread that is out of class lets the mount move. |
| Why it happens | The mount is heavy, the joint vibrates, and the screw is turned with a fixture on the head. |
| What we control | Bearing face and fillet checked, the thread gauged, and the first article assembled with the fixture. |
Four reasons that matter on a big cylinder head cap screw formed by large-deformation heading, each tied to what the drawing has to prove:
|
Head volume and fillet reviewed first
The head volume, the press load, the fillet and the thread class are reviewed before the die is cut, so a part that cannot be headed or would crack at the fillet is raised first. Basis: Head volume and fillet reviewed before tooling. |
Headed, threaded and finished in one flow
The big head is upset by large-deformation heading, the thread is rolled, and the parts go to blackening as a batch, so the grain flow and the thread come from the same run. Basis: Heading and finishing recorded per batch. |
|
Head and thread checked on the part
The head diameter, face and fillet are checked on the projector and the thread is gauged, on the first article and per batch. Basis: Head and thread checked on the first article. |
First article to repeat production
The first article fixes the drawing revision, wire heat, die set and finish batch; repeat orders are compared against that record. Basis: First article signed off before the batch is released. |
Shi Shi Tong forms these big cylinder head cap screws by large-deformation heading: the wire is cut and the large head is upset to the drawing diameter and height, the fillet is formed in the die, the thread is rolled, and the parts are black oxidized. The first part of every run is measured on the head and gauged on the thread before the batch continues.
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Between runs the die insert is changed to the drawing head and the thread rolls to the size; the first part goes to the projector and the gauges before the run continues, and the setting is recorded. The head face is protected through finishing and packing so the visible surface arrives unmarked.
What decides whether a big cylinder head cap screw passes is not only the thread: it is the head diameter, the head height, the face and the fillet under the head, and then the thread class. The inspection agreement covers those, and the criteria come from the drawing.
Thread gauging against GO/NO-GO gauges |
Head, face and fillet on the projector |
Hardness testing where the drawing requires it |
Salt-spray testing of the agreed finish |
Each batch is recorded against the drawing revision: head and fillet from the first article, the face checked for marks, and the thread gauged per batch. If a gauge or the head check fails, the parts back to the last good setting are held and re-checked.
If the finish needs an independent report, it is planned with the batch so the paperwork and the parts ship together under one batch number.
Every shipment is traceable to the wire it was made from. The grade, heat number and standard 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 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. Big screws are approved with the head face and the fillet measured, because both show on the finished machine. Buyers visit during the process to review samples and to see how the big heads are formed.
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8,678+
customers served
|
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 heading press and the blackening 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 large-diameter screw with a plain cylindrical head and a machine thread, formed by large-deformation heading. This one is carbon steel, black oxidized, with no slot in the head.
With a strap wrench, a split clamp or a special fixture that grips the head diameter. The drawing states the method and the diameter it grips, and the first article is assembled with that fixture.
Large-deformation heading makes the grain flow follow the head and the fillet under it, instead of cutting across it as a machined part would. That is stronger at the head-to-shank transition and avoids wasting bar.
Big cylinder head cap screws of this type are quoted from M10 to M24 and in lengths to suit the drawing. Where a long version is required, custom lengths up to 2,000 mm are subject to DFM review after drawing submission.
No. Black oxide is a conversion coating that adds no measurable thickness, so the head diameter and the thread keep the dimensions they had before finishing.
Head diameter and height, the face finish, the fillet under the head, thread size and length, total length and datum, material, finish and the fixture used to turn the head.
How a big cylinder head cap screw project runs from drawing to repeat delivery:
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1
Send the drawing or sample
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→ |
2
Head volume and fillet review
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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 big cylinder head cap screw quotation, send the drawing with the head diameter and height, the face finish, the fillet under the head, thread size and length, total length and datum, material, finish, and the fixture used to turn the head.
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Head diameter and height
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Face finish
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Fillet under the head
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Thread size and length
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Total length and datum
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Material, finish and fixture
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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
