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:Knurled socket head cap carriage shoulder screws
Materials:Carbon steel
Surface treatment:Black oxide + locking patch (half circumference)
Head Type:Knurled cap head
Drive type:Hex socket (Allen)
Thread:Machine thread with locking patch
Forming:Multi-station cold heading with knurled head and square neck
Number:1734
We manufacture knurled socket head cap screws in carbon steel with a knurled cap head, a square neck, a shoulder and a half-circumference locking patch, black oxidized and made to drawing. Neck size, shoulder length, patch position and finish are settled before the batch runs.
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.
A knurled socket head cap screw is a cap head screw with a knurled band around the head and a hexagon socket in the top. The one on this page adds a square neck and a shoulder below the head, and carries a half-circumference locking patch on its thread, so it locates, resists rotation and resists loosening in one part.
Knurled cap head. The knurl gives the head a grip for fingers or a soft fixture and a finished edge that does not cut a hand. The hex socket is still the primary drive; the knurl is the second way to hold the screw when the key has to be kept free.
Square neck and shoulder. The square neck keys into a square hole in the panel, so the screw cannot turn while a nut is run down on the thread. The shoulder below it sets the stack height and locates the plate the screw passes through.
Half-circumference locking patch. A nylon patch is bonded to one half of the thread. The free half lets the screw start and run down without resistance, and the patch fills the thread clearance on the engaged side to resist vibration loosening.
Together these decide the joint: the square neck keys, the shoulder locates, the patch holds, and the knurled head gives a place to hold the screw while it is assembled.
This screw is formed from carbon steel wire on a multi-station header, thread rolled, patched and black oxidized. The grade comes from the drawing, and the wire heat number stays traceable to the material certificate.
The knurled cap head is formed in the die, with the knurl and the hex socket struck in the same operation. The square neck is produced under the head, and the shoulder behind it sets the length that passes through the panel.
The thread is rolled before the patch is applied. The locking patch is a nylon plug bonded to half the circumference over a defined length, and its position on the thread is as important as its size: too close to the tip and it is damaged at start, too far and it does not engage the nut.
Black oxide is a conversion coating, not a plated layer. It adds no measurable thickness, so the knurl and the thread keep the dimensions they had before finishing, and the oil film that follows the oxide gives the black parts their colour.
Screws of this type are quoted from M5 to M12 and in lengths to suit the drawing, with the head, the square neck and the shoulder 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 and height | The knurled cap head | Measured across the knurl on the first article |
| Knurl | Pitch and depth around the head | Checked on the projector and against the sample |
| Square neck | The neck that keys into the square hole | Checked with the mating hole on the first article |
| Shoulder | The length that passes through the panel | Measured from the head face |
| Thread and patch | Machine thread and patch position | Gauged and patch-checked per batch |
| 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 panel it passes through. The square hole, the neck across flats and the shoulder length are reviewed together, because a neck that is right for one panel rattles in another.
Head diameter is measured across the knurl ridges, and the total length from the top of the head. The batch is checked on the features the process can drift on: knurl diameter, neck size and patch position.
The square neck is the feature that makes a knurled socket head cap screw behave like a carriage screw. It sits in a square hole in the panel, so the screw is held against rotation while the nut is tightened from the other side. The across-flats of the neck and the square hole are a pair, and the first article is checked in the actual hole.
The shoulder sets the stack. It runs through the panel and stops at the neck, so the plate is located at a fixed height. A shoulder that is too long leaves the neck standing off the panel; one that is too short lets the panel move under the head.
The locking patch is bonded to half the thread circumference. The free half is what lets the screw start by hand or by key without the patch dragging on the first turns, and the patched half does the work once the nut is on. Patch length and position are on the drawing and checked on the first article.
Black oxide keeps these features as they were made. Because the coating adds no measurable thickness, the neck still fits its hole and the patch still sits in the thread clearance after finishing.
This knurled socket head cap screw is black oxidized and lightly oiled. The oxide is a conversion layer on the carbon steel, so it does not build on the knurl or change the thread, and the oil film that follows it is part of the finish rather than a separate coating.
| Finish | How it protects | Effect on knurl and thread | Typical use |
|---|---|---|---|
| Black oxide | Conversion coating, minimal thickness | No measurable build-up; patch position unchanged | Indoor equipment and fixtures |
| 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 corrosion 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 part sees condensation or wash-down, a zinc or flake coating is specified instead, and the thread is gauged after that coating.
Packing protects the knurl and the patch. Screws are packed so the heads do not rub and the patches are not crushed against each other, and the label carries the batch, the wire heat and the finish reference.
Three assemblies where knurled socket head cap screws are chosen to key, locate and resist vibration, and what the screw has to do instead:
| Where it sits | The screw passes through a plate into a nut, and the square neck keys in the plate so the screw does not turn during tightening. |
| When it goes wrong | A neck that is loose in the square hole lets the screw spin, and a shoulder that is too long holds the plate off its datum. |
| Why it happens | The plate is set to a datum, the screw is assembled from one side, and the joint sees vibration. |
| What we control | Square neck checked against the hole, shoulder length measured, and the patch inspected per batch. |
| Where it sits | The screw holds a bracket or a panel where the head is visible and a knurled cap gives a finished look. |
| When it goes wrong | A knurl that is too coarse marks the hand, and a patch that is in the wrong place makes the screw hard to start. |
| Why it happens | The parts are assembled on a line, the heads are visible, and the joint is not re-opened often. |
| What we control | Knurl and head checked, patch position measured, and the thread gauged after finishing. |
| Where it sits | The screw holds a cover or a mount on a machine that runs continuously, where a plain thread would work loose. |
| When it goes wrong | A patch that is too short loses its grip after a few cycles, and a black oxide part that sees condensation rusts at the knurl. |
| Why it happens | The machine vibrates, the joint is assembled once, and the parts are indoors. |
| What we control | Patch length and position checked, and the finish agreed for the environment. |
Four reasons that matter on a knurled socket head cap screw with a square neck and a locking patch, each tied to what the drawing has to prove:
|
Neck, shoulder and patch reviewed together
The square neck, the shoulder length and the patch position are reviewed before the die is cut, so a screw that would spin in its hole or seize on start is raised first. Basis: Neck, shoulder and patch reviewed before tooling. |
Headed, knurled and patched in one route
The knurled head, the square neck and the thread are produced in one heading route, and the patch is applied in a controlled position, so the features stay on the same axis. Basis: One route for head, neck and patch. |
|
Neck and patch checked on the part
The neck is checked against the mating square hole, the knurl on the projector and the patch position on the first article and per batch. Basis: Neck, knurl and patch checked in the finished condition. |
First article to repeat production
The first article fixes the drawing revision, wire heat, die set and patch batch; repeat orders are compared against that record. Basis: First article signed off before the batch is released. |
Shi Shi Tong forms these screws on a multi-station header: the knurled head and the hex socket are struck in the die, the square neck and shoulder are produced behind the head, the thread is rolled, the locking patch is applied, and the parts are black oxidized. The first part of every run is checked on the head, in the square hole and on the thread before the batch continues.
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Between runs the die insert is changed to the drawing head and the socket punch to the key size, and the neck tool is set with the shoulder length; the first part goes to the projector and the gauges before the run continues. The patch is applied in a controlled step and its position is recorded with the batch.
What decides whether a knurled socket head cap screw passes is not only the thread: it is the knurled head, the hex socket, the square neck, the shoulder length and the position of the locking patch. The inspection agreement covers those, and the criteria come from the drawing and the mating hole.
Thread gauging and patch area checked |
Knurl, neck and shoulder 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 neck from the first article, the neck tried in the square hole, the patch position checked, and the thread gauged. If a gauge or the neck check fails, the parts back to the last good setting are held and re-checked.
A third-party test report, where the drawing calls for one, travels with the shipment and is filed under the same batch number as the inspection record.
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. Parts with a square neck are approved with the mating hole, and parts with a patch are approved with the nut, so the neck and the patch are signed off as pairs. Buyers visit during the process to review samples and to see how the heads and patches are produced.
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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 header, the patch station 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 cap head screw with a knurled band around the head and a hex socket in the top. This one adds a square neck, a shoulder and a half-circumference locking patch on the thread.
It keys into a square hole in the panel so the screw cannot turn while a nut is run down from the other side. The across-flats of the neck and the square hole are matched as a pair.
A nylon patch is bonded to half the thread circumference. The free half lets the screw start and run down, and the patched half fills the thread clearance once the nut is on, resisting vibration loosening.
Screws of this type are quoted from M5 to M12 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 square neck and the thread keep the dimensions they had before finishing. A zinc coating would build and the thread would be gauged after plating.
Head diameter and height, knurl pitch, hex socket size and depth, square neck across flats, shoulder length, thread size and length, patch position and length, total length and datum, material and finish.
How a project runs from drawing to repeat delivery:
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1
Send the drawing or sample
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→ |
2
Neck and patch 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 knurled socket head cap screw quotation, send the drawing with the head diameter and height, knurl pitch, hex socket size and depth, square neck across flats, shoulder length, thread size and length, patch position and length, total length and datum, material and finish.
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Head diameter and knurl
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Socket size and depth
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Square neck across flats
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Shoulder length
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Thread and patch
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Material and 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
