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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:Hex Head Machine Screw
Materials:stainless steel
Surface treatment:plain
Head Type:hex head
Drive:Hex Head
Thread:Half Machine Thread
Point:Blunt
Forming:Single Die Heading
Size:M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M14
Number:462
We make hex head machine screws in passivated stainless with six flats, a full bearing face and a half machine thread, quoting them from M1 to M14. Across flats, face, thread run and grade come from your drawing, and the first article is turned with your spanner.
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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 hex head machine screw has six flats on the outside of its head and a machine thread for a tapped hole or a nut, and it is turned with a spanner rather than a driver. The recorded item is stainless with a plain finish, a hex head and a half machine thread, quoted from M1 to M14 with Number 462.
Hex head. Six flats with a flat bearing face underneath. The head is shallow for its diameter and the drive is the outside of it, so the torque arrives at the full radius rather than at a small recess.
Half machine thread. Thread from the point to a defined position, with a plain shank under the head. The plain length passes the top member of a stack without cutting it, and on a hex head it is also what lets the head sit down against a washer.
Stainless, plain. Passivated and uncoated, so the flats keep their corners and the bearing face is metal against metal, with no film to compress when the joint is tightened.
The case for a hex head over a socket head is the bearing face. Both drives can apply high torque, but the hex turns the outside of the head, so the head can be made with a full flat annulus underneath instead of a thin wall around a recess. On a soft panel, or on a joint that has to spread its clamp load, that annulus is the feature that matters.
The trade is clearance. A hex head needs room around it for the spanner, which a socket head does not, so a hex belongs where the head is out in the open and a socket belongs where it is recessed. On a joint that is packed with other parts, the hex is simply the wrong choice however strong it is.
The head height is shallow for its diameter, and that is deliberate: the load path from a spanner runs through the flats and down into the bearing face over a short distance, and extra height would add nothing but weight. What the shallow head does need is a partner that can take the load, which in practice is a washer on anything softer than steel.
The half thread is what lets the joint work properly. In a stack, the plain shank passes the upper member and the thread engages only below, so the head comes down onto its bearing surface without the thread cutting into anything on the way. On a hex head with a washer underneath, that is a clean path from spanner to panel.
Plain stainless is passivated after forming. There is no coating to be squeezed out at the bearing face or worn off the flats, and on a part that is turned with a spanner the flats are exactly where a plating would fail first.
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 hex head machine screws the across-flats dimension and the head height follow the standard named on the drawing, because the spanner has to match.
| Item | How it is defined | What we control |
|---|---|---|
| Head | Hex head, six flats | Across flats, height and face squareness |
| Thread | Machine thread, half length | Thread length and position from the end |
| Shank | Plain, under the head | Diameter and length |
| End | Blunt, chamfered | Chamfer cut, not deburred |
| Finish | Plain stainless, passivated | Surface condition and film |
| Length | From under the head to the end | Measured on the shop plate |
Across flats is quoted with the standard rather than chosen freely. A head that is a little under size still looks like a hex, and a spanner that is loose on it rounds the corners on the first pull; because there is no plating to hide the damage, the mark shows immediately.
Length is measured from under the head, because that face bears. On a half thread the thread length is quoted from the point as well, so a screw can be correct overall and still wrong if the thread starts a turn early and the plain shank no longer clears the top member.
Three features define this part: the hex flats, the bearing face and the half thread. The first gives high torque, the second spreads the load and the third lets the joint close without interference.
| Feature | What it gives | What it costs |
|---|---|---|
| Hex flats | High torque at the full head radius | Needs spanner clearance |
| Full bearing face | Load spread without a deep recess | A washer is still needed on soft material |
| Half thread | Plain shank passes the top member | Thread length must be specified |
| Shallow head | Low profile for a spanner drive | Less height for fingers or a second tool |
| Plain stainless | No coating to compress or wear | Galls against stainless |
The comparison that customers make is with a socket head cap screw. The socket can be recessed, which is why it wins inside machinery; the hex has the larger face and the spanner access, which is why it wins on structural and outdoor joints where a washer sits under the head and the fixing is out in the open.
The second comparison is with a hex bolt. A bolt is typically partially threaded and larger, and the difference that matters here is the thread run. A machine screw with a half thread and a blunt end is designed to run into a nut or a tapped part with a defined engagement, which is what makes it a screw rather than a stud with a head.
The recorded finish is plain, passivated stainless. Nothing is added, so the flats keep the corners the spanner loads and the bearing face stays flat, which on a joint without a washer is the difference between a load spread and a line of contact.
| Option | How it protects | Effect on flats and bearing face | Typical use |
|---|---|---|---|
| Stainless A2, plain | Passive chromium oxide film | None; gauged as formed | Outdoor and general joints |
| Stainless A4, plain | Passive film with molybdenum | None; gauged as formed | Coastal and washdown |
| Zinc plated steel | Sacrificial zinc | A few microns; flats re-checked | Indoor, cost-driven work |
| Black zinc on steel | Sacrificial zinc, dark passivation | A few microns; re-checked | Dark visible assemblies |
| Dacromet on steel | Zinc-aluminium flake layer | Film builds; flats re-checked | Outdoor steel structures |
Plating a hex head is a different problem from plating a recessed head. There is no socket to fill, but the coating rounds the corners of the flats, so a spanner that fitted before plating becomes a loose fit afterwards, and a loose spanner is what rounds a head. The first article is turned with the spanner after plating.
Stainless has the usual limit: it is resistant within the grade. A2 handles most weather inland; where chloride is present the grade is the answer rather than any coating, and the certificate is the only evidence the customer sees before the parts are in service.
Three assemblies where a hex head machine screw is the fixing:
| Where it sits | The screw clamps a bracket, a plate or a fitting where the joint carries a real load, the head is exposed, and the fixing is tightened with a spanner. |
| When it goes wrong | A recessed head cannot spread the load over the same area, and a plated head rusts at the flats within a season. |
| Why it happens | The joint is loaded, the head is visible, and the tool is a spanner. |
| What we control | Across flats and bearing face checked, thread gauged, grade confirmed on the certificate. |
| Where it sits | The screw holds a frame member or a guard where the head sits in the open against a washer and the joint is tightened to a value. |
| When it goes wrong | A loose spanner rounds the head, and a bearing face that is not square loads one side of the washer. |
| Why it happens | The joint has a torque value, the head is accessible, and the plant runs continuously. |
| What we control | Face squareness checked, thread gauged, first article turned with the spanner. |
| Where it sits | The screw joins a cover or a flange where the head is against a washer on a machined face and the joint has to be repeatable. |
| When it goes wrong | A head that is not square seats on one edge, and a thread that is short leaves the joint under-clamped. |
| Why it happens | The joint is machined, the head is accessible, and the torque is specified. |
| What we control | Bearing face and thread checked, length under the head matched to the stack. |
Four reasons that matter on a spanner-driven screw, each tied to what the drawing has to prove:
|
Flats, face and thread reviewed together
The across flats, the bearing face and the thread run are reviewed as one set, so a head that would take the spanner badly or a shank that would not clear the stack is raised before the die is cut. Basis: Flats, face and thread reviewed as one set. |
Heading, rolling and passivation in one route
The hex head is formed, the half thread is rolled and the parts are passivated in one route, so the flats and the shank stay concentric. Basis: One route from wire to passivated screw. |
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Spanner and thread tried on the part
The first article is turned with the spanner size and the thread is gauged, so both the drive and the fit are proved before the batch runs. Basis: First article turned with the spanner. |
First article fixes the setting
The first article fixes the wire heat, the die set and the passivation; repeat orders are compared against that record. Basis: First article signed off before the batch is released. |
Shi Shi Tong forms these hex head machine screws from stainless wire on single-die headers that upset the hex head, rolls the half thread to a blunt chamfered end and passivates the parts. The first part of every run is measured across the flats, turned with the spanner and entered into a thread gauge before the batch continues.
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The hex is formed in one blow, and the corners are what the die has to get right. A die that is slightly worn leaves corners that are rounded rather than sharp, and the across-flats measurement still reads correctly — the spanner is the only check that catches it, which is why the first article is spannered rather than measured alone.
What decides whether hex head machine screws pass is the flats, the bearing face, the shank, the thread and the alloy. The inspection agreement covers those, and the criteria come from the drawing.
Across flats and face squareness on the projector |
Thread gauged per batch |
Hardness checked on the formed head |
Salt-spray testing of the stainless grade |
The head is checked across flats at both ends and for face squareness. Squareness is the dimension that gets assumed: a head that is square on top and out at the face still sits crooked when the joint is tightened, and it loads one side of its washer.
The shank is measured where the drawing makes it functional, and the thread is gauged per batch with the thread start checked on the half thread. On a stainless part the surface is also inspected, because there is no coating to hide a tool mark or a rust bloom from free iron.
Every shipment of hex head machine screws is traceable to the wire it was made from and to the passivation 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 grade or the passivation. 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 hex head the first article is also turned with the customer’s spanner, because the fit is the function and a gauge cannot feel it. Buyers visit during the process to review samples and to see how the 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 headers and the passivation 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 |
The hex spreads the load over a full bearing face and needs spanner clearance around it. The socket is recessed and fits into tight assemblies.
On anything softer than steel, yes. The hex face is large for a screw but small for a soft panel, and a washer is what turns the load into a spread rather than a ring.
So the plain shank passes the top member of a stack without cutting it, and the thread engages only in the member below.
More than a cross recess and more than a small socket, because the drive is at the full head radius. The limit is the joint, not the head.
Yes. A coating rounds the corners of the flats, so the first article is turned with the spanner after plating.
Across flats and head height, the standard the head follows, thread size and length with the datum, overall length, and the stainless grade.
How a hex head machine screw project runs from drawing to repeat delivery:
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1
Send the drawing and the spanner size
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→ |
2
Flats, face and thread review
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→ |
3
First article turned with the spanner
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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 across flats and head height, the standard the head follows, the thread size and length with the datum, the overall length and the stainless grade.
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Across flats
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Head height
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Standard
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Thread and length
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Overall length
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Stainless grade
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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
