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:Slotted Machine Screws
Materials:Steel
Surface treatment:Black Zinc Plated
Head Type:Cap Head
Drive:Slotted
Thread:Machine Thread
Point:Blunt
Forming:Single Die Heading
Size:M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M14
Number:342
We make slotted machine screws in black zinc plated steel, a cap head with a single slot across a flat top and a machine thread, quoting them from M1 to M14. Slot width, head height, thread and finish come from your drawing, and the first article is driven with your own blade.
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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.
Slotted machine screws are machine screws driven by a single straight slot, supplied here with a cap head in black zinc plated steel. The head is the tall cylindrical form normally used for a hexagon socket, but the top carries one slot instead of a pocket. The thread is a machine thread for a tapped hole or a nut, and the family is quoted from M1 to M14 with Number 342.
Cap head. A tall cylinder with a flat top and a full flat bearing face, made to be tightened and to seat in a counterbore.
Single slot. One straight slot across the top face, driven by a flat blade.
Machine thread. A rolled thread for a tapped hole or a nut, ending in a blunt chamfer.
Black zinc. A dark sacrificial zinc deposit, thin enough not to close the slot.
In use slotted machine screws with a cap head are specified where the top of the fixing has to stay clean and flat, and the drive is a blade on a bench rather than a key.
A hexagon socket cap screw has a deep little well in its head, and in most assemblies that well is harmless. In some it is not. It collects swarf on a machine tool, it holds liquid in a washdown area, it traps dust in a food zone, and it gives corrosion a sheltered place to start. A slotted machine screw in a cap head does not have that well: the top is a flat face with one slot, and everything that lands on it can be wiped off.
The height that would have carried a socket is still there, which is what makes the slot deep. A cheese head of the same thread has a shallower slot because the head is shorter; on this part the slot sits in a tall head and takes a blade properly, so the drive is better than a shallow slotted head and the head still seats on a full bearing face in a counterbore.
On slotted machine screws the trade is the drive itself. A slot takes high torque from a flat blade but gives no warning before it slips sideways, and the blade runs across the top face when it does. On a tall flat top that mark is visible and permanent, which is why the joint should be driven with the blade seated and, where the torque matters, with a setting rather than by hand.
On slotted machine screws the absence of a pocket is not only a cleaning argument. A flat top can be sealed against, wiped, or covered with a label that sits flat; a socket head has a hole in the middle of the same face. Where a cover, an inspection sticker or a tamper seal has to sit over the fixing, the flat head is the one that works.
Black zinc suits the part for the same reason — a thin coating that does not fill the slot and does not change the flat face. Where the joint is wet or washed, the same geometry in stainless is the answer, and the slot behaviour does not change.
The recorded range is M1 to M14, covering M1, M2, M3, M4, M5, M6, M7, M8, M9, M10 and M14. Custom lengths up to 2,000 mm are subject to DFM review after drawing submission. For slotted machine screws the quotation carries head diameter and height, slot width and depth, the thread and the finish, because the slot depth depends on the head height and the blade depends on the slot width.
| Item | How it is defined | What we control |
|---|---|---|
| Head | Cap head, flat top | Head diameter and height |
| Slot | Single slot across the top | Slot width, depth and burr |
| Thread | Machine thread | Pitch and length, gauged per batch |
| End | Blunt, chamfered | Chamfer cut, not deburred |
| Finish | Black zinc | Deposit thickness and adhesion |
| Length | Under the head | Measured on the shop plate |
Slot width should be matched to the blade that will actually be used. A slot that is slightly narrow binds the blade and lifts a burr at the ends; one that is slightly too wide lets the blade rock and rounds the slot floor. On a tall head there is depth to spare, so the width is the only real variable.
Head diameter and height follow the cap head form for the thread, so a counterbore cut to the standard will accept the part. Where the head is deliberately reduced, the slot depth comes down with it, and the advantage of this head over a cheese head disappears.
Three features define this part: the flat top, the slot and the cap head body. The first has nothing to trap, the second is a drive with real depth, and the third gives a full bearing face and a counterbore seat.
| Feature | What it gives | What it costs |
|---|---|---|
| Flat top, no pocket | Wipes clean, takes a seal or label | Nothing to grip if the slot fails |
| Deep slot in a tall head | Better drive than a shallow slotted head | Blade can slip sideways |
| Full bearing face | High preload in a counterbore | Needs a flat, square seat |
| Black zinc | Thin, dark, sacrificial | Wears at the slot edges |
| Machine thread | Repeatable clamp in a tapped hole | Needs a nut or a tapped hole |
On slotted machine screws the clean face is the reason to choose this over a socket head, and it is worth testing against the actual environment. On a machine tool with coolant and chips, a pocket fills in a week; on a food line it is a cleaning risk that a washdown procedure cannot reach. In both cases the flat top is the answer and the trade in drive quality is easy to accept.
On slotted machine screws the drive is not as poor as a slot on a short head. Because the head is tall, the slot has depth, so the blade is held over a useful length and the torque it takes is close to what the head can bear. What it does not have is the self-centring of a star or hexagon: the blade must be positioned, and the operator has to hold it down as well as turn.
The recorded finish is black zinc over carbon steel. On a flat top with a slot, the deposit is thin enough to leave the face and the slot as made, and dark enough to suit the equipment the part usually goes into. It is sacrificial, so a scratch across the face does not start rust the way it would on a barrier coating.
| Option | How it protects | Effect on slot and face | Typical use |
|---|---|---|---|
| Black zinc | Sacrificial zinc, dark | Thin; slot as plated | Dark equipment and covers |
| White zinc | Sacrificial zinc, trivalent | Thin; neutral tone | Indoor general work |
| Blue zinc | Sacrificial zinc | Thin; bright appearance | Cost-driven indoor |
| Black oxide | Conversion film, oiled | No measurable build | Internal mechanisms |
| Stainless, plain | Passive chromium oxide film | Slot as cut | Washdown and outdoor |
Where the reason for choosing the part is cleanliness, the finish matters for the same reason. A bright zinc in a washdown area produces white corrosion in the slot; a black zinc does the same in time; stainless does not, which is why the washdown version of this screw is the one that keeps its flat face and its open slot.
The coating also affects the slot edges, where the blade presses. A deposit that builds on the crest of the threads or the slot walls narrows the drive, so the slot is checked on the plated part rather than on the bare one.
Three assemblies where slotted machine screws are the fixing:
| Where it sits | The screw fixes a cover or a plate where chips and coolant reach the head and a socket would fill up and seize. |
| When it goes wrong | A filled socket will not take a key, and a rusted pocket has to be cleaned before the screw will move. |
| Why it happens | The head is exposed to swarf, the joint is serviced, and the face must be cleanable. |
| What we control | Slot depth and finish checked, first article driven with the production blade. |
| Where it sits | The screw closes a panel where the head sits in a counterbore and the cleaning routine cannot reach a deep recess. |
| When it goes wrong | A pocket in the head is a soil trap, and a rusting pocket contaminates the surface around it. |
| Why it happens | The joint is washed, the head is visible, and the material must not rust. |
| What we control | Stainless grade confirmed, slot and face checked, passivation inspected. |
| Where it sits | The screw fixes a cover where a seal, a sticker or an inspection label has to sit flat over the fixing. |
| When it goes wrong | A socket head breaks the seal at the recess, and a raised or slotted face disturbs the label. |
| Why it happens | The face must be flat, the seal is the function, and the fixing is set once. |
| What we control | Face flatness and slot checked, first article sealed in place. |
Four reasons that matter on a flat-faced slotted head, each tied to what the drawing has to prove:
|
Slot width and blade agreed
The slot width and the blade the customer uses are confirmed together, because the blade is the drive and a slot that binds or rocks damages a visible face. Basis: Slot width and blade agreed. |
Head, slot and thread in one route
The cap head and the slot are formed in the heading stroke, the thread is rolled and the parts are black zinc plated in the same route. Basis: One route from wire to plated screw. |
|
Face and slot checked on the plated part
The first article is checked for face flatness and slot depth after plating, because both decide whether the part wipes clean and drives properly. Basis: First article checked after plating. |
First article fixes the setting
The first article fixes the wire, the slot cutter and the plating; repeat orders are compared against that record. Basis: First article signed off before the batch is released. |
Shi Shi Tong forms these slotted machine screws from carbon steel wire on single-die headers that form the cap head and cut the slot in one stroke, rolls the machine thread to a blunt chamfered end and plates the parts in black zinc. The first part of every run is measured on the head and slot, driven with the production blade and entered into a thread gauge before the batch continues.
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A slot across a flat cap top is a simple cut and a visible one: the ends of the slot are open at the rim of the head, and a cutter that is slightly worn leaves a torn edge there. That edge catches the blade, marks the face and holds dirt, which is the opposite of what the part was chosen for.
What decides whether slotted machine screws pass is the slot, the face, the thread and the plate. The inspection agreement covers those, and the criteria come from the drawing.
Face and slot on the projector |
Thread gauged per batch |
Hardness checked on the wire |
Salt-spray testing of the plate |
On slotted machine screws the head is checked for diameter, height and face flatness, and the slot for width, depth and a clean edge at both ends. It is then driven with the production blade, because a slot that measures correctly can still catch a blade that is slightly worn.
The thread is gauged per batch and the plate is checked for thickness and adhesion, with attention to the slot walls and the top face. Where the part is chosen for cleanliness, the finish inside the slot is as important as the finish on the outside.
Every shipment of slotted 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 plating record is kept with the inspection file.
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 plating. The documents carry the drawing revision and the batch number, so a repeat order is made to the same slot width that was approved.
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 slotted part the first article is driven with the customer’s blade, because the blade is the drive. Buyers visit during the process to review samples and to see how the heads and slots 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 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 |
Because a slot leaves a flat top with no pocket. There is nothing to fill with swarf or liquid, and the face can be wiped, sealed or labelled.
It takes torque well because the slot is deep in a tall head, but it does not self-centre. The blade must be positioned and held down while turning.
It follows the head height. A cap head has the height to carry a full slot; a shorter head of the same thread would not.
The head needs a flat seat. A counterbore or a spot face is the usual way to provide one, and the cap head seats on the full bearing face.
No. Water sits in the slot and starts white corrosion. For washdown or outdoor work use the stainless version of the same screw.
Head diameter and height, slot width and depth, thread size and length, the finish, and the blade that will drive it.
How a slotted machine screw project runs from drawing to repeat delivery:
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1
Send the drawing and the blade you use
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→ |
2
Slot width, head height and thread agreed
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→ |
3
First article driven with your blade
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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 head diameter and height, the slot width, the thread size and length, the finish and any sealing or labelling requirement on the face.
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Head diameter
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Head height
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Slot width
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Thread size
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Length
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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
