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 Head Machine Screw
Materials:Stainless Steel
Surface treatment:Plain
Head Type:Pan 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:127
We make slotted head machine screws in passivated stainless with a pan head, a single slot and a machine thread, quoting them from M1 to M14. Slot width and depth, head, thread and grade come from your drawing, and the first article is turned with your own blade.
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 slotted head machine screw is a machine screw with a single straight slot across the head, driven with a flat blade and threaded for a tapped hole or a nut. The recorded item on this page is stainless with a plain finish, a pan head and a machine thread, quoted from M1 to M14 with Number 127.
Single slot. One straight groove milled across the top of the head, with parallel walls and a flat floor. The blade bears on the two walls, and the torque the screw will take is set by the width and depth of the slot.
Pan head. A low dome on a flat bearing face, following the DIN pan head form. The dome gives the slot its depth, and the flat face bears on the part without a washer.
Machine thread. A rolled thread with a blunt chamfered end, made to run into an existing thread rather than to form one. It can be taken out and put back without cutting into the part.
Stainless, plain. Passivated and uncoated, so the alloy is the whole of the protection and the slot is exactly as milled.
A slotted head machine screw transmits torque through two parallel walls. The blade sits in the slot and presses on both walls; there is no taper and no self-centring feature, which is why a slot needs the operator to align the blade rather than the driver finding the recess for itself. That is slower, and it is also why a slot works with a coin, a knife, a rule or a screwdriver.
The slot dimensions are what decide whether the joint can be tightened. Width sets what blade will fit, depth sets how much of the blade is engaged, and length sets how far the blade can travel sideways before it climbs out. A slot that is deep but narrow takes a thin blade and carries little torque; one that is wide but shallow lets a wide blade engage only a fraction of its thickness.
The ends of the slot are the weak point. Where the slot runs out at each end there is a small radius or a sharp corner, and that is where a blade that is slightly too thick or slightly misaligned starts a burr. On stainless the burr rolls rather than breaks, and a rolled burr at the slot end closes the opening enough to stop the blade the next time.
The pan head is the right carrier for a slot. A low or wafer head would not have the depth to make a slot that carries torque, and a countersunk head would leave the slot at the very top of a shallow cone. The dome of a pan head gives the material, and the flat face gives the bearing.
Plain stainless is passivated after the slot is cut. Passivation removes the free iron the cutter leaves in the slot walls and lets the oxide film rebuild, which matters because the slot is the one place on the screw that is handled by a tool on every assembly.
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 slotted head machine screws the slot width and depth are quoted with the head, because the blade is the specification.
| Item | How it is defined | What we control |
|---|---|---|
| Head | Pan head, flat bearing face | Diameter, height and face flatness |
| Slot | Single straight slot | Width, depth and burr-free ends |
| Thread | Machine thread | Pitch and length, gauged per batch |
| 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 |
Slot width is quoted in the drawing rather than assumed from a table, because the blade the customer uses is the real specification. A slot that is a few hundredths narrow refuses a worn blade; one that is a few hundredths wide lets the blade rock, and a rocking blade rounds the slot walls instead of turning the screw.
Length is measured from under the head, because that face bears on the part. On a pan head the head height adds to the overall length, so a screw quoted into a counterbore has to allow for it or the face will never touch.
Three features define this part: the slot, the pan head and the stainless body. The first is the drive and its limits, the second is the bearing area, and the third is why the part can be opened year after year without a coating to fail.
| Drive | Tool needed | Torque it carries | Where it is right |
|---|---|---|---|
| Single slot | Any flat blade, coin or rule | Limited by slot depth | Service with whatever tool is at hand |
| Cross recess | Phillips bit | Medium, cams out early | Volume assembly |
| Hex socket | Hex key | High | Machine and fixture work |
| Torx | Star bit | High without cam-out | Powered assembly |
The slot is the one drive that a person without tools can usually open. A coin, the back of a knife, a steel rule: all of them fit a slot well enough to loosen a screw that is only lightly tightened, and that is the reason the form survives in equipment that is serviced in the field. It is also why a slot is a poor choice for anything that must be tight, because the same openness lets a blade that is too small round the walls.
The second reason is torque limitation. A slot cannot deliver what a socket can, and on a stainless joint going into an aluminium or plastic part that limit protects the part. Where the customer wants the fixing to be opened but not over-driven, a slotted head machine screw does that without any extra feature.
The recorded finish is plain, passivated stainless. Nothing is added, so the slot is as milled and the walls keep their edges, which is what the grip of the blade depends on.
| Option | How it protects | Effect on slot and thread | Typical use |
|---|---|---|---|
| Stainless A2, plain | Passive chromium oxide film | None; gauged as milled | General fitting and service covers |
| Stainless A4, plain | Passive film with molybdenum | None; gauged as milled | Coastal and washdown |
| Brass, plain | Natural oxide, conductive | None; gauged as machined | Electrical and decorative work |
| Nickel plated steel | Hard barrier deposit | A few microns; slot re-checked | Visible decorative fixings |
| Zinc plated steel | Sacrificial zinc | A few microns; slot re-checked | Indoor, cost-driven work |
On a slotted head the coating is judged at the slot, because that is where the blade rubs. A plated slot loses its coating on the first few turns and then shows a bright line along both walls; a plain stainless slot keeps its appearance but galls more easily, and a stainless screw in a stainless part can seize in the slot so that the blade turns a burr rather than the screw.
The stainless choice pays off where the joint is opened repeatedly in a damp place. There is no coating to chip into the mechanism and nothing to rust at the slot walls, which is the failure that ends most plated slotted screws in service.
Three assemblies where a slotted head machine screw is the fixing:
| Where it sits | The screw holds a cover or a panel that is opened by an engineer who may not carry a tool kit, where the joint is finger-tight plus a little and the head is visible. |
| When it goes wrong | A cross recess needs a bit that is never where it should be, and an over-tightened screw strips the insert in the first week. |
| Why it happens | The joint is serviced often, the torque is low, and no tool is guaranteed. |
| What we control | Slot width and depth checked, blade tried on the first article, thread gauged. |
| Where it sits | The screw clamps a terminal or a plate where the fixing is opened for wiring changes and a flat blade is the tool everyone has. |
| When it goes wrong | A slotted screw driven with a blade that is too small rounds the walls and leaves the terminal loose. |
| Why it happens | The joint is wired on site, the torque is modest, and the head is accessible. |
| What we control | Slot width held to the blade, thread gauged, parts checked for burrs at the slot ends. |
| Where it sits | The screw replaces a fastener in equipment that has to be opened in the field with improvised tools, where a coating would fail and a special bit would stop the repair. |
| When it goes wrong | A plated screw rusts at the slot and a star-drive screw cannot be opened without its bit. |
| Why it happens | The equipment is old, the service is improvised, and the fixing is small. |
| What we control | Plain stainless confirmed, slot and thread checked, parts packed dry. |
Four reasons that matter on a slotted head, each tied to what the drawing has to prove:
|
Slot and blade reviewed together
The slot width, depth and the blade the customer uses are reviewed as one set, so a slot that would refuse their screwdriver is raised before the die is cut. Basis: Slot and blade reviewed as one set. |
Heading, slotting and threading in one route
The pan head is formed, the slot is milled and the thread is produced in one route, so the slot stays centred on the shank. Basis: One route from wire to passivated screw. |
|
Slot checked and tried with a blade
The slot is measured for width and depth and tried with a blade of the drawing width, because a burr at the slot end will refuse a blade the gauge accepts. Basis: Slot tried with a blade on the first article. |
First article fixes the setting
The first article fixes the wire heat, the slot cutter, the roll 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 slotted head machine screws from stainless wire on single-die headers that form the pan head, cuts the slot across the top, rolls the machine thread to a blunt chamfered end and passivates the parts. The first part of every run is measured on the head and slot, tried with a blade of the production width and entered into a thread gauge before the batch continues.
|
|
Cutting the slot in stainless is the operation that decides the part. The cutter work-hardens the walls as it cuts, and a tool that is slightly dull pushes a burr to the ends of the slot instead of shearing it; that burr survives the wash and closes the slot at one end. The slot is checked with a blade after deburring as well as after cutting.
What decides whether slotted head machine screws pass is the slot, the head, the thread and the alloy. The inspection agreement covers those, and the criteria come from the drawing.
Slot width and depth on the projector |
Thread gauged per batch |
Hardness checked on the formed head |
Salt-spray testing of the stainless grade |
The slot is measured for width, depth and position on the projector and then tried with a blade. The blade is the check that catches the burr, and the burr is the defect that comes back from a customer rather than from a gauge: on stainless it rolls into the opening instead of breaking away.
The head is checked for diameter, height and face flatness, and the thread is gauged per batch. On a stainless part the hardness is also read, because the alloy and temper decide how much torque the slot walls will take before they deform.
Every shipment of slotted 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 slotted head the first article is also turned with the customer’s own blade, because the slot is judged by the tool that will use it. Buyers visit during the process to review samples and to see how the heads and slots are produced.
|
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 slotting operation 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 it can be opened with whatever flat blade is at hand, and because it limits the torque. That suits service covers and terminals and rules it out for anything that has to be tight.
The one whose width and thickness match the slot on the drawing. A blade that is too thin loads the slot ends; one that is too thick will not enter.
The walls can be rounded by a blade that rocks. A slot carries less torque than a socket, so the joint is designed for that rather than driven harder.
Yes. A pan head gives enough depth for a slot that holds torque; a low or countersunk head leaves a slot that is shallow and easy to damage.
So the slot does not rust and the part can be opened long after installation. There is no coating to chip at the walls or into the mechanism.
Head diameter and height, slot width and depth, thread size and length with the datum, overall length, and the stainless grade.
How a slotted head machine screw project runs from drawing to repeat delivery:
|
1
Send the drawing and the blade you use
|
→ |
2
Slot, head and thread review
|
→ |
3
First article turned with the blade
|
→ |
4
Batch production and repeat orders
|
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 and depth, the thread size and length with the datum, the overall length, and the stainless grade.
|
Head diameter
|
Head height
|
Slot width
|
|
Slot depth
|
Thread and length
|
Stainless grade
|
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
