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:Stainless cap head screw, slotted (turned)
Materials:Stainless steel
Surface treatment:Passivation
Head Type:Cap head
Drive type:Slotted
Thread:Machine thread
Forming:CNC turning (bar stock)
Number:1818
We manufacture small stainless cap head screws with a single slot, turned from bar and passivated, from M1.4 to M12 with length quoted per drawing. Head diameter, slot width, thread start and material grade are made to your drawing, and the slot is checked with the driver that will turn it.
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 stainless cap head screw is a small machine screw with a cylindrical head, a flat top and a single slot for a flat driver. In the sizes this page covers the screw is a few millimetres across, so the head, the slot and the thread are all produced on a lathe and the tolerances are read on a projector rather than with a caliper.
Cap head on a small part. The cylindrical head gives a taller driving face than a pan or cheese head of the same thread, which matters when the screw is turned with a small driver and the slot is only a fraction of a millimetre wide. The head also gives a flat bearing face that sits on a bracket or a board without digging in.
Single slot, small driver. A slotted drive is chosen where the screw has to be turned with a flat driver that is already in the service kit, and where the head must stay low. On a tiny screw the slot depth is the critical dimension: too shallow and the driver slips, too deep and the head splits under torque.
Passivated stainless. The screw is supplied with the metal as the finish and passivated so the surface is clean and the passive film is restored after machining. There is no plating to build up the thread or fill the slot, which is what keeps a small screw usable after it has been handled and stored.
Together these decide how the part behaves on site: it sits flat on a small bracket, it can be driven with the tool on the bench, and it does not rust in a damp instrument housing.
These screws are turned from stainless bar, not headed. Bar is cut to length and machined on a CNC lathe: the cap head, the slot, the shank and the thread relief are cut in one setup sequence, so the head and shank stay concentric and the slot is centred on the head instead of being stamped in afterwards.
A tiny cap head with a slot is difficult to head in a die, because the punch has to form a narrow slot in a head only a few tenths of a millimetre thick while the body is being upset. Turning removes that limit: the slot is cut with a slitting saw or a milling step that reaches the face squarely, and the head diameter is turned rather than extruded.
On parts this small, deburring is the step that decides whether the batch is usable. A burr at the slot edge stops the driver seating; a burr at the thread start cross-threads the first engagement. The screws are deburred after turning, cleaned, passivated and then checked on the projector before packing.
Stainless cap head screws are quoted from M1.4 to M12, with the small sizes down to M1.4 and M2 produced as turned parts. Length is quoted per part against the drawing; where a long version of the same screw 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 |
|---|---|---|
| Total length | From the top face of the cap head to the tip | Datum stated on the drawing; length measured under the projector |
| Head diameter and height | The cap head that carries the drive | Head diameter and height turned to the drawing |
| Slot width and depth | The flat-driver recess across the head | Slot cut to the driver width and checked with it |
| Thread length and position | Where the thread starts and how far it runs | Thread start taken from the drawing, not a sample |
| Thread size and pitch | The metric thread called out on the drawing | GO/NO-GO gauging on the thread, per batch |
Each diameter and length combination is checked against the drawing before a quotation is issued. At these sizes the part is measured on an optical projector rather than with hand tools, because a slot depth or a head height of a few tenths cannot be read reliably from a caliper.
Length is measured from the top face of the head, and the slot width is read at the same time. Head diameter, slot depth and thread start are gauged on the first article before a batch is released, because those three dimensions decide whether the driver seats and whether the thread engages.
For a stainless cap head screw the drawing fixes five things: thread size and pitch, thread length and position, total length and its datum, head diameter and height, and the slot width. A sixth line matters on stainless: the grade and the surface condition the parts are supplied in.
| Parameter | Why it matters on a small screw | What we control |
|---|---|---|
| Thread start position | It sets how much plain shank sits under the head | Start dimension checked on the first article and per batch |
| Engaging length | Too short leaves the joint weak; too long runs the thread through a thin bracket | Thread length taken from the drawing |
| Slot width and depth | The driver must seat without slipping or splitting the head | Slot cut to the driver width and checked with it |
| Handedness | A left-hand thread on a right-hand assembly will not pull the joint closed | Direction marked on the part and on the packing |
A stainless cap head screw is supplied with the metal as the finish, passivated after machining so the passive film is restored and free iron from tooling is removed. On a small screw the surface is most of the part, so finish and cleanliness are checked as carefully as the dimensions: a burr or a residue in the slot is a functional defect, not a cosmetic one.
| Finish | How it protects | Effect on slot and thread | Typical use |
|---|---|---|---|
| Passivated stainless | Machining residue removed, passive film restored | No dimensional change; slot stays as cut | Instrument and electronics assemblies |
| Electropolished stainless | Surface levelled and enriched in chromium | Edges smoothed; slot checked after polishing | Laboratory, hygienic and optical equipment |
| Passivated plus light oil | Passive film plus a temporary barrier for transit | No dimensional change; oil cleaned before use | Parts stored before assembly |
| Zinc electroplated (carbon steel) | Sacrificial zinc layer | Build-up in the slot; driver checked after plating | Carbon steel parts in dry indoor service |
| Dacromet flake (carbon steel) | Zinc-aluminium flake layer | Thin film; slot checked over the coating | Wet or outdoor carbon steel assemblies |
Plain stainless parts are checked for finish and cleanliness rather than salt spray; salt-spray exposure is agreed only where the drawing specifies a coating. After passivation the parts are rinsed and dried, and the slot is checked again with the driver before packing, because residue left in a small recess is enough to stop the driver seating.
Packing protects the head and the thread. Small screws are packed in layers or in bags with the count stated, so the heads do not rub against each other and the slots stay clean, and the label carries the batch and material heat.
Three assembly conditions where a small stainless cap head screw has to sit flat and take a driver, and what it has to do instead:
Medical and laboratory instruments
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Medical instruments – flush heads on a thin housing |
Electronics assemblies and PCB stacks
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Electronics – small screws on stacked boards |
Self-service kiosks and vending equipment
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Vending equipment – small screws on sheet-metal trays |
Four reasons that matter specifically on a small stainless cap head screw, each tied to what the drawing has to prove:
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Engineering review before the bar is cut
Head diameter, slot width and thread start are settled before the first bar goes on the lathe, so the first sample is measured against the drawing instead of against a guess. Basis: Drawing or sample reviewed before turning starts. |
Turned one-piece, slot cut in the head
The head, slot and shank are produced on a CNC lathe, so the slot is centred on the head and the head stays concentric with the thread. No joined or welded shank is used. Basis: One-piece turning route, slot cut with the head. |
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Measured on the projector, not by eye
Head height, slot depth and thread are checked on the optical projector and with GO/NO-GO gauges, so a few tenths of a millimetre is a measured number rather than an opinion. Basis: Small features measured on the optical projector. |
First article to repeat production
The first article fixes the drawing revision, material heat and turning set-up; repeat orders are compared against that record. Basis: First article signed off before the batch is released. |
These stainless cap head screws are turned from bar, not assembled. The bar is cut to length, the head, slot, shank and thread relief are turned on a CNC lathe, the thread is produced after the body is turned, and the parts are deburred, cleaned and passivated before they reach the gauges. The operator checks the first parts of every run against the drawing before the batch continues.
Between runs the lathe is set to the drawing head and slot dimensions; the first parts go to the projector before the run continues, and the setting is recorded. Small parts are handled in trays rather than loose, so a batch cannot be mixed with another size, and the first article stays with the record so a repeat order can be compared with it.
What decides whether a stainless cap head screw passes is not its appearance: it is the head sitting flat on the assembly, the slot taking the driver, and the thread matching the tapped part. The inspection agreement covers those, and the criteria are the ones written on the drawing rather than a generic standard.
Thread gauging against GO/NO-GO gauges |
Head and slot profile on the optical projector |
Hardness testing of the base material |
Salt-spray testing where a coating is specified |
Each batch is recorded against the drawing revision: head and slot from the first article, the slot checked with the driver, thread gauging per batch, and the material heat on the certificate. If a gauge or the slot check fails, the parts back to the last good setting are held and re-checked before anything ships.
Where the material needs a third-party report, it is specified on the drawing and filed with the batch, so the label and the inspection record carry the same number.
Every stainless cap head screw shipment is traceable to the bar 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. 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. Buyers visit during the process to review samples and to see the turning, threading and finishing steps their parts will go through.
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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 turning cells, the thread production and the finishing 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 small machine screw with a cylindrical head, a flat top and a single slot for a flat driver, made in stainless steel and passivated. In the small sizes on this page the head, slot and thread are produced on a lathe.
They are turned from stainless bar. The head, slot, shank and thread relief are cut on a CNC lathe, then the thread is produced and the parts are deburred, cleaned and passivated.
Stainless cap head screws are quoted from M1.4 to M12. Length is quoted per part against the drawing; where a long version is required, custom lengths up to 2,000 mm are subject to DFM review after drawing submission.
A flat screwdriver of the width and thickness given on the drawing. The slot is cut to that width and checked with the matching driver, because an oversize driver rounds the slot and an undersize one slips.
No. Passivation cleans the surface and restores the chromium oxide film on stainless steel; it does not add a layer. That is why the thread and slot keep the dimensions they were cut to.
Thread size and pitch, thread length and position, total length and datum, head diameter and height, slot width and depth, material grade, surface condition, and quantity.
How a stainless cap head screw project runs from drawing to repeat delivery:
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1
Send the drawing or sample
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→ |
2
DFM review and quotation
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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 stainless cap head screw quotation, send the drawing with thread size and pitch, thread length and position, total length with its datum, head diameter and height, slot width and depth, material grade and surface condition. Head, slot and thread are confirmed with you before production.
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Thread size and pitch
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Thread and total length
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Head diameter and height
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Slot width and depth
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Material grade
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Surface condition and quantity
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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
