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+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 Steel Self Tapping Screws, Self Tapping Screw Manufacturer
Materials:Stainless Steel
Surface treatment:Plain
Head Type:Flat Head (CSK)
Drive:Phillips cross recess
Thread:Self-tapping
Point:Sharp, tapered
Forming:Single Die Heading
Size:M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M14
Number:419-1
We make stainless steel self tapping screws with a countersunk head, a Phillips recess and a hardened sharp point, quoting them from M1 to M14. Cone angle, thread, point and pilot hole come from your drawing, and the first article is driven into your own sheet.
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.
Stainless steel self tapping screws form their own thread in sheet, in extrusion or in soft metal, and being stainless they need no coating to resist corrosion. The part recorded here is a countersunk screw with a Phillips recess and a sharp tapered point, quoted from M1 to M14 with Number 419-1.
Countersunk head. A cone that seats flush in the countersink and carries the clamp on its face.
Phillips recess. Four tapered arms driven with a standard bit, releasing the driver at a set torque.
Self-tapping thread. A hardened thread with a sharp point that forms its way into the pilot hole.
A2 stainless, passivated. No plating on the point or the recess, which matters because both are formed features that a coating would blunt.
These screws are used on stainless and aluminium sheet, in washdown equipment, marine fittings, food machinery and outdoor enclosures, where a plated screw would rust at the point and where the joint has to be opened without a coating flaking into the assembly.
A self tapping screw works by displacement: the hardened thread pushes the sheet metal aside and leaves a thread-shaped groove behind it. In mild steel that happens easily. In stainless sheet the material work-hardens as it deforms, so the first turn is easy and every turn after it is harder, and the screw has effectively one chance to form the thread correctly.
That is what makes the pilot hole critical. If it is too small, the screw work-hardens the sheet before the thread is formed and then stalls or shears; if it is too large, the thread cuts a shallow groove that strips under load. The window is narrower in stainless than in mild steel, and it moves with the grade of the sheet, so a hole that suited 304 is not automatically right for 316.
Aluminium is different again. It is soft and easy to form, but stainless galls against it: the oxide on the stainless screw and the soft aluminium weld together under pressure, and the screw seizes partway in. A thread-forming screw with a single-lobe or a cutting point behaves better in aluminium than a fully forming one, and a drop of lubricant at assembly removes most of the rest.
The point is the feature that decides whether any of this starts cleanly. It is hardened and concentric, and its transition to the first thread has to be smooth; a screw that has to be pushed hard to start will walk off the hole and form its thread at an angle, and in stainless there is no second attempt because the material around the hole is already hardened.
Because the screw has no coating, the finish question becomes a grade question. A2 covers rain and condensation, A4 covers chlorides, and there is nothing else to specify: no plating thickness to hold, no coating to blunt the point, and no layer that can flake into a wash area.
The recorded range is M1 to M14, with lengths made to the drawing. Custom lengths up to 2,000 mm are subject to DFM review after drawing submission. For stainless steel self tapping screws the quotation carries head diameter and cone angle, PH size, thread pitch and point, the pilot hole and the overall length.
| Item | How it is defined | What we control |
|---|---|---|
| Head | Countersunk, 90-degree cone | Diameter, angle, thickness and rim |
| Recess | Phillips, PH size per diameter | Arm depth and floor thickness |
| Thread | Self-tapping | Pitch, core diameter and crest condition |
| Point | Sharp, tapered | Length, concentricity and hardness |
| Pilot hole | Sized for sheet and grade | Stated on the drawing with the sheet grade |
| Material | A2 or A4 stainless | Grade and heat number on the certificate |
The pilot hole is the number the supplier cannot invent. It depends on sheet thickness, sheet grade and the thread form, and it has to be agreed with the screw rather than chosen at the press. On stainless sheet a hole that is half a tenth out changes a joint from holding to stripping.
Point hardness belongs on the drawing where the sheet is stainless. The point has to be harder than the sheet to start a thread in it, and that is a heat treatment requirement rather than a dimensional one.
Four features define stainless steel self tapping screws, and each one is a trade:
| Feature | What it gives | What it costs |
|---|---|---|
| Self-tapping thread | No tapped hole or insert | Pilot hole tolerance is narrow |
| Sharp hardened point | Starts cleanly in sheet | Blunts in very hard sheet |
| Countersunk head | Flush finish | Removes material where the thread holds |
| A2 stainless | No coating to rust or flake | Galls in aluminium; softer than steel sheet |
| Passivated finish | Point and recess as formed | Shows tool marks on a bright head |
The value is a corrosion-resistant joint without a coating step. There is nothing to inspect for thickness, nothing to repair after a scratch, and nothing to flake into product. On washdown equipment that is the whole argument.
The cost is that the screw is now competing with the sheet. In stainless-on-stainless the screw work-hardens the panel and can seize; in stainless-on-aluminium the two metals gall. Both are managed with the pilot hole and with a lubricant rather than with another feature on the screw.
The recorded finish is passivation with no coating. On a self tapping screw that is not a preference but a requirement: a coating thick enough to protect the head would blunt the point and narrow the thread crest, and the screw would stop forming in the hole it was designed for.
| Option | How it protects | Effect on point and thread | Typical use |
|---|---|---|---|
| A2, passivated | Passive chromium oxide film | Point and thread as formed | Outdoor and washdown |
| A4, passivated | Passive film with molybdenum | Point and thread as formed | Marine and chloride |
| A2, electropolished | Thicker passive film, bright | Slight edge rounding; point checked | Visible and hygienic |
| Steel, zinc plated | Sacrificial zinc | Coating abraded at the point | Indoor sheet work |
| Steel, dacromet | Inorganic zinc-aluminium layer | Build noticeable; thread re-checked | Damp outdoor |
The grade decision is about chlorides, not humidity. A2 handles rain and condensation; A4 is the answer for salt spray, chlorinated water and marine air, and on a self tapping screw the difference shows first at the point, where the metal is thinnest and the coating — if there were one — would already be gone.
Where a plated steel screw is used instead, the plating is abraded at the point as the thread is formed, and the bare crest is the first place to rust. That is not a coating defect; it is what happens when a coated screw is asked to cut its own way in.
Three assemblies where the stainless version is the only sensible choice:
| Where it sits | The screw closes a panel onto stainless sheet where the joint is cleaned and no coating may enter the process area. |
| When it goes wrong | A plated screw loses its coating at the point and rusts inside the housing. |
| Why it happens | The joint is washed, the sheet is stainless, and the head must sit flush. |
| What we control | Pilot hole and grade agreed; first article driven into a sample sheet. |
| Where it sits | The screw fixes a fitting onto aluminium or stainless where salt is present all year. |
| When it goes wrong | The thread galls and the screw seizes halfway into the joint. |
| Why it happens | The joint is chloride-exposed, the metals differ, and the drive is by hand. |
| What we control | Grade and pilot hole checked; first article driven with the agreed lubricant. |
| Where it sits | The screw holds a cover on a coated panel where the flush head and the corrosion resistance both matter. |
| When it goes wrong | Rust runs out of the countersink where water collected around the head. |
| Why it happens | The joint is exposed, the seat is flush, and the panel is thin. |
| What we control | Cone and thread checked; first article fitted and left exposed. |
Four reasons that matter on a screw asked to form its own thread in stainless, each tied to something the drawing has to prove:
|
Pilot hole and grade agreed
Pilot hole, sheet grade and thread form are agreed together, because in stainless the hole decides whether the screw forms or stalls. Basis: Pilot hole and grade agreed. |
Headed, rolled, pointed and passivated
The cone and recess are formed, the thread rolled, the point cut and hardened, and the parts passivated as a batch. Basis: One route from wire to passivated screw. |
|
Point hardness and recess proved
Point hardness is checked against the sheet and the recess is proved with the production bit, because both decide whether the joint closes. Basis: Point hardness and recess proved. |
First article in your sheet
The first article is driven into the customer sheet with the customer driver, because the forming behaviour belongs to the pair. Basis: First article driven in your sheet. |
These screws are headed on single-die machines that form the countersunk cone and the Phillips recess, rolled with the self tapping thread and cut to a sharp point which is then hardened before passivation. The first part of every run is measured on cone angle, recess, thread, point and length.
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Hardening the point without hardening the head is the balance the process has to hold. The point must be harder than the sheet it forms in; the head must stay tough enough to take a driver and not crack at the recess. A part that is hard throughout fails at the recess, and one that is soft at the point folds over and stops halfway in.
Rolling the thread in stainless is slower than in carbon steel because the material work-hardens as it is formed in the die. The rolls are checked for wear on the first part of every run rather than by count, because a worn roll produces a thread that measures close to the drawing and grips noticeably less.
What decides whether stainless steel self tapping screws pass is the cone, the recess, the thread, the point and the grade. The inspection agreement covers those, and the criteria come from the drawing.
Cone, recess and point |
Thread and point checked |
Point and core hardness |
Salt-spray testing of the grade |
Cone angle is measured against a master and proved on a countersink block; the recess is proved with the production bit; and the point is checked for length, concentricity and hardness. Any of the three being out is enough to make the screw fail in the sheet even though it looks right.
A sample from every batch is driven into the customer’s sheet at the line setting and then removed. On stainless that cycle is the only practical measure of whether the screw will work: it shows a stripped thread, a stalled point or a seized joint, and none of them appear in a dimensional record.
Every batch is traceable to the wire it was made from and to the passivation batch that finished it. The grade and heat number appear 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 shipment we supply the material certificate, the inspection record for the dimensions on the drawing and, where the grade is listed, the third-party report that covers it. The documents carry the drawing revision and the batch number, so a repeat order keeps the same point and the same thread.
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 stainless steel self tapping screws the first article is driven into the customer sheet at the line setting, because forming behaviour belongs to the screw and the sheet together. Buyers visit during the process to review samples.
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8,678+
customers served
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87%
of orders from repeat customers
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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 |
Stainless work-hardens as it forms. A hole that is too small stalls the screw, one that is too large strips it, and there is no second attempt.
Yes. Stainless and aluminium seize under pressure; use a lubricant and a slower drive, or a cutting-type thread.
A2 covers rain and condensation; A4 covers salt spray, chlorinated water and marine air.
Once or twice in the same hole at most. A formed thread in stainless does not close up again.
A coating would blunt the point and narrow the thread crest. The grade does the corrosion work instead.
Head diameter and cone angle, PH size, thread pitch and point, pilot hole, sheet grade and length.
How a stainless self tapping screw project runs from drawing to repeat delivery:
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1
Send the drawing and the sheet
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→ |
2
Pilot hole and grade agreed
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→ |
3
First article driven in your sheet
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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 cone angle, PH size, thread pitch and point, pilot hole, sheet grade and length.
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Head size
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Cone angle
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PH size
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Point
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Pilot hole
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Sheet 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
