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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:316 Stainless Steel Screws, Oval Head Screw
Materials:SUS 316
Surface treatment:Passivation
Head Type:Oval Head (raised countersunk)
Drive:Phillips cross recess
Thread:Machine thread
Point:Plain, chamfered
Forming:Single Die Heading
Size:M1 M2 M3 M4 M5 M6 M7 M8 M9 M10
We make oval head screws in 316 stainless with a raised countersunk head, a Phillips recess and a machine thread, quoting them from M1 to M10. Cone angle, dome height, recess and thread come from your drawing, and the first article is seated in your own countersink.
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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.
Oval head screws — also called raised countersunk — have a 90-degree cone that seats in a countersink and a domed top that stays above the surface. The part recorded here is 316 stainless steel, passivated, quoted from M1 to M10.
Oval (raised countersunk) head. A cone for seating plus a shallow dome above it, so the fixing centres itself but finishes with a rounded face.
Phillips recess. Four tapered arms in the dome, driven with a standard cross-tip bit.
Machine thread. A uniform thread for a tapped hole, a nut or an insert.
316 stainless (A4). The molybdenum-bearing grade, chosen where chlorides are present, passivated with no coating.
Oval head screws are used on boat fittings, outdoor hardware, instruments and vintage-style equipment: places where a countersink exists but a flush head is not wanted, because the domed top is part of the look or because it protects the edge of the hole.
The oval head is two forms stacked. The cone works exactly like a countersunk head: it self-centres in the countersink and carries the clamp on its face. The dome above it does not touch the panel at all; it stands proud and gives the fixing its rounded appearance. That combination is why the part is often chosen by eye rather than by calculation.
What the dome costs is flushness. An oval head can never finish level with the surface, so it is the wrong part for a face that is slid across or sealed against. What it buys is a softer edge: the head is rounded where a countersunk head has a sharp rim, so it does not catch a cloth, a rope or a hand, and it protects the countersink edge from being chipped.
The head height budget is split between the cone and the dome. That leaves less material for the recess than a flat countersunk head of the same diameter, so the cross is shallower and the drive gives out earlier. On an oval head the recess depth and the dome height have to be quoted together, or the part ends up with a cross that is too shallow to drive.
Cone angle is the silent variable, as on every countersunk form. Ninety degrees is the metric and Japanese standard, eighty-two the North American one, and a mismatch leaves the cone touching on a ring instead of its face — the head then rocks, and on an oval head the movement is visible because the dome is above the surface.
316 stainless is what makes the part worth specifying. The molybdenum addition is what holds up in chlorides, so the screw survives salt spray and chlorinated water where 304/A2 would pit; passivation leaves the head and recess as formed, with no coating to fill the cross or round the cone.
The recorded range is M1 to M10, with lengths made to the drawing. Custom lengths up to 2,000 mm are subject to DFM review after drawing submission. For oval head screws the quotation carries head diameter, cone angle, total head height, the PH size and recess depth, thread pitch and overall length.
| Item | How it is defined | What we control |
|---|---|---|
| Head | Oval, raised countersunk | Diameter, cone angle, dome height and total height |
| Recess | Phillips, PH size per diameter | Arm depth and floor thickness |
| Thread | Machine thread | Pitch, length and start position |
| Length | Overall, head included | Length tolerance and thread start |
| Material | 316 stainless (A4) | Grade and heat number on the certificate |
| Finish | Passivated, plain | Surface condition and recess edges |
Total head height and dome height are two numbers, not one. The cone has to fit the countersink, and the dome is whatever is left above it; a drawing that gives only the total leaves the split undefined, and the recess then has to be cut out of a height nobody chose.
Cone angle belongs on the drawing with the countersink it will sit in. Since the dome shows, a head that rocks is more obvious here than on a flush part, and the pair has to match.
Four features define oval head screws, and each one is a trade:
| Feature | What it gives | What it costs |
|---|---|---|
| Oval head | Rounded face; protects the countersink edge | Never finishes flush |
| Countersunk cone | Self-centring seat | Removes material where the thread holds |
| Phillips recess | Standard bit; torque release | Shallow because the dome takes height |
| 316 stainless | Chloride resistance; no coating | Galls in aluminium; softer than the bit |
| Passivated finish | Head and recess as formed | Marks show on a bright dome |
The value is a countersunk joint with a soft edge. On a boat or a piece of outdoor hardware, the domed head is what keeps a rope or a sleeve from catching the rim of a countersink, and it is what makes the fixing look deliberate rather than sunk.
The cost is flushness and drive depth. Where the joint must be flat, this is the wrong head; where it must take a real torque, the recess in a domed head is the limitation, and a flat countersunk form or an internal drive does the job better.
The recorded finish is passivation on 316 stainless with no coating. It is the only sensible finish for a chloride-resistant part: a coating would sit on the cone and in the recess, and the grade underneath is what does the work.
| Option | How it protects | Effect on head and recess | Typical use |
|---|---|---|---|
| 316 / A4, passivated | Passive film with molybdenum | Head and recess as formed | Marine and chlorinated |
| 304 / A2, passivated | Passive chromium oxide film | Head and recess as formed | Outdoor general |
| 316, electropolished | Thicker passive film, bright | Edges rounded; recess checked | Visible marine hardware |
| Steel, nickel plated | Hard bright barrier | Thin build; bright finish | Indoor visible panels |
| Brass, plain | None needed indoors | Softer; recess wears faster | Period hardware |
The grade question on an oval head is decided by where the joint lives. Rain and condensation are 304 work; salt spray, chlorinated water and marine air are 316 work, and on an oval head the difference shows at the cone face and on the dome, which are the two surfaces the customer sees.
Electropolishing is worth it on visible marine hardware: it brightens the dome, removes the burr at the recess edge that a bit would catch, and leaves a thicker passive film, which is why the recess is checked after the process.
Three assemblies where a seated but rounded head is the specification:
| Where it sits | The screw holds a cleat, a hatch fitting or a bracket where the seat is countersunk and the head must not catch a rope. |
| When it goes wrong | A flush head’s sharp rim chafes a line and the countersink edge chips. |
| Why it happens | The joint is marine, the seat is a countersink, and the head is handled. |
| What we control | Cone angle and dome checked; first article fitted with the grade recorded. |
| Where it sits | The screw fixes a bracket on painted or powder-coated steel where the countersink is machined and the head shows. |
| When it goes wrong | Water collects on a flush rim and rust starts at the edge. |
| Why it happens | The joint is exposed, the head shows, and the seat is machined. |
| What we control | Dome and grade checked; first article fitted and left exposed. |
| Where it sits | The screw closes a panel where the original form was an oval head and the look has to match. |
| When it goes wrong | A flat countersunk head is substituted and the panel reads as wrong. |
| Why it happens | The part is judged visually, the seat is countersunk, and the joint is assembled once. |
| What we control | Dome height and recess checked against the original; first article fitted. |
Four reasons that matter on a domed countersunk head, each tied to something the drawing has to prove:
|
Cone, dome and recess agreed
Cone angle, dome height and recess depth are agreed as a set, because the dome takes height from the recess on this form. Basis: Cone, dome and recess agreed. |
Formed, recessed and passivated in one route
The cone and dome are formed in one stroke, the cross cut, the thread rolled and the parts passivated as a batch. Basis: One route from wire to passivated screw. |
|
Recess proved with the bit
The recess is proved with the production bit, because in a domed head a shallow cross can measure correctly and refuse a worn bit. Basis: Recess proved with the bit. |
First article in your countersink
The first article is seated in the customer countersink, because the cone angle and the seat are properties of the pair. Basis: First article seated in the countersink. |
These screws are headed on single-die machines that form the cone and the dome together and cut the Phillips recess in the same stroke, rolled with the machine thread and passivated as a batch. The first part of every run is measured on head diameter, cone angle, dome height, recess depth and thread.
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Forming a cone and a dome in one stroke is what makes the oval head difficult. The die has to press the cone to its angle and leave a dome above it, and the punch then cuts the cross into the top of that dome; a die that has worn shifts the split between cone and dome, so the part still measures correctly overall and sits differently in the countersink.
Cone angle is checked against a master at the start of each run rather than by sampling. A cone that is slightly off angle contacts the countersink on a ring instead of its face, and because the dome shows, the resulting rock is visible on the product rather than hidden inside the joint.
What decides whether oval head screws pass is the cone, the dome, the recess and the grade. The inspection agreement covers those, and the criteria come from the drawing.
Cone, dome and recess |
Thread and start checked |
Core hardness checked |
Salt-spray testing of the grade |
Cone angle is measured against a master and proved on a countersink block; the dome height is measured in the same pass, because it is the number that decides how much recess is left. The recess is proved with the production bit, and the thread is gauged after passivation.
A sample from every batch is seated in the customer countersink and removed. That cycle shows a cone that rocks and a recess that dulls, and on a visible oval head both are immediately apparent on the finished product.
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 cone and the same dome.
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 oval head screws the first article is seated in the customer countersink, because the cone angle and the seat are proven together. Buyers visit during the process to review samples.
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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 |
No. The cone seats in the countersink and the dome stands above the surface; a flat countersunk head is the flush option.
The rounded top does not catch a rope, a cloth or a hand, and it protects the edge of the countersink.
Ninety degrees in the metric and JIS form, eighty-two in the North American form. The countersink has to match.
The dome takes part of the head height, so less is left for the cross. Recess depth and dome height belong on the drawing together.
Chlorides. 316/A4 holds up in salt spray and chlorinated water where 304/A2 would pit.
Head diameter, cone angle, dome and total height, PH size and depth, thread pitch and length.
How an oval head screw project runs from drawing to repeat delivery:
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1
Send the drawing and the countersink
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→ |
2
Cone angle and dome agreed
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→ |
3
First article seated in your panel
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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, cone angle, dome and total height, PH size and depth, thread pitch and overall length.
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Head diameter
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Cone angle
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Dome height
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PH size
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Thread pitch
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Length
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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
