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
Place of Origin:Guangdong,China(Mainland)
Brand Name:Shi Shi Tong
Materials:Stainless Steel
Surface treatment:Plain stainless, cleaned and passivated; no plating over the bearing face
Head Type:Cup head, oversized
Drive:Hexagon socket
Thread:Machine thread
Point:Plain, chamfered
Forming:CNC turning from bar; head faced flat; passivated
Size:M5*6.6mm,Diameter 14mm,Thickness 4.5mm
We turn stainless cup head socket screws with an oversized head, 14 mm on an M5 thread in this part, and a flat faced bearing ring. The wide head does the work of a washer, so the joint depends on that face staying flat — a dished face puts the load back on the rim.
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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.
A cup head socket screw has a cylindrical head with a hexagon socket, and this one is sized well beyond the standard: a 14 mm head on an M5 thread, 6.6 mm long. It is stainless steel, plain and passivated, and is quoted with the head and length made to the drawing.
Cup head. A straight-sided cylindrical head with a flat, full bearing face.
Hexagon socket. Six flats for a standard key, in a head tall enough to take them.
Oversized head. 14 mm on an M5 thread, where a standard cap head is about 8.5 mm.
Stainless body. No coating, so the bearing face is exactly as machined.
Cup head socket screws of this size are used where a small screw has to hold a large area: thin panels, plastic covers, glass clamps and equipment faces, in short, anywhere a washer would be an extra part on the line.
This part carries a head that is nearly twice the standard diameter for its thread. The reason is arithmetic: bearing pressure is the clamp load divided by the area under the head, so doubling the diameter roughly triples the area and cuts the pressure by the same factor. On a thin panel or a soft moulding, that is the difference between a joint and a dent.
What the oversized head gives, the bearing face has to keep. A wide head is only as good as its flatness: if the underside is slightly dished or the panel is not flat, the head touches on its rim and the pressure goes back up, this time concentrated in a ring at the edge. A head of this size is therefore checked for flatness rather than assumed flat.
There is a second consequence, which is clearance. A 14 mm head needs 14 mm of room, and on a dense assembly it can foul a neighbouring component, a wall or a cable. That is why the head diameter is written on the drawing and not left to a standard.
The short length is part of the same design. At 6.6 mm under the head, this screw is made to clamp a thin stack, and the thread is short because the joint is short. A screw that is used where the stack is thicker simply bottoms, which is a mistake in the drawing rather than in the part.
Stainless matters here more than usual. With no plating, the bearing face is bare metal on bare panel, and the flatness of that face is the whole of the load path. The passivation keeps the face free of free iron, which is what would otherwise stain a light panel around a clamp ring.
So this is a screw chosen for what its head does rather than for its thread: a wide, flat face that spreads load, on a body that is only there to hold it down. The drawing carries the head diameter, the head thickness and the length, and those three decide the joint.
Cup head socket screws are quoted by head diameter and thickness, thread size and pitch, length under the head, socket size and depth, material and finish. Custom lengths up to 2,000 mm, subject to DFM review after drawing submission. The quotation carries the material, the head, the socket, the thread and the passivation.
| Item | How it is defined | What we control |
|---|---|---|
| Body | Stainless steel | Grade and mechanical properties |
| Head | Cup head, oversized | Diameter, thickness and flatness |
| Socket | Hexagon socket | Across-flats and depth |
| Thread | Machine thread | Size, pitch and length |
| Length | Under the head | Stack the screw can clamp |
| Finish | Plain, passivated | Surface condition and burr |
The head diameter is written with the head thickness, because a wide head that is thin will dish under load and give back the bearing area it was bought for. On this part the thickness is 4.5 mm on a 14 mm head, which is what keeps the face flat.
The socket is written with its depth, since it sits in the middle of that thickness. A deeper socket leaves less material under it, and on an oversized head the temptation is to cut deeper for a better key engagement.
The length under the head is the stack dimension. A cup head socket screw of this form is made for a thin clamp, and the drawing should state the material thickness it has to hold rather than only an overall length.
Four properties decide this part, and each carries a cost:
| Property | What it gives | What it costs |
|---|---|---|
| Oversized head | A bearing area near a washer’s | A face that has to stay flat |
| Flat underside | Full-ring contact on the panel | Any dish sends the load to the rim |
| Hexagon socket | A full-depth drive | A thicker head than a low form |
| Short length | A joint for a thin stack | Bottoms if the stack is thicker |
The value of the part is a fixing that behaves like a washer without being one, on a thin or soft panel where a standard head would dent the surface and no washer can be fitted.
The cost is clearance and flatness: the head needs room around it, and the face under it has to stay flat for the whole of that area to be of use.
The recorded finish is plain stainless, cleaned and passivated. On a head this wide that is the right choice: nothing is plated over the bearing face, so the face is flat to the machining tolerance and the contact with the panel is metal on metal.
| Option | How it protects | Effect on the face | Typical use |
|---|---|---|---|
| Plain stainless | Natural oxide | No build; face as cut | Panels and covers |
| Passivated | Clean, thickened oxide | No build; free of free iron | Food and lab equipment |
| Black oxide | Conversion layer | Thin, matte | Dark equipment |
| Dry film lubricant | Low-friction film | Thin; eases the thread | Joints opened often |
| Nickel plated steel | Hard barrier layer | Builds; face re-checked | Cost-driven panels |
A plated version at this head diameter has to be checked on the face, because the film changes the flatness by a few microns and the face is the working surface. On a wide head that is enough to change where the load lands.
Where the panel is seen, plain stainless also avoids the colour change that a dyed zinc shows after cleaning around a clamped ring.
Three products where the head has to spread load over a wide area:
| Where it sits | The screw holds a panel that would dent under a standard head. |
| When it goes wrong | The panel dishes around the fixing, or the screw pulls through. |
| Why it happens | The bearing area is too small, and no washer is fitted. |
| What we control | Head diameter matched to the panel; first article clamped and inspected. |
| Where it sits | The screw clamps a brittle or soft material where point pressure is the risk. |
| When it goes wrong | The material craze or cracks at the edge of the head. |
| Why it happens | The head is narrow, and the clamp load concentrates on a small ring. |
| What we control | Head diameter and face flatness agreed; sample clamped on the material. |
| Where it sits | The screw fixes a guard where a large, flat head is preferred to a washer. |
| When it goes wrong | The head fouls a neighbouring part, or marks the face. |
| Why it happens | The head diameter was not checked against the clearance. |
| What we control | Clearance checked on the assembly; sample fitted in place. |
Four points that decide whether an oversized head spreads load or simply stands out:
|
Head diameter and thickness both written
The drawing gives the diameter and the thickness, because a wide thin head dishes and loses the area it was bought for. Basis: Face kept flat. |
Head faced and checked
The bearing face is machined and checked for flatness on the projector, not inferred from the diameter. Basis: Flatness proved. |
|
Clamped on the panel
The first article is clamped on a sample of the customer panel, and the ring of contact is inspected. Basis: Ring proved. |
Same face every lot
Head diameter, thickness and plating are recorded with the drawing revision, so a repeat lot bears the same. Basis: Same bearing area. |
An oversized head is easy to make and easy to make ineffective: a face out of flat by a few hundredths turns a ring into an edge. These four points are what keeps the area working.
These screws are turned from stainless bar, with the head turned to diameter and thickness, the face faced flat, the hexagon socket cut, and the thread cut or rolled before passivation. The first piece of every run is measured on head diameter and thickness, face flatness, socket, thread and length.
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The face is the feature this part exists for, so it is faced last and checked flat. On a 14 mm head a face that runs out by a couple of hundredths contacts the panel on one side, and the clamp then behaves like a much smaller head.
The socket is cut into a head that is thick enough to take it. That thickness is the reason this form is chosen over a low head: a cup head socket screw with a wide face needs material to stay flat, and the socket uses part of it.
Passivation follows the machining and removes free iron from the turned face. On a light panel, a spot of free iron under the head shows as a stain around the ring, which looks like a plating fault and is not one.
What decides whether a batch of cup head socket screws passes is the bearing face that spreads the load, the socket that drives it and the length that fits the stack. The inspection agreement covers all three.
Head and socket on the projector |
Thread checked with gauges |
Material checked |
Salt-spray testing where required |
The head is measured for diameter and thickness and the face for flatness across its full width. A face that is flat at the centre and low at the rim is the defect that matters on this part, and it is invisible from the top.
The socket is measured and driven with the key at the joint torque. On a head this thick the socket is deep enough for a full key, so a rounded hexagon here points to a worn key rather than to a shallow recess.
The length is checked under the head, and the sample is clamped on a stack of the customer’s thickness. A short screw that bottoms looks correct on a drawing and leaves the joint open.
Every batch of cup head socket screws is traceable to the bar it was made from. The material certificate states the grade, the heat number, the chemistry and the mechanical properties, and the inspection record carries the head, socket and thread against the drawing.
ISO 9001:2015 |
RoHS test report |
Registered trademark |
Patent: security screw and driver |
With each shipment we supply the material certificate and the inspection record for the head, socket and thread. The records carry the batch number, so a repeat order can be compared with the first on the head diameter and face flatness that decide the bearing area.
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 an oversized head the first article is clamped on the customer’s panel, because the ring of contact is the whole reason for the head. 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
|
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 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 |
To spread the clamp load. A 14 mm head on an M5 thread gives close to the bearing area of a washer.
No. The thread and the key set the torque; the head sets the pressure on the panel.
The face is not flat, or the panel is not, so the load lands on the rim instead of the ring.
Clearance. A head this wide needs room around it, and it can foul a neighbouring part.
It is made for a thin stack. A thicker stack needs a longer screw, or the joint never closes.
Head diameter and thickness, face flatness, socket, thread, length and the stack it clamps.
How a cup head socket screw project runs from drawing to repeat delivery:
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1
Send the drawing and a panel sample
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→ |
2
Head diameter, thickness and thread agreed
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→ |
3
First article clamped and checked
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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 used for the first article is what repeat orders are checked against.
For a quotation, send the drawing with the head diameter and thickness, socket size and depth, thread and length, the stack it clamps, and the finish.
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Head dia
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Thickness
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Socket
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Thread
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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
