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:Ultra Low Profile Screws
Materials:Carbon Steel
Surface treatment:Black Zinc Plated
Head Type:Ultra Low Head
Drive:Phillips
Thread:Half Machine Thread
Point:Blunt
Forming:Single Die Heading
Size:M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M14
Number:719
We make ultra low profile screws from carbon steel with a flattened disc head, a shallow cross recess and a half machine thread, black zinc plated and quoted from M1 to M14. Head height, recess depth, thread and plating come from your drawing, and the first article is fitted under the cover it has to clear.
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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.
Ultra low profile screws are machine screws whose head is flattened to a thin disc so the fixing barely stands above the surface, with a cross recess cut into what height is left. The recorded item on this page is black zinc plated carbon steel with an ultra low head and a half machine thread, quoted from M1 to M14 with Number 719.
Ultra low head. A disc with a chamfered edge and a very short height, lower than a pan head and lower than a wafer. Its purpose is clearance: it lets a cover, a label or a sliding part pass over the fixing.
Cross recess. A Phillips cross, and a shallow one, because the head has almost no material above the bearing face. The bit that drives it has to be short and in good condition, and the torque the joint can take is set by the recess rather than by the thread.
Half machine thread. Thread from the point to a defined position, with a plain shank under the head. The plain length passes a clearance hole without cutting it and can locate the joint.
Black zinc. Electroplated zinc with a dark passivation, applied after the thread is rolled. It is sacrificial and thin, and on a head this flat the deposit is a measurable fraction of the recess depth.
A low head is a budget problem. The head height, the recess depth and the material left under the recess have to fit into the same few tenths of a millimetre, and every one of the three can be wrong. On ultra low profile screws the budget is tighter than on any other head form, because the height is the feature being bought.
The recess is the first item. A cross needs depth for the bit to seat, and a shallow cross means the bit sits high and the wings carry the load on a short engagement. That is why the drive on this form is torque-limited: it is not that the thread cannot take more, it is that the cross leaves before the thread does.
The material under the recess is the second item. Cut the cross too deep in a thin head and the wall between the slot floor and the bearing face becomes thin enough to dish under the driver. Dish the head and the joint stops being flat, which on a part bought for clearance is the one thing it had to be.
The bearing face is the third. On a disc there is no dome to hide a variation, so a head that is two hundredths thicker at the rim shows as a rock on the panel. The first article is checked at the rim and at the centre for that reason, not just across the top.
The half thread sits below all of this and is the least constrained part of the design. The plain shank passes the top member of a stack, the thread clamps in the member beneath, and on a low head the thread is proportionally the largest feature of the screw — which is why the failures on this family are almost always at the head.
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 ultra low profile screws the head height is the first dimension to settle, because it fixes everything else.
| Item | How it is defined | What we control |
|---|---|---|
| Head | Ultra low, flat disc | Height, diameter and face flatness |
| Recess | Phillips cross, shallow | Depth within the head, bit tried after plating |
| Thread | Machine thread, half length | Thread length and position from the end |
| Shank | Plain, under the head | Diameter and length |
| End | Blunt, chamfered | Chamfer cut, not deburred |
| Length | From under the head to the end | Measured on the shop plate |
Head height is quoted with the recess rather than on its own. A height without a recess depth says nothing about whether the part can be driven, and a recess depth without the height says nothing about whether the head will sit where the cover needs it. The two are read together on the first article.
Length is measured from under the head, because that face bears. On a half thread the thread length is quoted from the end independently; a screw can be right overall and still wrong if the thread starts a turn early and the plain shank no longer clears the top plate.
Three features define ultra low profile screws: the flattened head, the shallow cross and the half thread. The first two are a compromise that has to be understood before the part is specified, because a low head with a cross is not simply a smaller version of a pan head.
| Combination | Torque it will take | Where it fits | Where it fails |
|---|---|---|---|
| Low head, cross | Limited by the shallow recess | Low-torque joints with clearance needs | Any joint that needs real clamp load |
| Low head, socket | Higher for the same height | Counterbored joints, repeated assembly | Joints needing the tallest head |
| Standard pan, cross | Full for the thread size | General assembly | Anywhere the head height fouls |
| Flat countersunk | Limited by the countersink | Flush surfaces | Thin sheet that cannot take a cone |
A cross in an ultra low head is acceptable when the joint needs very little. Holding a label, a film, a plastic cover or a trim where the load is a few newtons and the part is assembled once: the recess will transmit that comfortably. It is the wrong choice where the joint has to stay tight under vibration, because the cam-out torque is low and the head marks easily.
The practical rule is to keep the torque well inside the recess limit and let the joint design do the rest. Where a customer needs a low head and a real clamp load, the answer is a socket drive in the same height or a slightly taller head, and that conversation is worth having before the die is cut rather than after the first batch cams out.
The recorded finish is black zinc with a dark passivation, applied after the thread is rolled. It is a sacrificial coating, so a scratch at the rim still has zinc around it, and the dark tone keeps a head that is already small from catching the eye.
| Finish | How it protects | Effect on the shallow recess | Typical use |
|---|---|---|---|
| Black zinc | Sacrificial zinc, dark passivation | A few microns; bit tried after plating | Dark covers and panels |
| White zinc | Sacrificial zinc | A few microns; re-checked | General indoor work |
| Black oxide | Thin conversion film, oiled | No measurable build | Unseen low-head joints |
| Nickel plate | Hard barrier deposit | Thicker; recess re-checked | Visible decorative low heads |
| Dacromet | Zinc-aluminium flake layer | Film builds; recess re-checked | Outdoor and wet panels |
On a head this shallow the coating has less room than anywhere else. A few microns inside a cross that is already shallow is enough for the bit to sit proud, and on ultra low profile screws that is the difference between a part that drives and one that rounds. The recess is tried with the production bit in the plated condition, every batch.
The rim is the other place the finish shows. A low head has a thin edge, and thin edges wear through a coating first — in handling, in the barrel and on the driver. A black zinc head that has been through a feeder will show bright nickel at the rim, and that is normal rather than a defect.
Three assemblies where ultra low profile screws solve a clearance problem:
| Where it sits | The screw closes a cover or fixes a module under a label, a film or a sliding battery door where a pan head would stand proud and show. |
| When it goes wrong | A proud head tents the label, and a recess that has filled with adhesive cannot be driven. |
| Why it happens | The surface is covered after assembly, and the fixing is under it. |
| What we control | Head height and recess depth checked, bit tried after plating. |
| Where it sits | The screw fixes a trim or a plate where the panel is stacked against another part and the head has to sit inside the stack. |
| When it goes wrong | A standard head holds the layers apart, and a head that saddles the hole rocks instead of bearing. |
| Why it happens | The layers are stacked, the head is hidden, and the fixing repeats. |
| What we control | Face flatness checked at rim and centre, thread gauged per batch. |
| Where it sits | The screw holds a component inside a case where the head must clear a moving part or a cable route. |
| When it goes wrong | A tall head fouls a moving part, and a joint that will not take torque is over-driven until it rounds. |
| Why it happens | The clearance is tight, the load is light, and the part is assembled once. |
| What we control | Recess and head height checked, torque agreed with the joint design. |
Four reasons that matter on a head flattened to its limit, each tied to what the drawing has to prove:
|
Height and recess reviewed together
The head height, the recess depth and the bit are reviewed as one set, so a head that is too low for its driver or a recess that would dish is raised before the die is cut. Basis: Height and recess reviewed as one set. |
Heading, flattening and rolling in one route
The head is formed and flattened to height, the half thread is rolled to a blunt point and the parts are plated in one route. Basis: One route from wire to plated screw. |
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Bit and face checked on the part
The recess is driven with the production bit after plating, and the face is checked for flatness at the rim and the centre. Basis: First article checked after plating. |
First article fixes the setting
The first article fixes the wire heat, die set, flattening height and plating; repeat orders are compared against that record. Basis: First article signed off before the batch is released. |
Shi Shi Tong forms these ultra low profile screws from carbon steel wire on single-die headers that upset the head and form the cross in one stroke, flattens the head to its drawing height, rolls the half thread to a blunt point and black zinc plates the parts. The first part of every run is measured on the head, driven with the production bit and driven into a sample of the customer’s panel before the batch continues.
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Flattening sets the whole part. Press the head down too far and the recess loses the depth the bit needs; leave too much and the head fouls the cover it was bought to clear. Because the die forms the recess before the head is flattened, the two operations have to be matched, and the height is measured on the first article rather than trusted to the setting.
What decides whether ultra low profile screws pass is the head height and face, the recess, the thread and the plating. The inspection agreement covers those, and the criteria come from the drawing.
Head height and recess on the projector |
Thread gauged after plating |
Hardness testing against the property class |
Salt-spray testing of the black zinc plate |
The head is measured for height at the rim and at the centre and for face flatness. On ultra low profile screws those two readings together tell you whether the recess has the depth it needs; a head that is thicker at the rim is a head that has lost depth where the bit seats.
The recess is driven with the production bit in the plated condition. This is the acceptance check on the family: a shallow cross that measures in tolerance can still refuse a bit that is a season old, and the customer’s driver is the authority.
The thread is gauged after plating and the thread start is checked on the half thread. A start that is a turn early removes the plain shank and turns a cover that sat flat into one that stands off.
Every shipment of ultra low profile screws is traceable to the wire it was made from and to the plating 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 material or the plating. 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 low head the first article is also fitted under the cover it has to clear, so the clearance and the drive are proved together. Buyers visit during the process to review samples and to see how the heads are flattened and the parts plated.
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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 plating 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 |
Below a wafer head: a flat disc with a chamfered edge, low enough for a label or a sliding cover to pass over it. The figure is on the drawing and it is limited by the recess it has to contain.
It can. A shallow recess transmits less torque, so on ultra low profile screws the joint is designed for a low clamp load. Where more torque is needed, the drive changes rather than the driver.
Yes, that is a typical use. The head sits below the film, and the recess does not fill because the film is applied after the screw is driven.
The torque the recess will take without camming out, which is lower than the thread could carry. It is set from the first article and the joint design, not from a table.
Yes. A few microns in a recess this shallow is a large fraction of its depth, so the bit is tried in the plated condition on every batch.
Head diameter and height, recess size and depth, thread size with its length and datum, shank dimensions, overall length, material and plating.
How an ultra low profile screw project runs from drawing to repeat delivery:
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1
Send the drawing and the clearance envelope
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→ |
2
Head height, recess and thread review
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→ |
3
First article fitted under your cover
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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 height, the recess size and depth, the thread size and length with its datum, the shank dimensions, the material and the plating.
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Head height
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Head diameter
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Recess size
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Thread and datum
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Shank
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Material and plating
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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
