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 button socket head SEMS screw with captive washer
Materials:Stainless steel
Surface treatment:Electrophoretic orange + white locking patch (half circumference)
Head Type:Button head
Drive type:Hex socket (Allen)
Thread:Machine thread
Forming:Cold heading with captive SEMS washer
Number:1827
We manufacture stainless socket head sems screws with a button head, a hex socket and a flat washer captured by the rolled thread, coated in orange electrophoretic paint with an optional white locking patch on half the thread, from M2 to M10 and up to 200 mm. Washer size, socket depth, patch position and coating colour are made to your drawing.
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 socket head sems screw is a machine screw with a hex socket and a flat washer already assembled on it, held under the head by the rolled thread so it cannot drop off. The washer stays with the screw through handling, kitting and assembly, which is the whole point of the SEMS form.
Washer captured by the thread. The screw is headed, the washer is placed on the blank, and the thread is rolled so the first thread crest stands larger than the washer bore. The washer can turn and float, but it cannot come off the shank, so the assembly line never has to pick up a separate washer.
Button head and hex socket. The button head sits low on the panel and takes the hex socket without a tall driving face. On a socket head sems screw the washer under the head spreads the clamping load, so a thin panel is held without the head digging into it, and the socket still has enough depth to drive.
Coat one part, keep the fit. The orange electrophoretic coating is applied to the assembled screw and washer, so head, shank and washer all come out the same colour. The white locking patch on half the thread is applied separately and must survive the coating line and the assembly torque.
Together these decide how the part behaves on site: the washer is always there, the colour matches the panel it closes, and the thread does not walk out under vibration.
The washer is the feature that defines a socket head sems screw. It is a flat washer, seated under the button head, with an outside diameter matched to the head and an inside diameter that clears the thread but not the first rolled crest. Get that bore wrong and the washer either falls off before assembly or seizes on the shank and stops floating.
The ORANGE electrophoretic coat is applied after the washer is captured, by immersion with an electric field, and cured. Because the parts are assembled first, head, washer and shank are coated together and the colour is continuous across the joint. The film is thin enough that the socket still takes the Allen key and the thread still gauges.
The white nylon patch is applied to half the circumference of the thread, below the washer, where it presses against the mating thread. On a socket head sems screw the patch has to sit clear of the washer so the washer can still float, and clear of the thread start so it does not interfere with engagement.
Socket head sems screws are quoted from M2 to M10 and up to 200 mm, with length usually held to +/-0.1 mm on the drawing. Where a long version 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 of the button head to the tip | Datum stated on the drawing; length measured on the shop plate |
| Head diameter and height | The button head that carries the socket | Head diameter and height held to the drawing |
| Washer diameter and thickness | The flat washer captured under the head | Washer O/D, bore and thickness checked on the first article |
| Socket size and depth | The hex recess that takes the Allen key | Socket checked with the matching key after coating |
| Thread length and position | Where the thread starts and how far it runs | Thread start and patch position taken from the drawing |
Each diameter and length combination is checked against the drawing before a quotation is issued. On a socket head sems screw the washer is part of the assembly, so the check covers the washer bore and its freedom to float, not just the screw dimensions.
Length is measured from the top of the head, and the thread length is read as a position from the same datum. Washer thickness is measured where the washer seats, and the socket is checked after coating, because the e-coat builds up inside the recess.
For a socket head sems screw the drawing fixes six things: thread size and pitch, thread length and position, total length and its datum, head and washer dimensions, patch position, and right- or left-hand direction. A seventh line matters on a coated part: the condition in which the thread and socket are gauged.
| Parameter | Why it matters on a sems screw | What we control |
|---|---|---|
| Thread start position | It sets how much plain shank sits under the washer | Start dimension checked on the first article |
| Washer bore | It must clear the thread but not the first crest | Bore and washer freedom checked on the first article |
| Patch position | The patch must sit in the engaged thread and clear the washer | Patch masked to the drawing position |
| Socket size | Coating builds up in the recess | Socket gauged with the key after coating |
The orange electrophoretic coating on a socket head sems screw is a cured paint film driven on by an electric field. It covers the head, the washer and the shank in one pass, so the joint between washer and head is coated too, and the colour does not break at the seam.
| Finish | How it protects | Effect on socket and thread | Typical use |
|---|---|---|---|
| Orange electrophoretic | Cured e-coat over screw and washer | Film in the socket; key checked after coating | Panels where the screw colour is part of the design |
| Black electrophoretic | Cured e-coat, black | Film in the socket; key checked after coating | Black chassis and instrument covers |
| Plain / passivated stainless | No coating; the alloy is the finish | No dimensional change | Stainless assemblies without colour matching |
| Zinc electroplated (carbon steel) | Sacrificial zinc layer | Build-up on thread and socket | Carbon steel parts in dry indoor service |
| Dacromet flake (carbon steel) | Zinc-aluminium flake layer | Thin film; socket checked over the coating | Wet or outdoor carbon steel assemblies |
Salt-spray exposure and the acceptance state are agreed per project and written on the drawing. On an orange part the colour is checked against an accepted sample under the same light, because an e-coat batch can shift a few shades and a panel that is half orange and half brown reads as a defect.
Packing protects the coating and the washer. Parts are packed in layers with the heads up so the e-coat is not chipped at the head edge, and the washer is not pressed flat against the carton. Batch and colour information go on the label.
Three assembly conditions where a socket head sems screw saves a separate washer and keeps the colour consistent, and what it has to do instead:
Electronic chassis and panel assemblies
|
Electronic chassis – colour-matched screws with captive washer |
Power tools and portable equipment
|
Power tools – SEMS screws on thin cast housings |
Hydraulic power units and pump skids
|
Hydraulic power units – SEMS screws on painted covers |
Four reasons that matter specifically on a socket head sems screw, each tied to what the drawing has to prove:
|
Engineering review before tooling
Washer bore, head height, socket depth and patch position are settled before a die is cut, so the first sample is measured against the drawing instead of against a guess. Basis: Drawing or sample reviewed before tooling is released. |
Washer captured by the rolled thread
The washer is placed on the blank and the thread is rolled over it, so the washer cannot come off in the box or on the line. No separate washer is packed. Basis: Washer captured by the thread-rolling step. |
|
Colour, socket and thread checked together
The orange coat is checked against the accepted sample, the socket with the Allen key, and the thread with gauges after coating, so the part that ships is the part that was approved. Basis: Colour sample, key fit and thread gauges recorded per batch. |
First article to repeat production
The first article fixes the drawing revision, material heat, washer lot, coating batch and colour sample; repeat orders are compared against that record. Basis: First article and colour sample signed off before the batch. |
These socket head sems screws are formed and assembled in one route. Stainless wire goes through the heading aisle, the button head and hex socket are formed, the flat washer is placed on the blank, and the thread is rolled so the last crest captures the washer. The assembled parts are then coated, patched if the drawing calls for a locking patch, and gauged.
|
|
Between runs the die insert is changed to the drawing head form and socket size, and the washer lot is checked against the drawing before it goes into the feeder. The first parts go to the gauges before the run continues, and the setting is recorded so a repeat order can be compared with the approved sample.
What decides whether a socket head sems screw passes is not its appearance: it is the washer staying on the screw and floating freely, the socket taking the key after coating, and the thread matching the tapped part. The inspection agreement covers those, and the criteria are the ones written on the drawing.
Thread gauging against GO/NO-GO gauges |
Head and washer profile on the optical projector |
Hardness testing of the base material |
Salt-spray testing of the e-coat |
Each batch is recorded against the drawing revision: head and washer from the first article, the washer checked for capture and freedom, the socket checked with the key, and the thread gauged after coating. If a gauge or the washer check fails, the parts back to the last good setting are held and re-checked before anything ships.
Where a third-party report is required for the material or the coating, it is listed on the drawing so the paperwork ships with the parts, and the batch number on the label matches the record used for the gauge.
Every socket head sems screw shipment is traceable to the wire it was made from and to the washer lot that went into it. The grade, heat number and standard are recorded on the material certificate, 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 coating. 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 forming, coating and assembly steps their parts will go through.
|
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 header, the thread rolling and the coating 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 machine screw with a hex socket and a flat washer assembled on it, held under the head by the rolled thread so it cannot drop off. The washer stays with the screw through handling and assembly.
The washer is placed on the blank before thread rolling, and the first rolled crest stands larger than the washer bore. The washer can float and turn, but it cannot come off the shank.
The orange electrophoretic coat is applied after the washer is captured, so head, washer and shank are coated in one pass and the colour is continuous across the joint instead of stopping at the seam.
Socket head sems screws are quoted from M2 to M10 and up to 200 mm, usually held to +/-0.1 mm. Where a long version is required, custom lengths up to 2,000 mm are subject to DFM review after drawing submission.
It is a nylon locking patch applied to half the thread circumference. It presses against the mating thread when the screw is driven, adding friction that resists loosening under vibration.
Thread size and pitch, thread length and position, total length and datum, head diameter and height, washer diameter, bore and thickness, socket size, patch position, material grade, coating colour and gauging condition.
How a socket head sems screw project runs from drawing to repeat delivery:
|
1
Send the drawing or sample
|
→ |
2
DFM review and quotation
|
→ |
3
First article approval
|
→ |
4
Batch production and repeat orders
|
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 socket head sems screw quotation, send the drawing with thread size and pitch, thread length and position, total length with its datum, head diameter and height, washer diameter, bore and thickness, socket size, patch position, material grade and coating colour.
|
Thread size and pitch
|
Thread and total length
|
Head diameter and height
|
|
Washer diameter, bore and thickness
|
Socket size and patch position
|
Material grade and coating colour
|
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
