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 Steel Micro Screws
Materials:Stainless Steel
Surface treatment:Plain
Head Type:Low head
Drive:Phillips cross recess
Thread:Fine machine thread
Point:Plain, chamfered
Forming:CNC turning; recess milled
Size:M1 M2 M3 M4 M5 M6 M7 M8 M9 M10
We make stainless steel micro screws with a low head and Phillips recess, quoting the controlled dimensions and the inspection method with the part. At a millimetre, hand tools cannot measure the features, so head and recess are checked optically and the fit is proved by assembly.
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 micro screws are screws of about a millimetre in diameter, used in watches, eyewear, hearing instruments and small electronic assemblies. The part recorded here is stainless steel left plain, with a Phillips recess and a low head, quoted from M1 upward.
Micro diameter. A thread around 1 mm, with a pitch of a quarter of a millimetre and a head a millimetre or two wide.
Machine thread. A fine thread that goes into a tapped hole or a small nut rather than forming its own.
Low head with a cross. A head that sits close to the surface and a recess sized to the smallest standard bit.
They are the screws that hold the smallest products together, and the ones whose quality depends most on how they are measured rather than on how much material they contain. That is why the drawing for stainless steel micro screws is as much an inspection document as a geometry one.
A caliper is not a suitable instrument for a stainless steel micro screw. Its resolution is a fraction of the tolerance, and its measuring force compresses the thread crest, so the number it gives depends on how hard it was closed. At this size the part cannot be checked with hand tools, and the way it is inspected becomes part of the specification.
The thread is the first problem. An M1 thread has a pitch of a quarter of a millimetre and a thread depth of about a tenth of that. A thread gauge will tell you whether the screw goes into a gauge, but not where in tolerance it sits, and a projected shadow tells you the flank angle only if the screw is held on axis. The result is that micro threads are usually verified by gauging and sampled by optical measurement rather than measured individually.
The head is the second. The recess is a few tenths of a millimetre deep, and the head height is comparable. A measurement that is off by five hundredths is a significant fraction of the feature, which is why the inspection is done on a projector with a defined magnification and the result recorded as an image rather than a number read off a dial.
The third is that some features cannot be measured after the fact at all. Fit into the bore, for instance, is not a screw dimension: it is a pair. The same applies to the recess and the bit. Those are checked by assembling a sample with the customer part, and the result is a pass or fail on a joint rather than a dimension on a drawing.
For the customer this changes what a supplier has to provide. A micro screw with a certificate of dimensions is not enough; the certificate has to say which features were measured, with what instrument, and which were proved by assembly. That is what makes the difference between a batch that can be accepted and one that has to be sorted.
The part is quoted to the drawing with the controlled dimensions named. Custom lengths up to 2,000 mm, subject to DFM review after drawing submission. The quotation for stainless steel micro screws carries the thread, the head, the recess, the length under the head, and the inspection method for each.
| Feature | How it is verified | Why that method |
|---|---|---|
| Thread diameter and pitch | Thread gauge plus optical sample | Hand tools compress a micro crest |
| Recess depth and width | Optical projector | Too small for a dial reading |
| Head diameter and height | Optical projector | Sub-hundredth resolution needed |
| Shoulder or seat | Projector and fit check | Seat is a pair with the part |
| Recess to bit | Assembled with the customer driver | Only the joint shows it |
| Bore fit | Assembled in the customer part | Fit is a pair of tolerances |
The drawing lists which of those is controlled and which is reference. On a micro part not every dimension can be held at once, and asking for all of them turns into a part that passes on paper and fails in assembly.
The length under the head is the one most often mis-stated. It is measured from the seat face, and on a low head the face is a small annulus, so the measurement reference has to be defined rather than assumed.
The material grade is the other dimension that cannot be measured on the part. It appears on the mill certificate and is confirmed per heat, which is why the certificate is part of the delivery rather than paperwork attached to it.
Four properties decide these micro screws, and each one carries a cost:
| Property | What it gives | What it costs |
|---|---|---|
| Micro size | Fits the smallest assemblies | Cannot be checked with hand tools |
| Machine thread | A repeatable joint in a tapped hole | Needs a tapped hole and galling control |
| Low head | Nearly flush in a small part | Shallow recess, limited torque |
| Stainless, plain | No rust from handling | Galling and no sacrificial layer |
The value is that the fixing exists at a size where nothing else will fit, and that a proper inspection record makes it usable in a product line where every part has to be traceable.
The cost is that the quality is carried by inspection rather than by the part’s bulk. At this size a batch without a clear inspection agreement is a batch that will be sorted at the customer’s expense.
The recorded finish is plain stainless steel. On a micro screw a coating is a large fraction of the features: a plate measured in microns is a visible share of a recess that is a few tenths deep, and it can close a slot that was cut to take a 0.2 mm blade.
| Option | How it protects | Effect on recess and thread | Typical use |
|---|---|---|---|
| Plain, passivated | Passive film, no coating | Recess and thread as cut | Watch, eyewear, instruments |
| Passivated 316 | Higher alloy passive layer | No build; harder to machine | Medical and marine |
| Dry film lubricant | Low-friction film | Thin; reduces galling | Frequently serviced joints |
| Nickel plated | Hard bright barrier | Thin build; recess re-gauged | Visible decorative parts |
| Black oxide | Conversion film, oiled | No measurable build | Dark optical assemblies |
Where a coating cannot be avoided, the recess is the first feature to check after plating, because it is the feature with the least margin. A cross that is a few tenths deep has no room for a layer that adds a tenth to both walls and the floor.
Passivation is the finish that changes nothing dimensionally, which is why it is standard on micro parts: the inspection record and the delivered part describe the same geometry.
Three products where the screw is the smallest controlled component:
| Where it sits | The screw holds a case, a lens rim or a temple where nothing may stand above the surface. |
| When it goes wrong | The recess rounds during service, or the head stands proud of the frame. |
| Why it happens | The head height is wrong, or the recess is at the bottom of its depth range. |
| What we control | Recess and head height checked; first article fitted into the frame. |
| Where it sits | The screw closes a shell that is handled daily and is smaller than a coin. |
| When it goes wrong | The joint loosens, or the head catches on the case. |
| Why it happens | There is no locking feature, and the head is too tall for the shell. |
| What we control | Thread and head height checked; first article assembled and re-opened. |
| Where it sits | The screw fixes a board or a bracket where the assembly is placed by a machine. |
| When it goes wrong | The screw will not pick up, or the recess is damaged by the placement tip. |
| Why it happens | The head form does not suit the pickup, and the recess is shallow. |
| What we control | Head and recess checked against the pickup; first article run on the line. |
Four reasons that matter on a part whose quality is carried by inspection, each tied to something the drawing or the first article proves. All four show in the record.
|
Controlled dimensions named
The drawing names which dimensions are controlled and how each is verified, because at this size not every feature can be held at once. Basis: Controlled list agreed. |
Optical inspection, not calipers
The head and recess are checked on an optical projector and the thread by gauging, because hand tools compress a micro crest. Basis: Optical and gauge records. |
|
Joint proved by assembly
The features that only exist as a pair, like recess to bit and bore fit, are proved by assembling a sample with the customer part. Basis: Pair features proved. |
Same record on repeat runs
Instrument, method and limits are recorded with the drawing revision, so a repeat batch is accepted the same way. Basis: Same method across orders. |
These screws are turned from stainless bar with the head formed and faced low, the recess cut and the thread cut; the parts are cleaned, passivated and inspected. The first piece of every run is checked on the projector for head and recess, gauged for thread, and measured for length under the head.
|
|
The recess is cut with a tool that is smaller than the cross it makes, and the depth is set from the finished head face. At this size the tool has to be changed on a count rather than when the recess starts to look wrong, because a worn cutter produces a cross that measures close to size and will not hold a bit.
The thread is cut rather than rolled, so the crest stays clean and the major diameter stays predictable against the gauge. Rolling a micro thread in stainless can smear the crest, and a smeared crest is the kind of defect that passes a gauge and fails in a tapped hole.
Passivation comes last and is followed by inspection rather than the other way round, because the inspection record has to describe the delivered surface. Parts are then counted and packed so the customer can pick them individually, since a mixed batch of micro screws cannot be sorted by hand.
What decides whether stainless steel micro screws pass is the controlled list and the record that proves it. The inspection agreement covers both, and the criteria come from the drawing.
Head and recess on the projector |
Thread gauged |
Material checked |
Salt-spray testing where plated |
The projector is used for everything that cannot be gauged: head diameter and height, recess depth and width, and the squareness of the seat. Each result is recorded with the magnification and the sample reference, so a repeat order can be compared with the first article.
The thread is gauged and sampled for flank form. A gauge tells pass or fail; the sample on the projector shows whether the batch sits near the middle of the tolerance or at an edge, which is what predicts how the next batch will compare.
The assembled checks come last, because they are the only ones that test the pairs: the recess with the customer’s bit and the thread with the customer’s tapped hole. Those results are recorded as pass or fail on the joint, not as dimensions.
Every batch of stainless steel micro screws is traceable to the bar it was made from and to the passivation lot that finished it. The grade and heat number appear on the material certificate supplied with the parts, and the inspection record names the instrument used for each controlled dimension.
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 controlled dimensions, and the passivation record. The records carry the drawing revision and the batch number, so a repeat order of stainless steel micro screws is accepted against the same method.
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 micro part the first article comes with its inspection images rather than only a certificate. Buyers visit during the process to review samples.
|
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 inspection bench and the projector 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 |
At a millimetre the resolution and the measuring force are both inside the tolerance, so the reading depends on how the tool is used.
On an optical projector for depth and width, and with the matching bit on a sample from each batch.
The drawing names them: usually thread, head, recess and length under the head, with the rest reference.
Some features only exist as a pair, like recess to bit and thread to tapped hole. Those are proved by assembling a sample.
It can, but the plate is a large fraction of a micro recess, so the recess is re-checked after plating.
Thread and pitch, head diameter and height, recess size and depth, length under the head, grade, and the inspection method.
How a micro screw project runs from drawing to repeat delivery:
|
1
Send the drawing and the mating parts
|
→ |
2
Controlled dimensions and method agreed
|
→ |
3
First article with inspection images
|
→ |
4
Batch production and repeat orders
|
Each step is confirmed with you before the next one starts; the drawing revision and method from the first article are what repeat orders are checked against.
For a quotation, send the drawing with the thread and pitch, head diameter and height, recess size and depth, length under the head, the grade, and the mating part and driver.
|
Thread
|
Head size
|
Recess
|
|
Length
|
Grade
|
Mating part
|
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
