Black Zinc Plated Truss Wafer Head Screws

We make wafer head screws in carbon steel with an eco black zinc plate, a wide shallow head and a self tapping thread, quoted to the drawing. The wide face spreads the clamp so thin material is not marked, and the head and the material it holds are agreed before the first article.

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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.

What Wafer Head Screws Are

Wafer head screws have a very wide, very shallow head, wider than a truss head and lower than a pan head, used to hold thin or soft material without pressing into it. The part recorded here is carbon steel with an eco black zinc plate, with a Phillips recess and a self tapping thread, quoted from M1 upward.

Wafer head. A broad, flat head that spreads the clamp over a large area with almost no height.

Phillips recess. A cross recess sized to the small head height, driven with a standard bit.

Self tapping thread. A coarse thread that forms its own thread in plastic or thin sheet.

They are used on films, membranes, thin mouldings and soft panels, where a smaller head would print a ring into the surface. Wafer head screws are also chosen where the fixing will be seen on a dark panel, because a wide low head reads as part of the surface rather than as hardware.

The Wide Head Spreads Pressure, Not Clamp

A wafer head is chosen for what it does to the material under it, not for what it does to the joint. The head diameter is large and the height is small, so the clamp load is spread over an annulus several times wider than a pan head of the same thread. That is what keeps a thin plastic sheet from dishing and a painted panel from showing a ring.

The consequences run both ways. A wide head means low pressure, which is good on soft material; but because the head is low, there is very little material for the recess, and the recess therefore limits the torque the screw can take. On a wafer head screw the drive is the weak feature, and the joint has to be specified around what the drive can transmit rather than around what the thread could carry.

The self tapping thread adds a second constraint. A wide head is often paired with a coarse thread into thin material, and the forming action pushes material outward under the head. If the head is wide enough and the material thin enough, the displaced material has nowhere to go and the sheet buckles slightly around the head. That is why the head diameter and the sheet thickness have to be considered together rather than separately.

The head also takes up space. A wafer head is wider than the counterbore that a normal screw would need, so the clear area around the fixing has to be planned, and on a dense assembly two wafer heads can touch. On a small product that is often the reason a different head form is chosen.

The finish is the last part. Eco black zinc gives a dark, uniform head on a carbon steel screw, and on a wide visible head the coating is judged over a large area; a plate that looks even on a small head can show a wave on a wafer head, which is why the head face is inspected as a surface rather than only as a dimension.

Head, Recess and Thread

The part is quoted to the drawing with the head, the recess and the thread stated separately. Custom lengths up to 2,000 mm, subject to DFM review after drawing submission. The quotation for wafer head screws carries the head diameter and height, the recess, the thread and point, the length, and the thickness of the material it holds.

The head diameter is the dimension that changes the joint. It has to be wide enough to spread the load and small enough to clear whatever is around the fixing, and on a thin product those two limits can meet.

The recess is limited by the head height. A wafer head is low, so the cross is shallow, and the torque it takes is lower than on a pan head of the same thread. That is a designed limitation, not a defect, and the assembly torque has to respect it.

The thread and the material are agreed as a pair. A coarse thread into a thin sheet displaces material under the head, so the sheet thickness is part of what the screw has to suit.

What Wafer Head Screws Give and Costs

Four properties decide wafer head screws, and each one carries a cost:

The value is a fixing that does not leave a mark. On a film, a membrane or a thin painted panel, the wide head is the only way to hold the material without a washer and without dishing it.

The cost is space and torque. The head takes up area, and the recess takes less torque than the thread could carry, so the joint has to be designed around the head rather than around the screw’s strength.

Eco Black Zinc on a Wide Head

The recorded finish is eco black zinc, a trivalent black passivation over a zinc layer. It gives a dark, uniform head that disappears against a dark panel, and sacrificial protection on a carbon steel screw.

Surface Options for Wafer Head Screws

On a wide head the coating is a visible surface. Coverage over a large flat face is easier than over a dome, but a thin plate shows as a lighter ring at the edge, and on a wafer head that edge is a long perimeter.

The recess is the functional side. A low head has little material above the shank, and a heavy plate inside the cross changes which bit enters, so the recess is checked with the matching bit after plating.

Where Wafer Head Screws Are Used

Three assemblies where the material under the head is the concern:

Why Shi Shi Tong for Wafer Head Screws

Four reasons that matter on a head whose job is to spread load, each tied to something the drawing or the first article proves. All four show in the sample.

How Wafer Head Screws Are Made

These screws are cold headed from carbon steel wire, with the wide head formed and faced, the cross recess cut and the thread rolled; the parts are then black zinc plated. The first piece of every run is measured on head diameter and height, face flatness, recess depth and width, thread and length.

The wide face is the feature that decides the part. It is formed in the heading die and then faced flat, and the flatness of a large annulus is harder to hold than the flatness of a small one: a die that is slightly off leaves a face that bears on its outer edge and lifts in the middle, and on a thin panel that shows as a ring.

The recess is cut after the face is finished, so its depth is taken from the bearing surface. On a wafer head the head is low, so the recess depth is limited; cutting it deeper than the drawing is the fastest way to make a head that collapses under the bit.

The thread is rolled and the parts are plated last. Because the head is wide and visible, the plate is checked across the whole face and at the edge, and the recess is checked with the key bit after plating.

Inspection: Face, Recess and Thread

What decides whether wafer head screws pass is the head face, the recess and the thread. The inspection agreement covers those, and the criteria come from the drawing.

Head face and recess on the projector	Thread and start checked
Core hardness checked	Salt-spray testing of the black zinc

The head face is checked for flatness across its full width and for mark freedom. On a wafer head the face is the bearing surface and the visible surface at once, so a waviness or a tool mark is both a cosmetic and a functional defect.

The recess is measured for depth and width and checked with the matching bit. On a low head the recess is shallow, and a burr on one wall is enough to stop the bit or to round the cross on the first turn.

The thread is gauged and a sample is driven into a sheet of the customer’s thickness, with the head face inspected afterwards for the mark it leaves. That test is the one that shows whether the wide head is doing its job.

Certificates and Material Documentation

Every batch of wafer head screws is traceable to the wire it was made from and to the plating lot that finished it. The grade and heat number appear on the material certificate supplied with the parts, and the plating report carries the layer thickness and the lot number.

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, including the head face and recess, and the plating report. The records carry the drawing revision and the batch number, so a repeat order of wafer head screws bears the same way.

Customers and Projects

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 wide head the first article is assembled on the customer’s material, because the mark the head leaves is the property being bought. Buyers visit during the process to review samples.

Buyers and quality engineers visit for sample review, process discussion and supplier audits; the visit is arranged around production so the heading cell 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

Related Products and Guides

Technical Guides

What Are Truss Head Screws Where a wide, shallow head is the right choice, and how it is customised. Read the guide

Benefits of Stainless Self Tapping Screws Where a forming thread makes sense, and where it does not. Read the guide

Products

Truss Head Shoulder Screws The truss head version in stainless steel. Truss Head Shoulder Screws	Self Tapping Washer Head Screws The pan washer head self tapping version. Self Tapping Washer Head Screws	Pan Head Phillips Screws The pan head Phillips self tapping version. Pan Head Phillips Screws
Stainless Self Tapping Metal Screws The stainless version for metal joints. Stainless Self Tapping Metal Screws	316 Stainless Self Tapping Screws The 316 stainless self tapping version. 316 Stainless Self Tapping Screws	Tiny Self Tapping Screws The countersunk flat head tiny version. Tiny Self Tapping Screws

Wafer Head Screw FAQ

Order Wafer Head Screws

How a wafer head screw project runs from drawing to repeat delivery:

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.