One Way Security Screw, Stainless Steel Book Screws

We make one way security screws in stainless steel with a truss head, quoting them from M1 to M10 with lengths made to the drawing. The slot is proved in both directions with your blade, and the first article is bound and pull tested.

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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 One Way Security Screws Are

A one way security screw has a single slot cut on a slope, so a flat blade can drive it in but cannot drive it out. The part recorded here is stainless steel with a plain finish and a large truss head, quoted from M1 to M10 with lengths made to the drawing.

One way slot. A single slot whose walls are ramped in one direction, so torque drives the screw clockwise and the blade rides out counter-clockwise.

Truss head. A wide, low head that spreads the clamp and gives a book or a panel a large face to bear on.

Stainless body. No coating to wear at the slot, and no corrosion in a part that is handled for years.

Machine thread. A uniform thread for a nut, a binding post or a tapped insert.

They are used on sample books, swatch books, menus, photo albums, security covers and access panels, where a fixing has to be assembled once and not opened casually afterwards.

A Slot That Only Goes One Way

The one way drive is a slot cut with a ramp. Clockwise, the blade presses against a near-vertical wall and turns the screw; counter-clockwise, the blade meets the ramp and is pushed up and out of the slot before it can transmit anything. There is no second set of walls to hold it, which is what makes the drive work in only one direction.

That is a different idea from a pin or a star, and it has a different consequence. A pin excludes a standard key and lets the owner keep one; a one way slot excludes the removal direction for everyone, including the owner. Once the screw is in, it is removed by cutting a slot, by gripping the head, or by destroying the part.

So the joint this part belongs in is one that is assembled once. Sample books, swatch books and menus are exactly that: they are built in a workshop and are not meant to come apart in the field. On those products the one way screw is a simple, cheap way to stop a binding being opened and re-sorted.

The truss head is the other half of the design. A binding part is thin and usually covered with a printed or laminated surface, so the fixing needs a wide bearing face to spread the clamp without marking the cover. A truss head gives that, and its low height keeps the binding flat.

Stainless is chosen for the service life of the product rather than for strength. A menu or a sample book is handled daily and cleaned occasionally, and a plated screw would wear at the slot and stain the edge of the binding. A plain stainless part keeps its slot and does not mark what it touches.

Sizes, Head and Slot

The recorded range is M1 to M10, with lengths made to the drawing. Custom lengths up to 2,000 mm are subject to the drawing submission and DFM review. The quotation for a one way security screw carries the diameter, the head diameter and height, the slot width and depth, the thread pitch and the overall length.

The slot geometry is the specification, and it is worth describing as a behaviour rather than only as a width. The blade has to enter, transmit torque in the drive direction, and be pushed out in the other; a slot that is too deep or too shallow changes one of those three and the part no longer behaves as a one way drive.

Length is measured over the head. On a binding the usable length is the overall length minus the thickness of the stack, and on a Chicago-style fixing that stack is the cover, the leaves and the back cover.

The thread is usually a machine thread that engages a binding post or a nut rather than cutting into the material, which is what lets a book be bound tightly without splitting the board.

What One Way Security Screws Give and Costs

Four properties decide one way security screws, and each one carries a cost:

The value is a fixing that stays put without a special tool. Nothing has to be issued to the assembly team and nothing has to be kept on file: the part simply cannot be undone in the normal way.

The cost is that the decision is final. When a sample book has to be re-sorted or a cover replaced, the fixing has to be cut out, and that has to be understood before the product is designed around it.

Plain Stainless and the Alternatives

The recorded finish is plain. On a one way slot that matters because the slot is the drive: a coating inside it changes the ramp the blade follows, and on a shallow head the difference is enough to stop the blade entering at all.

Surface Options for One Way Security Screws

Where a coating is used, the slot is checked after plating and proved with the blade. A film that closes the ramp by a few hundredths will stop the blade seating, and the part then cannot be driven at all, which is the most expensive kind of failure on an assembly line.

Black oxide on stainless is the sensible way to get a dark one way screw. It keeps the ramp as cut and gives a colour without a deposit that changes the drive.

Where One Way Security Screws Are Used

Three settings where a fixing is assembled once and not reopened:

Why Shi Shi Tong for One Way Security Screws

Four reasons that matter on a fixing that cannot be undone, each tied to something the first article has to prove:

How One Way Security Screws Are Made

These screws are headed on single-die machines that form the truss head, cut with the one way slot, thread rolled and passivated. The first part of every run is measured on head diameter and height, slot width and depth, ramp form, thread and length.

Cutting the one way slot is the operation that decides the part, and it is a cutting geometry rather than a size. The ramp has to be steep enough to hold the blade in the drive direction and shallow enough to expel it in the other, and both are set by the tool rather than adjusted afterwards.

A truss head gives more width than a pan head at the same diameter, which is what a binding needs, but it also leaves a shallower section for the slot. The head height and the slot depth are therefore measured together on the first article, since a slot cut a little deep in a wide head leaves too little material under it.

Passivation follows and reaches into the slot. That is the smallest feature on the part and the one that holds contamination, so the batch is proved with a blade in both directions before packing rather than only inspected on the head.

Inspection: Slot, Head and Thread

What decides whether one way security screws pass is the slot, the head, the thread and the surface. The inspection agreement covers those, and the criteria come from the drawing.

Slot width and ramp on the projector	Thread and start checked
Hardness against the stainless spec	Salt-spray testing of the slot

Slot width and depth are measured on the projector together with the ramp form, and the head is measured for diameter, height and bearing face flatness. On a truss head the wide face is the feature the binding bears on, so its flatness matters as much as the slot.

The functional check is a pair of drives with the blade the customer uses: one in the drive direction at the assembly torque, and one against the removal direction to confirm that the blade rides out. A part that fails the second check is not a one way screw, whatever its slot measures.

A sample from every batch is bound into the customer’s book or cover and pulled open, which shows whether the head crushes the material or the thread pulls through.

Certificates and Material Documentation

Every batch is traceable to the heat of stainless it was made from. The grade and heat number appear on the material certificate supplied with the parts, and the inspection record carries the measured slot and head against the drawing.

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 slot, and the passivation records for the batch. The documents carry the drawing revision and the batch number, so a repeat order of one way security screws drives 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 one way part the first article is driven and then tested against removal with the customer’s blade. 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 headers and the slotting station 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

Security Screws: What Each Drive Actually Stops How one way, pin-in-hex and star-pin drives differ in what they exclude. Read the guide

Plating Requirements for Screw Surface Treatment What a coating does inside a drive, and why the slot is re-gauged. Read the guide

Products

Security Socket Head Cap Screws A pin-in-hex drive for the socket family. Security Socket Head Cap Screws	Pan Head Security Screws A Y drive on a pan head. Pan Head Security Screws	Pan Head Torx Pin Anti Theft Screw The star pin drive version. Pan Head Torx Pin Anti Theft Screw
Large Head Self Tapping Screws The wide head form for soft materials. Large Head Self Tapping Screws	Cross Recessed Pan Head Screws A standard drive for bindings that open. Cross Recessed Pan Head Screws	Brass Pan Head Machine Screws A single slot that can be undone. Brass Pan Head Machine Screws

One Way Security Screw FAQ

Order One Way Security Screws

How a one way 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.