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- The AS568 O-Ring Size Standard and Why It Saves You Tooling
AS568 is the reason some O-ring quotations come back with no tooling charge and a short lead time, and others do not.
What AS568 Actually Is
AS568 is the aerospace derived standard that fixes a family of O-ring inside diameters and cross sections, each identified by a dash number. Its usefulness is not technical elegance. It is that a tool already exists somewhere in the world for every size in it, so a designer who stays inside the standard never pays for a mould.
Why We Hold the Complete Mould Set
We possess all the moulds for the AS568 O-ring size range, which is why we can supply standard parts from the series promptly. For a buyer this means a standard dash number is a stock production item rather than a tooling project, and the compound becomes the only open question.
AS568 O-Ring Series →
Reading a Dash Number
A dash number encodes a cross section family and a size within it. The practical consequence is that two parts with similar inside diameters may have very different cross sections, and a cross section mismatch is the most common cause of a seal that fits the groove diameter and still leaks. Always quote the full dash number rather than measuring the inside diameter alone.
When to Stay Standard and When Not To
If your groove is not yet fixed, design it around a standard dash number and you remove a tooling cost and a lead time from the project permanently. If the hardware is already in production, then the size is what it is, and the right answer is a properly tooled non standard seal rather than the nearest standard size forced into the groove. Our mould workshop cuts those tools.
Where AS568 O-Rings End Up
The range of equipment using these sizes is very wide: machine tools, agricultural machinery, instrumentation, construction machinery, automobiles, ships, aerospace equipment, engineering machinery, chemical machinery, mining machinery, plastic machinery and petroleum machinery. That breadth is exactly why standardising on the series is worth doing.
O-Rings →
Products Mentioned in This Guide
AS568 O-Ring Series
We possess all the moulds for the AS568 O-ring size range, which lets us supply standard parts of the series promptly and without a tooling step.
O-Rings
An O-ring is the cheapest part in most assemblies and the most common cause of a warranty return.
NBR O-Rings
NBR is the working compound for anything that meets oil or fuel at moderate temperature.
Quick Answers
No. We hold the complete AS568 mould set, so standard sizes need no new tool.
Tell us the dash number and the compound you want and we will confirm. The size is not the constraint, the compound and quantity may be.
Send a photo with a measurement of the inside diameter and the cross section thickness. We can usually identify the dash number from that.
Put This Into a Quotation
Send the size, the medium and the quantity, and we will apply exactly the reasoning in this guide to your part.
Request a Quote
We reply to every enquiry within one business day. Write to us directly by email or WhatsApp — both reach our sales desk immediately.