science

Spring pin

Spring pin is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Spring pin rather than just read about it. In short: A spring pin (also called tension pin or roll pin) is a mechanical fastener that secures the position of two or more parts of a machine relative to each other. Spring pins have a body diameter which is larger than the diameter of the hole they are intended for, and a chamfer on either one or both ends to facilitate starting the pin into the hole.

Key takeaways

Spring pin belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Spring pin to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Spring pin from memory before moving on to harder problems.

Reference excerpt

A spring pin (also called tension pin or roll pin) is a mechanical fastener that secures the position of two or more parts of a machine relative to each other. Spring pins have a body diameter which is larger than the diameter of the hole they are intended for, and a chamfer on either one or both ends to facilitate starting the pin into the hole. The spring action of the pin allows it to compress as it assumes the diameter of the hole. The force exerted by the pin against the hole wall retains it in the hole, therefore a spring pin is considered a self retaining fastener. Spring pins may be used to retain a shaft as a journal in a plain bearing, as a type of key to fasten one shaft to another, or to precisely fasten flat faces of mating parts together through symmetric hole locations.

Types There are two types of spring pins: slotted spring pins and coiled spring pins.

Coiled spring pins

A coiled spring pin, also known as a spiral pin, is a self retaining engineered fastener manufactured by roll forming metal strip into a spiral cross section of 2+1⁄4 coils. Coiled spring pins have a body diameter larger than the recommended hole diameter and chamfers on both ends to facilitate starting the pin into the hole. The spring action of the pin allows it to compress as it assumes the diameter of the hole. When coiled spring pins are installed, the compression starts at the outer edge and moves through the coils toward the center. Coiled pins continue to flex after insertion when a load is applied to the pin thus providing excellent performance to counter fatigue in dynamic applications. Coiled spring pins were invented by Herman Koehl circa 1948. Coiled pins are commercially available in three different duties, standard (ISO 8750), heavy (ISO 8748) and light duty (ISO 8751), which provide for a variety of combinations of strength, flexibility and diameter to suit different mating host materials and performance requirements. Typical materials for coiled spring pins include high carbon steel, stainless steel and alloy 6150. Coiled pins are used extensively in cosmetic cases, automotive door handles and locks, and latches as hinge pins. They are also used as pivots and axles, for alignment and stopping, to fasten multiple components together—such as a gear and shaft—and even as ejector pins to remove motherboards from PCs. The automotive and electrical industries use coiled pins in such products as steering boxes and columns, pumps, electric motors and circuit breakers.

Slotted spring pins

Slotted spring pins are cylindrical pins rolled from a strip of material with a slot to allow the pin to have some flexibility during insertion. Slotted spring pins are also known as roll pins, sellock pins or "C" pins.

International Standards Slotted spring pins: ISO 8752 Standard Duty: UNE–EN-ISO 8750, NASM10971, NASM51923, NAS1407, ASME B18.8.2, ASME B18.8.3M Heavy Duty: UNE–EN-ISO 8748, NASM10971, NASM39086, NAS561, ASME B18.8.2, ASME B18.8.3M Light Duty: UNE–EN-ISO 8751, NASM10971, NASM51987, NAS1407, ASME B18.8.2, ASME B18.8.3M Standard duty coiled spring pins offer the best balance between flexibility and strength and are recommended for most applications. Heavy duty coiled spring pins are typically used in high shear strength applications and hardened host materials. Light duty pins are used in applications with soft metals and plastics holes where there is a high risk of enlarging or breaking the host using a traditional press fit solid pin.

See also Circlip – Type of fastener or retaining ring Split pin – Metal fastener with two tines that are bent during installation Spring plunger, spring-loaded device for indexing, locating, positioning, or locking components against a pin or ball by means of spring force

References

Further reading Parmley, Robert, Standard handbook of fastening and joining. 1st edition. Chapter 2. McGraw-Hill (New York). 1977. ISBN 0-07-048511-9

Illustrations

Worked examples

Example 1 — a first encounter with Spring pin

Start with the simplest possible case. Write down what Spring pin claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Spring pin before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Spring pin ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Spring pin

In research: Spring pin appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Spring pin in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Spring pin is common in secondary-school and first-year university syllabi. It links to neighbouring topics Fasteners, so understanding it makes those chapters shorter.
In everyday life: Look for Spring pin outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Spring pin in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Spring pin means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Spring pin out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Spring pin in simple terms?

Why does Spring pin matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Spring pin?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Spring pin.