Split Lock Washer vs. Spring Lock Washer: What’s the Difference?

Quick Answer Box

Is a split lock washer the same as a spring lock washer?
In many practical fastener catalogs, yes. A split lock washer is often also called a spring lock washer because it has a split helical shape that creates spring tension when compressed.

Is every spring washer a lock washer?
No. “Spring washer” is a broader category. It can include split lock washers, conical spring washers, wave washers, Belleville washers, and other elastic washer designs.

What is the main difference?
A split lock washer describes a specific shape: a ring split at one point and twisted into a helical form. A spring lock washer describes a locking washer that uses spring force. In many cases, both terms refer to the same common washer, but not always.

Where are they used in mechatronics?
They are commonly used around sensor brackets, aluminum extrusion frames, light motor brackets, actuator covers, control panels, cable carrier supports, and general machine structures.

Popular sizes in mechatronic assemblies:
M3, M4, M5, M6, M8, M10, and M12.

Introduction

Fastener terminology can be oddly dramatic for something as small as a washer. Ask whether a split lock washer and a spring lock washer are the same thing, and the answer may depend on who you ask: an engineer, a buyer, a maintenance technician, or a product catalog.

In many purchasing, maintenance, and assembly contexts, the terms split lock washer and spring lock washer are often used almost interchangeably. This is because the most common spring lock washer has a split, slightly twisted shape that creates spring force when compressed under a nut or bolt head.

However, the two terms are not always exactly the same. Split lock washer describes a specific washer shape, while spring lock washer describes the washer’s locking function through spring tension. In many standard fastening applications, both names may refer to the same part. In more detailed engineering selection, the actual washer geometry, size, material, surface finish, and working conditions should still be checked.

This guide clarifies the definition, explains how the two terms overlap, and shows how split lock washers and spring lock washers are selected for practical fastening applications. It also covers where these washers work well, where they may not be enough, and when a stronger locking method should be considered.

In mechatronics, fasteners are not just background hardware. They help secure sensor brackets, motor mounting plates, aluminum extrusion frames, actuator covers, linear motion support structures, cable carrier brackets, and conveyor modules. A washer may be small, but when vibration, repeated motion, and maintenance cycles enter the picture, small parts start acting very important.

JLCMC provides washer options for mechatronic assemblies, including spring washers, lock washers, flat washers, tap washers, internal serrated lock washers, and double-stack self-locking washers. These washers can be selected together with screws, bolts, nuts, aluminum extrusion accessories, sensor brackets, linear motion components, and motor mounting hardware.

By the end of this guide, you will have a clearer answer to a common fastening question: when someone says “spring lock washer,” do they mean a standard split lock washer, or should the exact washer type be confirmed before assembly?

1. The Definition & Clarification

This is the core concept.

What Is a Split Lock Washer?

A split lock washer is a ring-shaped washer that has been cut at one point and twisted into a slightly helical shape. When a screw, bolt, or nut is tightened, the washer compresses. Because of its spring-like geometry, it tries to push back against the fastener and the mating surface.

In simple terms:

A split lock washer is a specific type of lock washer with a split and twisted ring shape.

It is called “split” because the ring is not continuous. It is called a “lock washer” because it is intended to help reduce loosening.

What Is a Spring Lock Washer?

A spring lock washer is a washer that uses spring force to help resist fastener loosening. In many catalogs, drawings, and workshop conversations, “spring lock washer” often refers to the same standard part as a split lock washer.

In simple terms:

A spring lock washer is usually a spring-type lock washer. In many common fastener contexts, it means a split lock washer.

However, the term can be less precise. Depending on the catalog or standard, “spring washer” or “spring lock washer” may also refer to other elastic washer designs.

What Is a Spring Washer?

A spring washer is the broadest term. It refers to washers that provide elastic force when compressed.

Spring washer types may include:

Core Clarification

The clearest way to understand the relationship is:

All split lock washers are spring-type lock washers, but not all spring washers are split lock washers.

Or, more simply:

Split lock washer = specific shape.
Spring lock washer = function-based or catalog-based name.
Spring washer = broader elastic washer category.

This clarification matters because different teams may use different names for similar parts. A buyer may search for “M6 spring lock washer,” while an engineer may specify “M6 split lock washer” on a drawing. In many cases, they may be talking about the same part. But in other cases, “spring washer” may mean a conical washer, wave washer, or another elastic design.

In mechatronic assemblies, that difference can affect assembly height, preload behavior, washer stiffness, surface contact, and vibration performance. Tiny washer, big terminology drama.

2. Why These Terms Are Often Confused

The confusion between split lock washer and spring lock washer comes from the way fasteners are named. Sometimes a part is named by shape. Sometimes it is named by function. Sometimes it is named by catalog category.

Named by Shape

“Split lock washer” describes the physical geometry.

It is a washer with a split and a twisted helical form.

Named by Function

“Spring lock washer” describes what the washer is expected to do.

It provides spring force and helps resist loosening.

Named by Category

“Spring washer” may be used as a broad category for multiple washers that provide elastic force.

This creates overlap.

A standard split washer may appear under several names:

· Split lock washer

· Spring lock washer

· Split washer

· Spring washer

· Helical spring washer

· Lock washer

· Standard spring washer

In everyday purchasing, these terms are often treated as equivalent. In engineering documentation, however, it is better to specify the actual washer geometry, material, size, and standard when possible.

Why It Matters in Mechatronics

Mechatronic equipment often combines structural frames, sensors, motors, electronics, and motion systems. A single assembly may include:

· M3 and M4 fasteners for sensors

· M5 and M6 fasteners for aluminum extrusion accessories

· M6 and M8 fasteners for actuator supports

· M8 and M10 fasteners for conveyor or machine frame structures

· M10 and M12 fasteners for larger equipment bases

If a drawing says “spring washer” but the purchasing team selects the wrong spring washer type, the joint may not behave as expected. For a simple cover, this may not matter much. For a vibration-prone motor bracket, it can matter more.

Good terminology does not make a machine faster, but it can prevent rework, assembly confusion, and very long email threads.

3. How Split Lock Washers and Spring Lock Washers Work

A split lock washer or standard spring lock washer works mainly through elastic deformation and frictional resistance.

When the fastener is tightened, the washer compresses. The split, twisted shape tries to spring back. This creates additional tension in the joint and can increase resistance against fastener rotation.

Basic Working Process

What the Washer Tries to Do

A split lock washer is intended to:

· Add spring tension

·Increase friction

· Help resist light rotational loosening

·Maintain some pressure in the joint

· Improve fastening stability in light-duty assemblies

What the Washer Cannot Do

A split lock washer cannot:

· Replace correct tightening torque

· Fix poor thread engagement

· Stop severe vibration by itself

· Compensate for a badly designed joint

· Prevent loosening in every dynamic application

· Work properly if it is flattened, cracked, or corroded

This is important. A spring lock washer is useful, but it is not a miniature superhero. It still depends on proper torque, correct washer size, good thread engagement, suitable material, and reasonable joint design.

Typical Working Environment

Split lock washers and spring lock washers are commonly used in:

They are popular because they are compact, inexpensive, easy to install, and widely available. That does not make them perfect, but it does make them practical.

4. Split Lock Washer vs. Spring Lock Washer: Comparison Table

The best way to explain the difference is to compare the terms directly.

Practical Interpretation

In many product catalogs:

Split lock washer = spring lock washer

In more technical discussions:

Split lock washer = one specific spring-style lock washer

That is why engineers and buyers should check the actual washer shape instead of relying only on the name.

Example 1: M6 Spring Lock Washer

If a drawing calls for:

M6 spring lock washer

The intended part may be a standard M6 split lock washer.

Example 2: M6 Conical Spring Washer

If a drawing calls for:

M6 conical spring washer

That is not the same as a split lock washer. It has a different shape, height, spring behavior, and load response.

The keyword is not just “spring.” The geometry matters.

5. When to Use Split Lock Washers or Spring Lock Washers

Split lock washers and standard spring lock washers are best suited for general fastening points where vibration is light to moderate and the joint is not safety-critical.

They are commonly used when the goal is to add basic anti-loosening support without increasing cost, complexity, or installation difficulty.

Suitable Applications

Popular Sizes in Mechatronics

For many mechatronic assemblies, M3, M4, M5, M6, and M8 are the most frequently used sizes. M10 and M12 appear more often in larger structures, machine bases, and heavy-duty supports.

Example: Sensor Bracket

A photoelectric sensor mounted on an adjustable metal bracket may use M3 or M4 screws. A spring lock washer can help keep the bracket stable after adjustment. This is a suitable use case because the load is small, the assembly may need occasional adjustment, and the washer is easy to replace.

Example: Aluminum Frame Cover

A machine guard or side cover mounted to an aluminum extrusion frame may use M5 or M6 screws. A split lock washer can provide basic anti-loosening support while allowing easy removal during maintenance.

Example: Cable Carrier Support

Cable carrier brackets experience repeated movement from the linear axis. M4, M5, or M6 spring lock washers may be used on light support brackets, especially when the assembly is inspected or serviced regularly.

These are the types of jobs where a split lock washer is comfortable. Ask it to secure a small bracket, and it behaves. Ask it to solve extreme vibration alone, and it may start looking nervous.

6. When Not to Use a Basic Split Lock Washer

A split lock washer is useful, but it is not the best choice for every fastening problem.

In high-vibration, high-load, or precision-critical assemblies, a basic split lock washer may not provide enough locking performance. It may flatten under high preload, lose spring action, or fail to prevent rotational loosening over time.

Avoid Basic Split Lock Washers When:

High-Vibration Examples in Mechatronics

· Servo motor bases

· Conveyor drive units

· Robotic arm structures

· High-speed actuator supports

· Ball screw support brackets

· Rotating equipment mounts

· Pneumatic impact mechanisms

· Heavy machine frame connections

For these locations, a standard split lock washer may be too basic. A more reliable locking method may be required.

Precision Linear Motion Warning

For linear guide rail mounting, do not add a split lock washer under the rail screw unless the machine design or component instructions require it. Precision rail mounting depends on clean surfaces, correct torque, stable seating, and proper alignment.

Adding extra washer layers can affect seating height, contact stiffness, and alignment. For precision parts, “more hardware” does not automatically mean “more secure.”

Aluminum Surface Warning

Split lock washers are less aggressive than serrated tooth washers, but they can still leave contact marks under load. On visible aluminum extrusion frames, anodized plates, or finished panels, surface appearance and contact pressure should be considered.

A washer is small, but it can still leave a very confident scratch.

7. Material and Finish Selection

Material selection affects strength, corrosion resistance, spring performance, and service life.

Common Materials

Spring Steel

Spring steel is commonly used for spring lock washers because it provides elastic recovery. It is suitable for general fastening applications where spring tension is needed.

Carbon Steel

Carbon steel spring lock washers are commonly used in indoor machinery, aluminum frame systems, brackets, covers, and general industrial equipment. They are practical for many cost-sensitive machine structures.

SUS304 Stainless Steel

SUS304 stainless steel is often selected when corrosion resistance is required. It is commonly used in humid environments, clean equipment, stainless steel structures, and sensor assemblies.

SUS316 Stainless Steel

SUS316 stainless steel provides stronger corrosion resistance than SUS304 in selected environments. It may be used in more demanding chemical, marine-related, or outdoor-related conditions.

Common Surface Finishes

Selection Note

For mechatronic assemblies, do not choose a washer only by price or finish. The washer should match:

· Fastener size

· Working environment

· Contact material

· Vibration level

· Maintenance plan

· Corrosion requirements

· Required spring performance

A shiny washer is nice. A suitable washer is better.

8. How to Use Split Lock Washers and Spring Lock Washers

Installation is simple, but correct placement matters.

Basic Placement Rule

Place the split lock washer or spring lock washer under the fastener side being tightened.

This usually means:

· Under the nut in a bolt-and-nut assembly

· Under the bolt head when threading into a tapped hole

· Under the screw head when fastening into a threaded component

Bolt and Nut Assembly

Recommended order:

Bolt head
↓
Parts being clamped
↓
Spring lock washer
↓
Nut

The washer sits under the nut because the nut is the part being tightened.

Bolt Into Tapped Hole

Recommended order:

Bolt head
↓
Spring lock washer
↓
Part surface
↓
Tapped hole

The washer sits under the bolt head because the bolt is tightened into the threaded hole.

Step-by-Step Installation

Using With a Flat Washer

A common arrangement is:

Nut or bolt head
↓
Spring lock washer
↓
Flat washer
↓
Part surface

The flat washer helps spread load and protect the surface. However, this arrangement may not be suitable for every washer type or every joint.

If the washer relies on biting directly into the surface, placing a flat washer underneath may reduce its effect. For standard split lock washers, the best arrangement should follow the drawing, assembly instructions, or design requirement.

Installation Checklist

Before tightening, confirm:

☐ The washer size matches the fastener size
☐ The washer is not flattened or cracked
☐ The contact surface is clean
☐ The fastener has enough thread engagement
☐ The tightening torque is suitable
☐ The washer is placed under the correct side
☐ The material is suitable for the environment
☐ The joint is not precision-critical unless specified

This is not complicated, but it is worth doing correctly. Fasteners rarely fail because someone cared too much about installation.

9. Applications in Mechatronic Assemblies

Split lock washers and spring lock washers are widely used in mechatronic equipment because these systems combine structural parts, moving parts, motors, sensors, and control elements.

Application Map

Sensor Brackets

Sensor brackets often use M3 or M4 fasteners. A spring lock washer can help maintain position after adjustment. This is useful for proximity sensors, photoelectric sensors, and safety light curtain brackets.

For small sensors, even slight movement can cause detection errors. A washer may be small, but sensor alignment is not a place for casual looseness.

Aluminum Extrusion Frames

Aluminum extrusion frames are common in automation machines. M5, M6, and M8 fasteners are frequently used with brackets, joining plates, covers, and guards.

Spring lock washers may help maintain joint stability, especially on parts that are serviced or adjusted.

Motor Brackets

Stepper motors and small servo motor plates often use M3, M4, M5, or M6 fasteners. A spring lock washer may be suitable for light motor brackets or covers.

For higher-vibration motor bases, consider stronger locking methods such as double-stack self-locking washers, lock nuts, or thread-locking adhesive.

Linear Motion Support Structures

Linear guides, ball screws, and actuators require stable support structures. Spring lock washers may be used on auxiliary brackets, covers, cable carrier mounts, and support plates.

However, for precision guide rail mounting or ball screw support unit installation, follow the component’s torque and installation requirements.

JLCMC Product Note

JLCMC spring washer and lock washer options can be used with related mechatronic components such as screws, bolts, nuts, aluminum extrusion accessories, sensor brackets, motor mounting plates, and linear motion parts. For general assemblies, spring washers and split lock washers may be practical choices. For higher-vibration assemblies, JLCMC’s washer category also includes stronger options such as double-stack self-locking washers and serrated lock washers.

The key is to choose by application, not just by product name.

10. Selection Guide: Which Washer Should You Choose?

The choice between a split lock washer, spring lock washer, and other washer types depends on how the term is used and what the joint needs.

Selection Summary

Practical Buying Checklist

Before ordering, confirm:

☐ Is the drawing asking for a split lock washer or a broader spring washer?
☐ What is the fastener size: M3, M4, M5, M6, M8, M10, or M12?
☐ What is the washer material?
☐ Is corrosion resistance required?
☐ Is the assembly exposed to vibration?
☐ Is the washer used on aluminum, steel, stainless steel, or plastic?
☐ Is the part visible after assembly?
☐ Will the joint be removed during maintenance?
☐ Is the joint precision-critical?
☐ Is a stronger locking method needed?

Quick Decision Table

The practical answer is this: if the assembly is simple and vibration is low, a split lock washer or standard spring lock washer may work well. If the assembly is dynamic, high-speed, heavily loaded, or difficult to maintain, choose a stronger locking method.

11. Common Mistakes to Avoid

Mistake 1: Assuming Every Spring Washer Is a Split Lock Washer

This is the biggest terminology mistake. A split lock washer is one kind of spring washer, but spring washers can include other shapes.

Always check the product drawing, dimensions, and geometry.

Mistake 2: Using Split Lock Washers Everywhere

Split lock washers are common, but they are not universal. High-vibration assemblies may need better locking methods.

Mistake 3: Ignoring Surface Material

A washer that works well on steel may not be ideal for aluminum or plastic. Soft materials can deform, settle, or show surface damage.

Mistake 4: Reusing Damaged Washers

Do not reuse a split lock washer if it is flattened, cracked, corroded, or no longer spring-like.

Mistake 5: Using the Wrong Size

The washer should match the fastener size. M6 fasteners need M6 washers. Creative mismatching is rarely creative in a good way.

Mistake 6: Adding Washers to Precision Mounting Surfaces

Do not add washers to precision rail or bearing mounting surfaces unless the design requires them. Extra layers can affect alignment and stiffness.

Mistake 7: Choosing by Name Only

“Spring lock washer” may mean different things in different catalogs. Always verify the actual washer type.

Mistake 8: Expecting a Washer to Fix Bad Torque

Correct torque matters. A washer cannot rescue a poorly tightened joint.

Fastening reliability is a system. The washer is only one member of the team.

12. FAQ: Split Lock Washer and Spring Lock Washer

1. Is a split lock washer the same as a spring lock washer?

In many practical catalogs, yes. A split lock washer is often also called a spring lock washer because it has a split helical shape and provides spring force when compressed.

However, the term “spring washer” can also refer to other elastic washer types, so it is best to check the product shape, dimensions, and specification before ordering or replacing the part.

2. Is every spring washer a lock washer?

No. Some spring washers provide preload or elastic compensation but are not mainly used for locking. A spring washer may help resist loosening, but its exact function depends on its design.

For example, a split lock washer is commonly used for basic anti-loosening support, while a conical spring washer may be selected for preload control or elastic compensation in a bolted joint.

3. Can I replace a split lock washer with a conical spring washer?

Not automatically. A conical spring washer has different height, stiffness, load behavior, and spring characteristics. It may be better in some applications, but the joint design must be checked first.

Before replacing one with the other, confirm fastener length, available space, torque requirements, surface condition, and whether the assembly needs a specific preload behavior.

4. Are split lock washers good for vibration?

Split lock washers may help in light-duty vibration applications, but they are not usually the best choice for high-vibration joints.

For servo motor bases, robotic structures, conveyor drives, actuator supports, or heavy machine frames, stronger locking methods may be more suitable, such as double-stack self-locking washers, wedge-lock washers, lock nuts, or thread-locking adhesive.

5. Can I use a split lock washer on aluminum extrusion?

Yes, a split lock washer can be used on aluminum extrusion assemblies, especially for brackets, covers, and frame accessories. Common sizes include M5, M6, and M8.

However, aluminum is softer than steel. If the surface is visible, anodized, or easily marked, consider whether a flat washer or another locking method is needed to protect the surface.

6. Can split lock washers be reused?

Sometimes, but replacement is usually safer during maintenance.

Do not reuse a split lock washer if it is flattened, cracked, corroded, distorted, or no longer provides spring action. For common sizes such as M3, M4, M5, M6, and M8, replacing the washer is usually cheaper than dealing with loosening, downtime, or rework.

Final Takeaway

The difference between a split lock washer and a spring lock washer is mostly about terminology.

A split lock washer is a specific washer with a split and twisted shape. A spring lock washer often refers to the same product, especially in practical fastener catalogs. A spring washer, however, is a broader category that may include split washers, conical spring washers, wave washers, Belleville washers, and other elastic washer designs.

For mechatronic assemblies, the important question is not only what the washer is called. The better question is:

Does this washer match the fastener size, vibration level, material, surface condition, and maintenance requirement of the joint?

For light-duty brackets, covers, sensor mounts, and aluminum frame accessories, split lock washers or standard spring lock washers may be practical. For high-vibration motor bases, actuator supports, robotic fixtures, and conveyor drive structures, stronger locking methods may be required.

JLCMC provides washer options for mechatronic component assemblies, including spring washers, lock washers, flat washers, internal serrated lock washers, and double-stack self-locking washers. Used together with suitable screws, bolts, nuts, sensor brackets, aluminum extrusion accessories, and linear motion components, these washers help build fastening connections that are more stable, serviceable, and ready for real machine operation.

A washer may be small, but good washer selection is not small thinking. In mechatronics, every stable machine starts with parts that stay where they are supposed to stay.