Spline vs. Welded Roll Connections in Plate Rolling Machine: Which is Better?

When it comes to metal fabrication, a lot depends on plate rolling machines operating 24*7 without breaking down or yielding sub-optimal products. 

A roll connection in the plate rolling machine plays a crucial role in both these cases. 

It is directly responsible for high torque transfer between the drive system and the rolls and decides:

• The metal-bending efficiency of the machine

• The machine’s durability over the years of operation under high load

There are two types of roll connections in a plate rolling machine: spline roll and welded roll connections.

You know the value of this roll connection, but two questions remain:

What’s the exact job of both?

Which one should you choose for your product and operating environment?

In this blog, we are going to answer both, so read on and find out which roll connection is right for you!

Spline vs. Welded Roll Connections in Plate Rolling Machine: Table of Contents

• Spline vs. welded roll connections: Table of differences

• What are roll connections?

• What is a spline roll connection?

• What is a welded roll connection?

• Spline vs welded roll connections: 5 key differences

• Our take on the right roll connection

• Spline vs. welded roll connections: FAQs
  

Spline vs. Welded Roll Connections: Table of Differences

If you’re in a hurry and want a quick overview of the differences between spline and welded roll connections, we’ve got you covered. Here’s a quick table of differences based on certain factors:

Factors	Spline Roll Connection	Welded Roll Connection
Permanence	Detachable and serviceable	Permanent joint
Torque Transmission	Torque is evenly distributed across multiple teeth	Torque is concentrated along the weld seam
Precision and Alignment	Excellent repeatability and concentric alignment	Depends heavily on welding accuracy
Total Cost of Ownership	Higher upfront cost	Lower initial cost
Application Suitability	For high-precision, high-load, and repeat-use machines	For simpler applications or budget-limited setups with moderate performance needs

What Are Roll Connections? 

In plate rolling machines, the roll connection serves as a mechanical link that transmits torque from the machine’s drive system to the rolls, powering the bending process.  

If you're bending thick metals, then there should be accuracy in the torque transfer for:

• Even curves

• No roll failure

• Consistent bending results

• No abnormal wear on the bending machine components

We’ll discuss both types of connections, where each has a unique way of delivering the same output. 

What is a Spline Roll Connection? 

A spline roll connection is basically a shaft with grooves on its surface. 

The roll hub also features grooves, and the spline is fitted in by aligning with these grooves. This entire setup transfers the torque output uniformly across the contact points. 

All these spline rolls are generally made of high-strength alloy steels like:

• EN24 

• 42CrMo4

The best thing about a spline roll connection?

• They can be disassembled for maintenance.

• They offer better serviceability,

• They enhance alignment accuracy.

That’s why they are mostly preferred in industries such as aerospace engineering, pressure vessel manufacturing, and shipbuilding. 

What is a Welded Roll Connection? 

A welded roll connection is a permanent joint. 

In this case, industrial-grade welding techniques are used to directly weld the roll shaft to the roll body. The techniques can be:

• MIG (Metal Inert Gas)

• TIG (Tungsten Inert Gas)

• SAW (Submerged Arc Welding)

Plus, welded roll connections don’t use mechanical interlocking.

Instead, they rely on the strength of the weld to transfer torque to the rolls. So, in basic applications, welded connections provide sufficient strength.

This connection is most commonly found in lighter-duty plate rolling machines and cost-sensitive production environments.

Note: As I said, it’s a permanent joint. So, once it is welded, it becomes difficult to disassemble or replace components without cutting.

Spline vs Welded Roll Connections: 5 Key Differences

Your choice between the two roll connections can be correct only if you understand the differences between them based on some important factors. 

In this part, we’ll discuss the differences based on those factors. 

1. Permanence

Since spline roll connections are attached by matching the grooves, they can be easily removed or replaced. 

However, welded roll connections are the ones that cannot be removed. After welding, it becomes a single, permanent unit.

Why Does it Matter?

If your business operates 24/7 and handles large loads, the bending machine parts and functions may be impacted.  

It may require more maintenance and part replacement after certain intervals. In spline connections, it can be done easily and without any disruption in the operations. 

Whereas any failure in welded connections would require cutting, grinding, or a complete replacement. Therefore, maintenance becomes time-consuming, labor-intensive, and expensive.

2. Torque Transmission

As we discussed, spline roll connections have grooves on them, and they are matched with the grooves present on the roll rub to attach with it. Therefore, the torque output gets distributed across the multiple teeth.

On the other hand, welded roll connections are considered permanent. They are welded to the roll hub to form a single unit. The torque output is concentrated along the welded surface. 

Why Does it Matter?

In the event of inconsistent torque transfer, it may lead to misshapen plates, machine failures, or imperfect rolls. Spline connections distribute the torque transfer over a larger surface area, reducing stress on components. 

In welded connections, stress is localized at the joints, and with cyclic loading or thermal expansion over time, it can lead to the formation of microcracks. This is especially true in high-capacity machines or under continuous load conditions.

3. Precision and Alignment

Spline connections come with a shaft with teeth that keep the rolls aligned, even after a disassembly or maintenance work. 

On the other hand, welded connections have a fixed alignment setting and depend on the quality of the weld. So, any misalignment in this case can throw off the roll’s axis, resulting in physical or financial damage and a mechanical breakdown.

Why Does it Matter?

If you want to produce metal products in large quantities, consistency and precision are crucial. With the perfect alignment setting on the roller, you can ensure both. 

In spline roll connections, you won’t have to worry about both. That’s because the interlocking teeth naturally maintain alignment, even after disassembly or prolonged use.

For welded connections, too, you don’t need to worry, only if it’s a light-duty job. 

However, welded connections rely on the quality of the weld done by the plate rolling machine manufacturer. If the weld quality is not of the highest standard, then the roll’s axis can misalign. This results in reduced precision and excessive wear on bearings.

4. Total Cost of Ownership (TCO)

Spline roll connects may come at a higher cost. That’s solely because it gets precise machining, tight tolerances, and sometimes even specialized surface treatments.

Whereas, if we consider a welded roll connection, it is comparatively cheaper than the other. Here, no complex machining is involved, and it gets manufactured quickly.

Why Does it Matter?. 

Although spline connections are slightly more expensive, they are worth the investment. That’s because you won’t have to cut or rework the entire roll assembly, and it becomes easy to service it. Plus, you save time and money on maintenance. 

The welded ones cost more, only in the long run. If the weld fails or the roll needs replacement, it often involves cutting, re-welding, and potential machine downtime.

5. Application Suitability

Spline roll connections are best suited for:

• High-precision applications

• Heavy-duty rolling ( wind towers, ship hulls, thick structural steel)

• Machines with long service life expectations

• CNC-integrated or automated lines

Welded roll connections are commonly used in:

• Low to medium-duty rolling

• Cost-sensitive systems

• Machines with limited maintenance access

• Shorter product runs or variable workloads

Our Take on the Right Roll Connection

Roll connection is key to your machine’s precision and durability: choose the right one, and you’ll get high-quality results tailored to your requirements. 

From what we have seen in this blog, the spline roll connection is the most practical solution compared to welded rolls: 

Spline rolls combine precision with flexibility and maintenance with durability. 

That’s why we at Himalaya Machinery use a spline-based design in our plate rolling machines. 

So, if you're looking for plate rolling machine manufacturers that can help you get high-quality spline rollers, you’ve come to the right place. 

We specialize in manufacturing rolls with: 

• Superior torque distribution

• Consistent alignment

• No complexity and easy to maintain

Plus, we have been providing this service for over four decades, and our extensive experience speaks volumes about the quality of our machines. 

If you need a reliable plate rolling machine equipped with the most advanced roll connection technology, why not connect with us?

Our expert engineers will help you select the ideal roll connection perfectly suited to your operational requirements!

Spline vs. Welded Roll Connections: FAQs

1. What is the main difference between spline and welded roll connections in plate rolling machines?

The main difference between spline and welded roll connections in plate rolling machines is that:

• Spline connections use interlocking grooves for torque transfer, offering flexibility and precision. Plus, since they can be detached from the rolling assembly, they are also easier to maintain.

• In welded connections, the roll is welded to the shaft, forming a permanent bond. It may be challenging to service, and the alignment accuracy may be compromised.  

2. Which roll connection is more durable in heavy-duty plate rolling operations?

Spline connections are more durable for heavy-duty operations due to:

• Uniform torque distribution

• Better fatigue resistance

• Ease of maintenance

3. Are spline roll connections more expensive than welded ones?

Yes, spline connections can be more expensive than welded connections. Generally, it has a higher initial cost due to precision machining and materials.  However, eventually, you’ll see that their lifecycle costs are low, as they are reliable, the parts can be easily removed and replaced, and there is a low risk of premature machine wear.

4. Does Himalaya Machinery offer both types of roll connections?

Primarily, Himalaya Machinery manufactures machines with spline roll connections. However, we also offer welded configurations for specific applications upon request.