What Is the Best Coupling for a Mixer? | Stafford Manufacturing Corp

04 Aug.,2025

 

What Is the Best Coupling for a Mixer? | Stafford Manufacturing Corp

What Is the Best Coupling for a Mixer?

Mixers are common industrial devices that consist of a motor and a propeller or paddle with a coupling acting as the connection point. Mixers are flexible, adaptable pieces of equipment found in a range of industries, from food processing to mining to chemical facilities.

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Choosing the correct coupling for a mixer can be challenging as it needs to have an exact, rigid fit . This blog will highlight how to determine the right coupling for your mixer and how our configurator tool can help you configure your rigid coupling to your needs.

What Is a Rigid Coupling?

Unlike flexible couplings, a rigid coupling does not allow any radial or axial motion between the driving shaft and the driven unit. It is primarily used for vertical applications. Rigid coupling types include:

  • One-piece split couplings when there is access to both the motor shaft end and the paddle attachment.
  • Two-piece split couplings for easy assembly when in-line installation is needed.
  • Three-piece split couplings when the end of the shaft will remain fixed while the other is moved or changed (very common for mixer situations when paddles would be changed or replaced).
  • Flanged couplings when mounting options are needed.

On mixers, the motor is bearing-supported, but the shaft on the impeller side is not. Using a flexible coupling would require close bearing support on the paddle, but the sleeve-like design of rigid couplings eliminates the need for a bearing to support the paddle. This makes rigid couplings the only viable option for mixers.

Rigid couplings have a simple and durable design, allowing greater transmission of power to mixers. They are more cost-effective than other options and offer more design flexibility. While requiring exact alignment between shafts, rigid couplings offer a stronger connection, higher torque, and more precision than flexible couplings.

Advantages of Rigid Couplings for Mixers

Rigid couplings provide advantages, such as:

  • Excellent Torque Transmission: They can transfer torque efficiently between connected shafts.
  • Low Production Costs: Manufacturers such as Stafford Manufacturing can produce custom and standard rigid couplings at affordable prices.
  • Torsional Stiffness: Its high torsional stiffness enables better positioning.
  • High Precision: Rigid couplings offer high precision with almost no windup or backlash.
  • Alignment Capabilities: They can establish shaft alignment between the connected parts and the motor.
  • Easy Assembly: Rigid couplings have a simple design, allowing for easy assembly, disassembly, and maintenance operations throughout the coupling’s lifespan. 

Considerations for Selecting a Rigid Coupling for a Mixer

Choosing the best coupling for a mixer requires precision. Stafford Manufacturing’s configurator tool can help you customize a rigid coupling that suits your exact needs. Configure it by bore diameter, coupling style, coupling material, screw material, finish, and other options available upon request.

Contact us to discuss your requirements of Rigid Coupling Supplier. Our experienced sales team can help you identify the options that best suit your needs.

Here are more details about the top considerations for choosing a rigid coupling for a mixer.

Bore Diameter

Bore diameter ranges from ¼” to 4”. Choosing the right diameter is key to ensuring a  precise alignment.  

Coupling Style

Coupling styles include one-piece, two-piece, and three-piece. One-piece styles have high torque capacities, unlike set screw type couplings. Two-piece styles allow for easy assembly and adjustment. Three-piece styles are used to maintain one shaft’s positioning while the other is adjusted.

Material Selection

Material selection is based on the substance your coupling is exposed to. Coupling materials include brass, 303 and 304 stainless steel, weldable steel, carbon steel, and aluminum.

How to Choose the Best Coupling for a Mixer

Consider these factors when deciding on the best coupling for your mixer:

  • Shaft size
  • Keyway size if needed
  • Required torque capacity
  • Bore diameter
  • Material requirements for specialized (i.e. food-grade) applications

Stafford’s rigid couplings meet these criteria as they are designed with end users’ needs in mind. Our rigid couplings come in different types, from the common one-piece split clamp coupling to precision sleeve couplings.

Are you interested in learning more about Flexible Grooved Coupling? Contact us today to secure an expert consultation!

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Rigid conduit couplings - Mike Holt's Forum

I have a contractor onsite that is installing couplings from a manufacturer with no UL listing & only the EC stamp. I would like them to submit to the AHJ for approval he says there is no need.
I have a contractor onsite that is installing couplings from a manufacturer with no UL listing & only the EC stamp. I would like them to submit to the AHJ for approval he says there is no need.
Actually there is a need,

344.6 Listing Requirements.
RMC, factory elbows and couplings, and associated fittings shall be listed.


With that said, how are you determining that they are not listed?

Roger


There is no UL or accepted NRTL on the box & the couplings possess an EC stamp. Upon writing an to the Mfg. Co., the reply was these items are "built to UL specs".

The EC is for "European commission" I believe the items are made in China.
I'd say you have good reason to reject them based on 344.6


Roger
I'd say you have good reason to reject them based on 344.6


Roger

I'd say he's got evidence to reject them but good reason hasn't been proven yet. Is the area c1d1? If not I'd like to hear some reasoning behind taking the time to pursue this trivial matter


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I'd say he's got evidence to reject them but good reason hasn't been proven yet.
No, good reason has been proven per the article mentioned, is a really necessary, not IMO but it is the code. If you have time why not submit a proposal to remove the listing requirement for a future code cycle.

Roger
No, good reason has been proven per the article mentioned, is a really necessary, not IMO but it is the code. If you have time why not submit a proposal to remove the listing requirement for a future code cycle.

Roger

Haha good one. Seeing as how that wouldn't financially benefit anyone on the cmp I think I'll save myself the effort and complain about it here


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Haha good one. Seeing as how that wouldn't financially benefit anyone on the cmp I think I'll save myself the effort and complain about it here
So, it will remain a code violation and enforceable.

BTW, I would prefer to buy American made anyways.

Roger
So, it will remain a code violation and enforceable.

BTW, I would prefer to buy American made anyways.

Roger

This seems like it would require incredible attention to detail, on an item as insignificant as a conduit coupling, relative to the total scope of the project. How likely is it that an inspector would notice the difference on a conduit coupling, that is still built to the same specs as most UL listed conduit couplings?

Plus, it very well could be that when you install a UL listed coupling, that the UL marking is out of view by pure luck, and major surgery to rework for showing the marking. If the inspector challenges you on this, even when you did install a UL listed fitting, what is your best course of action?
This seems like it would require incredible attention to detail, on an item as insignificant as a conduit coupling, relative to the total scope of the project. How likely is it that an inspector would notice the difference on a conduit coupling, that is still built to the same specs as most UL listed conduit couplings?

Plus, it very well could be that when you install a UL listed coupling, that the UL marking is out of view by pure luck, and major surgery to rework for showing the marking. If the inspector challenges you on this, even when you did install a UL listed fitting, what is your best course of action?

Show him the box they came in or an identical looking coupling with the mark visible?
If the inspector challenges you on this, even when you did install a UL listed fitting, what is your best course of action?

Show him the box they came in or an identical looking coupling with the mark visible?
As GoldDigger says, the listing information will be on the packaging or the manufacturer can provide it, this is covered in the UL White Book.


Roger
There is no UL or accepted NRTL on the box & the couplings possess an EC stamp. Upon writing an to the Mfg. Co., the reply was these items are "built to UL specs".

"Built to UL specs" does not mean UL listed It just means that the company thinks they meet. UL listing involves testing and manufacturing oversight (checking process and perhaps samples in an ongoing process) by UL.