Author Archives: Shelley Doherty

  1. Installation Guide for Rigid Shaft Couplings

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    Stafford Manufacturing Corporation is a leading manufacturer and distributor of a variety of shaft collars, specialty mechanical components, and rigid shaft couplings for use in many types of applications. At Stafford Manufacturing Corp., we offer a wide range of rigid couplings to allow two shafts to function as one.

    When deciding on the right coupling for your application, one key factor will be whether you need a one-piece,  two-piece or three-piece coupling. One-piece clamp couplings offer zero backlash and feature high torsional holding power with no damage to the shafts. Two-piece couplings feature the same advantages, with the added benefit of allowing in-place service. Three-piece couplings allow you to keep one shaft in place while the other is changed.

    In this guide, we’ll detail the steps for proper shaft coupling installation for the main types of rigid couplings, along with some factors that determine which couplings to use.


    Based on an application’s specific requirements, rigid shaft couplings can consist of a vast array of materials, including 303, 316, and 304 stainless steel, 2024 aluminum, carbon steel or black oxide-finished carbon steel, or brass. The installation steps for rigid couplings will differ depending on the coupling type (one, two or three-piece).

    Installation of a One-Piece Rigid CouplingInstallation of a One-Piece Rigid Coupling

    The steps for installing a one-piece rigid coupling are as follows.


    Rigid couplings are used when an application requires coupling of two aligned shafts (they can be shafts of the same sizes or different sizes). High stress could result if axial or radial misalignment takes place, potentially causing failure so they are only to be used with unsupported or fully aligned shafts. Once connected to two shafts, rigid couplings will prevent any relative motion from occurring. One-piece rigid couplings ensure alignment.

    Installation Process

    When installing a one-piece rigid coupling, take these steps:

    1. Wipe any excess dirt or oil off the shaft as well as the  bore of the coupling.
    2. Slide one end of the coupling over its mating shaft until that shaft is 1/32” short of the cross slot
    3. Adjust the center screw to half of the recommended seating torque.
    4. Adjust the outer screw to half of the recommended seating torque.
    5. Slide the other shaft into the remaining end of the coupling until it is 1/32” short of the cross slot.
    6. Adjust the center screw to half of the recommended seating torque
    7. Adjust the outer screw to half of the recommended seating torque
    8. Use a torque wrench to fully adjust all screws to the recommended seating torque, going from the center screws to the outer screws.
    9. If possible, slowly rotate shafts to ensure proper alignment.


    Installation of a Two-Piece Rigid CouplingInstallation of a Two-Piece Rigid Coupling

    The steps for installing a two-piece rigid coupling are:


    Like one-piece rigid couplings, two-piece couplings are used to join two aligned shafts. The use of a two-piece coupling allows installation while both shafts remain in place.

    Installation Process

    The steps for installing a two-piece rigid coupling are:

    1. Wipe any dirt or excess oil off shafts and coupling bore.
    2. Assemble the top and bottom halves of the coupling over the two shafts, making sure that the ends with the face groove are together.
    3. Assemble the two-piece coupling to the point where there is mild resistance in the screws.
    4. Use a torque wrench to adjust the center screws to half of the recommended seating torque.
    5. Use the same wrench to adjust the outer screws to half of the recommended seating torque.
    6. Use the torque wrench to adjust all screws until they’re at the full recommended seating torque, starting with the center screws and completing the process with the outer screws.
    7. Ensure the clamping is even by checking that the slot  gap is the same on both sides
    8. If possible, slowly rotate shafts to ensure proper alignment.
    (Click to Expand)

    Installation Guide for Rigid Shaft Couplings


    Installation of a Three-Piece Rigid CouplingInstallation of a Three-Piece Rigid Coupling

    The steps for installing a three-piece rigid coupling are:


    Designed for aligned shafts, the three-piece clamp coupling makes two shafts function as one. It can remain fixed to one shaft while the other is moved or changed, or come completely apart to allow the most convenient assembly and adjustment.

    Installation Process

    The following are the steps for installing a three-piece rigid coupling:

    1. Wipe any dirt or excess oil off shafts and coupling bore.
    2. Assemble the ends of the coupling with the matching face groove onto its mating shaft
    3. 3. Use a torque wrench to adjust the center screws to half of the recommended seating torque.
    4. Use the same wrench to adjust the outer screws to half of the recommended seating torque.
    5. Mate the other shaft with the open end of the coupling and loosely assemble the coupling top, making sure that the machined end is towards the outside..
    6. Use the torque wrench to adjust the center screws to half the recommended seating torque
    7. Use the same wrench to adjust the outer screws to half the recommended seating torque.
    8. Use the torque wrench to adjust all screws until they’re at the full recommended seating torque, starting with the center screws and completing the process with the outer screws.
    9. Ensure the clamping is even by checking the saw slot gap.
    10. If possible, slowly rotate shafts to ensure proper alignment.


    High-Quality Rigid Shaft Couplings from Stafford Manufacturing Corporation

    If your application requires rigid couplings, please check out our wide variety of couplings, precision couplings, and shaft adaptors at Applications include motion control, power transmission, automation, and other types of MRO and OEM applications for consumer or industrial products.

    To find out more about our products and custom capabilities, contact us today with any questions or request a quote for our products.

  2. Overview of Non-Standard Materials

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    Since 1975, Stafford Manufacturing Corp. has been a leading manufacturer and distributor of shaft collars, rigid shaft couplings, and specialty mechanical components. Our products are used for industrial, consumer, OEM, and MRO applications, including automation, power transmission, motion control, and many others. We have unique expertise in designing components with non-standard materials that meet the needs of unique or challenging applications. Some of the non-standard metals we work with include:

    • Titanium
    • Nylon
    • Bronze
    • Brass
    • Delrin
    • High Temp Alloys


    Titanium is a natural element with the highest strength-to-density ratio of any metal and a tensile strength ranging from 30,000 psi to 200,000 psi. This low-density, strong, and lightweight material exhibits a high melting point, low heat-induced dimensional change, good heat transfer, and high electrical resistance. Titanium is commonly used for airplanes, missiles, rockets, and various other applications such as springs and medical manufacturing due to its excellent elasticity, non-toxicity, and biocompatibility.


    Nylon has high abrasion resistance, good thermal resistance, high machinability, good fatigue resistance, and noise dampening capabilities. The different nylon grades include 66, 11, 12, 46, and 6, which are named for the length of their polymeric chains. Key benefits of nylon include low internal stresses, lower water absorption, more crystalline structure equating to higher mechanical strength, and a higher melting temperature.


    This copper and tin alloy is brittle, highly ductile, has low friction, doesn’t produce sparks when struck, expands as it hardens from liquid to solid, and produces a colored patina as it oxidizes. It is used in architectural structures and design elements as well as coins, bearings, electrical contacts, ship propellers, and shaft collars. Bronze can also be made into wool, avoiding some of the problems that steel wool presents, such as rust, broken filaments, and magnetic characteristics that can affect equipment. 


    This gold-colored copper and zinc alloy has excellent electrical conductivity, good machinability, and low friction. It is commonly used in architecture and manufacturing of gears, locks, pipe fittings, and musical instruments. There are many subtypes and finishes available, including electroplating, powder coating, painting, and polishing. Tolerances are +/- 125 μm (standard), as well as +/-100 μm and +/- 50 μm (achievable).


    Delrin is a plastic alternative to metal that offers good dimensional stability, excellent machinability, and high fatigue endurance. Natural-grade Delrin is NSF, FDA, and USDA compliant. 

    Other qualities include:

    • Tensile strength of 6,000-22,000 psi
    • Impact strength of  .75-2 ft-lb/in. 
    • Heat deflection of 180-300ºF
    • Chemical resistance to fuels and solvents
    • Low moisture absorption
    • Good wear and abrasion properties
    • Superior impact and creep resistance
    • High strength and stiffness properties

    Common components made from Delrin include gears, bearings, bushings, shaft collars, rollers, fittings, and electrical insulator parts. 

    High-Temperature Alloys

    High-temperature alloys are a mixture of at least one metal and another element that can withstand temperatures above 500º C. High-temperature alloys are used extensively in the military, medical, aerospace, and electronics industries. The alloys were designed for use in conveyors, furnaces, ovens, and oil and gas applications. They are costly and difficult to machine and shape. However, they are necessary for certain conditions. Stafford offers high-temperature alloy shaft collars in one piece, two piece, hinged, and flanged designs.

    Specialty Mechanical Components from Stafford Manufacturing Corp.

    Stafford Manufacturing Corp. is a leading manufacturer specializing in custom-manufactured shaft collars and rigid couplings in non-standard materials. To learn more about our products, please visit our product overview page. For pricing, please request a quote

  3. What Is a Threaded Shaft Collar?

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    A shaft collar is a simply-designed machine component composed of a plastic or metal ring fitted around a rod to act as stops, spacers, or for mounting components.  The collar can be loosened or tightened around the shaft using a clamp screw or multiple screws. They are used for tasks ranging from bearing loads to holding components in place along a rod. Among the many types of shaft collars are threaded shaft collars, which offer unique features that make them suitable for various applications. 

    What Is a Threaded Shaft Collar?

    Threaded Bore Shaft Collars

    A threaded shaft collar is a type of shaft collar defined by the threaded 

    pattern on the inside of the ID. While the standard shaft collar has a smooth interior, threaded shaft collars employ this textured interior to provide superior grip to the rod it is attached to. 

    Threaded shaft collars are paired with a threaded rod, making them fasten together much more securely than a smooth shaft collar on a smooth rod. This provides higher axial holding power with less chance of damaging the rod. Additionally, threaded shaft collars allow for precise positioning and easier adjustments along the rod’s length.

    In terms of variants, threaded shaft collars are typically manufactured in two distinct styles. The one-piece clamp collars are designed as a singular piece of equipment, which are fastened by being pressed together and then tightened once in position. Two-piece split collars consist of two separate halves of a single collar held together by a pair of screws that can be used to loosen and tighten the ring. Threaded shaft collars are typically made from steel or hard plastics. HInged threaded collars are also available for a simple, all-in-one assembly style.

    Applications of Threaded Shaft Collars

    threaded shaft collar

    Due to the various advantages threaded shaft collars have over smooth 

    shaft collars, they are typically used in applications where additional precision or strength are required. In machinery, threaded shaft collars are most frequently used for load-bearing applications and as spring tensioners. Their holding power and durability allow them to survive longer when placed under high stress than other similar parts. They are also used as end stop positioners and as limiters in repetitive operations.

    Hospitals and other medical facilities make use of threaded shaft collars in places ranging from surgical equipment to beds and equipment stands. Other applications include:

    • Automation machinery
    • Mechanical stops
    • Locating components
    • Sprocket hubs
    • Bearing holders
    • Shaft protectors
    • Measuring and testing equipment

    Stafford Manufacturing’s Threaded Shaft Collars

    Stafford Manufacturing produces a variety of threaded shaft collars, all made with quality materials and designed to be non-marring to the rods they attach to. In addition to the previously touched upon UNF/UNC one-piece and two-piece clamps, Stafford also makes hinged collars that combine the ease of use of the one-piece collars with the quick assembly and disassembly of the two-piece collars. Our other offerings include ACME threaded collars featuring left- and right-hand threading as well as custom manufacturing options. 

    Partner with Stafford Manufacturing

    The many beneficial features of threaded shaft collars make them useful in many industries. Their superior grip strength and reliability compared to other types of shaft collars make them the optimal choice for a variety of applications. At Stafford Manufacturing, we manufacture superior threaded shaft collars and other types of shaft collars, and we can work with you to create a custom solution for your needs. For more information, or to get started on your next shaft collar solution, contact us today.

  4. What Is Shaft Coupling Windup and Backlash?

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    Rigid shaft couplings connect two separate shafts by clamping onto their adjacent faces. When installed properly, the shaft coupling connects the shafts in a precise line that transfers rotary motion between the shafts without causing misalignment or breakage. However, there are two main obstacles to the perfect transfer of rotary motion:

    1. This occurs when the application of torque results in greater shaft rotation at one end compared to the other.
    2. Backlash is the unwanted reactive motion between connected mechanical parts that can break couplings or cause mechanical stress.

    This blog explores the causes and effects of windup and backlash in shaft couplings.

    What Is Torsional Rigidity in Shaft Couplings?

    Windup, otherwise known as torsional deflection, occurs when torque is applied and the rotation of one end of the shaft is greater than the other end. This creates unequal torsional deflection that engineers have to consider as they set up feedback mechanisms. The varying load on the gears causes unequal wear. Torsional rigidity can also put stress on the coupling, leading to deformation, breakage, and a more frequent need for parts replacement.

    What Is Backlash in Shaft Couplings?

    Backlash occurs whenever mating parts in a system aren’t precisely aligned. In shaft coupling systems, the coupling may have a poor grip on each of the shafts, resulting in slight angles and unequal wear and stress on the system.

    Shaft couplings can accommodate some degree of backlash, but it’s important to ensure that any backlash is well within the system’s threshold. For example, angular movements greater than 2° past the preferred angle are considered excessive backlash, and this can cause extreme wear, stress, and even breakage. Although not all backlash is bad, when the backlash is too great, it will result in erratic dial indicator and laser alignment readings. Operators should always reduce the backlash to within the 2° threshold before alignment begins.

    There are different types of misalignment based on the resulting misalignment angle. These include:

    • Angular misalignment. When the shafts of two coupled units form a wide ‘V’ or obtuse angle
    • Parallel misalignment. When the shafts are parallel but one is slightly higher than the other
    • Skewed misalignment. Involves both parallel and angular misalignment

    Any type of misalignment can cause backlash on the mechanical parts. It can also reduce the overall efficiency of the rotary motion transfer. It’s important to choose the right type of coupling that can prevent misalignment in the first place. Rigid shaft couplings, along with precise installation and setup, can reduce the risk of parts slippage and skew during operation of the system.

    Choose Stafford Manufacturing for Shaft Couplings and Mechanical Components

    At Stafford Manufacturing, we specialize in manufacturing rigid shaft couplings and other types of specialty mechanical components for energy transfer, motion control, automation, and other systems. Our rigid shaft couplings are designed to optimize the transfer of rotary motion. Browse our selection of one-piece split clamp, two-piece split clamp, three-piece split clamp, and precision sleeve couplings, or contact our team to learn more about our capabilities and inventory.

  5. What Is the Difference Between Rigid and Flexible Couplings?

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    There are two main types of couplings: rigid couplings, which connect two shafts with a solid and high-precision hold, and flexible couplings, which can be used to connect slightly misaligned shafts but which can’t provide the same level of torque transfer. While both coupling types have their advantages and disadvantages, it’s important to know which coupling to choose in a particular application.

    How Do Rigid Couplings and Flexible Couplings Differ?

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    Difference Between Rigid and Flexible Couplings

    Ultimately, the key difference between rigid and flexible couplings is in the connection they provide. Rigid couplings provide a rigid connection; the two shafts are firmly connected, and the coupling allows for a smooth transmission of torque throughout the system. Flexible couplings create flexible connections, and the components can lose some of the torque power through the interaction. While metallic flexible couplings offer greater torque capability than other flexible couplings, some torque is still lost.

    Other important differences between rigid and flexible couplings are:

    • Alignment Requirements: Flexible couplings can handle slightly misaligned shafts. Rigid couplings are torsionally stiff and can’t tolerate any misalignment. This applies to both shafts that are physically misaligned at rest and parts that may cause misalignment during operation due to thermal changes.
    • Backlash: Rigid couplings, especially newer models of aluminum rigid couplings, can significantly reduce backlash to at-zero or near-zero levels. Flexible couplings don’t offer the same protection.
    • Maintenance Requirements: Because rigid couplings are stiff, they do not absorb vibrations, which can lead to early wear on parts that aren’t properly aligned. Operators should routinely check rigid couplings for wear and alignment, and they should also routinely apply lubricant. Flexible couplings can handle vibration and shock without adverse wear.
    • Complexity: Flexible couplings often have more components and/or are more complex. This can make operation and maintenance more complicated. Rigid couplings are more simple and straightforward in comparison.
    • Applications: Flexible couplings can be used in servos with low or moderate torque levels and the potential for shaft misalignment. This includes applications such as machining tools, semiconductor manufacturing, and packaging equipment. Rigid couplings work best for high-torque requirements, shaft support applications, and push-pull use cases.
    • Cost: Rigid couplings are more affordable than flexible couplings, which tend to have a high cost.

    Advantages of Rigid Couplings

    Both rigid and flexible couplings have their place in almost any complex motion system. However, rigid couplings provide several advantages over their flexible alternatives that make them the preferred choice for many projects. Some of their key advantages include:

    • Excellent torque transmission: Rigid couplings can efficiently transfer torque from one shaft to the other connected shaft.
    • Low cost of production: Manufacturers can produce standard and custom rigid couplings at cost-effective rates.
    • Precision, with nearly zero windup and zero backlash
    • Torsional stiffness: High torsional stiffness allows for better positioning. 
    • Simplicity
    • Alignment capabilities: Rigid couplings can be used to establish shaft alignment between the motor and connected components.
    • Suitability for push-pull and support applications
    • Easy assembly, disassembly, and maintenance operations throughout the life of the coupling

    High-Quality Rigid Couplings From Stafford Manufacturing

    Rigid couplings provide excellent torque, minimal backlash (with some of our standard couplings providing zero backlash), and high torsional stiffness. This makes them ideal for a wide variety of precision applications that need high levels of power. At Stafford Manufacturing, we manufacture and supply our clients with high-quality rigid couplings for a range of applications. Learn more about how to choose the right rigid coupling for your needs, or browse our catalog to find the right products today. 

  6. What is a Shaft Collar and How Does it Work?

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    Shaft collars hold and position mechanical components around a shaft or mount shafts, tubes, and pipes onto flat surfaces, Available in a variety of styles and from numerous material types, shaft collar selection depends heavily on the details of the intended application.

    Stafford Manufacturing is a premier manufacturer of shaft collars, clamps, and related mechanical components. This blog will explain shaft collars in more detail to help users make informed decisions when sourcing these critical components.


    How a Shaft Collar Works

    Commonly found in power transmission applications, shaft collars are ring-shaped plastic or metal devices that clamp around a shaft. The purpose of the collar is usually to hold motor components, gear assemblies, sprockets, bearings, and other parts in place and sometimes facilitate their proper movement. The collars may specifically locate components, keep them appropriately spaced, or limit their movement. Shaft collars may also be used to connect one end of the shaft itself to a part or surface.

    The simplest shaft collars use set screws that tighten into the shaft to hold the collar in place. While these collars still see some use, the screws tend to mar the shaft which makes it difficult to remove and reposition the collars. Most modern shaft collars use a clamp that holds to the shaft. Clamp screws tighten the clamp around the shaft without the need to dig into the shaft itself.

    There are multiple types of shaft collars, each suited to different purposes. Some of the most common types of shaft collars include:

    • Hinge shaft collars have an open hinge on one side and a clamp screw on the other, enabling them to be easily assembled anywhere on the shaft. They are completely self-contained and eliminate the risk of dropping or losing screws.
    • One-piece shaft collars feature improved performance, allowing an easy increase in clamping force by tightening the clamp screw.
    • Two-piece shaft collars can be assembled anywhere on the shaft, including between other shaft collars.

    Shaft collars are also available in multiple bore configurations, including round, threaded, hexagonal, and square. While off-the-shelf shaft collars are suitable for many needs, standard shaft collars can be altered to meet specific application needs. Fully customized shaft collars are also an option for unique situations.


    Applications of Mounted Shaft Collars

    Mounted shaft collars are used in numerous industrial applications. Common use cases for shaft collars include:

    • Positioning or aligning moving components, such as gears, bearings, and pulleys in automated industrial equipment
    • Securely connecting tubes to hardware
    • Mounting sensor components onto shafts
    • Providing mechanical stops for actuators, cylinders, and other varied components in vehicles and heavy equipment
    • Use as spacers or stops on laboratory equipment, such as frames and clamps
    • Guides, spacers, or stops on medical imaging machines such as MRIs and CAT scanners
    • Facilitating precision positioning in optical measuring equipment
    • Provide appropriate positioning of gearbox or motor components in power transmissions


    Shaft Collars From Stafford Manufacturing

    Since 1975, Stafford Manufacturing has been fabricating and distributing standard and custom shaft collars for use across industries and applications. We offer extensive customization capabilities in terms of design, material, and finishing choices. We offer end-to-end support for any shaft collar project, including in-house CAD design and engineering capabilities that enable us to tailor a shaft collar to meet the specific needs of any customer.

    Our facilities are compliant with all relevant industry standards, including ASA, ASME, ANSI B18.3, ISO 9001:2015, REACH, and RoHS. We work with customers in an expansive range of industries, such as:

    • Agriculture machinery
    • Assembly
    • Automation
    • Conveyor systems
    • Heavy trucks/off-road
    • Laboratory and research equipment
    • Machine tools
    • Marine
    • Medical equipment
    • Military and defense
    • Mining
    • Mixing equipment
    • Maintenance, repair, and operations
    • Oil and gas
    • Optical
    • Packaging
    • Retail displays
    • Robotics

    Our team can help you identify the appropriate shaft collar design, material, and finish for any application. To see how our team can support yours, please contact us or request a quote today.

  7. Differentiating Types 303, 304, and 316 Stainless Steel

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    Class 300 stainless steels are austenitic chromium-nickel alloys that are highly corrosion resistant and non-magnetic, displaying excellent formability and temperature resistance. Three of the most common austenitic stainless steels are types 303, 304, and 316. Although related, these alloys differ in areas like chemical composition, material capabilities, and cost.

    Type 303

    The base composition of type 303 stainless steel is approximately 18% chromium and 8% nickel. The additions of 0.15% sulfur or selenium and phosphorus make type 303 the most machinable alloy of the class but slightly reduce its corrosion resistance. Despite this, it is still an optimal material for components that require significant machining or tight tolerances, such as nuts and bolts, screws, bushings, fasteners, bearings, and more. Type 303 is regarded as a cheaper, more machinable alternative to similarly composed 304 stainless steel.

    Type 304

    The most commonly used austenitic stainless steel, type 304, is composed of 18% chromium and 8% nickel with low levels of carbon. This alloy is highly resistant to oxidation and corrosion, durable, and easy to fabricate. Considered the most versatile stainless steel of the class, type 304 has uses in a range of applications across diverse industries—from architectural details to kitchen appliances to automobile parts. Type 304 is easily accessible and less expensive than 316 stainless steel.

    Type 316

    Composed of slightly higher levels of chromium (16-18%) and nickel (10-14%) than types 303 and 304, the most distinguishable properties of 316 stainless steel come from the addition of 2-3% molybdenum, an element which significantly improves the alloy’s corrosion resistance. Type 316 also exhibits improved heat tolerance, resistance to creep and pitting, and excellent tensile strength. Known for its ability to withstand the effects of exposure to chlorides, the alloy is used extensively in chemical and marine applications, as well as a number of other industries. Type 316 has lower formability than 303 or 304 stainless steels, but its higher resistances make it more expensive to source.
    The characteristics responsible for differentiating these common class 300 stainless steels also uniquely position each alloy to perform for specific applications.

    Applications of 303 Stainless Steel

    The highly machinable, non-magnetic, and non-hardening type 303 stainless steel is well-suited to applications requiring tight tolerances and heavy machining, like in the manufacturing of small parts. Typical uses of this alloy include things like:

    Applications of 304 Stainless Steel

    The extreme versatility of type 304 makes it the most widely used stainless steel on the market. Offering exceptional corrosion resistance and durability, this alloy is suitable for a spectrum of uses across nearly every industry. Some of the most common applications are:

    Applications of 316 Stainless Steel

    Offering the greatest resistance to a variety of corrosive elements, type 316 stainless steel is the most appropriate alloy for applications with continuous exposure to harsh environments or where strength and hardness are a critical factor. This includes uses such as:

    • Stainless steel floats
    • Marine parts
    • Outdoor electrical enclosures
    • Chemical and pharmaceutical equipment
    • Medical devices and equipment

    Stainless Steel Components by Stafford Manufacturing Corp.

    Stafford Manufacturing Corp. is a global manufacturer and distributor of shaft collars, rigid shaft couplings, and specialty mechanical components used in OEM and MRO applications for industrial and consumer products. The inclusion of types 303, 304, and 316 stainless steels in our standard and custom components plays a pivotal role in enhancing their quality and durability. Our selection of stainless steel products includes:

    • Threaded bore shaft collars
    • Two-Piece Split Clamp Collars
    • Set Collars
    • Hinge Collars
    • Square and hexagonal bore shaft collars
    • Rigid shaft couplings and shaft adapters
    • Metric shaft collars, rigid shaft couplings, and components

    For additional information on stainless steel material considerations for your next application, or to learn more about the Stafford advantagecontact us today.

  8. Material Spotlight: 316 Stainless Steel for Wastewater Treatment Applications

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    Wastewater treatment is essential for a healthy environment. Wastewater is used water from homes, businesses, and industries and can come from appliances and fixtures such as bathtubs, sinks, toilets, and washing machines. It also includes storm run-off from parking lots, roads, and roofs. Wastewater treatment reduces pollutants to a level that does not overwhelm nature when it is released back into the environment. 

    There are two main stages of wastewater treatment: primary and secondary. The primary wastewater treatment removes any solids that float or settle to the bottom while the secondary further cleans the wastewater using biological processes. In potable water treatment plants, the materials used for the aeration pipes, valves, tanks, and transfer pipes can affect the quality of the purification process. The most common option for wastewater applications is stainless steel. 

    Why Stainless Steel Is Used in Wastewater Treatment Plants

    Stainless steel is corrosive-resistant and adds no toxic chemicals to the water. Corrosion usually occurs in pipe crevices when there is a bend or join in panels. With stainless steel, crevice corrosion is rare. 316 Stainless steel contains 2% molybdenum, which helps resist corrosion from chlorides, making it popular for potable water treatment plants where certain chemical content could increase corrosion. Carbon steel has a much lower resistance to corrosion and is therefore not the best choice for wastewater treatment. Though stainless steel is more expensive than steel, it results in far lower maintenance and replacement costs. 

    Advantages of Stainless Steel

    Stainless steel is available in many grades, which depends upon varying levels of carbon in the steel. The two most common types used in wastewater treatment processes are duplex grade and austenitic grade. These have the highest corrosion resistance compared to the other types. Besides stainless steel’s low corrosive properties, there are many other advantages, including: 

    • Minimal loss of metal degradation
    • High strength
    • Ductility
    • No UV light degradation

    Limitations of Stainless Steel

    While choosing the right grade of stainless steel is important, there may be some limitations. In environments where there are changing pressures, stainless steel can risk fatigue over time. Several grades of stainless steel  (such as 303 and 304) are susceptible to certain types of corrosion, including crevice corrosion, chloride pitting, pinhole leaks, and external corrosion. Some ways to ensure the longest life of stainless steel used for wastewater applications include: 

    • Drain pipelines during periods of non-use to prevent stagnant water, which encourages microbial activity that causes corrosion to occur. 
    • Mill pickling stainless steel pipes to help control surface corrosion. Heat tints near welded areas can make them susceptible to biocorrosion and the pickling process helps provide a corrosion-resistant surface. 
    • Follow proper operation guidelines to prevent the beginning of corrosion caused by scaling, over chlorination, poor fabrication, or MIC. 

    Stainless Steel Products Suited for Harsh Environments From Stafford Manufacturing

    Stainless steel can be an effective material for use in harsh environments, such as wastewater treatment facilities. Stafford Manufacturing offers both standard and custom machined parts made from corrosion-resistant stainless steel in a variety of grades to best suit your application. Contact our team to learn more about our product selection for your water treatment needs.

  9. Guide to Shaft Collars

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    Simple yet highly effective, shaft collars are ring-shaped metal or plastic components that enclose shafts and serve three main purposes: holding components in place, positioning components on the shaft, and providing a point of contact between the shaft and other components. This reference guide provides an overview of shaft collars styles, what you should consider for the installation and disassembly, and the materials, finishes, and surface types that are available today. For more in-depth information, check out our product overview on shaft collars.


    Collar Style

    Shaft collars come in a diverse range of styles, including set screw, one-piece split, two-piece split, balanced, and hinged. One-piece split, two-piece split, balanced, and hinged models collectively fall into the same category: clamp-type collars. Clamp-type collars are fitted around the shaft and are not screwed to the shaft directly.


    Set Screw

    When a recessed screw is positioned inside the ring of a shaft collar, the system is called a set screw. To install this collar, the user must first tighten the screw onto the shaft, creating a slight indentation on the shaft material. Once the screw is tightened and the collar is secured, the shaft will become permanently marred with small burrs. The system is relatively easy to use and most effective when the screw is harder than the shaft material. 


    One-Piece Split

    A one-piece split collar tightens circumferentially around the body of the shaft without breaking the shaft surface. Like a set screw collar, the one-piece split also contains a screw which must be tightened or loosened to move the collar on the shaft—but, unlike the set screw model, the one-piece split can be repositioned and doesn’t damage the shaft. Instead, it distributes pressure evenly across the circumference, providing a more uniform and secure hold. 


    Two-Piece Split

    Made from two semi-circles that combine to form the collar, two-piece split collars are easy to disassemble and rearrange along the length of the shaft. If you have other components on the shaft, using a two-piece split instead of a one-piece split will allow you to reposition the collar without needing to remove anything else.



    A balanced collar looks similar to a two-piece split but contains interlocking studs on both sides to help minimize vibration and distribute weight as evenly as possible across the shaft circumference. Just like the one- and two-piece split, this collar won’t mar the surface of a shaft.



    As the name suggests, hinged collars contain a hinge that allow the user to install the collar at any point along the shaft. The hinge also ensures both pieces of the collar stay connected. Many users prefer to use a hinged collar over a standard two-piece split because the design makes it impossible to lose a component.


    Structural Features

    Clamp-style collars can have additional features, including, for example:



    Featuring weighty clamping screws and large diameters, heavy-duty collars provide exceptional holding power but are slightly bulkier than other models.



    Weldable collars are lead-free, offer permanent holding power, and are heavyweight bearing. 


    Installation and Disassembly

    A set screw collar is the oldest type of collar with the simplest design but has a few notable drawbacks. First, if you use a set screw collar, it will damage the shaft, which could make it challenging to reposition the collar later. The set screw collar also isn’t as secure as clamp-based models. 

    If you plan to reposition the collar along the shaft, a two-piece hinged collar will probably be the most convenient option. Rearranging or removing one-piece collars by sliding them along the shaft can be burdensome, especially if you’re working with a long, unwieldy shaft. A two-piece hinged collar is easy to move along the length of the shaft without separating the components. 



    The collar material significantly affects its overall performance. The material’s durability, holding power, and resistance to corrosion should all factor into your decision, in addition to its relative hardness compared to the shaft material. 

    At Stafford, we manufacture products from a wide range of materials, including aluminum and stainless steel.


    Finish and Surface Treatment

    Manufacturers can add surface treatments to change the collar’s appearance and increase its slip-resistance, anti-corrosive properties, and durability. Certain types of finishes are also chemically inert or specially engineered for food processing, the pharmaceutical industry, and other applications that require a sterile environment. 

    If you’re using a non-standard screw instead of the one that was provided with the collar, it’s also critical to determine how the material will interact with the shaft and collar.


    Shaft Collars from Stafford Manufacturing Corp.

    When selecting the right shaft collar for a job, consider the style, intended application, material, and surface treatments at your disposal. If you’re not sure what options are best-suited to your needs, talk to the experts at Stafford Manufacturing Corp. in Wilmington, MA. With over 45 years of experience manufacturing shaft collars, we have the expertise to answer all your questions and help you choose the best solution. We are ISO 9001:2015-certified and dedicated to complete customer satisfaction.

    Contact us today to learn more about our precision-manufactured collar shafts and coupling components. 

  10. Key Criteria to Guide Your Rigid Couplings Selection

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    Choosing the correct rigid shaft coupling for your application requires thorough analysis of the application and in-depth understanding of the different coupling designs. Due to the extensive selection of couplings on the market, it can be difficult to choose the right one for the job at hand. To this end, we have compiled a list of the most common errors users make when selecting rigid coupling, and ways to avoid making the same mistakes.

    Common Errors Choosing Rigid Couplings

    Rigid couplings are critical to the safe and reliable operation of a variety of systems. When considering which coupling is ideal for your project, avoid these common pitfalls.

    Focusing on Cost

    Although cost is an important aspect when determining which rigid coupling to use for your project, the function of the coupling should be the primary consideration. While a lower initial price point may be an attractive choice, using an incorrect coupling can result in costly failures, ultimately resulting in significantly higher repair and replacement costs. Rather than selecting your coupling based on price, choose the one that will function well within the system, optimize equipment operation, and extend the service life of the component parts.

    Waiting Too Long

    Often, couplings take a back seat during the design process and are added as almost an afterthought once the process is mostly complete. Rather than waiting to determine which couplings to use, include couplings in the initial design process. This allows you to select couplings based on the complex needs of the system so that they enhance the design rather than detract from it. Early selection of couplings will ensure that the couplings and system components operate smoothly and efficiently, with significantly less risk of error or premature failure.

    Excessive Misalignment

    One of the most common causes of coupling failure is the use of incorrect couplings for the misalignment conditions present in the application. Excessive misalignment forces the couplings to bear loads that exceed their specifications, resulting in damage and coupling failure. Since flexible shaft couplings are designed to accommodate a range of misalignments with a degree of flexibility, it is important to understand the limitations of the coupling you are using.

    3 Questions to Ask When Choosing the Proper Rigid Coupling

    To avoid the most common mistakes in choosing rigid couplings, ask yourself the following questions:

    1. Is a rigid coupling correct for my application? Rigid couplings are ideal for use with unsupported shafts. Supported shafts that exhibit any degree of misalignment are poorly suited for rigid couplings and can result in damage not only to the coupling but also to the shaft supports and associated component parts.
    2. Do I need keyways? Keyways are not always necessary. They should be used for couplings that are intended to maintain radial alignment between shafts and support loads with high torque. For applications in which radial alignment and high torque are not considerations, keyways may not be required.
    3. Why would I choose a clamp coupling rather than a (less costly) set-screw style? Although it may be tempting to choose a cheaper set-screw clamp for your application, keep in mind that clamp couplings are more versatile. One-, two-, and three-piece styles allow clamp couplings to be applied to a variety of shaft and tubing sizes and materials with a high degree of precision, thereby reducing the risk of damage and coupling failure.

    At Stafford, we offer hundreds of clamp coupling designs, including a broad range of shaft size combinations, torque capabilities, component materials, and shaft shape designs. Some of the primary factors to consider when selecting the best coupling for your application include:

    • Shaft Shape: Determine the design of the shaft to which the coupling will be applied. Couplings are designed to operate on round, square, and hexagonal shafts, so choose the best coupling for the shaft shape.
    • Standard of Measurement:Clamping screws may be designated using either English or the metric system. Be sure to check that the standard of measurement for the coupling components is consistent with the system design.
    • Shaft Size Combination: A variety of off-the-shelf rigid couplings are available in different bore sizes, using both metric and English standards. If you are unable to locate a coupling that specifically matches your required measurements, consider re-machinable and customizable couplings for a cost-effective and efficient solution.
    • Durability Requirements: Although most applications will require standard strength couplings, heavy-duty couplings are available for more demanding applications.
    • Keyway Selection:Analyze the system to determine whether radial alignment or extra torque will factor into overall operation, and use this information to determine whether a keyway is necessary.

    Stafford’s Selection of Rigid Couplings

    Professional designers and engineers must take into account a variety of factors when choosing the ideal coupling for a given applications. The intended purpose, application environment, accessibility, and maintenance requirements are all important considerations. At Stafford, we pride ourselves on offering quick and affordable coupling manufacturing services from the initial design phase through the finished product. We are dedicated to swift service, and quote requests are answered within 24 hours of submission.

    Our broad range of quality shaft couplings include:

    • Standard Rigid Shaft Couplings
    • Shaft Adapter Couplings
    • Specialty Shaft Couplings
    • Customizable Steel Clamp Couplings

    We are also pleased to offer a range of shaft collars, specialty components and accessories, mounting components and clamps, and dedicated maintenance, repair, and retrofit services.

    To learn more about choosing the best rigid coupling for your project, visit our Resource Library, or contact our experienced specialists today.