PRODUCT OVERVIEW

FAMILIES

Stafford offers products in six families, which are broad classifications for similar types of products and are shown in the search options on the home page:

• Round Bore Shaft Collars
• Threaded Bore Shaft Collars
• Square and Hexagonal Bore Collars
• Rigid Shaft Couplings
• Metric Collars, Coupling and Components
• Special Purpose Mechanical Components

Metrics are categorized separately as per convention. The products within the family share the form and function of their inch counterparts, but are fully metric in all aspects, including hardware.

Special Purpose Mechanical Components have distinctive features and benefits in applications beyond conventional collars or couplings, and many of them are Stafford proprietary designs. Visitors to the site who are familiar with the company will recall these as the “Stafford Unique” collection, which has grown significantly over the years.

CATEGORIES

Within each family, there are different categories of products, reflecting the particular attributes of the products. The next section provides a general description of the major categories within the families. Click on the “More Info” links on the Search pages for an in-depth explanation of the specific features and benefits of the category.

SHAFT COLLARS

Shaft Collars are used as stops or locators on shafts in a wide variety of applications. The two basic types are the Set Screw and the Clamp-Type collar:

Set Screw Collars

Set Screw Collars are the oldest type of shaft collar. These units function by gouging the set screw into the surface of a soft shaft. They are a low-cost answer when frequent adjustment is not a consideration.

Clamp-Type Collars

Stafford Clamp-Type Collars (also known as Split Collars) are designed to retain their position through the clamping power generated by tightening one or more clamp-screws which do not touch the shaft, tube or pipe. The primary benefits of clamp-type collars are that while they are non-marring and easy to adjust, they have a consistently high holding power when used on hard or soft shafts, as well as on thin-walled tubing. They are offered in a variety of materials and styles.

A Clamp-Type Collar functions:

• the same as a shoulder on a shaft when it is clamped in position. However, it is much less expensive than machining a shoulder and it can be easily moved to a new location.
• as the clamping mechanism over a split-hub. In this case, the clamping power is transmitted from the collar to the hub-shaft interface. The self-centering split-hub design is a common way to connect components to a shaft
• as a torque-transmitting component when other torque-inducing components (such as lever arms, pulleys, sprockets, etc.) are fastened to it.

Within the Clamp-Type category, Stafford offers three basic variations:

1-Piece Clamp Type Collars have a single screw and do not come apart, so they can be used in situations where the user has access to the end of the shaft.

2-Piece Clamp Type Collars have two screws and can be completely disassembled, so they can be used anywhere on a shaft. Also, a two-piece collar will function well on shafts .015" or more under nominal diameter. A two-piece collar generally has about 10% more holding power than an equivalent one-piece collar.

Hinge-Type Collars are available only from Stafford and feature a triple-link hinge and captive screw in one unit. Combining the flexibility of the two-piece collar with the simplicity of the one-piece, they can be assembled anywhere on the shaft without all the loose parts that can be dropped or lost. They are perfect where fast operation is required, such as hostile environments or situations where there are space and time constraints. Hinge Shaft Collars are functionally similar to two-piece collars, for use on standard round shafts, hard or soft, as well as on thin wall tube or over a split hub.

Stafford also offers several categories of specialty collars. Please refer to the More Info link on the Shaft Collar search pages for these categories for additional details.

Rigid Clamp-Type Couplings

A Rigid Clamp-Type Coupling functions by clamping onto and joining two shafts. It does not accommodate misalignment of any type. In essence, it makes two shafts function as one. It is ideal for overhung or unsupported shafts and is an excellent way to attach items such as mixer paddles and shaft extensions. Stafford manufactures couplings to join shafts of the same or different diameters, with and without keyways. They are offered in a variety of materials and styles.

1-Piece Clamp-Type Couplings are sized to be a close slip-fit over the shaft ends. They are clamped by gradually and sequentially tightening the screws, allowing the coupling to "seat" on the shaft.

2-Piece Clamp-Type Couplings perform essentially the same function as one-piece, except that they come completely apart and can thus be assembled anywhere within a mechanism.

3-Piece Clamp-Type Couplings can be installed anywhere, like the two-piece. In addition, they can remain assembled on one shaft while they are disassembled from the other. This can be a welcome convenience in some situations.

Shaft Adapters are in the coupling family, but have a male shaft as the output end. They can be used as-is to extend or repair an existing shaft or they can be machined to provide an entirely different output shaft configuration.

Stafford also offers several categories of specialty couplings. Please refer to the More Info link on the Rigid Shaft Couplings search pages for these categories for additional details.

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COLLAR AND COUPLING STYLES

High Strength is our most popular style, where the heads of the clamping screws are recessed.

Low Profile features the ability to be used in tighter quarters. This style has a smaller outside diameter but the screw head does protrude.

Heavy Duty has larger clamping screws for greater holding capacity. Heavy Duty collars have twice the Axial Holding Power of standard collars. Heavy Duty Couplings have three times the Torsional Holding Power of regular couplings. They are longer, have a larger outside diameter and have more screws than standard couplings.

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MATERIALS AND FINISHES

The highlighted materials and finishes described below refer to the standard options offered on Stafford catalog products. Additional materials and finishes are available as Specials.

MATERIALS

Steel parts are made from mild steel (12L14, 1026, etc.). They are machineable and can be case hardened. Except in the case of plain-finished or plated set-collars, all steel parts are supplied with a black-oxide finish. They include alloy steel screws. Imported collars are made from A283grC.

1018 Steel is used on Stafford weldable steel collars. It welds more easily than alloys with lead and is a safer alternative.

1117 Steel provides easier machineability than standard mild steel and is used on Stafford parts where more complex machining operations may be employed.

Stainless Steel parts are made from 303 stainless, a non-magnetic alloy offering corrosion resistance, strength and good machineability. All stainless parts are supplied with a plain finish and 18-8 stainless screws.

316 Stainless Steel parts offer additional corrosion resistance and are suitable for applications where harsh chemicals are used. Applications include medical, pharmaceutical, laboratory, semiconductor, food processing, marine, wastewater, and water purification equipment. 18-8 stainless screws are used.

Aluminum parts are generally made from 2011 or 6061 aluminum for strength, light weight and corrosion resistance. All aluminum parts are supplied with a plain finish and alloy steel screws.

Nylon 6/6 plastic can be used for a variety of applications including food processing and pharmaceutical equipment and packaging machinery. Suitable for use where frequent washdowns are necessary. 18-8 stainless screws are used.

Delrin® can be used for a variety of applications including food processing and pharmaceutical equipment and packaging machinery. Suitable for use where frequent washdowns are necessary. 18-8 stainless screws are used.

ABS Plastic is used on Grip-Fast™ collars to provide the housing for the quick release mechanism. It is lightweight and durable, and can withstand high impacts.

PTFE is a fluoropolymer plastic with a low coefficient of friction, is chemically inert and operates effectively over a wide range of temperatures. It is used in our Thrust Washers to provide a bearing surface.

Neoprene is a versatile and durable synthetic rubber used in Stafford’s End Stop Cushions in Shore-A 50 (medium) and Shore A-70 (hard) durometers to soften impact and reduce noise.

FINISHES

Black Oxide is used on mild steel products to add a degree of corrosion resistance and improve the torque rating by allowing a better grip on the shaft.

Zinc Plating is a low cost option for enhanced corrosion resistance to mild steel. Used on our imported set screw collars.

Chrome Plating is a decorative shiny finish over mild steel that also offers additional corrosion resistance. It is used where an attractive appearance is important.

Anodized (Black) is a reacted finish that provides aluminum an integrated, durable and attractive surface.

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WELDABILITY

Stafford recommends that only catalog products using 1018 Steel and 316 Stainless Steel should be welded. Welding plated materials may produce toxic fumes. Consult with our Engineering Department to discuss the material that would be most appropriate for your application and we will be pleased to quote a Special.

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RoHS COMPLIANCE

The Restriction of Hazardous Substances Directive (RoHS) adopted by the European Union in 2003 restricts the use of six hazardous materials in the manufacture of various types of electronic and electrical equipment. A product is determined to be compliant if levels of the material used in its components are at or below the acceptable limit.

Stafford’s catalog products are RoHS compliant with the exception of the following:

            Zinc Plated

            Black Anodized Aluminum

            2011 Aluminum (parts 3-1/2" O.D. and smaller)

If you require RoHS-Compliant parts in any of these categories, we can manufacture them as Specials.

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HARDWARE

Socket Set Screws

Alloy Steel Socket Set Screws, Cup Point, heat treated. Meet or exceed ASA specification B18.3. Forged Socket.

18-8 (300 Series) Austenitic Stainless Steel Socket Set Screws, Cup Point. Meet or exceed ASA specification B18.3. Forged Socket

Socket Head Cap Screws

Alloy Steel Socket Cap Screws, heat treated. Meet or exceed ASA specification B18.3.

18-8 (300 Series) Austenitic Stainless Steel Socket Cap Screws. Meet or exceed ASA specification B18.3

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AXIAL HOLDING POWER

Since the primary function of a shaft collar is to retain its position on a shaft, the amount of axial load (pounds) required to initiate slippage of a properly installed collar is defined as the Axial Holding Power. Since this result is a function of tension induced by the screw as well as the coefficient of friction between the collar and shaft, it can be affected by many variables (smoothness of the friction surfaces, plating or lubrication on shaft or screw, size of screw and wrenching torque applied.).

As such, it is impossible for us to guarantee an axial holding power for all conditions. What we can do, however, is offer the following test results obtained by mounting standard steel collars on standard steel shafting with the screws torqued as shown. These results are for reference only and should not be relied on in any given situation. The user must test the product suitability in a particular application.

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TORSIONAL HOLDING POWER

Since the primary function of a shaft coupling is to retain the relative positions between two shafts, the amount of torsional load (inch-pounds or newton-meters) required to initiate slippage of a properly installed coupling is defined as the Torsional Holding Power. Since this result is a function of tension induced by the screws, the diameter of the shaft as well as the coefficient of friction between the coupling and shaft, it can be affected by many variables (smoothness of the friction surfaces, plating or lubrication on shafts or screws, size of screws and wrenching torque applied.).

As such, it is impossible for us to guarantee a torsional holding power for all conditions. What we can do, however, is offer the following test results obtained by mounting standard steel couplings on standard steel shafting with the screws torqued as shown. These results are for reference only and should not be relied on in any given situation. The user must test the product suitability in a particular application. It should be noted that in couplings with keyways, the strength of the key is the determining factor.

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FITS AND TOLERANCES

All Stafford collars and couplings are precision machined to provide consistent fit and function. The statements below indicate the minimum specifications for our parts. Refer to the More Info section of each product category for features that may exceed these specifications.

The Inside Diameters (also ID or bore) of Stafford collars and couplings are sized so as to have a smooth slip-fit over standard shaft material. Depending on shaft size, this is anywhere between .001" to .005" over nominal. A close fit means better seating and better clamping.

The Width of Stafford collars is held between -.005" and +.005" on small parts and -.010" and +.010" on larger parts.

The Length of Stafford couplings is held between -.015" and +.015".

The Outside Diameter (also OD) of Stafford collars and couplings is held between -.015" and +.015". An indicator on the Outside Diameter of a properly mounted collar should show total run-out of not more than .010".

An indicator on the Face of a properly mounted Stafford collar should show total run-out or out-of-flat of not more than .005" for a small part and .015" for a large part.

In a Stafford coupling, Concentricity of bore A to bore B is defined as follows: With one end of the coupling properly mounted on a shaft known to have "0" run-out, an indicator is placed 1" from the opposite face of the coupling on the surface of a properly mounted output shaft. When the first shaft is rotated, the Total Indicated Run-Out (TIR) of the second shaft should be less than .002" for small couplings and .004" for large couplings.

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SPECIALS

Whether it’s a simple modification of an off-the-shelf part, or one we build from the ground up, we can probably meet your requirements with a special design. With no minimum order requirements and 24-hour turnaround on quotes, we make it easy to get the custom part you need.

For more information, visit our Specials page.

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REQUEST A QUOTE

Know what you need? Visit our Request a Quote page. We’ll usually have an answer in 24 hours or less.

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CAD DRAWINGS

Most of the catalog parts shown on this web site are available in IGES format as a CAD download. Visit our CAD Drawings page.

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