Written by G.L. Huyett Marketing Department on 03/22/2021 with 0 comments
Understanding the standards and tolerances (permitted variance) of key stock can be complicated. Key stock is called out by nominal or named size. Among squares and flats, tolerances are referred to as "oversize" (over nominal) or "undersize" (under nominal).
UNDERSIZE
Actual size is nominal to less than nominal.
Common Names: Bar Stock; Redi‑Key; Key Bar Stock; Machine Key Bar Stock; Broad Key Stock; Negative Key Stock
Applicable Standards: ANSI B17.1, Class 1 fit; Metric DIN 6880 for key stock; DIN 6885 for machine keys
Fabrication: Typically cold drawn. DIN may be polished to make bright.
Common Grades (AISI and DIN References): 1018; 1045; 1060; 4140; SS303; SS314; SS316; DIN 6880; A2; A4; DIN 178; DIN 179
Common Uses: Used in field applications for repair, with no filing normally needed.
Comments: Some commercial tolerances deviate from the ANSI spec. Plated parts are marked with the size. Plating normally adds .0005" to the height and width. Relatively free fitting bar stock keys. Only applies to parallel keys.
MOLTRUP
Actual size is very slightly over nominal.
Common Names: Moltrup Steel; True Key Stock; Bright Steel; Close Key Stock
Applicable Standards: ANSI B17.1, Class 2 fit
Fabrication: Typically cold drawn. May be polished to make bright.
Common Grades (AISI and DIN References): 1045; 8630; 4140
Common Uses: Most popular in original equipment manufacturing due to precision finish and tight fit in key way.
Comments: This is true +.0010" Class 2 ANSI spec key stock with tight tolerances. Material is difficult to draw and is not always easy to find in the U.S.
OVERSIZE
Actual size is nominal to greater than nominal.
Common Names: Bar Stock; Redi‑Key; Key Bar Stock; Machine Key Bar Stock; Mak‑A‑Key™; Close Key Stock; Plus Key Stock
Applicable Standards: None known, though popularized as Mak‑A‑Key™
Fabrication: Cold drawn steel.
Common Grades (AISI and DIN References): 1018; 1045; SS303; SS304
Common Uses: Based on Mak‑A‑Key™ specifications, which require filing in the field for repair applications.
Comments: Used when a custom fit is required or desired for an oversize key way, for field repairs, or in worn key ways.
SPECIALTY GRADES
Actual size can be above or below nominal.
Common Names: Bar Stock; Mak‑A‑Key™
Applicable Standards: Depends on material grade. ASTM 829; ASTM 484; ASTM 582; ASTM B16; ASTM A276
Fabrication: Cold drawn material. Some nonferrous may be extruded.
Common Grades (AISI and DIN References): 1095; 6061; CDA 360; some grades of stainless steel.
Common Uses: Typically used in field applications for repair.
Comments: Does not match ANSI spec, and is a frequent source of confusion. Most desirable grade in maintenance repair operations, and has wide acceptance, but limited commercial availability.
STEP KEY STOCK
T‑form, offered in both oversize and undersize tolerances.
Common Names: Offset Key Stock; Repair Key Stock
Applicable Standards: Sizing aligns to ANSI B17.1 Class 1 fit, bar stock.
Fabrication: Cold drawn steel. Milled for step and to size; usually plated and marked with size.
Common Grades (AISI and DIN References): 1018; 1045; SS304; SS316
Common Uses: Used in repair of damaged key ways in shafts, sprockets, and pulleys.
Comments: Step key stock is often erroneously called "offset key stock," which generally refers to "Z" shaped rectangle key stock machined with inverse steps on opposing faces.
ROUND
Round form, with undersize tolerances.
Common Names: Round LInear Shaft; Round Bar; Round Stock; Rod; Round Axle; Mak‑A‑Pin
Applicable Standards: Depends on material grade. ASTM A108; ASTM A681; ASTM A686
Fabrication: Cold drawn steel. Sometimes turned and polished.
Common Grades (AISI and DIN References): 1018; 1045; O‑1; W‑1; 1095; SS303; SS304; 6061; CDA 360
Common Uses: Versatile material used as shafting, straight pins, rails, or for locating in a wide range of applications and industries.
Comments: Round key stock is not drill rod. Drill rod is precision ground to size and surface finished.
HEX
Hex form, with undersize tolerances.
Common Names: Hex Bar Stock; Hexagon Shaft; Hex Shaft Stock; Hex Stock; Hex Rod; Hex Axle
Applicable Standards: ASTM A108
Fabrication: Cold drawn steel.
Common Grades (AISI and DIN References): 1018; 1045; 8630; 4140
Common Uses: Machinery, gears, machine parts, structural components, automobile parts, axles, and drive shafts.
Comments: The primary benefit of hex key stock is that there is no key needed and no key way to cut which saves machining time.
Depending on your application, a secondary process may be necessary.
Heat Treating
Heat treating is used to increase strength by raising the temperature of the steel and then cooling it in a controlled manner to change the grain structure of the steel.
Tumbling
Parts are umbled to remove burrs prior to shipment or plating. Using friction, the tumbling media is engineered to polish the parts in a controlled manner.
Plating
The primary purpose of plating is to protect steel from oxidation and corrosion. Zinc electroplating is one of the most common types of electroplating.
View a copy of the G.L.Huyett Key Stock Catalog or download your own today.
Machine keys are used to transmit torque from a rotating shaft to a gear or sprocket. They can be finished in a variety of shapes, sizes, and materials for just about any application. Standard sizes are ready to use with little or no cutting or filing.
MACHINE KEY - FORM B
Common Names: Machine Keys; Sunk Keys; Key Stock
Applicable Standards: ANSI B17.1; DIN 6885
Fabrication: Cold drawn steel; cut to length; tumbled to remove burrs.
How to Identify: Imperial is measured height x width x length. Metric is measured width x height x length.
Common Uses: Original equipment, including motors, gear boxes, gear reducers, and transmissions.
Comments: Square ends are more common in U.S.
MACHINE KEY - FORM A
Common Names: Feather Key; Pratt & Whitney Key
Applicable Standards: ANSI B17.1; DIN 6885
Fabrication: Cold drawn steel; cut to length; both ends radiused.
How to Identify: Imperial is measured height x width x length. Metric is measured width x height x length.
Common Uses: Original equipment, including motors, gear boxes, gear reducers, and transmissions.
Comments: Radiused ends are more common in Europe.
GIB HEAD
Common Names: Gib Head Key; Cotton Picker Key
Applicable Standards: DIN 6884/6887; Industry norm
Fabrication: Cold drawn steel; cut to length; machined tapered surface; tumble to deburr.
How to Identify: Imperial is measured width x length. Metric is measured width x effective height x length. Commercial keys do not usually meet the ANSI specification
Common Uses: Original equipment, including motors, gear boxes, gear reducers, and transmissions. Farm equipment, especially cotton pickers, harvesters, and combines.
Comments: Used to progressively install the key and take up slack from one access end. The head serves as a concussion point for hammering without damage to the shaft of the key. Common taper is 1/8" taper per foot.
WOODRUFF
Common Names: Half‑moon Key; Round Key
Applicable Standards: ANSI B17.7; DIN 6888
Fabrication: Cold drawn profile; cut to width; grind; tumble.
How to Identify: Imperial is measured diameter x width. Metric is measured width x height. Woodruff keys may have round or flat bottoms depending on specifications.
Common Uses: Original equipment, where an arbor cutter is used to cut a key way that is half‑moon shaped.
Comments: Alloy hardened keys usually have has marks (small lines) embedded into the surface of the key along the top.
HI‑PRO
Common Names: High Profile Keys
Applicable Standards: ANSI B17.7; Industry norm
Fabrication: Cold drawn profile; cut to width; grind; tumble.
How to Identify: Width x length x lip height. Hi‑pro keys have small "feet" to keep them from rocking in the key way.
Common Uses: Original equipment, where an arbor cutter is used to cut a key way that is half‑moon shaped.
Comments: Alloy hardened keys usually have has marks (small lines) embedded into the surface of the key along the top.
Special Order Metric DIN 6885
Machine keys can be designed with special dimensional features like set screws, tapers, and other attributes. Mechanical features like tensile strength, shear strength, and wear resistance can be enhanced by material and secondary processes (like heat treating) that give parts added benefits.
Form C
Form D
Form E
Form F
Form G
Form H
Form J
Form K
LEARN MORE ABOUT KEY STOCK AND MACHINE KEYS HERE
FAQs
What is the purpose of a key stock? ›
Key stock is a small metal block or wedge inserted between a shaft and the hub of a pulley, gear, sprocket, or other rotating power device. It provides driving torque and prevents movement. One part of the key fits into a precut slot in the shaft known as a key seat.
What material is key stock made from? ›Typically, key stock is made from carbon steel or stainless steel, but can also be made from aluminum, brass, copper, monel, and even nylon, all with varying material grades.
What is undersized key stock? ›Undersize key stock is key stock 12 inches or greater in length with an actual size slightly smaller than a specified size while remaining within an acceptable tolerance range.
How are woodruff keys measured? ›How are woodruff keys measured? Woodruff keys, identifiable by their half-moon shape, are measured two ways depending on if it is an imperial or metric key. Imperial woodruff keys are measured by their width and diameter, whereas metric woodruff keys are measured by their width and height.
How do you determine keyway? ›Look at the large end of the key (also called the bow). If the bow has straight sides and a triangle-shaped top (like a house), you probably have a KW1 keyway. If the key is diamond-shaped (narrower at the top and bottom and wide in the middle), you probably have a SC1 keyway.
How do you cut a key stock? ›Lap 2 Cut Key Stock - YouTube
What grade steel is key stock? ›The material is 1018 carbon steel and is available with either zinc plated or plain finish. Also available in 303 stainless steel.
How do machine keys work? ›Explanation of Different Type of Keys | Machine Design - YouTube
How thick is a key? ›| Thickness Comparison Table | ||
|---|---|---|
| Thickness | Imperial | Metric |
| Nickel | .074 in | 1.95 mm |
| House key | .08 in | 2 mm |
| Standard car windshield | .25 in | 6.35 mm |
Standard key stock does not have enough carbon to harden well, it will still be pretty soft afterwards. It could be case hardened but that process is too much trouble for a tool bit.
What is key steel used for? ›
Key Steel is widely used for many general engineering applications. Typical key steel applications include taper, gibhead, plain and parallel keys.
What grade steel is key stock? ›The material is 1018 carbon steel and is available with either zinc plated or plain finish. Also available in 303 stainless steel.
What is stainless steel key stock? ›Key stocks are designed to transmit torque (rotational force) in keyways without causing wear on a machine. They can be made from a number of different metals, including stainless steel.