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THE VOICE OF THE CONVEYOR INDUSTRY OF THE AMERICAS

Conveyor Chain and Sprocket Section Meeting 7:30 a.m., Monday, March 12, 2018 Naples Grande Beach Resort, Naples, FL AGENDA 1. Call to Order and Roll Call 2. Approval of the Minutes of September 20, 2017, Meeting 3. Discussion of Issues

a. Conveyor Chain, Installation, Maintenance & Best Practices-001 & CEMA TR 2017-01, Chain Types & Definitions

b. Sprocket Types and Definitions - 1st Draft (attached) c. Future projects, Technical Papers/Guides i.e. Types of

corrosion chain; Unit Handling Maintenance Guide: Selection/Performance; How to / Definition of Replacing Chain

4. Conveyor Chain and Sprocket Section Membership 5. Election of Officers 6. Other Business 7. Adjournment Glenn Spungen, Chair Dean Bogner, Vice Chair/Secretary

5672 Strand Ct., Suite 2 • Naples, Florida 34110 Tel: (239) - 514-3441 • Fax: (239) - 514-3470

www.cemanet.org

Conveyor Equipment Manufacturers Association

CEMA FM 2017 – MINUTES – CONVEYOR CHAIN AND SPROCKET SECTION MEETING

O'Hare Hilton Hotel, Chicago, Illinois

Tuesday, September 20, 2017, 7:00 A.M.

Attendees: George Basel ‐ U.S. Tsubaki Dan Fannin – Regal Beloit Jeremy Fogo – Peer Chain Phil Hannigan – CEMA

Corey Langner ‐ Timken Mike Nisenbaum – Timken Joe Pahlow‐ Arrowhead Conveyor Glenn Spungen – Peer Chain

1. Meeting minutes approved from the March 13, 2017 Meeting 2. Installation Maintenance & Best Practices Final Edits were approved 3. Conveyor Chain & Types Definitions Final Edits were approved 4. Sprocket Types and Definitions ‐ 1st draft needs to be sent to Tom Perdue in January 2018 5. Prioritized future projects for engineering group

a. Types of corrosion chain i. Define types of corrosion resistant chains (stainless, nickel plated, zinc plated,

coated, etc.) ii. When to use coated vs. stainless steel chain? iii. When to use plastic chain in applications?

b. Enhance Unit Handling Section i. Maintenance Guide on selection and performance ii. Provide definition and detail on how (and when) to replace chain

6. Interchange Charts a. CEMA participants who attend the meetings and “do the work” must get the

recognition. There must be some type of incentive for the participants! 7. The CEMA members need to understand the concept of “Internet of Things” and how it will

impact their business. 8. Membership Committee

a. Always trying to recruit, but maybe there should be an incentive program for companies that recruit new members.

9. Adjournment at 7:50 A.M.

Conveyor Equipment Manufacturers Association

Conveyor Chain and Sprocket Section DRAFT 1‐Conveyor Chain Sprocket Types/Def's‐Committee USE ONLY, No distribution w/out CEMA permission. February 5, 2018

Conveyor Chain

Sprocket Types

and Definitions Compilation‐DRAFT 1

Chair: Tom Perdue / Vice‐Chair: Roger Bruere

The CEMA Conveyor Chain & Sprocket Working Group has prepared this document for the

purpose of providing a common level of understanding and terminology of the various types of

sprockets used for conveying chains and belts found throughout the industry today. The scope

of this document includes descriptions and definitions of several sprocket types used for the

following types of chains: roller chains, forged chains, cast chains, welded steel chains,

agricultural chains, steel bushed chains, chain drive belts, and plastic chains. Overall, this

compilation is not intended to be exhaustive, but it does cover most of the types of sprockets

one would find when working with conveyor chains and belts used in the most typical industry

applications.

Standard Roller Chain Sprockets

Standard roller chain sprockets are a series of toothed wheels that are designed to engage

with its conjoining roller chain counterpart in effort to transmit power from the driver

sprocket to the driven sprocket. They can be made with many different types of hub styles

and sizes. A few of the most common hub styles are A ‐ Hub (sprocket plate only),


B‐Hub (hub projected on one side of sprocket plate),

and C‐Hub (hub projected on both sides of sprocket plate).

Standard roller chain sprockets can also consist of plain bore styles and finished bore styles.

Plain bore styles can be found with a minimum bore diameter in A‐Hub, B‐Hub, and C‐Hub

sprockets with the capability to machine the bore size to the maximum bore diameter

allowed. Finished bore styles can be found in B‐ Hub and C‐Hub sprockets with various fixed

bore sizes with keyways and 2 set screws that are per ANSI regulated standards. The set

screws are commonly placed with one right on the keyway and the second set screw at 90

degrees from the keyway.


These sprockets are generally made of steel to ensure strength requirements for transmitting

power. Most finished bore sprocket sizes, typically used as the drive sprocket are made of

induction hardened teeth that provide wear resistance, while having anywhere between 2– 3

times the service life as compared to non‐hardened sprockets made of a mild carbon steel.

Standard roller chain sprockets are also available for extended chain pitch sizes. For corrosive

environments, carbon steel sprockets can be black oxidized, plated, or stainless steel.

Common sizes of sprockets are readily available which can be used with their chain

counterpart such as: 25, 35, 40, 41, 50, 60, 80, 100, 120, 140, 160, 180 standard roller chains in

A‐, B‐, or C‐Hub styles, or double pitch (extended pitch chains) in A‐ or C‐Hub styles typically

2040/2042, 2050/2052, 2060/2062, and 2080/2082.

Agricultural Chain Sprockets

Sprockets used with agricultural, pintle, or detachable chains are typically made from cast or

wrought ferrous materials. Wear resistance is frequently designed into the material of the

tooth faces. Sprocket bodies are of many configurations. When hubs containing the sprocket

mounting bore are employed, they may project from either side or from both sides of the

sprocket body (B‐ and C‐Hub styles). Since these sprockets are often used in areas where debris

is likely to engage it, root diameters should be decreased and pitch line clearances increased

accordingly. Mud reliefs may be incorporated to prevent root diameter build up. ASME

B29.300 contains specifications relating to these sprockets.

Forged Chain Sprockets

Forged chain sprockets are typically of segmental construction consisting of four segments

bolted onto a solid or split B‐ or C‐Hub types. The segmental construction facilitates the

replacement of worn tooth segments by allowing the hub to remain mounted to the shaft.

Sprocket segments are generally made from carbon steel, case hardened to 450‐550 BHN, or

AR400‐500 steel. They are also available in grade 420 stainless steel for corrosive applications.

Sprocket hubs are typically made from mild steel or 304 stainless steel.

The engagement method with drop forged chain is quite different from traditional chains. The

spine of the chain links engage between sprocket segments as shown in Figure 1. As such, it is

critical that the channel between segments remain clear for the chain to engage. For this

reason, sprocket cleaners are normally incorporated onto the return rail to strip away any

product build up within this area.


Sprockets are fabricated and hardened at a

slightly lower hardness compared to the chain to

minimize wear. Sprocket replacement is

recommended when the teeth are worn ¼” below

original surface engagement with the chain, as

illustrated in Figure 2.

Operating the chain on worn sprockets creates an

improper pitch diameter, which can result in

damage to the chain, circlips, and lead to chain

separation. This condition will also shock load the

chain and cause “hooking”, resulting in higher

stress loads on the chain due to

improper sprocket engagement.

Although sprockets are critical to proper conveyor operation, they often get overlooked during routine maintenance. Typically, sprocket tooth segments should be replaced 1 or 2 times throughout the lifecycle of the chain.

Always install new chain with new sprocket segments.

Figure 1

Figure 2


Engineered Class Chain Sprockets

Cast Chain Sprockets

Cast sprockets are generally used with cast chains. They are used in applications that handle

abrasive materials such as sand, gravel, ash or cement.

Cast iron chilled rim (C.I.C.R.) sprockets differentiate themselves because of their hardened

teeth. The hardened teeth are achieved by adding a steel ring or rim in the sprocket pocket of

the mold. The steel then quenches the iron creating a hard surface. The resulting hardness is

approximately 350 BHN at 3/16” depth.

The three types of construction that are available for cast sprockets are solid, split and

segmental. The solid and split construction are furnished with either a solid center plate or a

spoked arm center. Lightening holes are occasionally used in solid center plates to reduce

weight and ease the handling process. The spoked arm sprockets are used on larger sprockets


to reduce weight as well. Split and segmental sprockets are used when ease of installation is

required without disturbing the shaft, bearings or other sprockets.

An additional feature of cast sprockets is the opportunity of chain saver rims. They are often

used in sewage treatment applications. The rims are located under the sidebars, and as the

chain wraps the sprocket, they allow for the sidebars to rest on them. The chain saver rims help

the chain to run at the pitch diameter of the sprocket.

Lastly, hunting tooth designs are available on cast sprockets. Hunting tooth sprockets have an

odd number of teeth, with the pitch of the teeth one half that of the chain. This makes the

chain barrel advance one half pitch for each sprocket rotation. This action allows the teeth to

alternate which teeth come in contact with the chain, thereby doubling the sprocket life.

Cast Iron Sprocket with Spoked Arm Center and Chain Saver Rims

Welded Steel Chain Sprockets

Welded Steel Chain is generally categorized as mill or drag chain. These two chains contain

diverse design characteristics and features. Mill chains are typically narrower than drag chains.

Therefore, the sprocket requirements for the two are different.

Mill Chain Sprockets

Flame cut flame hardened (F.C.F.H.) sprockets are normally operated in conjunction with mill

chains. These sprockets are generally manufactured from medium carbon steel. The teeth on

carbon steel sprockets are flame hardened. The flame hardening of medium carbon steel


results in a hardness of 40 Rc minimum, with an approximate depth of 1/8”. Flame cut flame

hardened sprockets can also be manufactured from alloy steels, as well as stainless.

The two types of construction that are available for mill chain sprockets are solid and split. The

split sprockets are used when ease of installation is required without disturbing the shaft,

bearings or other sprockets. Four basic hub types are available in both solid and split

construction.

Type “A” is a flat plate with no hub extensions on either side.

Type “B” is a flat plate with a hub extension on one side of the plate.

Type “C” is a flat plate with hub extensions that project the same amount on both sides

of the plate.

Type “C Offset” is a flat plate with hub extensions that have different length projections

on both sides of the plate.

Type “A” Type “B” Type “C” Type “C Offset”

An additional feature available on mill chain sprockets are mud reliefs. Mud reliefs are used to

help keep material from building up in the pocket of the sprocket. The relief is normally

machined, burnt or ground in the sprocket plate.


Flame Cut Sprocket with Mud Reliefs

Drag Chain Sprockets

Drag chain sprockets are found in applications where wide drag chains are used. These

sprockets are manufactured with full width teeth or a double plate design. The benefit of a full

width tooth sprocket design is that they allow for a greater contact area. Larger contact area is

a benefit because it allows for better wear on a sprocket. In the case where material build up is

an issue, double plate sprockets are preferred. The double plate allows the extra clearance for

material to pass over the drum in the conveyor. Lastly, many drag chains are manufactured

with a non‐round barrel. The barrel could be a formed, have a two piece welded design or an

elliptical shape found in cast chains. These deviations from a round barrel along with chain

direction need to be accounted for in the sprocket design.

The two types of construction that are available for drag chain sprockets are solid or split. The

teeth are normally flame hardened and in some instances the drum is also. The teeth are

welded to a drum, which is typically either a pipe or a piece of rolled steel. The center part of

the drum would consist of one center plate or for wider sprockets they could have end plates

with hubs.


Drag Sprocket with Full Tooth

Drag Sprocket with Double Plate

An additional feature of drag chain sprockets is the option of flanges. Flanges are side

extensions added to the drum that keep material from falling onto the shaft. This sprocket

feature is usually used in conjunction with drag chains that contain wing attachments. It is

imperative that the location of the flange does not interfere with the chain articulation.


Drag Sprocket with Full Tooth and Flanged Rim

Elevator Chain Sprockets

Elevator chain can operate on sprockets or traction wheels. Sprockets and Traction wheels can

be found at the head shaft or the tail shaft.

Traction wheels do not have teeth to engage the chain, consequently they rely on friction to

drive the chain. Traction wheels are normally made from medium carbon steel, but can also be

made from alloy steels as well as stainless. As a general rule of thumb, the weight of the

buckets, material and chain on the carrying side vs. the return side must not exceed a ratio of

1.5:1. Due to the nature of traction wheels, they should not be used when materials are oily or

have high lubricity. Additionally, they should not be used in conjunction with chains that

contain rollers. Traction wheels are designed so that the outside diameter plus the bushing

diameter of the chain do not equal the pitch diameter of a toothed sprocket. This allows the

chain to engage in a different spot of the traction wheel increasing the wear life of the traction

wheel and the chain bushings. Another advantage of a traction wheel is that the chain will slip

in the event of an obstruction or an overload.

Traction Wheel

Flame cut flame hardened (F.C.F.H.) sprockets are generally used in conjunction with elevator

chains. These sprockets are normally made from medium carbon steel. The teeth on carbon

steel sprockets or the outside diameter on traction wheels are flame hardened. The flame

hardening of medium carbon steel results in a hardness of 40 Rc minimum, with an


approximate depth of 1/8”. To achieve higher hardness and deeper case depths, sprocket and

traction wheel could be carburized and induction hardened. Flame cut flame hardened

sprockets can also be made from alloy steels, as well as stainless.

The three types of construction that are available for elevator sprockets are solid, split and

segmental. The solid and split construction is furnished with either a solid center plate or a

spoked arm center. Spoked arm sprockets are used on larger sprockets to reduce weight. Split

and segmental sprockets are used when ease of installation is required without disturbing the

shaft, bearings or other sprockets. Lightening holes are sometimes used in solid center plates

for reduced weight as well as for handling.

Solid Construction Split Construction


Segmental

Rim Construction

In double strand elevator chain, sprocket

configurations are important for the head

and tail shafts. The head sprockets must

have teeth that are in line with each other.

This is achieved by having the sprockets

matched.

Plastic Chain and Belt Sprockets

Section to be added.

Matched Sprockets


Technical Note: Chordal Action

Chain drives experience a vibration known as chordal action or polygonal effect which occurs as

the effective radius of action in the chain and sprocket system changes during each revolution.

Chordal action can cause increased wear on the chain and sprocket. The effect can be

minimized by using a sprocket with more teeth and virtually eliminated with a sufficiently large

sprocket.

As the sprocket rotates, the engagement position of the chain is restricted by the pitch points

of the links. These pitch points create a polygon, with the number of vertices equal to the

number of sprocket teeth. The resulting polygon defines the maximum and minimum effective

radii illustrated in Figure 3. The radii can be calculated using Error! Reference source not found.

and 2. During rotation, the instantaneous speed of the chain changes, however, the percent

variation will always be constant for a sprocket with a number of teeth N. Figure 4 illustrates

the percentage speed variation versus the number of teeth.

Figure 3: Defining Effective Radii

∗

Equations 1 and 2 Minimum and maximum effective radii

Figure 4: Percentage speed gap for common sprockets

Chordal action can be minimized by reducing th

0.0%

2.0%

4.0%

6.0%

8.0%

10.0%

12.0%

14.0%

16.0%

0 5 10 15 20 25 30 35 40 45 50

Percent Chordal Spee

d Variation

Number of Sprocket Teeth

Speed Differential by Sprocket Size


Chordal action can be minimized by reducing the speed of the chain or by using a sprocket with

more teeth. As the percentage chordal speed variation is solely dependent on the number of

teeth, the percentage can be found using Equation 3.

Δ 1 cos180°

Equation 3: Speed Differential

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