Conveyor Chain FAQ

FAQ

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What chain is best suited for high precision conveyors that require highly accurate positioning?
What are the temperatures of use for the high precision conveyor chains?
What plastic roller chain can be used at high temperatures?
What are the characteristics of Double Plus Chain Lambda Series (lube free)?
What cautionary measures should be taken when using two chains in parallel?
How can I differentiate the usage of S-Rollers and R Rollers?
Can RS standard sprockets be used with double pitch chain?
What are the appropriate methods for guiding curved chain?
What is the minimum number of sprocket teeth when using GNK1 attachments?
What are the allowable loads for Rollers on chains other than General Use Conveyor Chain (DT Series) and Heavy Duty Conveyor Chain (AT Series)?
What are the limits for the different conveyor chain parts?
What are the plans to improve the anti-wear capabilities of Flow Conveyor Chain?
Why is the Bearing Roller Conveyor Chain considered economical?
What precautions/considerations are necessary when using conveyor chain in environments over 400°C?
What are the causes and countermeasures for the stick-slip phenomenon?
How much should the take up force on a conveyor chain be set to?
How are chains guided?
What types of attachments are available for conveyor chains?

1. What chain is best suited for high precision conveyors that require highly accurate positioning?

Within automated manufacturing, assembly, and inspection lines there are straight line type base machines (high precision conveyor) that preserve positioning accuracy. Chains are utilized as one type of conveyance method for these applications, but with regular chains sliding wear occurs between the pin and bush, causing the chain to elongate and eventually loose its positioning accuracy. Because of this it becomes necessary to carry out frequent positioning maintenance.

However, Tsubaki has solved this problem with the introduction of high precision conveyor chains. By inserting cylindrical bearings into the area between the pin and bush this area has changed from a sliding bearing to a rolling bearing, considerably lowering wear elongation and making high speed high accuracy precision positioning possible.
There are 4 types of high precision conveyor chains that are differentiated by their use and level of required accuracy.

2. What are the temperatures of use for the high precision conveyor chains?

The temperature of use for high precision conveyor chain is determined by the temperature range that allows for a continuation of the chains performance and efficiency as well as the characteristics of the materials used. As these change depending on the chain, please use the chain within the temperature range listed below only after confirming the conditions of use for the chain in question.

Name	Tsubaki Chain No.	Temperature Range	Positioning Precision (reference)
Bearing Cage Chain	RF20○○R-NC	-10~60°C	±0.7mm
Bearing Bush Chain Standard Series	RF20○○R-NB	-10~150°C	±0.5mm
Bearing Bush Chain High-Precision Specifications	RF20○○ R-NBH	-10~150°C
Bearing Bush Chain Stainless Steel Specifications	RF20○○ R-NB-SS	-10~60°C
Mini Tact Chain	BCM	10~40°C	±0.05mm
Indexing Table Chain	BC	-10~60°C	±0.1mm

Positioning precision figures are results from customers and are for reference purposes only. These figures are in no way an indication of any kind of guarantee on the part of Tsubaki.

3. What plastic roller chain can be used at high temperatures?

Plastic Roller Chain makes full use of the plastic materials used in its fabrication, allowing for lower weight, noise and wear, in a wide variety of applications. However, because the temperature of use for plastic roller chain (roller material: polyacetal) is -10~80°C, meaning they cannot be used in applications with pre-heaters or dryers that are over 80°C, customers must use steel or stainless steel for these applications. In January of 2003 though, Tsubaki introduced the Heat-Resistant Plastic Roller Double Pitch Chain with super engineering plastic rollers which provide heat resistance up to 180°C. (Base chain is stainless steel) Furthermore, added to the original characteristics (lower weight, noise and wear); the super engineering plastic rollers also provide chemical and burn resistance, as well as conductivity. As these chains can be used in both wet and dry environments, they are able to fulfill a vital function is a wide variety of equipment: washers, steamers, boilers, dryers, heaters, etc.

4. What are the characteristics of Double Plus Chain Lambda Series (lube free)?

(1) Lube Free and Long Life
Double Plus Chain Lambda Series (lube free) is used as a lube free chain that provides 5 times the wear elongation life of standard double plus chain (based on in-house test results). Also, the take up needed to adjust the chain's tension and other general maintenance can be carried out less frequently.

(2) Eliminating Laborious Lubrication Keeps Goods Clean
Just as with other chains, Double Plus Chain needs to be lubricated to inhibit noises, wear elongation, etc. but it is necessary to ensure that lubrication is carried out in a way as to keep the lubricant from adhering to the plastic rollers, and to remove any lubricant that may inadvertently become adhered. This is because if the chain is used with lubricant on the rollers, there are instances where the chain will no display the double speed feature.
With Double Plus Chain Lambda Series (lube free) though this kind of time consuming labor is eliminated. This means goods are no longer contaminated from lubrication spatter, allowing customers to maintain a clean working environment with less time and effort.

(3) Low Noise
Because Double Plus Chain Standard Series transfers goods at 2.5 times the speed of the chain; it produces 15% less noise compared to Outboard Roller Chain, Top Roller Chain, etc. However, if Double Plus Chain Standard Series is used for extended periods without additional lubrication, a distinct creaking noise will begin to emanate from the area between the pins and bushes. Double Plus Chain Lambda Series (lube free) on the other hand has lubrication impregnated bushes that provide proper lubrication to the area between the pin and bush, thus preventing creaking sounds, and helping to maintain a quiet work environment for a longer period of time.

running time

5. What cautionary measures should be taken when using two chains in parallel?

Chain lengths will vary within standard tolerance levels. However, when using two chains in parallel, there are times when applications require chains to be aligned to a very high degree of accuracy. For example, when using slats or other types of jigs that are attached across both chains. In these instances, if it is indicated that the customer would like the chains "Matched and Tagged" at the time an order is placed, Tsubaki measures the length of each pare and provides a left and right chain with the smallest possible difference in total length. Also, attachment chains such as those in 2-5 gif have unique distances between the attachments, so that when they are used in parallel, the positioning of the attachment can become unaligned. However, if customers request "Mirror-Image Strands" at the time an order is placed, sets of chains can be fabricated to have symmetrical attachments.

mirror image strands in pairs

Not Same as Example Chain

Order Example
RF2040R-2LA2…6 Units (Set Length, 6 Strands)
Application: Two chains run in parallel X 3
Mirror Image Strands
Matched and Tagged

6. How can I differentiate the usage of S-Rollers and R Rollers?

Two types of Rollers are used for Double Pitch Chains: S-Rollers and R Rollers. The characteristics and difference in usage are as listed below.

Roller Type	Comparison 1*						Difference of Use
Roller Type	External Appearance	Chain Mass	Roller Allowable Load	Roller Wear Life	Roller Coefficient of Friction	Price	Difference of Use
S-Roller	The outer diameter of the roller is smaller than the plate width.	Light	Low	Short	High	Low	Generally used where equipment length is under 10ms, and speed is less than 20m/min. Elevates some of the impact when engaging the sprocket.
R Roller	The outer diameter of the roller is larger than the plate width.	Heavy	High	Long	Low	High	Generally used where equipment length is above 10ms, and speed is more than 20m/min. A low roller coefficient of friction allows for smooth rotation with less vibration.

*1 Comparison made when chains are of the same size, and run on the same application conditions.

s-roller r-roller

7. Can RS standard sprockets be used with double pitch chain?

When using R Rollers, please unsure that only sprockets specialized for double pitch R Rollers are used.

rf chain engaged with sprocket When using S-rollers, please unsure that sprockets specialized for double pitch S-rollers are used; however, if the sprocket has 30 or more teeth, RS standard sprockets may also be used. Please be aware though that if RS standard sprockets with 29 or less teeth are used, the chain and sprocket will not properly engage, and conveyance will not be smooth due to fact that the chain pitch and pitch of the sprocket teeth will not match.

*As show in the figure to the right, S-rollers engage the sprocket on every other tooth. Because of this, when there are an odd number of sprocket teeth, the rollers engage a different tooth with each rotation, allowing for less wear and a longer life. When considering the use of RS sprockets of 30 or more teeth please first consider is sprockets with an odd number of teeth may be used or not.

8. What are the appropriate methods for guiding curved chain?

When guiding curved chain, it is important to understand that the possibility of chain derailment increases greatly if the roller surface alone is guided.

Because of this, it is highly recommended to guide curved chain at two points; 1) the roller surface and 2) the plate surface.
However, to ensure the end of the pin and the guide do not come into contact when the link sides meets the guide, it is important to install a grove in the guide to allow the protruding pin end to escape through. Alternatively, chain with guide plates (a second outer plate is installed so the pin end and plate surface is flush), chain with outer guide rollers, etc., is also available. Please consult your local Tsubakimoto Chain representative for details.

Please see below for an example of possible guiding methods.

guiding curved chain

9. What is the minimum number of sprocket teeth when using GNK1 attachments?

When bars are installed in the holes of the GNK1 attachment for GNK1 Double Pitch Chain (an attachment with holes of both sides of the plate), the bottom of the sprocket teeth and the bars will interfere with each other if there is not the sufficient number of teeth on the sprocket.
When using standard GKN1 attachments ensure sprockets with 12.5 effective teeth / 25 actual teeth or more are used.

If sprockets with 30 or more teeth are required, RS standard sprockets may be used.

10. What are the allowable loads for Rollers on chains other than General Use Conveyor Chain (DT Series) and Heavy Duty Conveyor Chain (AT Series)?

The allowable loads for General Use Series (DT Series), Heavy Duty Series (AT Series), plastic roller series, bearing roller series, and needle bush series, are listed in the "Tsubaki, Large Size Conveyor Chains" catalog. The allowable roller loads that are not listed in the catalog are as listed below.

Series	Stainless 400 Series		Stainless 300 Series	Applicable Series
Code	DS	GS	SS	BT	GT	CT	MT	RT	YT
R Roller F Roller Allowable Load	DT	DT	DT/2	AT	AT	AT	DT	DT	DT

11. What are the limits for the different conveyor chain parts?

In generally, the life of a conveyor chain is determined by the amount of wear on the individual parts. What part meets its life first is determined by the conditions of use. The wear life limit for the individual parts is as listed below.

(1) R Roller / F Roller

The roller has met its limit when the bottom of the plate begins to touch the rail due to wear on the contact surface or the sliding area with the bushing.

r roller / f roller

If there is a curve in the rail there will be less wear allowance for only the corresponding S dimension as seen in the diagram below. Special care is needed when compared to flat conveyance.

curve in the rail

(2) S Roller

When roller thickness wears to 40%

(3) Bush

When bush thickness wears to 40%

(4) Plates

Wear will develop from abrasion between plates as well as roller and plate contact at points (A) and (B) in the below diagram. Chain strength will be insufficient when wear exceeds 1/3 of the plate's normal thickness.
If items are conveyed directly on the plate, wear will occur against the height of the plate as shown in the diagram below on the left. The chain life will have been reached when the plate height is worn by 1/8, as seen below.

plate wear

(5) Chain Wear Elongation

measuring chain length

Chain articulates when it engages the sprocket or along the curved portion of a rail, at which time the chain will elongate due to sliding wear between the bush and pin. The chain elongation limit is 2% (2mm of elongation on one link if pitch is 100mm). As shown in the diagram above, measure as many links as possible (at least four links) when measuring. Measure from:

(A) center of pin to center of pin

(B) end of pin to end of pin

Measure chain using one of the above methods, compare to standard length, and determine the chain elongation (%).

chain elongation calculation

12. What are the plans to improve the anti-wear capabilities of Flow Conveyor Chain?

Within the Flow Conveyor Chains used to transport cement, etc., the BT Series was developed with innovations to the materials for the pin, bush and roller as well as the heat treatment process which allowed for an increase in the anti-wear capabilities of the individual parts. However, for the conveyance of the highly abrasive fly ash (one base material of cement) an even higher level of anti-wear was demanded. So, in June of 2000, Tsubaki introduced the Fly Ash Conveyor Chain (FA Series) which implements a special hardening treatment to the outer surface of bushes and rollers, greatly increasing the anti-wear properties and wear life of the chain.

Comparing BT Series and FA Series (Fly Ash Conveyor Chain)

chain life comparison

[Wear Comparison]

BT Series

FA Series

13. Why is the Bearing Roller Conveyor Chain considered economical?

Compared to General Use Conveyor Chain of the same size, Bearing Roller Conveyor Chain is a more expensive chain. However, because of the various characteristics listed below, Bearing Roller Conveyor Chain can offer various cost-down benefits, as well as provide drastic and significant improvements to running costs.

bearing roller conveyor chain exploded

[Characteristics of Bearing Roller Chain]

(1) Low Coefficient of Friction

Bearing Roller Conveyor Chain features a unique construction of cylindrical bearings inside the roller which work as a point of contact for rotation. Therefore, the coefficient of friction of the rollers is reduced to 1/3~1/6 of General use Conveyor Chain. Because of this, The tensional forces applied to the chain are also reduced by 1/3~1/6.

General Use Conveyor Chain…without lubrication: μ=0.13~0.18, with lubrication: μ=0.08~0.12
Bearing Roller Conveyor Chain…μ=0.03

(2) Increased Load Capacity of Rollers

When compared to General Use Conveyor Chain (R Roller), Bearing Roller Conveyor Chain rollers have three times the allowable load. For conveyance on horizontal or slightly angled conveyors, the rollers allowable load is often what determines chain size. This, combined with feature (1) above, allow for conveyor chains up 2 sizes smaller to be used.

(3) Easier Maintenance & Longer Life

By installing cylindrical bearings, chain life has been extended 5-10 times (when lubricated) than that of General Use Conveyors with traditional sliding bearings, greatly reducing required maintenance. Furthermore, the wear life between the bush and roller is dramatically increased.

(4) Suppresses Stick-Slip Phenomenon

Fluctuation in the rotational coefficient of friction for the roller is minimal, allowing for a suppression of the stick-slip phenomenon.

*Please refer to question 15 for further details on the stick-slip phenomenon.

14. What precautions/considerations are necessary when using conveyor chain in environments over 400°C?

In general, if chains are used in high temperature environments the following problems may occur: (1) hardness levels will lower, causing a reduction in strength, (2) elongation will increase (clips may fracture/fail), (3) lower hardness levels and higher coefficient of friction will lead to an acceleration of wear, (4) thermal expansion, or if lubrication is being carried out, a loss/carburization of lubricant causing poor articulation. If the chain is to be used in an environment over 400°C, use stainless steel, and choose and install an appropriate only after fully considering the above issues. For applications over 400°C, please consult your local Tsubakimoto Representative.

15. What are the causes and countermeasures for the stick-slip phenomenon?

Stick-slipping is when even though items are to be continuously conveyed in a smooth motion; the conveyor stops and starts repeatedly, causing a hick-up like phenomena in the chain movement. In general this occurs when chains are over 10ms in overall length, and moving at a speed of 15m/min or less.

Causes:

Fluctuations in the coefficient of friction between the bush and roller
Insufficient chain rigidity
Insufficient rigidity of drive unit/frame

Countermeasures

Increase chain speed
Break conveyor up into several small conveyors
Use larger chains, and strengthen frames and guides to raise the overall rigidity of the conveyor
Lower the coefficient of friction between the bush and roller, increasing stability. The following two methods are recommended
- Use Tsubaki's anti-stick-slip lubrication to help eliminate stick-slipping
- Use Bearing Roller Conveyor Chain
  (However, if chain speed is below 2m/min, please consult with your local Tsubakimoto representative.)

16. How much should the take up force on a conveyor chain be set to?

Conveyor chain tension (take up) should not be too strong. It is best to use the chain with a slight sag below the motor unit.
However, in the cases listed below it is necessary to take up this chain sag.

Positioning takes place on the top of the chain
Frequent forward and reveres operation
When chain pushes goods along the conveyance side (c)

Generally, it is possible to set a proper level of sag by observing the chain visually and by simply touch with your hand, but see below for general numerical indicators.

conveyor take-up force

Chain Mass … M(kg/m) × N (No. of Chains)
Mass of Slats/Jigs Attached to Chain … W (kg/m)
Mass of Conveyed Goods … m (kg/m)
Distance Between Shafts … C (m)
Coefficient of Friction Between Chain (or jig) and Rail … Μ
(Return side of chain (bottom side))
Gravitational Acceleration … G (=9.80665m/s²)

Direction of Rotation for A (forward drive)
Take Up Force F ≥ {(M × N + W) × C × μ} × G/1000 × 2 × 1.2~1.5
Direction of Rotation of B (reverse drive)
Take Up Force F ≥ {(M × N + W + m) × C × μ} × G/1000 × 2 × 1.2~1.5

If there is forward and reverse drive set the take up force as listed in [Direction of Rotation of B (reverse drive)]

NOTE:

The above F is the take up general indicator. Watch the operational status while setting.
Ensure that the take up force (with operational tension added) dose not go over the chains maximum allowable load, and does not go under reasonable safety factors.
Applying too much tension to a chain will accelerate wear and thus shorten the life of the chain.