Conveyor Roller Introduction

Conveyor Roller Introduction

Conveyor Roller Selection

Is the package suitable for a roller conveyor?

Products:
A package with a hard and flat bottom surface such as cardboard, flat bottom plastic boxes, metal work bins, wooden pallets, etc. are suitable for roller conveyors. package with a bottom surface that is soft or irregular such as soft boxes, handbags, components with an irregular bottom etc. are not suitable to be conveyed on a roller conveyor.

Objects with a small contact surface i.e. point contact or line contact, may damage the roller (localized abrasion, damage to the tapered sleeve, etc.)

Environment:
1. Plastic components are fragile at low temperatures. Different series rollers are suited to different temperatures (check characteristics for each series). When exceeding the specified temperature range, please contact us for advice.
2. In some circumstances of powder production, rubber lagged rollers cannot be used in a dustless environment.
3. Polyurethane absorbs colours easily and may not be suitable for transporting coloured packages or goods.

Roller Length:

For curved conveying, please refer to P7 8 for rol ler lengthselection.

The suitable length of the roller should be selected according to the width of the product (length of roller surface, indicated by W). For straight conveying, calculate according to the formula below:

For goods with a very hard, sturdy base, where safety and normal conveying is not compromised, the width of the goods can exceed the length of the roller i.e. W≥0.8B.

Roller Pitch Selection:

To ensure the steady conveying of goods, the principles of selecting the correct roller pitch (roller centre distance, indicated by T) is a minimum 3 rollers to support the goods at any moment, i.e. T≤1/3L.
1. Products that require steady conveying, use T = 1/4 ~ 1/5 L or smaller.
2. For flexible, long and thin products, you need to check the deflection of the product. The product deflection should be less than 1/500 of the roller pitch otherwise it will greatly increase the running resistance.
3. The pitch of double sprocket conveyors must be calculated in multiples of 1/2 the chain pitch. For details refer to P52.
4. The pitch of poly-vee rollers is limited by the type of poly-vee roller. For details refer to P49.
The loading on each individual roller must not exceed its maximum static loading (This loading refers to a uniformly distributed load without impact. If applying concentrated loading, the safety index will need to be increased).

Different Conveying Modes:

1. Gravity conveying: Manual pushing or declined roller bed:

  • Polymer bearing housing: 1200 series
  • Steel bearing housing: 1100, 1800 series

2. Driven conveying: AC gear motor drive or motor roller drive:

  • O-belt conveyor roller: 2240, 2260 series
  • Poly-vee roller: 2250 series
  • Sprocket roller:
    • 2214/2224 series (polymer sprocket, polymer bearing housing)
    • 2411/2421 series (steel sprocket, polymer bearing housing)
    • 2311/2321 series (steel sprocket, steel bearing housing)

3. Accumulating conveying: AC gear motor drive. The product needs to accumulate on the conveyor line:

  • Friction driven accumulation:
    • 3214/3224 series (polymer sprocket)
    • 3211/3221 series (steel sprocket)
  • Adjustable accumulation: 3816/3826 series (steel sprocket)

4. Curve conveying:

  • Plastic tapered roller:
    • 1600, 2640, 2660, 2650, 2624 series
  • Steel tapered roller: 1500, 2521 series

Load Capacity

The main factors which determine the roller load capacity are the tube, shaft and bearing. The load capacity is dictated by the weakest of them:
1. Excessive load will distort the tube during roller operation which may result in permanent damage leading to unstable conveying of the product.
2. If the load capacity of the shaft is insufficient, it will change the adaptive capacity of the shaft and influence the running performance.
3. If the load exceeds the permitted load of the bearing, it will greatly reduce the bearing’s lifespan.

You need to know the following design information:

1. The rated load capacity of a single roller is the uniformly distributed load on the roller surface (not point load).
2. The method of mounting the shaft to the conveyor frame. For example a internal threaded shaft has a higher load capacity than a loose mounted shaft such as a spring loaded shaft.
3. For each application, you need to consider how flat the product conveying surface is and any partial forces encountered during conveying.
4. Steel tube and stainless steel tube have similar mechanical properties with regards to load capacity so are typically considered to have same load capacity.
5. Increasing the thickness can strengthen the tube’s impact resistance (not easy to dent), but has little influence on the roller’s load capacity.
6. In some modes of conveying, especially in belt conveying, duty plays a decisive role rather than the load. The duty depends on the driving force such as belt maximum tension and chain tension.

Duty: Maximum loading of driven roller. Load: Roller’s maximum weight capacity.

Run Out

Run out is the key factor in how smooth the roller runs. It will influence the stability and reliability of conveying. If the run-out is excessive, it will lead to product jolting, deviation from normal conveying direction, influencing the accuracy of conveying, causing higher noise levels and may even cause partial product damage or a reduction in the conveyor’s lifespan.

Damon’s conveyor rollers utilize high quality materials andstrict manufacturing processes to ensure better run out performance than specified by JB/T 7012-2008.

Unit: mm
roller length roller tapered roller
100~500 0.5 0.7
>500~1000 0.6 0.9
>1000~1600 1.0 1.4
>1600~2000 1.2 /

Remark: exclude PVC and grooved roller

Choose the maximum data from the three points as the inspection data

Tube Material

Steel

Following the ongoing development of tube making and welding techniques, steel pipes with a longitudinal electric weld, commonly known as Welded Tube, has been replaced with hot rolled seamless tube and has become the most commonly used material for conveyor roller manufacturing. Hot rolled seamless tube satisfies the requirements for mechanical properties and curvature. The advantages of hot rolled seamless tube is appearance, balance and cost.
. The two most commonly used material numbers are as follows:

Aluminium

The hardness of aluminium alloy is only 1/3 in comparison to steel tube and stainless steel tube. It weighs only 36% of steel tube and features water proof and rust proof properties. It is suitable for light weight applications and wet working conditions. It is also specified in some industries e.g. rubber.

PVC

The load capacity of PVC tube is much lower than steel tube of the same diameter but has the following features:
1. Corrosion resistant, good chemical stability.
2. Easy cleaning.
3. The roller is light, easy start-up.
4. Low noise, shockproof.

Common tube size:

Unit: mm
D t
Φ18 1.0
Φ25.6 1.0
Φ38 1.2
Φ48.6 1.5
Φ50.6 1.5
2.0
Φ60 2.0
3.0
Φ76 3.0
4.0
Φ80 2.0
3.0
Φ89 3.0
4.0

Stainless Steel

Welded stainless steel tube is a commonly used material for conveyor rollers. It has an attractive appearance, good corrosion resistance and is much more durable than common steel tube. The two most commonly used material numbers are as follows:

Unit: mm
Material 304 J4-200
Magnetic No
Corrosion
resistance
Excellent corrosion resistance to aqueous alkali and most organic acids and mineral acids. Low corrosion resistance, only suitable for long periods in the common air polluted environment without chloride pollution, rust free.
Main application Kitchen appliances,
automobile parts,
building materials, food
production facility,
hospital tools.
Mainly as decoration or replacement of zinc plated tube for some high temperature requirements.

We have used stainless steel 304 as an example only. If you have a requirement for J4-200, please contact us for code confirmation.

Tube Material

Zinc Plated

Forms a homogeneous, compact, well combined zinc coating through electrolysis. Compared with other metal, zinc is economic and easy to be coated. Corrosion prevention plating allows zinc to be used widely in the area of steel parts protection, specially in preventing oxide etch and is a common surface treatment for conveyor rollers.
1. Trivalent chromium blue white zinc plated, conforms to ROSH.
2. The acceptable thickness of the zinc layer for rollers is 8-12 μm.
3. Special sealing ensures our zinc plating is much more rust resistant than commonly available tube which has been proven in the salt spray tests (As pictured).
4. Zinc plating does not have strong resistance to abrasion. It will wear gradually during operation. If required, you can choose hard chrome platingor other surface treatments.
5. When rollers are shipped by sea, special packing for shipment is still needed.
6. Food is not permitted to come in direct contact with zinc plated surfaces.

Hard Chrome Plating

Thick chrome plating (above 20 μm) is formed on the surface of the component to improve the performance of the component with regards to hardness, abrasion resistance, temperature resistance and corrosion resistance.
1. Excellent abrasion resistance, as high as 1200HV hardness value.
2. The coefficient of sliding friction is only 50% compared to steel and iron.
3. Slight oxidation of the chrome layer leads to surface passivation, a thin and transparent film. After long periods of exposure at room temperature the passivation film causes discolouration and forms a protective layer for the chrome finish.
4. The chrome layer is brittle and is not suitable for bearing any large distortion which may cause breakage or spalling of the chrome layer.

Rubber Lagging

For effectively improving conveying efficiency, eliminating slip such as specified area acceleration, small inclines, etc., we need to add friction between the contact surfaces. Rubber lagging is the most commonly used method. It may also provide protection to the conveyed surface of the product and reduce the conveying noise.

Natural Rubber:
1. High elasticity under room temperature.
2. Good mechanical hardness, small loss on lag.
3. Good electrical insulation properties.
4. Alkali resistant. No resistance to strong acids.
5. Low resistance to oil and solvent.

Nitrile Butadiene Rubber (NBR):
1. Excellent resistance to oil.
2. Good abrasion and heat resistance.
3. Low elasticity.
4. Poor cold and ozone resistance.
5. Low electrical insulation properties.

PVC Sleeve

As an alternative to traditional rubber lagging, you can select PVC sleeving which combine most of the properties of rubber lagging. The PVC sleeve has similar properties to rubber lagging in the areas of increased friction, bottom surface protection and reduced noise. It has a short lead time and is cost effective.

Material Soft PVC
Tube diameter Φ50mm
Thickness 2mm
Colour Grey, RAL7037
Hardness Shore(A) 63±5
Resistance No resistance to oil and gasoline
Electrical insulation Non-conducting
Suitable temperature -25℃~+50℃
Other Not food grade material

1. Typically the sleeve covers the roller’s outside surface (As pictured).
2. If you only require a portion of roller to be covered, please confirm the length of PVC sleeve (Min. 50mm) and the position.
3. Where running the roller generates axial force, e.g. axial movement or axial push and pull, the length of PVC elastic sleeve should be increased.
4. We recommend that the side of the roller with a groove should not be covered with a sleeve (As pictured).

Shaft

The total load on the roller is borne by the shaft which must Installation Method sustain the entire weight. Damon has chosen to adopt high quality carbon structural steel as the shaft material which has a increased hardness and conforms to GB/T 905 requirements.

Shaft size

Surface Treatment

The standard shaft surface treatment is antirust oil. Zinc plated shafts are only used in stainless steel or PVC rollers.
rollers.

Installation Method

1. The roller installation method determines the complexityof roller assembly. Different installation methods also influence the load capacity of the roller.
2. Following are examples of common installation methods and their features. Installation method can be customized.
Spring loaded:
1. This is the most popular installation method for gravity rollers. Assembly and disassembly is simple and quick.
2. Installation clearance is required between the inner width of the frame and the roller. Different clearances are required for different roller diameters, shaft diameters and height of roller. Typically allow 0.5 ~ 1mm gap each side.
3. Cross braces are required between the frames to stabilize and reinforce the conveyor.
4. The spring loaded installation method is not recommended for sprocket

Internal thread:
1. This is the typical installation method for sprocket rollers. The roller is fastened to the frame with a bolt on each end.
2. Assembly and disassembly is more time consuming.
3. Bolt hole clearance in the frame should not be too large. Typically the clearance should be 0.5mm. For example, for an M8 bolt the recommended mounting hole is Φ8.5mm.
4.When using an aluminium frame, the shaft should be of a large diameter with a small diameter fixing bolt to reduce the risk of the shaft breaking through the aluminium frame.

Nuts are required on the inside and outside of the frame to ensure the roller runs smoothly.

Flat milling:
1. Originating from the mining idler roller, the round end of the roller shaft is machined flat to fit into a slot in the frame. Assembly and disassembly is very easy.
2. Flat milling shaft type rollers are not suitable for sprocket rollers, poly-vee rollers or other driven roller applications.

Bearing

The bearings are the most important component of the roller. The correct choice of bearing directly determines the reliability and lifespan of the roller.

Common Types

Depending on the roller application, the roller will utilize different types of bearings with the appropriate tolerance, lubrication and seal.

Unit: mm
Bearing type Outer ring Inner ring Width
6001 28 12 8
6002 32 15 9
6202 35 15 11
6003 35 17 10
6004 42 20 12
6204 47 20 14
6205 52 25 15

Lubrication:
1. Good adhesion, difficult to run off and leak.
2. Long lubricating life, no need to replenish or change the grease.
Clearence:
The clearence of the bearing ensures the bearing runs freely, smoothly and without resistance. To ensure the bearing runs reliability and the axis remains centred, the number of balls to bear the load is maximised. The clearence of the bearing suitable for the roller is C3. This has a large influence on the bearing’s dynamic performance including noise, vibration, friction, running accuracy and lifespan.
Seal:
The purpose of the bearing seal is to prevent inner grease from leaking and outside contaminants such as dust, water and other such contaminants from entering into the inside of the bearing. The seal ensures the bearing runs safely and with the utmost sustainably under all conditions.
We recommend using the RZ sealing method which combines the advantages of both the RS and ZZ. It has the same low friction as the ZZ and also has similar seal and dustproof performance to the RS.

Roller Part Number

1. Series features

The specifications and details including conveying method, structural features, driving mode. The first character refers to the
roller’s conveying method.
1 —— gravity conveying
2 —— driven conveying
3 —— accumulating conveying

2. Tube features

The specifications and details of roller tube material, diameter and surface treatment.

3. Shaft features

The specifications and details of shaft material, diameter, surface treatment and installation method.

4. Roller width

Roller’s theoretical working surface. This may vary between different types of rollers. Use W to indicate width. Units are in mm.

5. Length of shaft

Roller’s shaft length. Use L to indicate length. Units are in mm. In some installation methods such as internal thread, L=BF.

Frame inner width

1.Distance between two frames. Use BF to indicate.
2.Generally this is the key factor in determining the roller length.
3.Please use “BF” as the basis of calculating the length when selecting rollers.

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