Technical Data Large size conveyor chain Selection
14. Considerations for Special Environments
“Special environments” are anything but ambient temperatures and clean conditions: e.g. low/high temperatures, humidity, dust, and chemical reactive environments.
Conveyor chains are often used in these types of complex conditions, so it is vital that chains with just the right combination of part materials are selected to ensure a long service life.
14.1 Low Temperatures
When chain is used in freezers and cold regions, the following should be considered.
1) Low Temperature Brittleness of Material
In general materials become brittle at low temperatures, and their impact strength drops. The amount of drop varies with the material.
Usage limits with this in mind can be found in Table 13 below.
Table 13.Applicable Lowest Temperature
| Conveyor chain | Lowest Temperature (℃) |
|---|---|
| Conveyor chain DT・DTA・ATA | -20 |
| Heavy Duty Conveyor Chain AT | -60 |
| Environment-resistant conveyor chain GS・GSA | -70 |
| Environment-resistant conveyor chain SS・SSA | -100 |
Note) Contact a Tsubaki representative regarding use under -20°C.
2) Poor Articulation and Poor Roller Rotation from Freezing
Using chain at low temperatures will allow water to infiltrate between pin-bush, plate-plate, and roller-bush to freeze, or for condensation to form, resulting in poor chain articulation, poor roller rotation, and chain-rail freezing. This will put an excessive load on the chain and drive equipment.
Freezing should be avoided by generally filling gaps between parts with a lube that will not freeze at the operating temperature. A silicone grease is recommended for this purpose.
14.2 High Temperatures (Over 400ºC)
The strength of the chain decreases as the temperature of the chain increases from the heat of the material conveyed or the environment.
Usage limits for each chain are determined by the temperature of the chain and material.
1) Points Concerning Hot Chain
- (1) Friction factor increases more than usual.
- (2) There is a possibility of heat fatigue when different materials have been welded, due to the difference in heat expansion coefficients.
- (3) In environments over 400°C, heat expansion and clearance must be considered.
- (4) Creep breakage
- (5) High temperature brittleness
- (6) Carbide precipitation brittleness
- (7) Repeated thermal shock (cooling and expansion)
2) Lubricants
Silicone-based and fluorine-based greases containing graphite and MoS2 have excellent heat resistance.
14.3 Abrasiveness
Points concerning abrasive conditions
- 1) Select a conveyor that will not allow highly abrasive material to fall onto the chain. Install a cover.
- 2) Slow down chain speed as much as possible.
- 3) Increase the chain size to reduce pin-bush bearing pressure.
- 4) Lubricate using a grease nipple.
14.4 Corrosiveness
When chain is exposed to corrosive material:
- 1) Chain parts get thinner.
- 2) Wear from corrosion accelerates wear in general.
- 3) Rust will cause chain bending failures and roller rotation failures.
- 4) In environments such as acid or alkaline atmospheres, problems may occur such as stress corrosion and intergranular corrosion that will require particular attention
Refer to Table 14 for the corrosion resistance of chain material to various kinds of solvents.
GS and GSA Series (SUS400 Series) parts can rust depending on conditions.
Specifications against stress corrosion are available.
Please inform your Tsubaki representative of the material used for accessories and related equipment (e.g. rails, tanks, etc.).
Table 14. Corrosion Resistance to Various Kinds of Solvent
When selecting your chain, please check whether or not the material is fully corrosion resistant by referring to this table.
This table shows properties of material at 20°C and is only to be taken as a guide.
To determine final specifications of the chain, please consider all conditions together.
15. Clean Specifications
| Category | Applicable | Cleanliness | Application | Anti-rust Oil | Packaging |
|---|---|---|---|---|---|
| Class 1 | All stainless steel parts (SS Series ) | No extraneous matter (oil, grime, scale) or burrs, wiped with a clean cloth to remove dirt. | Pharmaceuticals or other materials come in direct contact with chain | None | Wrapped in a sheet, boxed in heavy duty paper and plastic |
| Class 2 | All stainless steel parts (GS Series, or a combination of GS and SS Series ) |
No extraneous matter (oil, grime, scale) or burrs. | Wrapped in a sheet, boxed in heavy duty paper and plastic Note) 1 Anti-atmospheric rust agent added to packaging. |
||
| Class 3 | Some or all parts regular steel | After assembly, chain is wiped of oil and cleaned to remove oil and grime. Scale still remains. |
Note)
- 1. Oil may be present on the chain from the manufacturing process. Contact a Tsubaki representative regarding other clean specifications not shown above.
- 2. Material surfaces are generally black (oxide film), but some reddish scale may be evident on some chain models. Contact a Tsubaki representative regarding long-term storage.
