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Avoiding cable breakage - Selecting the right energy chain
Many industries use machines or industrial robots. A stable power supply to these machines is essential to ensure trouble-free operation. Cable breakage and premature wear can lead to costly downtime. Energy chains provide reliable cable routing, increase the service life of the energy lines and improve operational reliability. But which energy chain is right for your application? This blog provides step-by-step guidance on how to best design your energy chains to ensure maximum efficiency and minimal maintenance.
What is an energy chain - definition, construction and applications
Energy chains, also known as drag chains or cable chains, are mechanical guide systems used in a wide range of moving applications to reliably route flexible lines such as electrical cables, hydraulic or pneumatic hoses while simultaneously protecting them against mechanical stress. They are used wherever moving machine components require continuous power and data supply, for example in industrial robots, machine tools or conveyor systems.
Chain links form the basic element of the energy chain and are usually made of high-strength plastic or metal. They are connected to form a flexible chain that can bend in a defined radius. Thanks to its modular design, the length of the chain can be adjusted according to the requirements. The side links are the sturdy, load-bearing elements of the chain. They provide the connection between the individual links and thus determine the stability of the entire construction. Cross bars and dividers keep the cables and hoses in defined channels within the energy chain. Adapters are mounted at the beginning and end of the drag chain. They are used for stable attachment to machines and systems.
Plastic energy chains are lightweight, corrosion-resistant, and offer high flexibility while minimizing maintenance. They are ideal for dynamic applications in machines and automation systems. Metal energy chains are extremely robust and temperature-resistant. They are particularly suited for heavy-duty applications, extreme environments or long travel distances with high mechanical loads.
Energy Chain Selection Procedure
Choosing the right energy chain or drag chain is essential for reliable and long-lasting routing of cables and hoses in moving applications. An improperly sized drag chain may cause excessive wear, cable breakage, or mechanical damage. To avoid this, several factors must be taken into account, including the design, size and load capacity of the chain. Smooth integration of energy chains also requires an accurate understanding of components in linear motion processes.
Step 1: Preliminary selection of the energy chain design
Energy chains are available in different designs, which differ by material, construction and design principle. These differences significantly influence the properties of the chain, such as its load capacity, flexibility and resistance to external influences. Different types of energy chains are required depending on the application.
In the slotted version, cables can be inserted through an opening in the chain for quick installation. The compact design eliminates the need for foldable elements, making it particularly space-saving, robust and resistant to external influences. A hinged cover, on the other hand, offers maximum flexibility as the flaps can be opened either from the right or left, making it easier to maintain and retrofit the cables.
In the following overview, you can find a list of the different versions and in which versions the different series supplied by MISUMI are available.
| Type | MISUMI series | Features |
|---|---|---|
| Slotted type | SE, SZ | - Cables/hoses can be inserted easily via outer and inner sides - Available for cleanroom use - Cable link assembly not required |
| Compact type | MHPKS | - Space-saving type for protection and guidance even with one cable/hose. |
| Hinged cover, open |
MHPUS | - Covers can be opened on both sides. |
| Hinged cover, closed | FHPS | - Closed type protects cables/hoses from dust. |
| Low-friction, low-noise type | MPSPS | - Lower friction on cables/hoses causes less noise. |
| Low-particle, low-noise type | MPSCS | - Low particle emission helps achieve cleanroom class 1,000 and causes less noise. |
Step 2: Selecting the energy chain size
When selecting the energy chain size, there are a few important points to consider:
- Height: The maximum outer diameter of the cable/hose must not exceed 80% of the internal height of the energy chain.
- Space requirement: Cable/hose cross sections may cover no more than 60% of the available area in the energy chain. Available space = internal height x internal width.
- Bending radius: When accommodating different cable/hose types, each line must be individually checked for its minimum bending radius. The largest of the determined bending radius values forms the basis for the selection. The minimum energy chain bending radius should not be less than the minimum bending radius of the lines to be routed.
- Distance to the inner wall: The distance between the routed cable/hose and the inner wall of the energy chain must be at least 10% of the outer diameter of the routed cable/hose.
- Distance to cables/hoses: The distance between adjacent cables/hoses must be at least 10% of the outer diameter of the thicker cable/hose.
Step 3: Calculating the self-supporting length of energy chains
The self-supporting length refers to the portion of the energy chain that remains stable without additional support (such as guide channels or support profiles), i.e., it neither sags nor rests. In this region, the chain bears its own weight as well as that of the guided cables and hoses. The self-supporting length determines whether an energy chain can be used without additional guide systems. If the self-supporting length is exceeded, the chain will begin to sag or rest, which in turn may affect the function and reduce the service life of the energy chain and the guided lines.
The self-supporting length calculation depends on the required free movement, the bending radius, and the fixed end position. The bending radius defines how much the energy chain can bend without mechanically overloading the guided cables or hoses. It is determined by the cable diameters and their minimum bending radii. The movement stroke is the entire path traveled by the moving machine part – the energy chain must be able to cover it completely. The fixed end position also affects the calculation. If the fixed end of the energy chain is positioned in the center of the movement stroke, the cantilevered length corresponds to half of the movement stroke. If the fixed end is outside the center, an additional adjustment factor must be taken into account, as the energy chain must cover a longer or shorter cantilevered section.
• R - Bending radius
• S - Total stroke
• S/2 - Half of the movement stroke
• FLG - Cantilevered length
• ME - Moving end
• FE - Fixed end
Step 4: Confirm load capacity and cantilevered travel range
The cantilevered length of an energy chain is directly related to the load being carried, that is, to the weight of the cables and hoses carried in the chain, as well as the chain itself. This relationship is significantly influenced by the design and construction of the energy chain.
Essentially, the following applies: The heavier the load, the shorter the maximum possible cantilevered length, unless the energy chain is specifically designed for high loads. The following load diagrams illustrate how the maximum permissible cantilevered length behaves depending on the load. These diagrams help with proper sizing.
Step 5: Calculating the Number of Links
The correct number of links in an energy chain ensures optimal movement and reliable cable routing. The number of links must be calculated to ensure that the entire movement stroke is covered without over-tensioning or compressing the chain. Factors such as the movement stroke, the bending radius and the position of the fixed end play a central role. A simple formula can be used to accurately determine the number of links needed to ensure smooth operation and a long service life of the energy chain. In most cases, the result is a decimal number that should be rounded up to avoid stress.
n = \frac{\frac{S}{2} + K + A}{P}
• n = number of links
• S = movement stroke
• K = arc + margin (see data sheet)
• A = distance of S/2 in mm (see sketch above)
• P = chain link distance
When calculating the number of links, a safety allowance should be planned, especially in dynamic applications, to minimize tension and wear. In addition, it is important to follow the manufacturer’s instructions as they provide specific recommendations on the length, bending radius and load-bearing capacity of the energy chain. This ensures optimal function and longevity.
Notes for long travel paths in energy chains
With long travel distances, the energy chain can often no longer be used exclusively in a self-supporting manner since the dead weight of the chain and the guided cables would lead to uncontrolled sagging. Special guide systems or roller systems are used to ensure the stability and functionality of the chain. These reduce wear and ensure uniform movement of the energy chain.
For long travels, special guide channels can also be used to enable low-friction movement. These are particularly common in medium to long stroke industrial applications, such as machine tools, belt conveyors or conveyor systems.
For very long travels, roller energy chains are an efficient solution. Instead of allowing the energy chain to slide on itself, it runs on rollers, which drastically reduces frictional resistance. Purposeful use of guide and roller systems can significantly extend the service life of the energy chain. Choosing the right system depends on the length of travel, the speed of movement, and the load.
