How does blanking function in industrial automation systems? Blanking is a crucial safety mechanism that manages the protection of hazardous zones without disrupting machine operations. It allows light curtains to be tailored to specific production process requirements, ensuring operator safety and operational continuity. In this article, we will delve into what blanking is, its types, and how it can be applied in industrial automation. We will also explore the differences between blanking and muting to determine the best use cases for each function.
Table of Contents
What is Blanking?
Blanking is a feature used in light curtains that enables the system to ignore interruptions in certain parts of the protective field. This allows the machine to continue operating without downtime, even when non-hazardous items are present in the protective zone. Implementing this feature allows protective systems to be better adapted to the specific needs of a production line, leading to reduced downtime and increased efficiency.
Types of Blanking: Fixed and Floating
Blanking can be categorized into two main types: fixed and floating, each differing in operation and application.
Fixed Blanking
Fixed blanking allows the system to ignore specific, static elements within the protective field, such as supports, brackets, or other machine parts that remain in a constant position. This option is ideal for machines with structural components within the protective zone that pose no threat. This solution ensures these elements are ignored, while protection remains active in the rest of the detection field.
Floating Blanking
Floating blanking, on the other hand, allows for the dynamic ignoring of interruptions in the protective field, meaning it can accommodate elements moving through the zone. This type of solution is useful where predictable elements, such as cables or flexible installation components, periodically pass through the protective zone, temporarily disrupting protection without posing a threat to operators.
Practical Applications of Fixed and Floating Blanking
- Fixed Blanking is used where the same static elements are always present in the protective zone and pose no risk, such as machine supports. It is a simple and effective solution that allows these elements to be ignored, keeping the rest of the zone active.
- Floating Blanking is suitable for situations where moving elements, such as cables or flexible installation parts, may appear in the protective zone. Their presence is predictable and controlled, allowing protection to remain in the rest of the zone, which is crucial for ensuring safety.
Application Example:
- Fixed: On a production line where structural machine parts, such as supports, are always present in the protective zone, fixed blanking can be applied to ignore these elements without deactivating the entire protective zone.
- Floating: In systems where cables or other flexible elements move within the protective zone, floating blanking allows the machine to continue operating without stopping, ignoring only those predictable and safe interruptions.
Differences
Muting, in contrast, temporarily deactivates the protective zone, allowing large objects, such as pallets or AGVs, to pass through. Unlike blanking, muting requires additional sensors to verify that a safe object, not a person, is passing through the zone. This is particularly useful where full deactivation of protection is necessary but only for the duration of the object’s passage.
The key difference is that blanking allows for the selective ignoring of light curtain beams, so the entire protective zone does not need to be deactivated. Muting, however, deactivates protection entirely for a specified time, ideal for scenarios where various objects frequently pass through the zone.
Practical Application of Blanking
Blanking plays a significant role in industrial automation, especially when combined with other safety devices like light curtains. This function enables the safe passage of objects through the protective zone without stopping the machines. Such flexibility increases production efficiency and minimizes downtime.
This function is particularly effective on dynamic production lines where materials frequently cross protective zones. Tools like Safety Automation Builder or the SISTEMA library assist in designing safety systems, ensuring compliance with standards such as ISO 13849-1. Performance Level calculations enable designers to correctly integrate safety systems.
When to Use Them?
The application of blanking or muting depends on the specifics of the production line and the type of objects crossing the protective zone.
| Function Type | Application | Typical Elements |
|---|---|---|
| Fixed Blanking | Static machine elements in the protective zone | Supports, brackets, structural parts |
| Floating Blanking | Moving elements temporarily breaching the zone | Cables, flexible installation elements |
| Muting | Large objects that need to pass through the protective zone | Pallets, AGVs |
Technical Details and Safety Standards
Fixed blanking allows the system to ignore specific, static elements, ensuring that the rest of the protective zone continues to function. This is ideal when a machine has structural parts that must be present in the zone but pose no threat. Floating blanking is more dynamic, suitable for areas where elements can move within the protective zone, but their presence is predictable and safe.
The PN-EN ISO 11161:2007/A1:2010 standard emphasizes the need for risk analysis when using blanking functions in complex production systems. Any modification of protective zones requires adjustments in safety measures, including recalculating safety distances to minimize the risk of accessing hazardous areas.
Application in Automation Systems
In automated warehouses or production lines where AGVs regularly move between sections, muting is essential to avoid process interruptions. Floating blanking is ideal where elements like cables occasionally breach the protective zone, but their presence is predictable.
Floating Blanking vs. Muting
- Muting: Allows smooth passage of large, variable objects, minimizing downtime and increasing production efficiency.
- Floating Blanking: Enables ignoring safe breaches of the protective field, allowing work to continue without interrupting protection in other areas of the zone.
The choice of function depends on the application’s specifics and the type of objects breaching the protective zone. Muting is ideal where full deactivation of protection is needed for large, predictable objects. Floating blanking, however, is perfect for safe, predictable zone breaches that do not require complete protection deactivation.
FAQ: Blanking
Yes, muting always requires additional sensors to ensure that the object passing through the protective zone is safe and poses no threat to the operator.
Fixed blanking involves permanently disabling selected light curtain beams, while floating allows for dynamic ignoring of beams that may be breached by moving elements. Floating is more flexible but requires careful design of safety zones.
Muting is best when large, variable objects, such as pallets, pass through the protective zone, requiring complete protection deactivation. Blanking is suitable where predictable elements in the protective zone do not require full protection deactivation, like supports or cables.
No, floating blanking ignores selected interruptions of light curtain beams but cannot distinguish whether the breach is caused by a cable or a person. Therefore, in areas where there is a risk of human entry, it may not be an appropriate solution.
It is often used where cables or other flexible elements may temporarily be in the protective zone without posing a threat. This way, the system does not stop the machine with every beam breach, increasing work fluidity.