Automation Academy: Machine Guarding 101

As the business case for industrial automation continues to grow, machine safety is more critical than ever. Whether you're deploying your first cobot or expanding a robotic work cell, robot safety is non-negotiable and understanding the types of machine guarding available, and when they should be used, is foundational to protecting your team. 

Machine guarding exists to shield operators from mechanical hazards such as moving parts, pinch points, flying debris, and unexpected system behavior. This article breaks down two primary categories—hard guarding and soft guarding (aka presence-sensing devices)—so you can make informed, compliant decisions that meet industry standards.

The Basics of Hard Guarding

Hard guards are physical barriers made from durable materials like sheet metal, wire mesh, or polycarbonate panels. These fixed or adjustable components are designed to restrict human access to dangerous zones—especially around moving parts.

Per ISO (International Organization for Standardization) 13857, hard guarding must maintain a minimum safety distance between the guard and the hazard, factoring in potential operator reach.

Types of Hard Guards

• Fixed Guards: Permanently mounted barriers covering belts, gears, and shafts. They require tools for removal and are ideal for areas that don't need frequent access.
  
  
• Adjustable Guards: Can be manually repositioned for varying workpiece sizes. When paired with interlocks, they become smarter safeguards that prevent machine operation if misaligned.
  
  
• Self-Adjusting Guards: Automatically adapt to the size of the stock material, allowing operational flexibility while minimizing the exposed area.

Advantages

• Ideal for repeatable, high-volume operations
  
  
• Provide maximum protection against mechanical hazards
  
  
• Minimal maintenance over time

Limitations

• May reduce visibility for operators or technicians
  
  
• Can delay access during adjustments or repairs
  
  
• Not well-suited to agile, high-mix production lines

The Basics of Soft Guarding

Soft guarding refers to the use of presence-sensing devices, which monitor operator proximity and activate safety mechanisms if a breach occurs. These systems are especially useful in collaborative and semi-automated environments where access to a machine cannot be entirely restricted or for sites where machinery is moved or adjusted to accommodate changing production needs.

According to ISO 11161, soft guarding must be reliable, fail-safe, and integrated into machine control logic.

Common Soft Guarding Systems

• Light Curtains: Emit infrared beams. If any beam is broken, machine operation halts instantly.
  
  
• Area Scanners: Monitor a designated zone (often using lasers or LIDAR) and adjust machine behavior if someone enters the area.
  
  
• Safety Mats & Trip Controls: Detect pressure or unintentional contact, triggering an emergency stop.
  
  
• Two-Hand Controls & Trips: Require simultaneous use of both hands to engage machinery—keeping hands out of danger.
  
  
• Pullback and Restraint Systems: Physically limit operator movement, preventing contact with hazardous areas during operation.

Advantages

• Promote safer human-machine interaction
  
  
• Offer flexibility in collaborative work environments
  
  
• Can be seamlessly integrated with PLCs and emergency circuits

Limitations

• Require regular calibration, testing, and validation
  
  
• Provide reactive rather than preventive protection
  
  
• Initial setup may be technically complex 

Closing the Gate

To recap, hard guarding offers time-tested reliability and robust protection (especially in static setups) while soft guarding brings next-gen adaptability to fast-paced, collaborative environments. In practice, the best strategy may combine both approaches—using hard guards for perimeter protection and soft sensors for operational flexibility.

Need help mapping out your guarding strategy? Industrial Robot Help is here to help you translate technical requirements into practical solutions. Let’s keep your team safe and productive. Book your free consultation with us to get started today!