What is machine guarding? It’s a safety system to protect operators from hazards when working with machinery. Shields, gates, covers, and other safety devices prevent workers from coming into contact with the dangerous parts of the machine, when it’s running, and block sparks or debris.

Machine guarding is mandated by OSHA and essential to providing a safe work environment in industrial settings.

What Are the Types of Machine Guarding?

The common types of machine guarding are:

• Fixed Guards
• Interlocking Guards
• Adjustable Guards
• Self-Adjusting Guards
• Presence-Sensing Devices
• Two-Hand Controls

Let’s take a closer look at each, how they operate, and the advantages and disadvantages of each type.

Fixed Guards

Fixed guards are permanent physical barriers attached to machinery to prevent contact with hazardous areas. These guards are typically made of metal or other durable materials and remain in place at all times.

Fixed guards enclose dangerous machine parts, ensuring that workers cannot accidentally touch moving components. They are commonly found on saws, conveyors, and rotating equipment.

Pros:

• Highly effective at preventing contact with moving parts.
• Durable and low maintenance.
• No need for additional sensors or controls.

Cons:

• Can make machine maintenance or adjustments more difficult.
• Must be removed for some tasks, which can create safety risks if not reinstalled correctly.

Interlocking Guards

Interlocking guards include mechanical or electronic interlocks that stop the machine when the guard is opened or removed. When the guard is in place, the machine operates normally. If the guard is opened, an interlock mechanism automatically shuts down the machine.

This type of guarding is commonly used on presses, robotic systems, and cutting machines.

Pros:

• Allows access to machine parts without removing the guard completely.
• Enhances safety by stopping the machine immediately if the guard is bypassed.

Cons:

• Requires regular maintenance to ensure the interlocking mechanism functions properly.
• If interlocks fail, workers may be exposed to hazards.

Adjustable Guards

Adjustable guards provide flexibility for machines that handle different materials or workpieces of varying sizes. Operators manually adjust these guards to fit the specific task at hand on machines like drill presses and milling machines.

Pros:

• Can accommodate a variety of workpieces, materials, and sizes.
• Provide some level of protection while allowing for operational flexibility.

Cons:

• Require proper adjustment before each use, increasing the risk of user error.
• May not fully enclose hazardous areas, leading to potential safety concerns.

Self-Adjusting Guards

Self-adjusting guards automatically move into position based on the size and shape of the material being processed. These guards retract when the machine is not in use and adjust as the material is fed through. They are commonly used on saws and cutting equipment.

Pros:

• Provide automatic protection without requiring manual adjustments.
• Offer more flexibility than fixed guards.

Cons:

• May not provide as much coverage as fixed or interlocking guards.
• Moving components can wear out over time, requiring maintenance.

Presence-Sensing Devices

Presence-sensing devices use sensors, such as light curtains or pressure-sensitive mats, to detect when someone enters a work area. If the sensor detects movement within the danger zone, the machine automatically shuts down or prevents operation until the area is cleared.

You see these systems often around automated manufacturing and robotic workstations.

Pros:

• Allow for open access when the machine is not running.
• Automatically stop machinery when a safety risk is detected.

Cons:

• Can be more expensive to install and maintain.
• May not prevent hazards from flying debris or mechanical failure.

Two-Hand Controls

Two-hand control systems require the operator to use both hands to activate and maintain machine operation, preventing accidental activation. The operator must press two control buttons at the same time, ensuring their hands are away from moving parts. If one hand is removed, the machine stops immediately. We see these commonly on equipment such as stamping presses and hydraulic cutting machines.

Pros:

• Ensure the operator’s hands are away from dangerous areas during operation.
• Simple and effective safety measures for high-risk machinery.

Cons:

• Do not protect other workers who may be near the machine.
• Requires training to ensure proper use.

Choosing the Right Type of Machine Guarding for Your Operations

As you can see, each of the different types of machine guarding has pros and cons. It’s important to understand the proper type of machine guards for your use and make sure they operate properly.

You also need to work with experienced machine safety experts to ensure you comply with OSHA regulations and keep your workers safe.

Contact Pacific Blue Engineering today and let’s discuss your machine safety projects.