Keeping Operators Safe with Machine Guarding

The lack of proper machine guarding leads to approximately 800 deaths each year. This doesn’t count the numerous instances of serious injuries such as lacerations, crushed appendages, abrasions, blindness, and even instances of amputation. For that reason, safeguarding machines is incredibly important to minimize or eliminate these incidents.

To begin, machine safeguards must meet minimum requirements to provide a safe environment for employees. These minimum requirements are:

Staying compliant with OSHA's 1910.212 regulation for machine safeguarding can be attained by any company if they utilize any of the five basic machine safeguarding mechanisms and keep best practice methods in mind. In the end, employees and the company both benefit from a diminished number of hazards present in the workplace. By not safeguarding machines, those hazards have the potential to lead to injuries that result in labor loss, monetary compensation for an injury on the company’s end, and potential product/equipment damage.

What are Machine Guards?

Machine guards are an engineering control that aims to keep workers safe from moving machine parts. Machine safeguarding can be seen being used most often in facilities where fabrication work is common. Most hazards that are considered dangerous to employees are contained in three places around heavy machinery. Those are the point of operation, the power transmission apparatus, and moving parts. Those three areas are where most machine guarding mechanisms are found since employees are often assigned tasks in these dangerous places.

There are numerous motions and actions machines perform that can become hazardous to the operator. Identifying the types of hazards present within the machine is the first step in determining the kind of machine guard that needs to be put into place. Hazardous motions can be anything involving:

• Rotating
• Reciprocating
• Transversing

While machine actions that can become hazardous are:

• Cutting
• Punching
• Shearing
• Bending

These types of motions and actions are some of the hazards that need to be found and mitigated or eliminated to keep operators safe. Using any, or a combination, of the five basic means of safeguarding machinery will assist in getting rid of dangerous machine hazards.

The Five Basic Means of Safeguarding Machinery

There are five types of basic machine safeguarding techniques to choose from for maximizing employee safety. The first ones are physical machine guards. Machine guards are physical barriers that prevent operator contact. Guards can come in a handful of types, which are:

• Fixed guards: these are permanently attached to machines and can be made of sheet metal, plastic, wire cloth, bars, or any other type of material that can stand up to the machine’s task. Fixed guards are the most preferred type of physical guard because they're simple and effective.
• Advantages: Fixed guards can be constructed for many types of machines and applications, they provide maximum protection to employees, and they require minimal maintenance.
• Drawbacks: Visibility may be reduced and when a machine needs to undergo maintenance the guard may need to be taken off which causes an additional safety hazard.
• Interlocked guards: This type of guard relies on a tripping mechanism that shuts off power when the guard is opened or removed. The machine cannot be started back up until the guard has been put back into place. Interlocked guards can be electrical, hydraulic, pneumatic, or any of the three combined.
• Advantages: Interlocked guards provide maximum protection to the operator and it allows for easy access to machine parts without needing to waste time removing fixed guards.
• Drawback: There may be complications with adjustments and maintenance
• Adjustable guards: Adjustable guards allow flexibility for accommodating different sizes of products. They can be made of the same material as fixed guards.
• Advantage: It is adjustable and can be used in a variety of different productions.
• Drawbacks: Operator protection is not complete because they may have to reach into the dangerous zone, they require frequent adjustments, the operator may damage the guard by not using it correctly, and it can obstruct the operator’s view.
• Self-adjusting guards: This type of guard adjusts itself while the operator is putting through the material. After the item is removed the guard moves back into its original position to wait for the next item.
• Advantage: This kind of guard is often commercially available.
• Drawbacks: Self-adjusting guards don’t provide maximum protection, it may obstruct the operator’s view, and requires frequent maintenance and adjustment.

The next machine safeguarding options are sensing devices. Unlike guards that are a physical obstruction from the machine’s moving parts, sensing devices can shut off the machine when triggered by employees entering the dangerous area. There are also machine safeguards in this category that directly act upon the worker to prevent them from entering the hazardous zone.
specifications. 

• Presence-sensing: These can be photoelectric, radiofrequency, or electromechanical devices That shut off when interrupted. However, the time in which it takes employees to reach the danger zone before the machine can shut off needs to be taken into account before trying this type of machine safeguard.
• Advantages: These types of safeguards allow the operator freer movement, they're well-liked for their simplicity, and they protect passersby.
• Drawbacks: They don’t protect against mechanical failure and some require more adjustment to work properly.
• Pullback and restraint devices: Pullback machine safeguards have the employee’s arms, wrists, or hands strapped to cables that allow for employees to manually feed a machine and then draw the worker’s hands away when the machine proceeds with the task. Restraints, the other type in this category, only allow employee's hands to move at a fixed point. The goal is to have them far away from the machine hazard.
• Advantages: Pullback devices eliminate the need for barriers at the danger zone. Restraint safeguards have little risk of mechanical failure.
• Drawbacks: The pullback method limits movement which may obstruct the work area. The restraint mechanisms have to be adjusted to the job as well as the employee, they require frequent maintenance and inspections, the operator needs supervision, and movement and workspace is limited.
• Safety trip controls: These can be anything similar to a pressure-sensitive body bar, a safety tripod, or even tripwire. When activated by an employee who has lost their balance or has been drawn closer to the machine, it will be shut off.
• Advantages: Safety trips are very simple and easy to implement
• Drawbacks: The controls must be manually activated, they may be difficult to activate due to position, and they only protects the operator.
• Two-hand controls/Two-hand trip: There are two methods to this machine safeguard technique, the requirement of pressure on both controls by both hands to work the machine or the requirement of concurrent application of both buttons to activate the machine. These must be a safe distance from the danger area as well as be far enough apart to where the operator must use both hands to operate the machine.
• Advantage: Both methods keep the operator’s hands away from the danger zone while it is not in motion.
• Drawbacks: Both of these methods only protect the operator and they still have the possibility of reaching into the danger zone if something comes up.
• Gates: These are the last option for machine safeguarding devices. A gate is a mobile barrier that is moved into place by the operator before the machine cycle has begun. These are designed to be used at every cycle.
• Advantage: It prevents employees from reaching or walking into the danger zone.
• Drawback: These may require frequent maintenance and inspections and may interfere with seeing the work that is being done.

The third available method for machine safeguarding is adjusting the machine location/distance farther awayfrom the worker. This type of machine guarding method aims to remove the worker and their task away from the hazardous area. Before this is attempted, a thorough job hazard analysis is absolutely necessary to identify all possible hazards.

• Location: To use this method, the dangerous section of a machine must be placed in an area that is not accessible by employees. For example, the hazardous section of the machine can be placed against a wall while the employees work and walk around on the other side. Hazardous areas can be placed behind fences, walls, and even placed higher up to prevent employee exposure to those hazards.
• Distance: If the process requires an employee to feed parts into a machine, distancing them from machine hazards can protect the worker. The positioning of the operator’s control station is a good option for distancing employees from hazards presented by the machine.

Automated feeding and ejection mechanisms are another good machine safeguard technique. Automatic feeding and ejection systems for machine safeguarding help employees avoid reaching into dangerous areas of the machine by either manually feeding material in with a specific mechanism or by having it be completely autonomous. However, this method does not replace the need for physical guards.

• Automatic and semi-automatic feeding: Both of these greatly reduce the exposure of the operator to the machine’s dangerous moving parts by either making the process fully automatic or requiring the operator to use a special apparatus for feeding material into completely enclosed section of the machine.
• Advantage: These almost eliminate the operator completely and therefore reduces hazard risk.
• Drawback: These systems may require frequent maintenance and they don’t eliminate the need for a physical barrier guard.
• Automatic and semi-automatic ejection: Automatic ejection is completed with either a mechanical or air pressurized system that releases the product from the machine while a semi-automatic ejection system often uses a plunger and an ejector leg.
• Advantage: The worker does not have to enter a dangerous area to remove the completed work.
• Drawbacks: The possibility of debris being blown towards the operator is high and guards are still needed.
• Robots: Robots are able to do the work that employees would normally do in manufacturing processes.
• Advantages: Robots can work in conditions where people can’t which reduces the risk of injury from hazards.
• Drawbacks: Robots can create hazards themselves, they require more maintenance, and they are not suitable for every operation.

There are a few miscellaneous aids that can be implemented for safeguarding a facility, these include:

• Awareness barriers which are simply reminders for employees that there is a dangerous area ahead. These are not adequate enough to be the only machine safeguard.
• Shields can be used for power tools and other equipment to provide protection from flying particles and splashes.
• Special hand tools can be used for grabbing or pushing objects from points of operation. They can be things such as feeding tongs, pliers, magnets, push sticks, etc. Again, these must be paired with other machine safeguards.

OSHA 1910.212 + Operator Safety

If a facility has machines that pose risks to operators, the employer must be familiar with OSHA’s 1910.212 standard which lays out the general requirements for proper machine safeguarding. 1910.212 depicts the types of guards to be used, general requirements on where they are to be placed to provide maximum operator safety, and the machines that often need guards implemented. Some of the types of machines listed that need machine safeguarding are:

• Shears
• Power presses
• Milling machines
• Barrels, containers, and drums
• Fans

Training Requirements for Machine Guarding

Guards don’t help mitigate or eliminate machine hazards if the proper training hasn’t been given to the operator. Operator training should involve a combination of hands on training and verbal instruction regarding the following:

1.  Identification of the hazards involving certain machines.
2. The safeguards themselves, how they provide protection, and the hazards they are intended to mitigate or eliminate.
3. How to use the safeguards and why they are needed.
4. Circumstances in which safeguards can be removed, why they need to be removed, and the employees who are able to remove them.
5. What to do if a safeguard is damaged, missing, or not able to provide protection.

Best Practices for Protecting Operators from Machine Hazards

Aside from giving the employees proper training on the machine they will be assigned to, there are a few other best practices to consider for keeping employees safe while working with heavy machinery. With that being said, employees should not be working on machines they have not been trained on. Lack of training could result in horrific injury and even death; it is the employer’s job to provide all employees proper training on the machines they will be working with throughout the day.

The next best practice method to use in an environment such as this is machine labeling. Simply labeling machine hazards can be a lifesaver as they clearly communicate dangers to employees.

Lastly, requiring personal protective equipment should be considered as it can further protect employees from hearing, eye, skin, lung, and head injuries. However, PPE should be the last resort in protecting employees since any engineering controls implemented should have taken care of most hazards.

Overall, if the correct precautions are taken with machine safeguarding, then employees will have the correct tools to go about their day accident free. With that being said, OSHA’s 1910.212 regulation, guard mechanisms, training procedures, and all the best practice methods should be taken into consideration before any operators are allowed to enter working zones for the first time, just in case hazards are still lurking alongside the heavy machinery.