What is Machine Guarding?
Machine guarding is a safety feature that protects potentially dangerous parts of a machine.
Imagine yourself in the shoes of a Packaging Associate working near conveyor rollers – packing items to be shipped out. A variety of hazards may cause you to get injured.
For example, your shirt or finger could get pinched between the rollers.
Safeguards are put in place to protect workers in case of such accidents. Here are some safety guards that you may find in the above scenario:
- An emergency stop button
- Guard rails preventing you from coming into contact with rollers
- The width between rollers is wide enough that your shirt or finger won’t get caught
- The rollers do not operate unless someone at the end of the conveyor presses a button
Why use Safeguards?
The purpose of safeguards is to protect workers and reduce liability costs for a business. The OHSA and its regulations also make it mandatory for workplaces to implement safeguards.
Many workplaces operate machinery with zero safeguards or inadequate safeguards. Because no workers have been hurt, they believe that implementing safety precautions is a waste of money.
Implementing safeguards is a proactive control measure that prevents worker injury. It is always better to be proactive than react after a worker gets injured.
Shouldn’t the machine come with Safeguards?
Manufacturers may be unaware of the machine’s intended application. The type of safeguards used depends on the machine’s intended purpose. This is why employers must consult with the manufacturer when assessing safety risks.
Other times, the machine is modified after purchase, so experts need to be consulted on safeguarding techniques.
Mechanical vs. Non-Mechanical Hazards
Machine guarding implies protection from both mechanical and non-mechanical hazards!
Mechanical hazards result from human contact with a machine part. Hazardous contact is caused because of a snag, nip, pinch, crush, and shear points on the machinery.
Non-mechanical hazards result from debris that is caused by the machinery. For example:
- The fumes from a machine can cause respiratory diseases
- A saw cutting logs can send flying wooden chips
- Faulty wiring can cause electrical shock
- Chemicals can splash and irritate the skin
- Spills can cause slips, trips, and fall
How do I recognize Mechanical Hazards in the workplace?
You must conduct a machine guarding risk assessment of the hazards in the workplace. There are two models of risk assessment:
- Quantitative: This model looks at measurable numerical data to provide insights. This type of risk assessment is more accurate but depends on the quality of inputted data. For example, a specific dollar amount is given to each risk identified.
- Sources include databases, handbooks, and manufacturer specifications.
- Qualitative: This model utilizes the knowledge and experience of stakeholders to determine risk probability. It is faster than quantitative analysis and helps quickly understand what risks need to be focused on.
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Tips Observation – Notice how the worker interacts with the machine and how the device is being used. The worker may be behaving in an unsafe manner because of improper training. They may also be coming into physical contact with the machine while working. Determine the possible worst-case scenarios that could occur. Stakeholders Involvement – All workplace parties should be involved in the process of recognizing hazards. The internal responsibility system entails that we are all responsible for safety. You should also consult the worker, supervisors, maintenance crew, and the manufacturer to identify the dangers posed by a piece of machinery. |
What are the best Safeguards I can use?
The type of safeguard varies based on the scenario and its risk factor.
A risk factor is an arbitrary number you assign to any given risk. It is based on three factors:
- Severity – The seriousness of an injury
- Exposure – The likeliness of a worker being exposed to the hazard
- Avoidance – The probability of the accident occurring
Example: The likelihood of a worker being caught in a conveyor roller without any safeguards
|
Risk factors |
Score |
Explanation |
Total Score |
|
Severity |
10 |
The injury could be severe if fingers are caught and crushed |
10 |
|
Exposure |
10 |
The worker is frequently near the conveyor |
|
|
Avoidance |
10 |
The probability of it occurring is high |
In the example above, a risk factor of 10 means a very high risk of workers being injured. Therefore, safeguards should be installed to protect worker safety.
What are the types of Safeguard Controls?
Many different safeguards can be used to reduce the risk of hazards. Consider the hierarchy of controls:
Elimination:
- Can we eliminate the conveyor and still do the job efficiently?
- Can the conveyor rollers be replaced with a belt that has no pinch points?
- Can human interaction be replaced with robotic machinery?
Substitution:
- Can the conveyor be replaced with a less hazardous machine or equipment?
Engineering
- What kind of controls can prevent the worker from being injured?
- Guards, emergency stops, flashing lights, horns, two-hand controls, presence-sensitive mats, designated walkways, etc.
Administration
- What human controls can be used to prevent injury?
- Worker training, safety policies, work procedures, routine inspections of equipment and machinery
Personal Protective Equipment (PPE)
- What type of PPE can be provided to the worker to reduce their risk of injury?
- Gloves, safety shoes, eyewear, respirators, hearing protection, etc
Dual-Purpose Safeguarding
In some cases, guarding can be implemented in such a way that it minimizes the risk of a non-mechanical hazard as well.
WorkSafeBC has an excellent guide on Safeguarding Machinery and Equipment. It provides the following examples:
- A guard modified to prevent access to moving parts may also absorb noise
- Welding curtains designed to shield against arch flash can also protect passersby against spatter and burns
- A chuck guard and shield added to a lathe can help protect workers against flying chips
- Local exhaust ventilation systems attached to concrete grinders can reduce exposure to silica dust
How do I evaluate my Safeguards?
Document if your safeguard fulfills the purpose it was intended for. Consult with the worker and other stakeholders about any concerns they may have.
Make sure that your safeguards do not create other safety issues. For example, your machine guard may be created from inferior materials and cannot withstand the environmental forces being exerted.
What Regulations are in place to Protect Workers?
Ontario Regulation 851- Industrial Establishments specifies the mechanical and non-mechanical regulations that workplaces must comply with.
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Summary of Exemptions from Section 7 Table of Ont. Reg 851
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Disclaimer: This article is intended for educational purposes. Please consult with a professional for verification on the subject matter before application.