Workplace safety is at the core of PRISMONT’s values. This is why we recommend our clients implement interlocked protection rather than their unlocked versions. Safe and effective, most of the machine tooling safety guards offered by PRISMONT come with an interlocking system.

What is an Machine Safety Guards Interlocking System?

Interlocking is a safety mechanism that prevents accidents and ensures safe working conditions. Interlocks for machine tool guards prevent the machine from operating if the guards are not correctly in place. According to ISO 14119, an interlocking device is a: "mechanical, electrical or other type of device, the purpose of which is to prevent the operation of hazardous machine functions under specified conditions (generally as long as a guard is not closed).".

An interlocked guard must meet three criteria :

1. The machine stops automatically when the guard is opened.
2. The machine remains stopped as long as the guard is open or moved.
3. The machine does not restart automatically when the guard is put back in place or closed.

The definition of this type of guard may slightly differ between various safety standards, but the logic remains exactly the same. To be effective, an interlocking device must not be easily bypassed or disabled.

Why Choose and Interlocked Safety Guard Instead of a Non-Interlocked One?

Interlocked safety guards are safer than non-interlocked guards. Interlocked guards are equipped with locking systems that prevent the operator from opening the guard while the machine is running. This way, the operator cannot access moving parts, significantly reducing the risk of injuries. On the other hand, non-interlocked guards can be easily bypassed by the operator, leading to serious injuries or property damage.

Some machines have parts that continue to move after the machine is stopped. For example, a large saw blade or one spinning at very high speed may continue to spin for several seconds after the machine is stopped. In such a case, an interlocked guard is essential to prevent access to the blade until it is completely stopped.

Interlocking is a crucial element of machine tooling safeguarding and ensures that operations only proceed under safe conditions. This protects operators and ensures proper functioning of the equipment while adhering to safety standards. Therefore, it is highly recommended to install interlocked protective equipment on machines for safe and efficient use.

• Safety: Prevent accidents by ensuring operators cannot be exposed to dangerous moving parts.
• Reliability: Ensure the machine only starts and operates under safe conditions.
• Compliance: Meet safety regulations and industry standards.

How Does a Machine Safety Guard's Interlocking System Work?

An interlocking system on a machine tool uses various safety components to ensure the machine only operates when all safety conditions are met. Here are those components and their roles:

Components of the Interlocking System and Their Uses

Safety Door

A physical barrier preventing access to dangerous parts of the machine during operation. The operator must close this door to prepare the machine.

Safety Sensors and Safety Locks

Devices installed on the safety door and other dangerous points to detect their status (open/closed). Sensors send signals to the programmable logic controller (PLC).

Programmable Logic Controllers (PLC)

The PLC receives signals from the sensors and makes decisions based on programmed logic. It monitors sensor signals and verifies that all safety conditions are met (door closed, no obstacles, protective devices in place). If a safety condition changes (e.g., door opens or emergency button is pressed), the PLC immediately cuts power to critical components of the machine, stopping it immediately.

Relays and Contactors

Electromechanical devices controlling the power to the machine's components (motors, spindles, etc.). Once safety conditions are validated, the PLC activates these relays and contactors.

Emergency Stop Buttons

Allow immediate stopping of the machine in case of danger.

Safe Restart

After an interruption, the operator must correct the safety condition (e.g., close the safety door), reset the system via the PLC, and then restart the machine. The PLC rechecks all safety conditions before allowing the restart to ensure maximum safety.

Common Types of Interlocking Systems

Several types of interlocking are used to ensure the safety of operators and machine tools. Here are a few:

Mechanical Interlocking

Uses physical locks and latches: Uses latches, locks, or bars to block or allow the operation of the machine based on the guard's position. For example, a key inserted in a lock allows the machine to operate. The guard can only be opened if the key is removed, stopping the machine.

Electrical Interlocking

Limit switch : Detect the position of the guard and control the machine’s electrical circuits. If the guard is open, the circuit is interrupted, stopping the machine.

Electromechanical Interlocking

Combines mechanical and electrical elements to offer a robust and reliable solution. They often use key switches that require capturing a key when the guard is closed. The machine can only start if the key is in place.

Electromechanical Key Switch: Uses a solenoid with a key retention system to lock the guard until the machine is in a safe state. These systems can be used alone or in combination to maximize safety.

Electronic Interlocking

Advanced electronic controls: Uses systems like RFID to monitor and manage the position and status of the guard, offering high security and the ability to perform specific configurations. Sensors and electronic controllers monitor and manage the machine.

There are many other types of interlocking systems. To choose the right one, it is necessary to consider the type of machine, its use, its guard, and the applicable safety laws and standards.

A Custom Turnkey Industrial Safety and Machine Safeguarding Service

Our sales and design team can work with you to determine the appropriate type of stop for your application, taking into account factors such as the application and type of machine, your budget, and applicable laws and standards. Contact us today to start creating a safer workplace.

References

CNESST

La prévention des accidents liés aux pièces en mouvement

GUIDE EXPLICATIF DES EXIGENCES RÉGLEMENTAIRES À L’INTENTION DES MILIEUX DE TRAVAIL

Réglement sur la santé et la sécurité du travail

Amélioration de la sécurité des machines par l’utilisation des dispositifs de protection

IRSST

Les types de dispositifs d’interverrouillage

Intervention prévention

Les types de dispositifs d’interverrouillage

In machine safety, there are stop categories, emergency stop categories, and safety control categories. Each of them categorizes different safety elements, and before exploring emergency stop categories, it is important to make a clear distinction with the other categories.

Safety Control Categories

These categories classify the various parts of safety-related control systems based on their resistance to faults and their behavior following a problem. This is achieved through the structural arrangement of the control system, its level of fault detection, and its reliability (ISO 13849-1:2015).

Stop Categories and Emergency Stop Categories

These two categories are the stop categories that are well defined by standards (emergency stop and normal stop). The emergency stop category is small and is often considered a sub-category of general stops, despite its special characteristics. Emergency stops must comply with different standards, especially regarding the power system and maintenance.

According to the safety norm EN 60204-1 "Safety of machinery – Electrical equipment of machines Part 1: General requirements", there are three categories of stop functions:

• Stop Category 0 : Uncontrolled stop resulting in immediate termination of system power. Sometimes, additional measures, such as braking, need to be employed to make the stop smoother.
• Stop Category 1 : arrêt contrôlé par le maintien d’alimentation aux actionneurs jusqu’à l’arrêt de la machine, suivi de la coupure de la puissance quand l’arrêt est obtenu. Le système continue donc d’être alimenté jusqu’à l’arrêt complet du mouvement.
  Controlled stop by maintaining power to the actuators until the machine comes to a stop, followed by power cutoff when the stop is achieved. The system, therefore, remains powered until the complete cessation of movement.
• Stop Category 2 : Category 2 stops are also controlled, but unlike category 1 stops, the system remains powered even after the complete cessation of movement.

These three categories are taken from specific standards such as ISO 13850 and IEC 61800-5-2. According to the ISO 13850 standard regarding the emergency stop function, only a stop category 0 or 1 can be used for an emergency stop. Category 2 is therefore excluded and is a standard stop category. This same standard also allows for defining color codes for buttons, indicators, and wiring markers.

Some Stop Examples

The EN 61800-5-2 standard "Adjustable Speed Electric power drive systems Part 5-2: Safety Requirements – Functional" defines some examples of Safe Stop functions including:

• Safe Torque Off (STO) : Cette fonction est un arrêt de catégorie 0, et donc un arrêt non contrôlé. L’alimentation du moteur est coupée en toute sécurité, de sorte qu’aucun mouvement n’est possible. This safety function corresponds to a category 0 stop (uncontrolled stop). The power to the motor is safely removed, so that no further movement is possible.
• Safe Stop 1 (SS1) : Safety function which corresponds to a category 1 stop (controlled stop). It initiates and controls the motor deceleration rate to stop the motor and initiates the STO function when the motor speed is too low or after a specific time delay.
• Safe Stop 2 (SS2) : Safety function which corresponds to a category 2 stop (controlled stop). It initiates and controls the motor deceleration rate to stop the motor and initiates the safe operating stop function when the motor speed is too low or after an application specific time delay.

L’arrêt sécurisé 2 diffère de l’arrêt sécurisé 1 en ce sens qu’au lieu d’entrer en STO lorsque le mouvement s’arrête, le système entre en arrêt de fonctionnement sécurisé (SOS). Cela implique que le moteur est amené à une position spécifique et y est maintenu et surveillé par le variateur.
Safe Stop 2 differs from Safe Stop 1 in that, instead of entering into STO when motion stops, the system enters Safe Operating Stop (SOS). During a safe operating stop, the motor is brought to a specific position and held there by the drive. Full torque is available to keep the tooling in position. The stop is monitored safely by the drive.

How to Choose the Correct Industrial Stop Category?

The choice of stop category for your industrial machine should not be taken lightly and will depend on several criteria. In general, machines with moving parts without inertia and whose stop does not pose additional risks will require a category 0 stop. Machines with hazardous parts with inertia or requiring other safety systems typically require a category 1 stop. However, this generalization is not 100% reliable, and it is necessary to consider several pieces of information to make an informed choice.

First and foremost, it is imperative to verify which laws or safety standards govern the use of your machine and the types of stops available. Industrial safety norms and laws vary from one country to another, and it is important to comply with the applicable standards.

Secondly, a risk assessment of the machine and all possible situations must be conducted. The results of this analysis will allow you to choose the perfect stop category that will maximize the protection of your workers without hindering the smooth operation of your business.

A Custom Turnkey Industrial Safety and Machine Safeguarding Service

Our sales and design team can work with you to determine the appropriate type of stop for your application, taking into account factors such as the application and type of machine, your budget, and applicable laws and standards. Contact us today to start creating a safer workplace.

References

L'écho de Laval

Comment différencier les catégories d’arrêts en matière de sécurité machine?

Intervention prévention

Sécurité machine: Les catégories d’arrêts

Protecting their workers should be a leading priority for every industrial company. Unfortunately, most employers tend to believe that investing in workplace safety will negatively impact productivity, which couldn’t be further from the truth! Safe working conditions often go hand in hand with ideal operational conditions. Employees can focus on their work and be more productive, instead of trying to avoid dangers in their workplace.

Machinery safety guards and shields are an effective and essential means of protecting your workers, but they should not be the only security solution used. After all, the best way to stay safe is to be able to identify potential hazards and avoid them altogether. This is where the safety signs come in.

How to Use Safety Signs Effectively

Any potential hazards in a workplace should be accompanied by a safety sign to identify it and keep workers from harm. A simple slippery floor can be just as dangerous as a rotating machine part. Safety signs should be placed near the potential source of dangers and be clearly visible. If possible, place them at eye level in a well-lit area. If the place is poorly lit, use phosphorescent colors, reflective materials and / or artificial lighting. Avoid placing an excessive ammount of safety signs near each other to avoid confusion. They must be big enough to be seen and read from afar. It is recommended to use short, clear and concise text on the panels, since the operators tend not to read or only skim the signs with too long instructions. The use of symbols associated with hazards and actions to follow is recommended.

Safety signs must always include:

• A signal word expressing the seriousness of the risk, such as "Danger" or "Warning"
• The hazard associated with the hazardous area or machine, such as "rotating part"
• The consequence associated with the danger, such as "Danger of death"
• Security measures to avoid danger, such as "Do not approach"

The 4 Colors of Safety Signs

• Red: Hazard signs identifying immediate hazards, prohibitions and safety measures to be applied
• Yellow or orange: Warning signs used to warn of potential hazards or unsafe practices
• Blue : Obligation signs
• Green : Rescue and emergency measures or general safety measures signs

Train your Workers to Read and Understand Safety Signs

Simply putting safety signs everywhere in the workplace is not enough. For these safety signs to be efficient, your workers need to be trained to read and understand them. Each sign has a special color and its own symbols. Therefore, your employees must be able to understand which one is which and which security measures are appropriate. Here are some of the things a worker need to learn during safety signage training:

• The color code of each sign and the meaning of the symbols
• The location where a sign should be placed
• When and how to remove a sign

PRISMONT’s Industrial Turnkey Service and Personalized Safety Solutions

Of course, a safety sign should not replace complete industrial security solutions that comply with the standards. With all the support of the Prismont team, you will benefit from a complete safety solution including a custom design and installation service which comply with all the requirements of the most important conformity and standards
regulations (CSA / OSHA / ANSI / ISO / etc.). We offer a turnkey approach for all services needed including experienced personnel, complete tooling, project planning and scheduling your safety projects large or small.

With an in-depth machine guarding analysis, we can help you identify risks and design a custom safety plan for you to help you deliver optimal Return on Investment (ROI). Contact us today and protect what is most important in your company. votre entreprise.

Reférences

INRS
Signalisation de santé et de sécurité au travail
http://www.inrs.fr/dms/inrs/CataloguePapier/ED/TI-ED-6293/ed6293.pdf

IRSST
Sécurité des machines-outils
http://www.irsst.qc.ca/media/documents/pubirsst/Securite-Machines-outils.pdf

RÉSEAU ICIMÉDIAS
L’importance des panneaux pour la sécurité des machines
https://www.canadafrancais.com/publireportage/limportance-des-panneaux-pour-la-securite-des-machines/

Lose Less Money and Increase Production by Safeguarding your Workers

When it comes to investing in workplace safety, the perceived negative impact on productivity is a key concern. The truth is, a safe workplace is often a more productive and profitable one! Safe working conditions often go hand in hand with ideal operational conditions. With safeguards in place, employees can focus on their work, instead of the dangers in their workplace, thus increasing your productivity. You’ll spend less time aiding injured employees and more time creating quality products.

When choosing industrial safety equipment, you can’t compromise on your employee’s safety. Safety equipment can sometimes be very expensive. It is therefore crucial to ensure that your purchase generates an optimal return on investment (ROI).

How does a Company Evaluates its Machine Guarding Return on Investment?

Machine safeguarding can help businesses increasing ROI and reduce operating costs by eliminating costs of accident. But what are these potential costs?

Direct Costs

Direct costs are the costs recorded in the company's accounting system as a result of accidents. Any expense and loss of productivity due to work-related accidents are considered direct costs. They may include costs for repairs, hospitalization and medical expenses, but also workers' compensation, the purchase of new equipment, and a temporary closure of other machines. The bills can quickly accumulate for a single accident.

Indirect Costs

Contrary to popular belief, the costs of a work accident do not stop there. Analysis showed that the indirect costs are often 4 times higher than the direct costs. Indirect costs are the losses incurred by the company as a result of an accident at work, but which are not counted as such. They may include professional health care, victim follow-up, lost productivity, study costs following the accident, human resources, hiring costs, legal aspects, training, and more.

After an accident has occurred, fines and insurance costs often increase, leading to recurrent thicker bills. Legal fees and litigation costs can be very high in an accident resulting in the death or injury of an employee. In such cases, the costs can be unlimited and are even higher when a machine has been poorly protected. The lawyers' fees can then accumulate and the growth investments of the company must be diverted to cover these legal costs. In other words, you will spend far more on lost wages, productivity and legal costs than you would have needed to invest in securing your factory properly.

Secure your Machines with Safety Guards, Shields and Safety Equipment

To ensure safe operator use, machines must be protected using safety guards and devices. Any machine part, function or process that may cause injury must be protected to prevent crushing of hands and arms, finger fracture, blindness or other potential injury.

Workplace safety signs

In order to properly maximise employee safety, you need to ensure that they can easily identify and avoid potential hazards. An efficient way of doing so is by using safety signs, which will help prevent injury to both employees and public which might be around a certain hazard. By learning that the floor is slippery, or that a certain part of a machine may move, they can be more cautious and act accordingly. Any potential hazard must be accompanied by a safety sign to warn workers and keep them from harm. They must be placed near the source of danger and be clearly visible.

Workplace Safety Training

Sometimes, improperly using a machine is just as dangerous as using an improperly safeguarded machine. Properly training them on machinery usage et appropriate safety measures ensures that workers will be able to use the machines and safety equipment in the safest way possible, the way they were designed to be.

Customized Safety Solutions to suit your Every Need

Your employees’ safety should never be compromised, and a safety analysis is your first step in identifying your risks and implementing the perfect safety solution for your business. For years, we’ve helped industrial workplaces become safer and more productive through customized safety solutions. Our sales and design team can work with you to determine the type of safety guards that will fit your application, taking into account factors such as how often you need access to the machinery, how much space you have to work with and the budget for the project. Contact us today to get started on creating a safer workplace.

References

IRSST

Analyse des avantages et des coûts de la santé et de la sécurité au travail en entreprise
https://www.irsst.qc.ca/media/documents/PubIRSST/R-375.pdf