Machinery is a vital part of any manufacturing or production facility. It’s important to keep the machinery running safely and efficiently, which is why it’s important to use machine safeguard devices. These devices help protect workers and equipment from potential accidents or damage. In this blog post, we will discuss six types of machine safeguard devices and how they can help keep your facility safe!
Machine Safeguard Devices
A safety device may perform one of several functions. It may stop the machine if a hand or any part of the body is inadvertently placed in the danger area; restrain or withdraw the operator’s hands from the danger area during operation; require the operator to use both hands on machine controls, thus keeping both hands and body out of danger, or provide a barrier which is synchronized with the operating cycle of the machine to prevent entry to the danger area during the hazardous part of the cycle.
Presence-Sensing Devices
The use of presence-sensing devices has become increasingly common in recent years as a way to improve safety in the workplace. These devices use a system of light or radiofrequency sources and controls, which can interrupt the machine’s operating cycle if the light or electric field is broken. This prevents the machine from starting up again until the field is restored, which improves safety for workers who might otherwise be exposed to risks such as moving parts or flying debris. These devices have been shown to reduce the incidence of serious accidents and injuries, making them an important part of any safety program.
Several types of presence-sensing devices are available on the market, each with its own advantages and disadvantages. One type of device uses an infrared beam to detect the presence of a person or object in the path of the beam. These devices are often used in doorways or other areas where there is a danger of someone being struck by a moving object. Another device uses radiofrequency waves to detect the presence of people or objects. These devices are often used in areas with a danger of electrocution, such as near electrical panels or wet environments.
- Photoelectric presence-sensing device: When the light beam is broken, either the ram will not start to cycle, or, if the cycle has begun, the stopping mechanism will be activated so that the press stops before the operator’s hand can enter the danger zone.
- Electromechanical sensing device: This device has a probe or contact bar which descends to a predetermined distance when the operator initiates the machine cycle. If an obstruction prevents it from descending its full predetermined distance, the control circuit does not actuate the machine cycle.
Pullback Devices
Pullback devices use a series of cables attached to the operator’s hands, wrists, and/or arms. This type of device is primarily used on machines with stroking action. When the slide/ram is up between cycles, the operator is allowed access to the point of operation. When the slide/ram begins to cycle by starting its descent, a mechanical linkage automatically assures the withdrawal of the hands from the point of operation.
Restraint Devices
The restraint (holdout) device in the figure to the right uses cables or straps attached to the operator’s hands at a fixed point. The cables or straps must be adjusted to let the operator’s hands travel only within a predetermined safe area. No extending or retracting action is required because the hands are never allowed to extend into the danger area. Consequently, hand-feeding tools are often necessary if the operation involves placing material in a dangerous area.
Safety Trip Controls
Safety trip controls provide a quick means for deactivating the machine in an emergency. A pressure-sensitive body bar, when depressed, will deactivate the machine. If the operator or anyone trips, loses balance, or is drawn toward the machine, applying pressure to the bar will stop the operation. The positioning of the bar, therefore, is critical. It must stop the machine before a part of the employee’s body reaches the dangerous area.
Unfortunately, it may be easy to defeat the body bar by going under it into the danger zone. The figure here shows a pressure-sensitive body bar on the front of a rubber mill.
Two-Hand Control Devices
The two-hand control device requires constant, concurrent pressure by the operator to activate the machine. This kind of control requires a part- revolution clutch, brake, and a brake monitor if used on a power press. With this type of device, the operator’s hands must be at a safe location (on control buttons) and at a safe distance from the danger area while the machine completes its closing cycle.
Two-Hand Trip Devices
The two-hand trip device requires concurrent application of the operator’s control buttons to activate the machine cycle, after which the hands are free. This device requires the joint operation of two trigger buttons located away from the “danger zone” of the press. To be effective, both two-hand controls and trips must be located so that the operator cannot use two hands or one hand and another part of his/her body to trip the machine.
