7 safety-rules to guard packaging line workers: effective design and positioning of physical guarding should protect personnel without inhibiting normal operations

Food & Drug Packaging, April, 2002 by Robert Luciano

The concern for safety in operating packaging machinery should be never-ending. Thus, periodic reviews of safety rules and procedures on the packaging floor should be made to ensure worker safety.

Two equally important areas of packaging machinery design, manufacture and operation that need to be considered for overall safety compliance are (1) mechanical and (2) electrical. This article will focus on the mechanical aspects--specifically on the areas of man/machine interface. We'll look at electrical safety in the future.

FIND THE DANGER

Good safety design begins with identifying all specific "'points of operation" that have the potential of causing harm or bodily damage to people who are interacting with the machine. Another common term is "pinch points," which identifies a particular type of point of operation.

Once the potentially hazardous points have been identified, you must either isolate them, guard them or otherwise provide a positive way to prevent harmful human interaction.

One example is a set of power-driven, incoming "nip" rollers, which are common for feeding flexible packaging film. A good way to protect such a mechanism would be to enclose it in a fixed, rigid guard such that it would be impossible for any human member--such as a finger--to intrude far enough to reach the pinch point between the rollers. Access and egress openings would be required for the film to get in and out.

The oldest and still most common safety protection is to construct a mechanical guard around the offending point, so intervention by a human body member becomes impossible. Although the guarding system can be deceptively simple, if the design is not executed correctly, two undesirable results can occur:

(1) The guards could be sized and shaped in such a manner that the opening, itself, becomes a pinch point.

(2) More typically, the openings can be so made that it becomes virtually impossible for the worker to manually feed the film through when setting up. In such cases, it's not unusual for the worker to completely remove the guard or otherwise defeat it, thus, returning the machine to an unsafe, potentially dangerous operation.

DESIGN SAFETY IN

A number of "rules" emerge for good, effective machine guarding design:

1 The primary rule is that the guard must completely prevent the possibility of any human body part from physically interacting with any part of the "point of operation " that has the potential of harming it.

2 Any openings that are required for access of packaging materials must be designed such that they give free, unimpeded access for the materials without the openings, themselves, becoming safety hazards.

3 The guard design must be such that it will allow efficient, normal attendance by the machine attendant(s) without "getting in the way."

4 To prevent the machine from operating unsafely with the guard removed, a suitable interlock (either mechanical or electrical) should be provided so that the machine cannot be run. For access by trained maintenance personnel only, a protected means should be provided to operate the equipment with the guard compromised. Lockout/Tagout procedures should be in place.

5 Ideally, the guard should let operators view and monitor the process to enable efficient setup procedures. Plain or tinted transparent polycarbonate, wire mesh or tempered safety glass panels are acceptable.

6 Permanent warning signs (such as "Danger") should be prominently displayed on the guard or in the immediate vicinity. On the main machine surface, close to the guarded point, should be a permanent sign stating "Do Not Operate This Machine Without Guard in Place."

7 An "Emergency Stop" (E-Stop) button should be located close to the danger point so that a "trapped" or nearby person can quickly stop the machine if an incident does occur. Sometimes, if the machine has multiple danger points, a continuous trip cord, attached to the E-Stop circuit, is strung along the length of the machine.

PERIPHERAL GUARDING

One system of safety guarding that's becoming dominant within the packaging industry involves completely enclosing the packaging machine. Literally, it involves building a self-contained "fence" around the entire periphery of the machine.

This is especially suitable for machines that have multiple potentially hazardous points of operation that would each ordinarily require individual guarding. By correctly designing the peripheral system, the overall safety aspects can be met completely and cost effectively.

Machine guarding must also adhere to U.S. safety standards. Some common points of which are:

* If an opening is big enough for a finger to penetrate, the guard must be far enough away so that the finger cannot reach the danger point.

* If the guard can be reached around so that the danger point can be touched, it is not safe.

* If the guard is fastened to the machine in a way that requires tools to remove that only the trained maintenance personnel would normally carry, it is safe.

* If it is hinged or latched so that no tools are required for its removal and it is not interlocked, it is not safe and will not meet industry standards.