From time to time, I and other engineers here at Warren are asked to evaluate a case involving an injury that has been caused by machinery designed to produce or fill packaging. The hazards associated with packaging machinery are often similar to other commonly-used industrial machinery, but packaging machinery has its own voluntary consensus standard for machine safety.
The standard is ANSI/PMMI B155.1, titled “Standard for Packaging Machinery and Packaging-Related Converting Machinery – Safety Requirements for Construction, Care and Use”. The ANSI B155.1 standard was created in 1972 and has been revised regularly over the years, including in 2016.
According to its scope statement, ANSI B155.1 applies only to:
Apparatus which is used to:
– Produce, decorate, identify, fill, weigh, inspect, close or seal a container;
– Prepare packaging materials with decoration or identity, and/or with coating that impart mechanical functions or protective characteristics; or
– Convey and/or coordinate the packaging functions which must take place in sequence on the production line.
The standard specifically excludes plastic molding machinery, glass container manufacturing machinery and non-packaging-related converting machinery.
Like more familiar safety standards including ANSI B11.0 and ISO 14121, ANSI B155.1 requires designers, manufacturers, rebuilders and modifiers of packaging machinery to identify the hazards and assess the risks of their machines, and to document their risk assessment. The relevant section reads as follows:
It shall be the responsibility of the manufacturer or of any person reconstructing or modifying packaging or packaging-related machinery to design and construct the machinery in accordance with the following design guidelines.
In selecting the most appropriate design, the designer shall apply the following principles:
a. Eliminate machinery hazards or reduce the associated risks as far as practical by eliminating dangerous parts and conditions.
b. To the extent dangerous parts and conditions cannot practically be eliminated, eliminate the hazard or reduce the associated risks by appropriate safeguarding…
In a case I analyzed a few years ago, a worker was injured by a heat sealing machine that had been modified. The modifier of the machine did not properly assess the risks associated with his modification and caused the machine to be improperly safeguarded and to function improperly. Two views of the heat sealer are shown in Figures 1 and 2 below.
A worker activated the heat sealer while another had her hand inside the machine. She received a severe burn.
Notice the “Danger” label in Figure 1. Not all of the label is visible. The machine manufacturer would have applied a warning sticker that fit properly in its designated location. A picture of the heat sealer from its manufacturer’s website shows the two “Danger” stickers intact, the clear plastic guards the same length and a smaller opening below the guard. I concluded that the guard on the left in Figure 2, where the employee’s hand entered the machine, was trimmed after the machine was manufactured. A guard that will allow a worker’s hand into the jaws of the heat sealer is an improper safeguard. The machine modifier violated ANSI B155.1 Section 4.1 by trimming the guard.
To make matters worse, the foot operated pedal that activated the heat sealer was improperly connected so that releasing the pedal would not cause the heat sealing jaws to release. The jaws would only release when a timer ran out. This modification was probably done to prevent workers from inadvertently “short-cycling” the heat sealer. When the employee’s hand was caught, she could not release the jaws by releasing the pedal. Her hand was trapped in the hot jaws until the timer ran out, increasing the severity of her injury.
Videos of the heat sealer in operation published by the manufacturer show workers holding down the activation pedal until the timer releases the jaws. The day after the injury, the operation of the foot pedal was changed so that the jaws would open if the foot pedal was released before the timer ran out. The foot pedal modification increased the severity of the worker’s injury, but was not the cause of the injury. If the guard had never been trimmed, the workers hand would not have been able to enter the hazard zone and be injured, and the foot pedal modification would have been reasonably safe.
If the modifier of the heat sealer had properly identified the hazards and assessed the risks of the machine, he would have found that the risk of injury associated with a heat sealer that will admit a worker’s hand and clamp down on and burn the worker’s hand with no way to release the jaws before the timer runs out is high and is not tolerable. The modifier of the heat sealer should not have allowed the machine to be operated in that condition. By enlarging the guard opening so that a workers hand could enter the modifier created a condition of defect in the heat sealer and made the machine unreasonably dangerous. Modifiers of machines have a responsibility to take reasonably prudent steps to ensure the machine modifications they make are reasonably safe. The modifier of this heat sealer failed to act in a reasonably prudent manner when he trimmed the guard and rewired the foot pedal.
Aron Olson, PE, holds a Bachelor of Science Degree in Mechanical Engineering from The University of South Carolina and a Bachelor of Science Degree in Packaging Science from Clemson University. His areas of emphasis are machine safeguarding, machinery analysis and three dimensional imaging. Aron has over six years’ experience as a product designer in the gas turbine and medical device industries. This experience includes implementing safety features such as lock out/tag out features and interlock devices into manufacturing machinery. Aron is experienced with collecting and processing three dimension images of machinery, building interiors and exteriors including structural collapse scenes, fire scenes, vehicles and other scenes and objects related to the forensic analysis of personal injury and property claims. A skilled user of SolidWorks and other computer aided design software, he brings his insight into the design process to the world of forensic engineering.