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From: Food Quality & Safety magazine, December/January 2005

Incorporating Safety Into Plant Expansions

Safety and zone control can enhance worker safety and ethic.

by Grant Noble

Completing a facility expansion in this day and age should involve more than simply ordering new machines and increasing the number of orders placed with suppliers. In today’s manufacturing environment, facility expansion plans also should include a careful evaluation of production methodologies, including a thorough analysis of safety processes and procedures.

In recent years, machine safety has become a key factor that will not only improve worker satisfaction, but also improve productivity. After all, even if your plant consistently produces a great product, how productive can your facility really be if your workers are afraid of getting too close to a particular machine or work area? If your plant is unsafe and experiences lost-time accidents (LTAs), how much money are you losing on insurance and worker-compensation claims? For these reasons – and many others – safety considerations should play a big role in the expansion plans of any facility.

American manufacturers must pay careful attention to this, because when it comes to machine safety, the burden to assure safety is on the user – not the machine builder. The federal Occupational Safety and Health Administration (OSHA) requires employers to provide workers with a safe and healthy work environment, including the use of new and existing machines on the plant floor. If it’s not done right the first time, you’ll likely need to retrofit machines in the future to make them safer – costing you even more in terms of machine parts and production downtime. In a worst-case scenario, inadequate levels of machine safety could result in a catastrophic accident – one that might’ve been prevented with proper advance planning.

Where to Start

Before beginning any expansion, it’s important to start with a risk assessment conducted by a qualified safety engineer. A risk assessment can help you identify the interactions between humans and machines that may pose a danger – either during a machine malfunction or during normal operations. Such assessments provide an analysis of the potential dangers workers might encounter and help identify where safety improvements can be made.

Higher-complexity machines are cause for greater safety concerns, because they often have more pinch points that can “grab” an employee and cause injury. For example, robotic machines used to prepare ready-to-eat meals can be some of the more dangerous types of machines to operate because they are made to move quickly and repetitively; potentially causing serious injury if a worker steps into their path.

Food manufacturers must work with machine builders to design safety into all their machines – from relatively simple devices to highly complex systems – to ensure they provide sufficient worker safety. Successful machine designs should require employees to take proper precautions such as shutting down the machine before they are allowed access to dangerous parts. A risk assessment will identify how a machine might harm employees, while also pinpointing recommendations for improvement.

Making a Plant Safe

A growing number of food manufacturers are turning to a concept known as “zone control” as another tool for ensuring worker safety. Employing zone control as a safety practice can help manufacturers create safe areas that allow a portion of the production line to slow or stop while the rest of the line remains active. Whether a minor malfunction, an obstruction or a pause in production, it can pose a safety hazard that can be handled without taking an entire line down. Because it enables production to quickly return to normal levels, zone control can help promote safety while also ensuring the productivity of the plant.

Zone Control Measures and Safety Steps

Manufacturers often can add zone control to the facility’s planning process by implementing safety programmable logic controllers (PLCs) throughout a control system. Safety PLCs represent a new step in the evolution of safety controls. Using safety PLCs, operators can program machines specifically with safety in mind – adding steps that enable zone control throughout a manufacturing line or process. Under current standards, safety PLCs are now permitted -control of safety circuits with regular PLCs is not.

Other products that can increase safety outside of the Safety PLC include special safety mats, which shut down a machine when a worker stands on the device, and interlock switches, which shut down a machine if a gate or door is open.

While food manufacturers are required to create a safe working environment in order to meet OHSA and other government regulations, the benefits of a safe facility go well beyond regulatory compliance issues.

Safe working environments are productive working environments. Employees who can operate a machine without fear of being harmed will have higher job satisfaction, and will be more motivated to help the company achieve its goals.

Whether it’s a design engineer building a machine, a plant manager overseeing operations or an employee operating a machine, it’s every worker’s responsibility – and every worker’s right – to work in a safe environment.

Grant Noble is machine safety consultant for Rockwell Automation. Reach him at 440-646-4638 or



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