Functional Safety

The traditional and age-old view on safety design was that it was a necessary but cumbersome component of the design process.  The expectation of the safety function was the protection of operators and it was a given that a reduction in productivity levels of a machine/concept would resulted.  A more current view and thought is that by using technology and appropriate design concepts that the safety design process yields an increase in productivity and other measurable Key Performance Indices (KPI).  It has been proven that the safety process can yield the traditional operator safety and also be a tool/process to increase machine productivity.    Safety can have a positive ROI that can be measured thru KPI.

Today functional safety commonly yields a production increases by two methods.

• Use of a programable Safety PLC with use of Technology as Safe Speed, Safe Direction, Safe Position and parameter scanners that can establish multiple safe “zones”. The additional benefit of having the safety function done on a programable Safety PLC level is that the various states of the safety system can be entered into the general fault, machine state/sensor status and data logging functions.  The state of safety devices can be correlated with other conditions. By knowing the specific safety event the machine “shutdown” and restart sequences can be finely adjusted to reflect the exact demands that the “safety event” places upon the machine.   This is the “hardware” side of functional safety.
• Management Information, The soft side of functional safety.   When the recorded states of safety devices are examined along with the traditional machine sequence steps it will yield documented insights into what is happening and how to take corrective action.  How is that operator on second shift, D Crew differ from the operator on first shift A Crew?

When explicitly contracted, Control and Automation Inc provides the service of risk and hazard assessment for a specific machine. This work is done jointly with the user and mechanical design teams to identify the specific risks and the extent of potential harm.

The result will be a document that recommend and lists costs to reduce operator risk and hazards for the specific machine that we work with for our customers.  Machinery and systems often have inherent situations that present risk and hazards.  CAI will review the risks/hazards using the applicable standards, guidelines and best practices for each situation.  Following established methods, the risk/hazards are parameterized and classified.   Protective and corrective guarding, equipment, procedures and training are outlined to mitigate the defined risks and hazards for the protection of users for each condition is addressed.  Owner input and participation will be required.

1. Risk and Hazard Assessment, Identify Problems Identification of Hazards and operational risks are listed.  These would be things like pinch and crush points, entanglement, ejected hot metal chips (skin burns), exposure to caustic/alkaline solutions, exposure to arc/laser welding lights, trip and fall hazards, radiation etc.
2. Determine the Functional Requirements, Assessment
3. Design of intervention devices and verification that design generated addresses each identified hazard
4. Installation and Validation.
5. Maintain and Improve, Respond to the collected data and any incident reports

Steps 1-4 are often part of the machine building scope of work.  Step 5 and subsequent passes thru steps 1-4 are ongoing and are a separate segment of work, usually done by customer as long as machine is functionally being used.  As machine functions change over time the owner/customer is responsible to repeat all steps of the process or secure a vendor who does.

Disclaimer: The above is not intended to be a detail statement on a specific safety study that CAI has done, but rather to give the reader an indication of breadth and depth of  work scopes that CAI staff can work with for the industrial control of machinery.