Addressing safety and noise issues

Aug. 1, 2007
Safety first. Much of modern machine life revolves around these two words. Protection of life and limb not to mention expensive equipment is top of mind

Safety first. Much of modern machine life revolves around these two words. Protection of life and limb — not to mention expensive equipment — is top of mind for design engineers and end users alike. Consider the following expert tips and tools for addressing safety and ergonomic issues that impact machines and the people who attend them.

Open safety protocol

Ethernet Powerlink (EPL) Safety Technology makes it possible for all open and available safety-oriented mechanisms to be implemented and accounted for in the data transfer process, so that safety-relevant information can be transmitted over a standard fieldbus. What's more, it doesn't require special cables because safety functions are integrated into the control system.

B&R Industrial Automation Corp.

Machine safety sensors brochure

This 12-page brochure includes several non-contact sensors and control units for industrial machine safety. Among the new products are a control unit for small machines with two separate safety circuits for a sensor and an emergency stop, and a control unit with two safety outputs and two sensor inputs. All products meet international safety standards.

Elobau Sensor Technology Inc.

Return idler guard

The lightweight Safe-Guard Return Idler Guard prevents injuries from pinch points and catches the return idler if it falls. Installing the guard on almost any conveyor belt helps protect workers from the hazard of contacting exposed elements. The durable UHMW slotted cage prevents material build-up and is easy to clean.

ASGCO Manufacturing Inc.

Quiet cable carriers

System E6 Energy Chain cable carriers move quietly and with little vibration thanks to abrasion-resistant connector strips and a short link pitch. With its modular design, these carriers can be shortened or lengthened at any time and offer easy snap-open cable access. System E6 is ideal for clean room applications as well as general manufacturing.

igus Inc.

Safe camera system

SafetyEYE, a camera system for 3-D safety monitoring, helps ensure operator safety by placing a customized, 3-D protective “cocoon” around a machine danger zone. It protects, controls, and monitors with detection zones that can be quickly and flexibly configured on a PC. The system includes a sensing device with three cameras, high-performance computer, and programmable safety and control system.

Pilz Automation Safety L.P.
(Developed with DaimlerChrysler)

Quiet stepper motors

SST43D NEMA 17 stepper motors provide 30% more torque than their predecessors and 3 to 6 dB lower audible noise than motors with comparable torque. Electrical frequency noise is lower as well. Motors are RoHS-compliant, available in D1 and D2 heights, and come standard with an integrated connector or, as an option, lead wires.

Shinano Kenshi Corp.

Safety-related position encoders

ExN 425/437 series and ExN 1325/1337 series rotary encoders for electrical drives are designed for safety-related applications and comply with ISO 13 849-1 (SIL 2) and IEC 61 508 (performance level d). The encoders include an EnDat 2.2 transmission component (a digital, bi-directional interface) in order to be part of a safe drive.

Heidenhain Corp.

Safe servo drives

Allen-Bradley Kinetix 6000 Safety servo drives with GuardMotion incorporate a safe-off functionality that lets users restart machines faster when unscheduled maintenance is required. Instead of disconnecting power at the drive, the safe-off feature immediately eliminates torque at the motor. This shuts the machine down safely, but keeps power on, enabling the machine to restart 20% faster than in power-off situations.

Rockwell Automation

DBO ✓ list

  • Design with safety in mind from the beginning

  • Follow a systematic risk assessment process in all phases of design and implementation

  • Understand how workers use equipment to do their jobs

  • Make sure safety devices are conveniently located and easy to use

  • Place safety curtains where they won't be accidentally triggered

  • Keep lockout locations close to controllers

  • Be certain that safety switches are easy to activate

  • Consider placing safety functions in the drive for autonomous monitoring and quick reaction times

  • Think about safeguarding equipment with physical guards as well as control products such as light curtains, laser area scanners, pressure-sensitive mats, safety relays, cable pull switches, interlock switches, safety gate switches, and non-contact switches

  • Consider system diagnostics that warn workers before catastrophic events occur or substandard parts are produced, which could lead to injury, death, or expensive safety recalls

  • Diagnostics are especially suited for critical machinery — equipment that has an effect on workers, the environment, or production

  • Consider permanently installed diagnostic systems, such as programmable automation controllers that can be used to predict failure and generate machine health reports

  • Collect machine health data and specify components that can autocorrect machine problems where possible

  • Get familiar with national and international safety standards, such as: IEC 61508, 61511, 62061; EN 954-1 and 1088; ANSI B11.20 and ANSI/RIA R15.06; and the RoHS directive regarding hazardous substances in electrical and electronic equipment

  • Keep an eye out for the new IEC 61800-5-2 standard covering safe position, direction, torque, speed, off, and hold (motion and safety)

  • Think of machine safety features as a competitive advantage

  • Read up on OSHA 1910.95, which addresses workplace noise exposure

  • Consider specialty lubricants such as damping greases to reduce noise and control motion

  • Think about placing a resilient material between gear drive and mounting base to reduce noise

  • Sound barriers with absorbing panels can protect workers from directional airborne noise

  • With large machinery emitting sound all around, consider complete and airtight enclosure, but don't forget about heat dissipation

  • Shaft misalignment at input and output points can cause noise within a speed reducer

  • Coupling wear may cause poor torque transmission and gearbox noise

  • Failed bearings are another probable noise source

  • Sometimes noise is silent ? it comes from electrical signals that cause electromagnetic interference (EMI)

  • With encoder signals, EMI can translate into detrimental noise, miscounts, and positional errors; keep a “twin” for every data line to iterate signals

  • Consider woven metal shielding to protect cables from electrostatic interference

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