An upgrade project for a platform lift used in a materials handling installation had its old mechanical limit switches swapped-out for 2-Wire inductive sensors to verify that loads are properly positioned before allowing the lift to move.

CUSTOMER APPLICATION

Cartons or pallets stacked on a lift platform in the down position may become unstable when the lift position changes. Also, if a load has any protruding parts, they may snag the edge of a floor as the lift rises or descends. This causes tipping, which can result in damage to both the load and the installation, with a risk of injury to persons nearby.

A metal bar is fitted on the lift to ensure the correct load position. Unless this bar has been pivoted into its cradle, the lift will not start. Also, any subsequent movement of the safety bar caused by an unstable load will stop the platform. Generally, this is a very simple electrical scheme with only AC power available on site.

Mechanical limit switches were proving to be unreliable because the frequent switching was wearing out the mechanical contacts, whilst dust and moisture also adversely affected reliability. The customer therefore wanted an equally simple, non-contact solution.

CUSTOMER SOLUTION

A Contrinex inductive sensor from it’s 600 Series family fulfils the customer’s requirements. To verify that the bar has cleared the load and lodged in the cradle, a 2-wire AC/DC sensor with a 4 mm operating distance is embedded in the cradle itself. The sub-flush mounting position protects the sensing face from any mechanical contact.

With a wide voltage range and short-circuit protection, these sensors also meet the customer’s on-site electrical requirements. Since the safety bar can become deformed with prolonged use, a sensor is chosen with an increased operating distance. This allows compensation for gradual target drift by simple range adjustment, rather than by repositioning the sensor itself.

The sensor closes an enabling circuit for the start button, which in turn latches a relay controlling the lift motor. Any movement of the safety bar caused by an unstable load will open the circuit and unlatch the relay, stopping unsafe movement of the platform.

PRODUCT ADVANTAGES

  • Best-in-class sensing range
  • High-performance detection
  • No readjustment over time
  • No wear and tear and relatively tamper-proof
  • Fast & easy setup and adjustment
  • No maintenance
  • Long-term reliability
  • On-board LED indicator
  • Excellent temperature stability & temperature-resistant
  • Exceptional price/performance ratio
  • Large choice of cables and accessories

Click to download Contrinex’s Product Overview brochure to find out more.

Call PLUS Automation on 0121 58 222 58 or email Sales@PLUSAutomation.co.uk to discuss how they can help you #MakeSenseofSensors using Inductive, Machine Safety, Photoelectric, Pressure, Process, RFID & Ultrasonic sensors from Contrinex, ReeR & Satron.

With over 2,000 sensors in UK stock, supported by stock held in Europe and short manufacturing lead times, they’d welcome the opportunity to talk about improving automation and machine performance, or how to reduce costs.