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Making light work of machine safety

22 September 2017

Light curtains have long been an attractive option for automation systems integrators needing safety solutions for operator protection and access control.

Active optoelectronic protective devices (AOPDs) are convenient, unobtrusive and highly reliable, eliminating the need for cumbersome mechanical guarding mechanisms and the associated cycle-time penalties.

Type 4 AOPDs, characterised by fail-safe operation, are mandatory for areas where there is an identified risk of severe injury or death. Type 2 devices, which typically lack the inbuilt redundancy and periodical auto-test features necessary to achieve Type 4 ratings, are designed for use in lower-risk areas.

Hand protection is commonly required for semi-automated processes where parts are loaded manually; here, Type 2 AOPDs with 30mm resolution are ideal. Many first- and second-tier automotive suppliers, under constant pressure to improve production efficiencies and reduce lead-times, invest in AOPD-based access-control systems as a means of increasing productivity and reducing unit costs.

Safety first for automotive trim manufacturers 

Traditionally a labour-intensive sector, automotive-trim production is an increasingly high-tech operation; increased efficiencies derive largely from shorter cycle times and reduced manning levels. Here, the widespread elimination of physical guarding mechanisms, and their replacement with modern access-control systems has played a major part. Lamination and edge-folding are two processes where this approach pays big dividends.

A single operator has responsibility for a cell comprising two or more machines that perform successive operations. Trim finishes range from modern thermoforming plastics to more traditional materials, including cloth and leather. Each cell processes contoured blank formers to become laminated, finished trim assemblies.

The operator loads pre-cut panels of material onto the lower tools of the laminating machine, followed in each case by a former, and then withdraws from the hazardous area. On initiation of the operating cycle, the upper tools descend and apply heat and pressure, creating a permanent joint between the trim material and the former. Once the head returns to the raised position, the operator removes the assembly from the fixture.

Edge-folding follows a similar sequence, initiated once the operator loads the laminated assemblies to the machine. A shaped pre-heating tool is lowered into position immediately adjacent to the perimeter of each assembly; following a suitable dwell period, the pre-heating tool is withdrawn. The assembly descends onto a multi-action forming tool where the heated edges are folded around the rear of the former and clamped in position until the cure is complete.

A balanced cell – one in which the operator loads each machine during the cycle time of the one immediately preceding it – is highly desirable; achieving this outcome is only possible without the use of mechanical safety barriers, which constrain throughput because of the time taken to open and close the guards during each cycle. Light-curtain access control systems provide effective hand protection while allowing unobstructed loading and unloading.

Safetinex Slim from Contrinex fits the bill

Once a risk assessment confirms that Type 2 AOPDs will ensure appropriate operator protection, the choice of devices is straightforward. Designed for applications where the risk has been evaluated as no more than moderate, the new Slim range of Safetinex IEC 61496 Type 2 light curtains from Contrinex are rated to EN/ISO 13849-1 Category 2 and Performance Level PL c, making them ideal for the application.

Safetinex Slim light curtains feature a space-saving profile – only 26 x 26mm – and with no blind zone, thanks to their innovative internal design, they ensure optimum workplace ergonomics. Laminating and edge-forming machines can now be open-fronted, allowing easy operator access. The light curtain has an operating range of up to 8m and a resolution of 30mm, ideal for hand protection; detection heights up to 1610mm are available as standard, ensuring safe operation without impeding the operator during loading and unloading.

Manufactured with rugged aluminium housings and IP65 protection, these units are well-suited to the production environment and will withstand shocks and vibrations. Industry-standard PNP configuration allows connection to the customer’s control system via an integral 5-pin M12 cable connector. The units have a dedicated alignment LED and permanent auto-control – a feature not usually found on Type 2 safety devices.

The new light curtains not only take up much less space than the mechanical guards they replace but are also significantly smaller than the industry-standard 42 x 48mm light curtains, minimising any intrusion into the working area. Loading and unloading is now unimpeded, increasing productivity while actively safeguarding operators. Safetinex Slim Type 2 light curtains, presented at SPS/IPC/Drives, provide a reliable and cost-effective solution.

Customer benefits 

• Cost-effective, active safeguarding

• Excellent workplace ergonomics

• Increased productivity arising from unimpeded loading and unloading

• Industry-standard interface for easy connection to control systems 

Advantages of Safetinex Slim Type 2 light curtains

• Permanent auto-control not usually found on Type 2 safety devices

• Slim profile – only 26 x 26mm

• No blind zone

• IP65 protection

• Non-contact operating principles

Safety certified to EN/ISO 13849-1 Cat. 2 PL c

• AOPD (active optoelectronic protective device) with aluminium housing and M12 cable connector

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