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What Will Revised ANSI Standards Mean to You?

By: James G. Barrett Jr.

James G. Barrett Jr. is president of Link Systems, Nashville, TN: tel. 615/833-4168;www.linkelectric.com.

Thursday, May 01, 2008
 
 
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The ANSI B11.1 standards revision, to be published in 2008, brings significant changes to the mechanical-power-press standards in previous versions as well as major additions not covered in past standards. The drivers of these changes are:
Revised voluntary ANSI B11.1-2008 standards for mechanical-power presses will be published in 2008

• Increasingly complex production systems;

• Standards harmonization;

• New pressroom technology;

• Increased emphasis relative to previous standards to address safety for the entire press system;

• The need for perimeter and area safeguarding standards for single- and multiple-press automated production systems, including tandem and transfer presses.

Driven By Complex Production Systems

The first press standards were published in 1922, when manual press operations ruled. Many revised ANSI standards editions have been published since the 1922 standards. These include the ANSI B11.1-1971 standards used as the source standards for OSHA’S CFR 29 1910.217 mechanical-press standards and the current ANSI B11.1-2001 standards.

The primary safeguarding emphasis of previous standards was directed toward point-of-operation injuries, although some other areas were covered. Previous standards tended to be very prescriptive, i.e., the writing committee generally identified specific hazards and gave a variety of methods in the design and construction and safeguarding sections to reduce the hazards.

Today, so many possible variations of press systems exist that the earlier approach of standards committees to identify and address solutions for all hazards no longer is practical. The proposed ANSI B11.1-2008 standards will provide increased prescriptive elements, but also will integrate requirements for risk assessment and risk reduction throughout the standards. It will require press users to identify and abate unique risks created by the many possible permutations and combinations of press-production machinery and auxiliary equipment.

For example, where previous standards for part-revolution presses addressed a “red color stop control” (emergency stop) for each operator station, the presumptive new standard calls for stop functions where “specified in other clauses of the standard” and “additional stop functions…based on risk assessment of a specific press-production system.”

More in Tune with International, NFPA Standards

In the past, ANSI standards gave little consideration to International Electrotechnical Commission (IEC) standards applying across European countries, and to International Standards Organization (ISO) standards, instead focusing on continued independent development of U.S. standards. A push for harmonization of U.S. standards with IEC and ISO standards began within the past two decades, led primarily by automotive and other multinational manufacturers and industrial-equipment suppliers.

The obvious benefit to companies and suppliers with multinational locations and sales areas: one common set of standards to comply with throughout their plants regardless of geographic location, and equipment constructed and safeguarded to similar standards at all locations. Regulatory harmony is a cost saver.

But obstacles remain to complete harmonization. These include:

• Diverse nature of standards authorities/writing organizations;

• Different legacy formats and rules for standards writing;

• Different legal systems in different countries.

While U.S. standards harmonize with some of the electrical, construction and safeguarding standards requirements for industrial machinery with IEC and Canadian standards, we are many years a—if ever—from complete harmonization.

Perhaps the greatest harmony between IEC and U.S. standards exists between NFPA 79 Electrical Standard for Industrial Machinery and IEC 60204, a similar European standard. NFPA 79 has many electrical standards applying generically to industrial machinery that are not contained in the B11.1 mechanical-power-press standards. In past years, some standards in NFPA 79 and B11.1 overlapped and conflicted due to NFPA harmonization with IEC 60204.

The presumptive B11.1-2008 standards will remove conflicts with NFPA 79 and, therefore, some conflicts with IEC standards, by harmonizing with overlapping NFPA 79 requirements. Examples include:

• Synchronous operation of individual two-hand controls within 0.5 sec. rather than as concurrent operations;

• Language concerning stop functions, stop circuits and stop actuators is added to the presumptive B11.1-2008 standards to agree with NFPA 79.

New Standards for Servo Presses, Press Systems and Perimeter Guarding

The introduction of direct-drive servo presses until now has represented a category of equipment that existing standards did not address. All previous versions of B11.1 have covered only full-revolution and part-revolution-clutch mechanical-power presses.

The presumptive B11.1-2008 standards now have design and construction requirements that address the new drive system and unique modes of operation possible with servo-motor-driven mechanical presses.

Also, previous ANSI B11.1 standards have tended to address hazards associated with the press and dies while neglecting hazards associated with an increasing array of ancillary and auxiliary press-system equipment. The 2008 B11.1 standards add safety requirements for “hazards associated with press-production systems other than (press) point-of-operation hazards,” including feeding, transfer, conveyer and other equipment and items.

Where previous B11.1 standards have addressed guards and devices for safeguarding each individual press point-of-operation, this often is not possible for automatic press systems using single or multiple presses, robots, feeding or transfer equipment, moving bolsters, and automatic part- and scrap-removal equipment. For years, coil-fed presses, tandem presses with blank and part transfer, and transfer presses have used perimeter guarding to protect individuals from multiple points of operation and coil- and blank-feeding equipment. The presumptive B11.1-2008 standards include requirements for perimeter and area safeguarding of multiple press-system hazards.

Safety Products

General Electrical Standards Expanded

General electrical requirements in the presumptive B11.1-2008 standards have been expanded and changed by bringing in many NFPA 79 electrical requirements.

Stop Functions

Stop-function categories in agreement with NFPA 79 and IEC 60204 are brought into the standards:

• A category 0 stop shall initiate an uncontrolled stop by immediately removing power from the actuator(s).

• A category 1 stop shall immediately initiate a controlled stop with power available to the actuator(s) to achieve the stop, then removal of power to the actuator(s) after stopping.

• A category 2 stop shall initiate a controlled stop with power left available to the actuator(s).

• Category 0 and category 1 stops shall be operational regardless of mode of operation.

 

 
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See also: Link Systems

Related Enterprise Zones: Presses


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