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 August 13, 1999 Ms. Connie Munschy Re: Proposed Amendment to General Industry Safety Standard Part 62. Plastic Molding; R 408.16234 - Injection Molding Machinery Dear Ms. Munschy: The Society of the Plastics Industry, Inc. (SPI) appreciates the opportunity to comment on the proposed amendment to rule R 408.16234 of the Michigan Department of Consumer and Industry Services Safety Standards Division (MIOSHA) General Industry Safety Standard Part 62, Plastic Molding. SPI is the trade association representing the fourth-largest manufacturing industry in the United States. SPI's 2,000 members represent the entire plastics industry supply chain, including processors, machinery and equipment manufacturers, and raw material suppliers. The U.S. plastics industry employs 1.3 million workers and provides $274 billion in annual shipments. SPI represents the interests of approximately 900 establishments in the state of Michigan that employ more than 61,000 workers and produce nearly $9 billion in annual shipments of plastics products. Founded in 1937, SPI is the voice of the plastics industry. A number of SPI member companies have plastic molding operations in Michigan and are subject to Part 62 regulations. In conjunction with Michigan molders, SPI has taken an active role in the discussions prompting MIOSHA to propose the amendment at issue here. SPI supports the proposed amendment, recommends some changes to the wording of the proposed rule, and applauds MIOSHA's efforts to develop a regulatory plan that is highly protective of employee safety and health while addressing outdated practices with new technology, equipment, materials, and processes. By adopting this progressive approach toward occupational safety and health regulation, MIOSHA moves one step closer to achieving the goal of forging a workable partnership among government, employer, and employee interests. As described below, the proposed amendment will be equally protective of worker safety as are the current regulations, and will enhance worker safety while permitting efficient business operation. A. Background 1. Machine Operation Horizontal Injection Molding Machines (HIMMs) convert solid thermoplastic plastic resin (or compound) pellets into a variety of molded plastic products by heating them into molten plastic and then injecting them into a closed mold under high pressure. A typical mold opens and closes (cycles) an average of four times per minute to eject each newly molded product. In the 25 years since Michigan promulgated Part 62, these machines have grown increasingly sophisticated, particularly in the area of control systems. The mold section of a HIMM is guarded by a barrier guard with interlocked gates on the front and rear of the machine. For an operator to gain access to the mold area, the "operator's gate" (front side) or the "rear guard" must be opened. Operators Gate: Opening the operator's gate on a HIMM that satisfies the design requirements of 6234(10) (a "covered HIMM") activates three redundant safety systems – an electrical interlock, a hydraulic or a redundant electrical interlock, and a functional mechanical safety device. All three of these safety systems prevent the open mold from closing. A significant number of HIMMs require the operator to reach into the open mold between cycles to remove the molded product; other machines may be fully automated. The interlocked operator's gate protects the worker removing the product by preventing the mold from closing between cycles. Rear Guard: Opening the rear guard on such machines activates two redundant safety systems. These interlocks separately interrupt the control circuit and the power circuit to prevent all HIMM movements if the guard is open or removed, thus preventing the open mold from closing. Machines produced prior to 1990 may not have a second rear guard interlock. Option (B) of the proposed amendment may not be used on machines without two rear guard interlocks. 2. Mold Changes The molds, which define the shape of each product, may be changed as often as several times each day on a single machine. The same safety systems described above, which protect workers during production, are also effective during the adjustment/positioning steps of each mold change. B. Adequacy of Interlock Safety Systems on HIMMs 1. Protection Against Unexpected Energization As noted, the safety systems that protect workers who access the mold area on a HIMM which incorporates three redundant interlocks on the operator's gate and two redundant interlocks on the rear guard consist of the following: (i) an electrical interlock on both the operator's gate and the rear guard, (ii) a hydraulic or a redundant electrical interlock on the operator's gate, (iii) a redundant electrical or hydraulic interlock on the rear guard, and (iv) a functional mechanical safety device that activates when the operator's gate is opened. These interlocks are activated when either the operator's gate or rear guard is opened and prevent the machine (mold) from closing. Collectively, these design elements, when used in conjunction with a requirement for shutting off the machine's motors, eliminate the potential for unexpected energization or release of stored energy during mold changes. Therefore, the workers performing mold changes are effectively protected without de-energizing and locking out the entire machine. 2. The Proposed Amendment Provides Effective Protection In applying occupational safety and health regulations, a standard is satisfied or deemed inapplicable when there is no worker exposure to the regulated hazard. This guiding principle should be employed when determining the propriety of the existing standard and whether the proposed amendment is equally protective of employee safety and health. SPI believes the safety systems described above eliminate the potential for unexpected energization or release of stored energy and are at least as effective as traditional lockout/tagout procedures. Furthermore, the MIOSHA proposal would also encourage companies to more promptly adopt safety features found in the most recent version of ANSI B151.1-1997, which includes the addition of safety enhancements to older machines. C. Proposed Language Change While the proposed
amendment would establish a practical and effective standard, a few clarifying
changes are needed to further enhance the overall effectiveness of the
regulation by making it more clear and precise. We propose that section
10 of Rule 6234 in R 408.16234 be changed to read as follows (underline
indicates addition and (10) ROUTINE MOLD
CHANGES ON A HORIZONTAL INJECTION MOLDING MACHINE MAY BE CONDUCTED IN
ACCORDANCE WITH (A) OR (B) BELOW IF THE MACHINE HAS AN INTERLOCKED (A) ON A HORIZONTAL
INJECTION MOLDING MACHINE WHICH HAS A FUNCTIONAL MECHANICAL SAFETY DEVICE
PLUS TWO INDEPENDENT INTERLOCKS ON THE OPERATOR'S GATE AND AN EMERGENCY
OR OTHER STOP WHICH SHUTS OFF THE (B) ON A HORIZONTAL
INJECTION MOLDING MACHINE WHICH HAS TWO INDEPENDENT INTERLOCKS ON THE
REAR D. Conclusion For the foregoing reasons, SPI believes the proposed amendment, when slightly modified, represents an acceptable alternative approach to safe mold change on a horizontal injection molding machine. The amendment recognizes the effectiveness of new technology, equipment, materials and processes that have resulted in these interlock safety systems and provide a degree of protection at least equal to that of traditional lockout/tagout. We applaud this progressive approach to occupational safety and health regulations and support MIOSHA efforts to see that the proposed amendment is adopted. Again, SPI appreciates the opportunity to comment on this amendment. If you have any questions regarding these comments, please do not hesitate to contact us. Sincerely, Lewis R. Freeman,
Jr. More
Public Policy: Environment
. Worker Safety . Transportation
. Codes and Standards . Food,
Drug,and Cosmetic Packaging . International
Trade
. Other Issues
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 © Copyright 2003 The Society of the Plastics Industry.
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