ANSI/PLASTICS B151.31-2014 (R2020): Blow Molding Machines

Do you know how plastic water bottles are created? Well, since the 1970s, stretch blow molding has been used for creating preforms of plastic bottles that are either sold to bottling companies or used to manufacture a bottle. Specifically, small pellets of plastic resin are pushed into an extruder and melted, and then they are injected into a steel mold that shapes them into plastic tubes. By injecting air into this heated preform, the bottle shape is formed from the blow molding machine into the desired mold shape. ANSI/PLASTICS B151.31-2014 (R2020): Safety Requirements For The Manufacture And Use Of Blow Molding Machines covers safety requirements for blow molding machines that process plastic materials.

The Blow Molding Machines in ANSI/PLASTICS B151.31-2014 (R2020)

1. Extrusion blow molding machines
2. Injection stretch blow molding machines
3. Injection blow molding machines
4. Reheat & blow molding machines

ANSI/PLASTICS B151.31-2014 (R2020) applies to the manufacture and use of all Blow Molding Machines (BMMs) that process plastic materials to:

• Blow a parison (i.e., a semi-molten hollow plastic tube from which an article is blow molded).
• Blow a preform (i.e., the injection molded part that is formed in the first stage of a multi-stage injection blow or injection stretch blow molding process). This includes injection blow, injection stretch blow, and reheat & blow into the shape of a mold cavity held together by a vertically or horizontally acting clamp(s).

This American National Standard is considered a “type-C” standard (more on the ABC structure for machinery safety standards), since it deals with detailed safety requirements for a particular machine or group of machines. It details an in-depth lists of all recognized hazards associated with BMMS, such as impact hazards due to barrel over-pressurization, entanglement hazards due to drive and motor of the machine, burn hazards caused by electrical systems, and much more. ANSI/PLASTICS B151.31-2014 (R2020) provides risk assessment reduction measures (e.g., applying fixed and movable guards) where all these hazards exist. It specifies that BMM suppliers and users shall use the risk assessment process in the manufacture, care, and use of the machinery.  

Safety requirements for the manufacture or use of ancillary equipment for BMMs are not covered by this standard.  

Blow Molding vs Injection Moldering

While “blow molding” and “injection molding” are similar and play a crucial part in manufacturing reusable and disposable plastic parts that are used worldwide in the research and biomedical fields and in medical diagnostic laboratories, they are not necessarily the same. Both blow molding and injection molding involve the use of liquid material—typically plastic—that is forced into a mold cavity. The difference is that blow molding is used to create hollow objects like bottles and beakers; whereas, injection molding is used to create solid objects like plates and disc or to produce solid parts or pieces for plastic products.

ANSI/PLASTICS B151.31-2014 (R2020) reaffirms the 2014 revision of the standard, which was a merger of two prior American National Standards, ANSI/SPI B151.15-2003: Extrusion Blow Molding Machines – Safety Requirements for Manufacture, Care, and Use and ANSI/SPI B151.21-2003: Injection Blow Molding Machines – Safety Requirements for Manufacture, Care, and Use. These two standards were merged, revised, and re-designated in 2014 as ANSI/SPI B151.31- 2014: Safety Requirements for the Manufacture and Use of Blow Molding Machines. They were revised and merged for the following reasons:

1. The scope needed to be expanded and the title modified
2. Some illustrations required modification to conform to the text and some illustrations were deleted to permit design freedom
3. Additional definitions were required
4. Some paragraphs required modification and some paragraphs were added to conform more closely with changes in technology
5. Some paragraphs required modification for clarity and intent

ANSI/PLASTICS B151.31-2014 (R2020): Safety Requirements For The Manufacture And Use Of Blow Molding Machines is available on the ANSI Webstore.

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